Chassis Set - Up

[LS MAN]

First time I drove Ron's car, a couple weeks ago, it was not very enjoyable to say the least. There is a great canyon road next to Ron's house, but pretty rough, with tar strips across it. I was having trouble just driving the car at normal speed, yet alone aggressively. The car was real twitchy, just going straight, & would almost jump off the pavement on the rough parts. After about 2 miles, I had enough & we turned around & went back to the shop.
1st thing we did was check the front toe in. There is much debate on this pretty simple subject. I have personally driven 4 GTMs - 3 street versions, & the PDG race car. On 3 of them, we have changed the toe from 1/8" toe in to 1/16" toe out. My opinion is this is the best adjustment to make, especially if you are castor limited. There are opinions that this is a really bad idea, but personally it has worked 3 out of 3 for me, including the race car. The race car has run for the last 3 season with this setting. We spent 10 min. making the adjustment, & went right back out for a back to back. Ron couldn't believe the difference this simple adjustment made, you could actually drive the car, but it still was bad over the bumps. My first thought was the front end was over-sprung/under-damped.
We installed the front sway bar kit & went back out. Directional stability & steering response was noticeably better, but the ride quality, especially on this particular road was still not acceptable.
Decided we needed do do more work.

Saturday Ron came over, & this is where we started:


http://vimeo.com/24086671

More to come.

[Martin]

This could become an epic thread if it delivers what I think it will. Can't wait to see this one unfold.

[fact5racer]

agree

[LS MAN]

So we make adjustments to balance the chassis out by using the spring adjusters to raise or lower each spring. The idea is if your ride heights are where you want them, you adjust up & down on each spring adjuster to balance the weight distribution, but not change the ride heights.
A couple notes. - if the spring rate is higher don't adjust as much, whereas if the spring rate is lower, you have to adjust more.
Example - front rate 450# - rear spring rate 550# - you would adjust the rear spring slightly less, & the front spring slightly more. The higher the difference in rate, the more the difference in adjustment.
So -- we raise the LF, by adjusting down against the spring that puts more load on that corner, but also raises the ride height at that corner of the car. We balance that by lowering the RF & LR. That brings the ride height back down to compensate the rise in the LF. But we also need to raise the RR to replace the lost height in the LR, RF. That is the way you can balance out the chassis & keep your ride heights even.

You CANNOT change weight distribution by this method! That is you can't make the front of the car heavier, or the rear lighter. to do that you have to physically move weight around, ie move the battery from the front to the rear etc. When you drive your car alone you are changing the weight distribution , especially to the left. On a race car we would set the car with the driver in the seat & move things like the fuel tank, dry sump tank or ballast to the passenger side to balance the car out.

Also note that I refer to adjusting "down" or "up" on the adjusters. What I mean is "up" means tighten the spring perch adjuster against the spring to raise that corner of the suspension, In actuality that means screw down on the front & Up in the rear. The difference is that the shocks are upside down in the front & right side up in the rear.


http://www.youtube.com/watch?v=uoDpJu-K9JE&feature=autoplay&list=ULdvt6r_1WrS4&index=1&playnext=1



So we now have the chassis balanced out, the sway bar installed, & have adjusted the toe out.
Next we wanted to take a pretty big swing at the chassis set-up.
Richard & Jim lent us the shocks off of the PDG race car to try. Went from the #450 springs & yellow Konis to - putting the #350 front springs on the Bilstein race shocks. & rebalanced the chassis corner weights. We are using the Medium sway bar.


http://www.youtube.com/watch?v=5PrdajsfQjA

Now a little fine adjustment


http://www.youtube.com/watch?v=wI5aCuYc8a8

You can see with the softer spring I should have made a bigger adjustment, Probably a turn & 1/2

Now the fun begins!
I drove it for a loop through the countryside & the changes made a pretty big improvement. The car really settled down & was more stable & way more fun to drive.
Then Ron took it out -


http://www.youtube.com/watch?v=l5WlOmAE9T8

Ron got on the power a little too much & the rear end stepped out about 45 deg, & did 3 big tank slappers - but he did a great job of keeping it out of my neighbors yard.
I have had Gtms this sideways including the race car & believe me you usually will lose the thing & go all the way around backwards, with potentially bad results.
I think we are really going in the right direction, but there is more work to be done.

[GTMKris]

I'm impressed. Where could the normal person go to get something like this done? Nice work LSman

[LS MAN]

http://www.youtube.com/watch?v=aQtJsaX9nvw

[kbentzel]

This is GREAT information. You're going to be a hero to a bunch finished GTM owners who are trying to get the twitch out of these cars. I couldn't tell if you have the bumps steer kit on your car but if you do can you give us a little insight on how you have that set as well? Oh and Ron nice recovery they are tough to bring back once they start to go.
Keith

[VD2021]

Ted,
Outstanding! Very impressive. Keep the info coming. I also sent you an email.

Ron,
Beautiful! You have to post some pics or add them to you current slide show.
.

[IRON MAN]

Have you come accross or found a reason why a GTM might be overly sensitive at high speeds and on the brakes from high speed ? to the point where it feels scarry even just driving in a straight line ... think that is a toe setting ? What do you guys have your rear toe at ?? in or out ? when you toe out the front ?
Thanks !

[Ron565]

Thanks Guys,

First off, before you guys go out and have your chassis set up, lets wait until we dial it out first. There's a lot of factors involved in setting up your chassis.
Originally I had my chassis set to ZO6 specs. I found that the car was very twitchy. Any little bump in the road would potentially send me off in another direction.

All of the suspension settings we have done was in Ted's garage. No fancy 80,000 dollar alignment rack were used. Just old fashioned racing techniques. Ted and I will walk you guys through it step by step. First of all set your ride height. My car is at 4.5 front and 5.0 in the rear. If you have a lot of bad roads or speed bumps in you area set the car a little higher. The biggest factor was the toe setting. It made a big difference, I mean huge difference! More videos to come.

Happy Building, Ron

[Kempo]

Thanks Guys,

First off, before you guys go out and have your chassis set up, lets wait until we dial it out first. There's a lot of factors involved in setting up your chassis.
Originally I had my chassis set to ZO6 specs. I found that the car was very twitchy. Any little bump in the road would potentially send me off in another direction.

All of the suspension settings we have done was in Ted's garage. No fancy 80,000 dollar alignment rack were used. Just old fashioned racing techniques. Ted and I will walk you guys through it step by step. First of all set your ride height. My car is at 4.5 front and 5.0 in the rear. If you have a lot of bad roads or speed bumps in you area set the car a little higher. The biggest factor was the toe setting. It made a big difference, I mean huge difference! More videos to come.

Happy Building, Ron

a lot of good info in this thread. Thanks guys. Ron when you measure the 4.5 and 5 in. of ride height from what point are you measuring each?

[Ron565]

I used the same points that the build manual said to use. Behind the front wheels where the wheel well sheet metal makes a 90 degree turn look rearward you will see were the belly skins mate. The back I used the 2" square tubing just forward of the rear wheels.

Ron

[LS MAN]

Hey GTMKris, there should be race shops around that have scales, & may be able to help you
kbentzel, not sure if Ron has the bump steer kit, will check with him. A good subject to address for sure
IRON MAN, We set our toe at 1/16 out front - 1/8 - 3/16 IN rear. Guys make sure you don't have toe out in the rear - that's evil!
As far as stability under braking - the sway bar really helps, as will the shocks - but try the toe out in the front first, see if you like it. There is also the brake bias that we will talk about soon, as I suspect that most guys may not have adjusted it.
Also, check your tire pressures - I forgot this---- Always check your pressures first! Try 24 front - 26 rear. Don't be afraid to try different pressures & feel the differences.


Setting your toe - in is easy. We will demonstrate soon - Here is a link for toe adjustment plates:
http://www.summitracing.com/parts/LNG-79500/
Pretty cheap to buy, or you can make your own - or just use 2 straightedges.

Here is a look at setting up the sway bar


http://www.youtube.com/watch?v=rDuH1cooxyU

[Ron565]

I do not have the bump steer kit. That's probably the only thing I didn't get.


Having fun, Ron

[VD2021]

I used the same points that the build manual said to use. Behind the front wheels where the wheel well sheet metal makes a 90 degree turn look rearward you will see were the belly skins mate. The back I used the 2" square tubing just forward of the rear wheels.

Ron

I'm still looking for the 4" tube.:confused: This is a cut and paste from the recently released e-manual.

"Make sure that the car is at the correct ride height before the alignment procedure is done. Ride height should be 4½” at the front and 4½” at the back measured to the bottom of the 4” round tube with the normal number of people/weight in the car."

[IRON MAN]

With you going a complete 180 on the toe settings it has really messed with my head trying to picture the difference in the driveability of the car ! It would seem that when you are going in a straight line you are always going to have some steering reaction from just having your hand on the steering wheel and correcting to keep it in a straight line. Each little pull on my car seems to create some extra pull from somewhere... now if the toe is in and Im correcting left... the car will lean on the right tire thats toed in making it turn left a little extra ... which seems like thats what Im feeling.

By making the toe out, correcting left will make the car lean on the tire thats probably going in an almost straight line.... which would keep it from "pulling extra" ... so with that said.. whats the point of ever having toe in ??? Would it help a car that has too much play in the steering or something ?

[LS MAN]

Vidal - 4" round tube? - sounds like a Roadster, not a GTM, they must have made a mistake.

IRON MAN - Everyone seems to think that the "ultimate" capabilities of this car is the most important thing - How much power does it have? - How fast will it go? - How big are the tires?
Don't get me wrong, those are the reasons for building a "supercar" for sure. The problem is we spend 99% of the time just driving down the road. This is where the car come up short - it just needs a lot of development in driveability.

I have felt the same feeling as you described on all the street versions I have driven.
Toe settings have different effects when you are cornering under load, & when you are just going straight down the road. What we are focusing on is directional stability - just driving straight down the road, with no cornering load. This is where irregularities in the pavement wreck havoc on the GTM. When 1 front tire catches a ripple, crack, or a seam in the road, is where the toe out really helps keep the car from following that influence from the road. I know it sounds backwards, but try it, see if you like it. We have tried setting the toe straight up, but found it is better just slightly toed out in the front.
Don't be afraid of trying different settings, that way you can feel the differences. Tire packages, wheel offsets can have a big influence also, just find what your car likes.
I added info in the previous post on toe adjustment.

[crash]

I would have to agree with Ted that "the proof is in the pudding", and "don't be afraid to try something."

That said, be VERY careful with suspension adjustments. Toe out, historically, generally speaking, usually equates to a "darty" car that turns in EXCELLENT(hence the reason for putting toe out into a race car) but can be a bit difficult to handle under power in a straight line.

As I have said before, you MUST be looking at things dynamically as well as statically when it comes to suspension adjustments. If you don't have the equipment or computers to simulate the motion of your suspension and what certain settings will do for you, then the next best thing is to just adjust and try.

My guess is that if Ron doesn't have the bump steer kit, and this hasn't been checked, then something interesting is happening when the nose lifts under accelleration.

As Ted mentioned, there is really no special equipment involved with this. Matter of fact, I have seen people use old beam scales that they got from feed stores to do car scaling. As long as the capacity is high enough they will work.

Scaling/alignment/ride height settings on a car is something I do before EVERY race event. Not sure you need to even get to the point of scaling your car, if it has the correct components and the adjustments are set correct, but it won't hurt either. :) Just don't think you HAVE to scale your car to make it work right...you don't. :) I believe that Ted's bar kit, along with some spring, and maybe shock adjustments are definitely some good additions to the equation.

[LS MAN]

Here is a quick look at the yellow KONI shocks.


http://www.youtube.com/watch?v=5iD6nhQp42Q

I am curious, how many have the yellow shocks or the black ones?

[The Stig]

So far, I still have the yellow Koni's. But I am quietly looking at different coil-over options that will work with the RamLift Pro lift kit.

http://i210.photobucket.com/albums/bb94/jmichaelbaskin/DSC_0628.jpg

This is a great thread to get some Real info in terms of set ups that really work, and not speculation.

Great Save Ron!

[Ron565]

Hey CRASH,

When I stab it she tracks really well. I don't feel the front end coming up at all. Ron

[VD2021]

Here is a quick look at the yellow KONI shocks.

I am curious, how many have the yellow shocks or the black ones?

Ted,
My Gen2 was shipped with the black pre-set ones. Are the black ones just as bad?

[Fred Brewer]

Ted & Ron,,,
Great info, thank you. OK so a few questions to help me level set. What were the initial settings on the front and rear suspension? Stock Bushings or poly? 750 Lb springs in the rear? What is the rate for the ARB? If you can share it, is that Speedway Engineering bar?

If it fair to say that if the yellow Koni is not enough for 350-450 Lb springs in the front it would be the same for the rear at 750lbs?

In your opinion, would 7 degrees of front caster make a difference in moving to toe-out vs toe-in on the front.

Thanks!!!!!

[The Stig]

I do not have the bump steer kit. That's probably the only thing I didn't get.


Having fun, Ron

What additional benefit does the Bump steer kit give you in the front suspension set up? It looks as though you completely turned you're cars handling around and made it much more predictable, by the addition of the sway bar kit, and Shock & Alignment changes.

[crash]

What additional benefit does the Bump steer kit give you in the front suspension set up? It looks as though you completely turned you're cars handling around and made it much more predictable, by the addition of the sway bar kit, and Shock & Alignment changes.

When the suspension travels, the length of all the arms, in the X axis, parallel to the ground, changes. Some change differently than others. Bump steer is simply that the tie rods for the steering change slightly differently than the upper and lower control arms with respect to the X axis. This causes the upright to "steer" slightly when the suspension goes through it's travel. The steering effects can either toe a car in or out, or sometimes both when the suspension goes through it's travel. The "bump steer kit" simply tries to put the mounting point of the outer tie rod end in a location that minimizes the bump steer throughout the suspensions travel. I have never seen a "perfect" suspension that did not experience at least small amounts of bump steer. You can minimize it, but there will always be some. This is due to the fact that the inner mounting point on the steering rack is neccessarily not a fixed point and therefore the tie rods will always make a slightly different arc than the suspension arms and their fixed mounting points.

HTH :)

[claybags]

This thread will become the new "Prepare to Win" !!! Thanks to Ron and Ted "Carroll Smith"!!!!

Cheers guys and keep it coming.
Jeff

[crash]

Hey CRASH,

When I stab it she tracks really well. I don't feel the front end coming up at all. Ron

Yeah, but that's with the Bilsteins, right?

[Ron565]

Hi Fred,

The original GTM setup from the factory came with 350 in the front and 450 in the back. Some time later FFR decided to update the the springs combinations and asked the builders to move the rear springs to the front and install the new 750 to the rear. FFR did change their Koni shocks to the newer updated version. We have note seen or tested them.
We at Quick Racing Products are in the processes of trying different shock and spring rate for the best ride possible. We intend to have a performance street and race suspension packages available soon. Regarding the anti sway bar setup, Ted has designed the sway bar system and they are made in house just for the GTM.
On my car I have the OEM suspension bushings with the old Koni shocks. I have the 750 on the rear and it's very predictable and not much more I will do with it except new shocks. I have the custom Bilstein racing shocks with 350 springs in the front. What a difference it made. I'll let Ted talk about chassis setting.

I'll be honest with you guys and gals. When I first drove the it I did not like it at all. It was twitchy almost to the point I was asking myself what the hell did I buy. I had the suspension setup with standard ZO6 specifications. With Ted's help It's bad to the bone. I love the car. I'm amazed on how much the car has improved. FFR you have a winer!

Happy Building, Ron QuickRacingProducts.com

[LS MAN]

Have you come accross or found a reason why a GTM might be overly sensitive at high speeds and on the brakes from high speed ? to the point where it feels scarry even just driving in a straight line ...

Well, IRON MAN apply illustrates where we are at so far. When you can't even drive straight down the road, without hanging on for dear life, we need to focus on directional stability first, before we need to address developing the cornering performance.
Castor defiantly helps here, no question, but what I have found on these cars so far is that the GTM responds to toe adjustments acutely. I don't think that bump steer is affecting direction stability much at all, & you really have to have large discrepancy in the pavement to have bump steer affect the car in a straight line. Now in hard cornering, bump steer plays a bigger role. Yes, defiantly be careful if you adjust your suspension, but as bad as these things can be, you probably won't make it much worse. Remember if you start jacking a bunch of castor in, your road feedback may diminish, & your steering effort will increase quite a bit in parking lot situations. 6-8 degs, & your will probably want power steering. I prefer the feel of the manual steering, so I use the least amount of castor I can get away with. The nice thing is, you can adjust these cars to find what you like best.

Fred, I believe Ron's car has 750s on the rear, & you bring up a good point.

If we look at the scale #s we come up with 41.1% front - 58.9% rear - weight bias.
Now with 350# F & 750# R spring rates, how is the same shock suppose to control such different weight & spring loads - they cant.

Another very important geometry that is key - is the motion ratio of the suspension - that is the ratio between the movement (displacement) of the wheel vs the movement of the shock/spring. because the shock mounts inboard of the spindle, & is mounted at an angle, when the wheel moves 1", the shock moves less, so does the sway bar.
So when you see me working the shock on the bench, remember the car has a mechanical leverage so - as an example, the wheel moves 1" the shock/spring will only move .6" So that says you have a spring rate of 350, your wheel rate is only 210# - same goes for the shock. Jim measured the ratios, so will get them & share here.

When I calculated the sway bar rates, I had to take this into consideration.

As you can see we all have a long way to go, but with feedback from everyone here, I know we can make huge improvements, & make your cars way more enjoyable to drive.

[JCHRacer]

Has anyone measured the cg height of a finished car ?

[Ron565]

It's probably mid line of the engine or slightly lower with tranny. The hoop is negligible.

Ron

[JCHRacer]

I agree, that is probably where it's at but I was wondering if someone has actually verified that by taking a measurement.

[The Stig]

Here is a quick look at the yellow KONI shocks.


http://www.youtube.com/watch?v=5iD6nhQp42Q

I am curious, how many have the yellow shocks or the black ones?

Would the fact that most all of us have the Koni's mounted inverted have anything to do with how they perform?
I've read here in forum(s) that it shouldn't. But...

[LS MAN]

Hey Stig, that was the first thing we thought was that the shock was cavitating, because it is inverted in the front. But these are "gas" shocks that have gas pressure inside to make sure the shock fluid is always flowing through the piston & foot valves inside the shock. I tried my okie test with the shock in both directions, seemed the same. That doesn't mean that under load they don't have a problem. A good reason to invest in quality shocks tho.

[Roger Reid]

Ted, when you were moving (by hand) the origional yellow Koni's thru the stroke did you notice any air moving through the piston. I could hear and feel air moving through my black Koni's (kit 233). I wonder if these Koni's have seperator pistons inside?

[LS MAN]

Hey Roger, actually I did notice some cavitation at first, but I cycled it a few times, & it seemed to work the air bubbles out of it. Could be that as they lay on their side they may trap some air that may have to cycle out? I don't know if these have a separator piston inside, as these are twin tube shocks. I think most mono tube shocks have separators.

[Roger Reid]

If these Koni's are twin tube design, there is no seperator piston. Therefore the air (even if it is pressurized) will mix with the oil becoming an oil/air foam that goes through the piston shims. This can mess with damping curves and when they get hot, the damping will change (more so than a shock with a seperator piston). This analogy is for a track car. For street use a twin tube should be ok. The worst case scenerio is off road where the shocks get really hot.

Clarify, I meant Nitrogen not air.

[Ron565]

Hey RCHRacer,

It would be a lot of calculations. Weight X means = moments

[The Stig]

I've been thinking of buying a set of replacement coil-over shocks. I've looked at the QA1, Aldan, Heidts Billet, Bilstein Adjustable, and Penske Adjustable. These shocks cover the price spectrum from inexpensive to fairly pricey. From $200.00+ per shock for the Heidts to $2000.00+ per shock for the Penske's.

I really don't have the expertise to know the true differences between the shocks to know whether the price differences make sense. Obviously, I don't really want to spend 2000 per corner, but I do want a quality set of adjustable (remote reservoir) shocks. I want adjustability to dial the handling in, for street and possibly a track day here and there.

Like Ted said earlier in this thread, I'm more concerned about finding the right control and balance of the car, so I don't have to be worried about driving in a straight line...

Can you guys offer some advice as to how to make the best choice in the available coil-over shocks?

[JCHRacer]

Hey RCHRacer,

It would be a lot of calculations. Weight X means = moments

Agreed....way too many calculations.

What I am talking about is taking physical measurements on a completed car. If someone is scaling the car as shown in previous posts, all that needs to be done is to raise one end of the car a known amount (a foot or more) and record the change in weight at the other end. A simple calculation later and you have the cg height. Knowing the real cg height can make calculating a good baseline spring and rollbar combination more accurate.

[crash]

Stig- I remember reading a good article/thread a couple years back that, IIRC, involved David Borden. I don't think it was on this site. I will look through my saved items and see what I have.

For a car like the GTM, I believe you should limit your shock search to a monotube design.

I just picked up a set of Ohlins tt44s for the race car, but I will be the first one to admit that I am not a shock guru. I know what to adjust when things are not working properly at the track, or at least I know which directions to try, but the ins and outs of finite shock performance are so involved that I really don't have the time or energy to be an "expert". I simply pay someone who is to get the shocks close to what I need. Kind of like the engine tuning stuff. I could take a stab at it, but it would probably end up costing me more and my results wouldn't be as good, so why knock myself out? "A man's got to know his limitations". :)

The Ohlins company is very "open" about their designs and applications. See these links for some interesting reading about general shock theory, application, and function.

http://www.motorsportsspares.com/files/inside_the_tt44_theory_and_design.pdf

And

http://www.motorsportsspares.com/files/inside_the_tt44_work_section_and_valving.pdf

[The Stig]

I don't really want to hi-jack Ted & Ron's thread with shock choices. I should have put this in Roger's thread about Penske shocks. However I have found a shop here in Mooresville, NC which supplies shocks and shock tuning services for many of the NASCAR teams (that don't do it themselves). They have a set of Penske 7500 series dual adjustable at a reasonable price compared to some of the prices that I've seen. ($500 per shock). They are not remote reservoir, but I'm not sure if that's really a feature that I need to worry about, given how I intend to use the car.

My question that I need to answer now, is what the shock length of the KONI shocks are, so I can get the correct sizing for the GTM. If I had it on the road, I'd just take it up to their shop and let them measure for the best fit and ride height. That may be the best idea anyway... Just wait until it's on the road, so I can explain what the car is doing, and what I need to change. They may have a more affordable solution that is just as good... I guess I won't know until I ask.

[crash]

The non reservoir shocks will do you just fine. I am doing just as you said. These tt44s came from an Indy Car team, so valving will have to be significantly altered, but I am not going to have this done until all other components are built and in place. There will always be good deals out there. :)

[JCHRacer]

I don't really want to hi-jack Ted & Ron's thread with shock choices. I should have put this in Roger's threat about Penske shocks. However I have found a shop here in Mooresville, NC which supplies shocks and shock tuning services for many of the NASCAR teams (that don't do it themselves). They have a set of Penske 7500 series dual adjustable at a reasonable price compared to some of the prices that I've seen. ($500 per shock). They are not remote reservoir, but I'm not sure if that's really a feature that I need to worry about, given how I intend to use the car.

My question that I need to answer now, is what the shock length of the KONI shocks are, so I can get the correct sizing for the GTM. If I had it on the road, I'd just take it up to their shop and let them measure for the best fit and ride height. That may be the best idea anyway... Just wait until it's on the road, so I can explain what the car is doing, and what I need to change. They may have a more affordable solution that is just as good... I guess I won't know until I ask.

The Penke 7500's are a good choice although the models I am familiar with are only single adjustable....for rebound...but a rebound adjustable is most likely enough unless you are really into different set-ups for different tracks/conditions. They do have a high pressure piston and reservoir....it's just integral with the main body of the shock.

I have the FFR Koni lengths and can post them tonight if no one else does. Before you buy the same lengths, I would check to see if that is the correct length for you. I think the ffr length can go solid in compression in the rear if you are running a big diameter tire. I also think that in some cases the spring rattles free in droop. Both conditions are not optimum. If you are going to spend the money on custom shocks, you may want to spend some time measuring your set-up and adjusting the lengths accordingly.

[LS MAN]

Here you go Stig - shock extended length is 15.75" - collapsed is 11.75" to the bump rubber. Keep the info on shocks coming.
We need to check the suspension vs shock travel at both ends of the car at some point to see where the shock bottoms/tops out. Another test to add to the list, along with C/G height.

[crash]

Stig-

Here's the link to the forum/thread I was thinking of. David continues to be active on this thread and it continues to grow. Some really good info over there.

http://forums.corner-carvers.com/showthread.php?t=41374

About 170 posts long...enjoy! :)

[The Stig]

Stig-

Here's the link to the forum/thread I was thinking of. David continues to be active on this thread and it continues to grow. Some really good info over there.

http://forums.corner-carvers.com/showthread.php?t=41374

About 170 posts long...enjoy! :)

Thanks Mike. I'll read through it tonight. I appreciate it!

[JCHRacer]

Here is a link to a GTM specific thread where David Borden actually provided calculated damper rates:

http://www.ffcars.com/forums/42-factory-five-gtm-forum-sponsored-mendeola-powertrain/258924-spring-damper-rates-shocks.html

Dont know if the OP tested the set-up yet.

[LS MAN]

Hey Joel, thanks for the good info & link. No I have not tested it, have you?

[Denny Olson]

Ted, Ron
Great info coming from you guys! I've got 400 miles on my GTM now and happy for the most part as to how it drives at this point, so the initial settings must be okay. Goes straight under hard power up to 90mph, haven't been above 90 and haven't done any hard cornering yet. I do notice the choppy ride coming from the front and feel the springs are too stiff. Your sway bar option was not available when I assembled the car, so I will have move some items in the way to incorporate it. Anxious to follow your suspension progress on Ron's GTM.
Thanks Denny

[LS MAN]

Hey Denny, good feedback. When we designed the sway bar kit, one of the main criteria was it had to fit onto already constructed cars. What parts do you have that may be in the way of the bar.
What shocks are you using?
Thanks

[kbentzel]

LS Man,
I have 6200 miles on mine with the FFR supplied shocks. Three black ones and one yellow.....FFR said other than the paint they are the same??? It was real twitchy at first. I reduced the rear toe in to 1/16 from 1/8 and that helped. Reducing the tire pressure on my PS IIs down to 24/26 from 32 helped as well. I would say I see more oversteer than understeer. I also get a fair amount of feed back to the wheel when the pavement is irregular or you hit bumps. It'll try to steer for you if you aren't paying attention. A more comfortable feel at triple digit speeds would be a welocome change. I appreciate this thread and if you come up with a shock/spring combo to go with the sway bar sign me up.
Keith

[LS MAN]

Hey Keith, thanks for the info - I think I screwed up on the rear toe specs. We use 3/32" -1/8" toe in - not 3/16". Good to see 1/16" work for you.
It just sucks when you get old!

[Fred Brewer]

Some info I pulled from the Koni site about the 30-5436 Yellow Coil Overs:

http://lsspecialists.com/Koni-Chart.jpg

More info here:

http://www.koniracing.com/oval30.cfm

And here:

http://www.koniracing.com/images/File/30force.pdf

[David]

The 7500 is a great shock and as you have found, they recently came out with a dual adjustable 7500. At $500 each, thats a great deal. Im thinking of them for the MK4 build. One thing I would like to know is what the compression adjustment affects. The rebound is bleed and affects slow shock speed(below 3-4 IPS). If the compression is the same, thats going to be a killer shock for the money!

Def check your compressed and extended length at ride height. Sometimes non remote res shocks are longer than normal to allow for nitrogen space.

David

[The Stig]

The 7500 is a great shock and as you have found, they recently came out with a dual adjustable 7500. At $500 each, thats a great deal. Im thinking of them for the MK4 build. One thing I would like to know is what the compression adjustment affects. The rebound is bleed and affects slow shock speed(below 3-4 IPS). If the compression is the same, thats going to be a killer shock for the money!

Def check your compressed and extended length at ride height. Sometimes non remote res shocks are longer than normal to allow for nitrogen space.

David

Thanks Dave,

I am working with a company called RE Suspension, here in Mooresville. They apparently do a lot of work with/for the NASCAR shops in the area. The tech that I am working with did mention that the shock lengths are usually a bit longer with standard shock bodies, versus remote reservoir shocks.

Ted gave the extended and compressed lengths of the KONI shocks that comes with the GTM kit. But I am starting to think that I need the shock length (at ride height) in order to get a feel for how much compression I need to account for as the car sits.

I am also concerned about the shock body length, since I am installing the "RamLift Pro" hydraulic lift kit. When that lift is activated, it extends the shock by a couple of inches, in order to help clear speed bumps and driveway entries.

If the "droop" is 2" then I would imagine that I will be Ok. But if it's only an inch, I would give up the other inch of extention in ground clearance. And I also don't want the lift to put repeated (negative) pressure against the shock body, rods, and internal components.

I need to go ahead and order the shocks, but I don't have my car to measure the corner weights. Would it be advisable to use the weights that Ron and Ted posted previously in this thread? I know they wouldn't be exact, but I would imagine that it would be a close comparison in weight.

Left Front - 572 # Right Front - 574 # Cross Weight - 1385 #

Left Rear - 811 # Right Rear - 809 # Cross Weight - 1381 #

What else would the technician need in order to set the shocks up for initial use?

Thanks for your help.

Ted / Ron, are you still planning to create a video for setting the toe at the front and rear? These videos are a huge help in understanding the set up process.

[JCHRacer]

Thanks Dave,

I am working with a company called RE Suspension, here in Mooresville. They apparently do a lot of work with/for the NASCAR shops in the area. The tech that I am working with did mention that the shock lengths are usually a bit longer with standard shock bodies, versus remote reservoir shocks.

Ted gave the extended and compressed lengths of the KONI shocks that comes with the GTM kit. But I am starting to think that I need the shock length (at ride height) in order to get a feel for how much compression I need to account for as the car sits.

I am also concerned about the shock body length, since I am installing the "RamLift Pro" hydraulic lift kit. When that lift is activated, it extends the shock by a couple of inches, in order to help clear speed bumps and driveway entries.

If the "droop" is 2" then I would imagine that I will be Ok. But if it's only an inch, I would give up the other inch of extention in ground clearance. And I also don't want the lift to put repeated (negative) pressure against the shock body, rods, and internal components.

I need to go ahead and order the shocks, but I don't have my car to measure the corner weights. Would it be advisable to use the weights that Ron and Ted posted previously in this thread. I know they wouldn't be exact, but I would imagine that it would be a close comparison in weight.

Left Front - 572 # Right Front - 574 # Cross Weight - 1385 #

Left Rear - 811 # Right Rear - 809 # Cross Weight - 1381 #

What else would the technician need in order to set the shocks up for initial use?

Thanks for your help.

Ted / Ron, are you still planning to create a video for setting the toe at the front and rear? these videos are a huge help in understanding the set up process.

I have a CAD model set up with the stock FFR/Corvette suspension system. If you can tell me what ride heights and tire diameters you are running, I can tell you the static position of the shock (eye to eye distance). I have also posted the motion ratio's in the other thread. That, plus the corner weights you have posted should be enough for the shock technition to determine the correct shock lengths. Are you specifying the springs to be used?

[The Stig]

I have a CAD model set up with the stock FFR/Corvette suspension system. If you can tell me what ride heights and tire diameters you are running, I can tell you the static position of the shock (eye to eye distance). I have also posted the motion ratio's in the other thread. That, plus the corner weights you have posted should be enough for the shock technition to determine the correct shock lengths. Are you specifying the springs to be used?

Thanks Joel, that would be great!

Front Tires are 245/40/18" (diameter - 25.712")
Rear Tires are 335/30/18" (diameter - 25.912")

Ride Height will be 4" - 4.5" (depending on how much real lift I get from the RamLift system).

Thanks for your help.

[Muadi]

LS MAN/Ron,

With the amount of tuning that you did, and showing us how sensitive the adjustments to the spring can be, would it be best to do that type of fine tuning with the driver in his seat? It seems that having a driver seated would give a better final balance?

Great work btw... I learned quite a bit.

[LS MAN]

Hey Maudi, checking your corner weights with a driver in the seat is Ok, but we usually don't. The driver position in the GTM is probably close to the C/G front to rear, so may not affect the F/R balance too much. Of course the driver will add left side weight, but not a lot you can do to a street car to balance that out. Adding a passenger would even the balance out. For street cars set your chassis without the driver, its easier to balance that way, & just accept that the driver will add left side weight. On a Road race car, move weight around to the right side in the vehicle to balance the drivers weight, & then always set the chassis with the driver or equivalent weight in the seat. On a oval track car you generally want as much left side weight as you can get, so they stack as much weight as they can on the left side, sometimes up to 60% left side or more as rules allow.

Just did more work on Ron's car today, so will post some updates soon.

Thanks

[Ron565]

Just wanted to give you a little update. Ted and I finally had some time to play with my suspension. We started with installing the rear custom Bilstein coilovers with the 600 lbs springs on the back. It's the first time that the car has the Bilsteins on all four corners.
We took it out for a spin. WOW I can't put it in words. It handles like a ultra high performance production sports car. You put in a turn in third gear and you think that your at it's limits and then you grab 4th and you keep on going and going and going! GONE.
Sorry Ted old buddy, you can't have your shocks back LOL. With the racing shocks and lighter springs it's perfection on wheels. We took some videos today and as soon Ted edits them he will post them. It's pretty go stuff about how to check and setup your rear chassis. Hope you guys and gals will like it. Happy Building, Ron

[Hitechmotorsports]

Cool....good info.

[spdnman]

Cool....can't wait. Like most mine handles like poop above 60 mph.

I want a GTM badly, but when I read about the handling I get a bit nervous. I understand it can be corrected, but it seems to add more time and more money. In the end, how well can they be made to handle with other coilover kits, alignment shims, changes, etc? Good luck to all....

[crash]

Take your Honda Civic, or whatever you drive daily, randomly "adjust" the suspension and then tell me how well it performs at high speeds!

Point is that this is not an inherent flaw of a GTM. It is a flaw that builders are not setting them up correctly.

Set a stock GTM up correctly and it will beat the pants off of just about anything. If you then want things to be more comfortable in the 100 MPH range because you really think you will be spending quite a bit of time up there, then start making all these performance changes.

I see nothing here that I wouldn't want to do to my daily driver to get more high end performance out of it.

Does this mean that FFR built the GTM wrong? NO!

Does this mean that Ted's products are not needed? NO!

It means that we build these cars for different purposes and different items are needed depending upon what we are building for, and no matter what you are building for, if the alignment is off, then the car, whatever car you have, will not be fun or comfortable to drive.

I do believe Ted is trying to address both issues with this thread. He is helping builders out by suggesting settings and showing you how to do the alignment, at least I think he is going to, and he is also offering items to help the GTM at higher speeds perform better. Same as any local tuner shop does for the ricers, but Ted is focused on GTMs and more meat than bling as far as solutions are concerned. At least that's what I understand from working with the guy. :)

[spdnman]

Take your Honda Civic, or whatever you drive daily, randomly "adjust" the suspension and then tell me how well it performs at high speeds!

Point is that this is not an inherent flaw of a GTM. It is a flaw that builders are not setting them up correctly.

Set a stock GTM up correctly and it will beat the pants off of just about anything. If you then want things to be more comfortable in the 100 MPH range because you really think you will be spending quite a bit of time up there, then start making all these performance changes.

I see nothing here that I wouldn't want to do to my daily driver to get more high end performance out of it.

Does this mean that FFR built the GTM wrong? NO!

Does this mean that Ted's products are not needed? NO!

It means that we build these cars for different purposes and different items are needed depending upon what we are building for, and no matter what you are building for, if the alignment is off, then the car, whatever car you have, will not be fun or comfortable to drive.

I do believe Ted is trying to address both issues with this thread. He is helping builders out by suggesting settings and showing you how to do the alignment, at least I think he is going to, and he is also offering items to help the GTM at higher speeds perform better. Same as any local tuner shop does for the ricers, but Ted is focused on GTMs and more meat than bling as far as solutions are concerned. At least that's what I understand from working with the guy. :).

Agree with you, as long as it is not a flaw of the GTM that's cool. Everyone has different goals. Mine will be best handling and high speed stability for the street. Looks like it can be done.

[Ron565]

Suspension setup is just another step in completing any build. Make no bones about it the GTM is thoroughbred and needs a little more attention to detail than most. With that said, We have a lot of knowledgeable people on this forum that are willing to share their Racing knowledge like Ted. It's the stuff no one tells you like using a two pieces aluminum two tape measures and a piece of string to set up your chassis. That's brilliant stuff.

I can say with no reservations that my car can now go over 100 without any el effects regarding handling.
It's smooth even going down a old and bumpy country road, If I was to go that fast.:D

Happy Building, Ron

[LS MAN]

Checking the front toe settings on Ron's car.


http://www.youtube.com/watch?v=78WJmjS3acU

[VD2021]

This thread makes me curious as to how much R&D FFR put into the suspension. I don't care about wind tunnel testing. Few would see a GTM and not know it’s more aerodynamic than a SUV. Redirect those resources to the drivability.

Maybe we can get Dave to contract Ted to really turn out GTMs into a driver's dream.:D


JMO.

[Ron565]

Hi Vidal,

I think FFR has addressed the issue. This is normal chassis tuning stuff. Factory Five Racing builds street legal race car's like the name implies.
I agree that FFR leaves a lot of stuff to the builders. That's the reason for the Forum. If anyone is in northern California and needs Ted and I to set up their car we would be happy to do so.

Happy Building, Ron

[VD2021]

Hi Vidal,

I think FFR has addressed the issue. This is normal chassis tuning stuff. Factory Five Racing builds street legal race car's like the name implies.
I agree that FFR leaves a lot of stuff to the builders. That's the reason for the Forum. If anyone is in northern California and needs Ted and I to set up their car we would be happy to do so.

Happy Building, Ron

Ron,
No worries. How about you bring Ted to the "happiest place on earth". I'm just dont the street from there.

[Ron565]

I can't tell you how much I have learned from Ted, Jim and Prototype development. It's a big learning curve. Ron

[sv650s]

Where is the video for the rear, or is rear done the sameway?

[Ron565]

Hey sv650s,

Yes it is. We will post the numbers soon. Ron

[LS MAN]

Here is the video for setting the rear toe


http://www.youtube.com/watch?v=rQazyegYTWk

[LS MAN]

Here is a video on using HP Tuners - scanner.


http://www.youtube.com/watch?v=h9ii-DOhd3c

[VD2021]

Ted,
Had you been able to access the PCM what perimeters would you have adjusted? I still get the P0171 and 74 codes every so often during my karting. I would just set them to not set a code, but I would prefer to tune as a resolution. There is a lot to the HP Tuner and it seams the more I read the more questions I have.

[spytech]

This is a great thread, very informative.

Not to divert the thread, but I thought I would post my GTM's suspension setup, as many that follow my build log have messaged me for 'details' now that I've fixed my high speed stability problems. Ride height is 4.25" at all four corners. Front has 3/16" toe-in, rear has 1/8" toe-in. Using the FFR black koni and no sway bar yet. Bump steer is set with 5 washers on top of the tie rod, one on the bottom. Right now I can drive one-handed at 120 on rough pavement. Driving on the highway at 80 is effortless, and it takes a pretty severe pothole to really make the car jump. Tire pressures are at 30 front, 26 rear. Fronts tires are 245/40/18, rears are 335/30/18.

I want to get the rear up to 4.75" but I need to get a tool to compress the springs as I can't get more adjustment out of my passenger rear coil without compressing the spring to get a few more turns. For what it's worth, it seems that one full turn on the FFR koni coils equates to a 1/4" difference in ride height for that corner. I plan on adding the sway bar, but need to figure out how to reroute the brake lines around it...Probably a winter project.

[GTMKris]

Thanks spy for posting up your final specs. Since I don't want to fight the alignment guys I'm just gonna tell them to get it as close to what you have and go from there. I noticed that you said that you have 5 washers on top of the tie rod now. In your build log you have a pic with three on top of the tie rod it looks like. I assume that this was your inital setup and you changed to 5 fr a better feel.

Thanks to LSman again for bringing this to my attention with this thread. I have found a guy with a setup like yours, he is going to help me do the weight bias.

[David]

hey Stig, remember if you mount a shock upside down, your bump and rebound settings in the shock are aLso reversed. Not a great idea unless the shock is set up to handle this

If im reading this right, you are saying that if you invert a shock it changes the valving(inverting it as well)?

If Im reading your statement correct, that is incorrect/not accurate. Shocks are valved based on compression and rebound and that does not change based on how the shock mounted(body or down)

If I miss ready your statement, please clarify. :)
David

[Racer86]

David,, your correct,, I need to slow down a bit and think before I post, sorry about that,,my bad

[The Stig]

Racer86 - Bob: It's good to see you on the forum! It's been a while.

[GTMKris]

My car will be out of the paint booth in a week or so. Not long after that I plan on taking it to the alignment shop. In trying to find out what I should tell the guy running the machine I have read so much conflicting info that I don't really no what I should say. I found this in the other forum, is this still close to what you would shoot for in castor and camber adjustments?

That said, I think I would start at these static #s

Front toe 1/8 toe in. No more though.
Front camber -.5 to -.9 degrees. If you put in too much you will get bad tire wear depending upon driving conditions.
Front caster AS MUCH AS YOU CAN GET! Normal car would be 3-5 degrees, but the Vette goes extreme at 10 degrees!! No way you can, or should, get that on a GTM.

Rear toe 1/16 to 1/8 toe in. 1/8 in the rear is alot and if you go too far with toe in or have ANY toe out in the rear the car will want to rear steer all over the place.
Rear camber -.5 to -.9 degrees again depending on tire wear from given driving conditions.
Rear caster is really not an issue because the rear upright should not be going through the travel that caster effects much if at all, so as long as both sides are straight up to a little positive caster, that should be fine, and both sides should match.

Take this into the alignment shop for referrence. If you are having issues with bump steer changes, I believe that FFR sells rack lengthing kits to help with this.

On reading this thread from front to back Ls man says 1/16 front toe out and 1/8-3/32 toe in rear.

While Spytech had his best luck at 3/16 front toe in and 1/16 rear toe in.

Just looking for something that I can print off and hand to the guy and say here.....get it as close to this as possialbe. I don't mind doing the leg work but when info starts to conflit I figured that I should ask instead of guess.

[Roger Reid]

...That said, I think I would start at these static #s

Front toe 1/8 toe in. No more though.
Front camber -.5 to -.9 degrees. If you put in too much you will get bad tire wear depending upon driving conditions.
Front caster AS MUCH AS YOU CAN GET! Normal car would be 3-5 degrees, but the Vette goes extreme at 10 degrees!! No way you can, or should, get that on a GTM.

Rear toe 1/16 to 1/8 toe in. 1/8 in the rear is alot and if you go too far with toe in or have ANY toe out in the rear the car will want to rear steer all over the place.
Rear camber -.5 to -.9 degrees again depending on tire wear from given driving conditions.
Rear caster is really not an issue because the rear upright should not be going through the travel that caster effects much if at all, so as long as both sides are straight up to a little positive caster, that should be fine, and both sides should match....

That sounds like a good plan Kris.

[crash]

I believe I am the one that wrote that quote in the other forum.

Let me explain what front toe does from my experiences.

If you have a slight bit of toe in you will have a car that tracks straight, but doesn't want to "dive" into the corners. If you put a bit of toe out into the car, which is actually what we do on the race cars, then the turn in to corners is improved. It doesn't make it terribly unstable on the straights, but at the same time, it's no Sunday cruiser either. In other words, both setups are correct depending upon what you are trying to achieve.

Personally, I wouldn't have toe out in my daily driver, hence my recommendations for initial settings, but a slight bit won't "kill you" either. As I have said before, don't be afraid to just try this stuff out. Just be aware that what seems like small changes can have big effects upon how the car handles. Toe can be done by ANY GTM builder with just a couple strings and 4 jack stands, or a simple toe bar that is used for measuring toe in about 60 seconds. This "toe bar" can be made for ZERO $$ from scrap pieces of metal from around the shop. Toe plates, such as you see in Ted's video can also be used, and again are pretty cheap to make.

Now, again, as I have said previously, messing with static numbers is fine, but the proof is in the pudding, and since our suspensions are not a static system, it is also important to consider what the wheels are doing throughout their length of suspension travel.

The two ways to do this are computer modeling or actually measuring at different points in the suspensions travel. At this point, I don't think either has been done with the GTM setup. Joel, aka JCHracer may have though, or possibly David Borden?

[GTMKris]

Thank you Crash for taking the time for a well thought out answer. As you mentioned I will more then likely have to make make minor changes to get the car to handle just like I like it. That I don't mind trying as long as I can get it close from the alignment shop. I have found a guy that I hope will let me put my car on his scales so that I can do the hole weight bias thing like they have done in this wonderful thread. Also I have the bump steer kit installed.

This car will never see the track.

Thanks again and I will post my updates with how these settings work for me. Kris

[JCHRacer]

I believe I am the one that wrote that quote in the other forum.

Let me explain what front toe does from my experiences.

If you have a slight bit of toe in you will have a car that tracks straight, but doesn't want to "dive" into the corners. If you put a bit of toe out into the car, which is actually what we do on the race cars, then the turn in to corners is improved. It doesn't make it terribly unstable on the straights, but at the same time, it's no Sunday cruiser either. In other words, both setups are correct depending upon what you are trying to achieve.

Personally, I wouldn't have toe out in my daily driver, hence my recommendations for initial settings, but a slight bit won't "kill you" either. As I have said before, don't be afraid to just try this stuff out. Just be aware that what seems like small changes can have big effects upon how the car handles. Toe can be done by ANY GTM builder with just a couple strings and 4 jack stands, or a simple toe bar that is used for measuring toe in about 60 seconds. This "toe bar" can be made for ZERO $$ from scrap pieces of metal from around the shop. Toe plates, such as you see in Ted's video can also be used, and again are pretty cheap to make.

Now, again, as I have said previously, messing with static numbers is fine, but the proof is in the pudding, and since our suspensions are not a static system, it is also important to consider what the wheels are doing throughout their length of suspension travel.

The two ways to do this are computer modeling or actually measuring at different points in the suspensions travel. At this point, I don't think either has been done with the GTM setup. Joel, aka JCHracer may have though, or possibly David Borden?

I have computer modeled the GTM/Vette suspension geometry but only as a baseline for the race suspension I am designing. With the stock Vette bushings, the computer model is of very little use....when the tires are loaded up under cornering, braking and acceleration, the tires are not going to point in the same direction as on the alignment rack.

I'm with Crash on this one. For a "well behaved" and stable street car, start with the recommendations of this thread and then experiment until you get the feel you are looking for.

[The Stig]

I have computer modeled the GTM/Vette suspension geometry but only as a baseline for the race suspension I am designing. With the stock Vette bushings, the computer model is of very little use....when the tires are loaded up under cornering, braking and acceleration, the tires are not going to point in the same direction as on the alignment rack.

I'm with Crash on this one. For a "well behaved" and stable street car, start with the recommendations of this thread and then experiment until you get the feel you are looking for.

Joel,

What type of bushings are you and Crash thinking of the keeps the tires/wheels pointed where they should be?

Since the Control arm assemblies are the only Donor parts left on my car, (and the steering column), I may as well consider "re-building" them as well at some point...

BUT... I don't want it to ride like a tank!!!

[spytech]

While Spytech had his best luck at 3/16 front toe in and 1/16 rear toe in.

Just wanted to clarify that I have 1/8 total rear toe-in. 1/8 seems to be the 'magic number' that many others have had success with.

Also remember that ride height itself is critical. My GTM drove like crap with 1/8 rear toe-in until I got the height set at over 4".

[Roger Reid]

...Also remember that ride height itself is critical. My GTM drove like crap with 1/8 rear toe-in until I got the height set at over 4".

I seem to remember quite a discussion on the other forum (back in 2009) about wheel diameters. That if they are too large, the a arm angles at normal ride heights become too extreme harming the handling.

[Roger Reid]

...Since the Control arm assemblies are the only Donor parts left on my car, (and the steering column), I may as well consider "re-building" them as well at some point...

BUT... I don't want it to ride like a tank!!!

I know this is not a donor thread but if you are only using the suspension components and the steering column, would you change your mind about going the donor route?

[JCHRacer]

Joel,

What type of bushings are you and Crash thinking of the keeps the tires/wheels pointed where they should be?

Since the Control arm assemblies are the only Donor parts left on my car, (and the steering column), I may as well consider "re-building" them as well at some point...

BUT... I don't want it to ride like a tank!!!

I don't think you can describe it as "should be", just a compromise. I am going with solid, teflon lined, spherical rod ends or needle/roller bearings at all inboard suspension pick-up points.....I am making all my control arms from scratch. Very little deflection under load but the "ride quality" suffers. Not something I would suggest for a daily driver. My car is intended for track days with occational street use so I can live with the harshness. As a compromise some people replace the soft rubber bushings with a harder plastic (usually urathane) but I dont like that option because they tent to stick if you dont grease them often. Pfadt (sp?), the Corvette racing guy has a spherical replacement kit I believe for the stock Corvette control arms. For a daily driver, I would stay with the Stock Corvette bushings and play with the alignment untill I got something comfortable.

[JCHRacer]

I seem to remember quite a discussion on the other forum (back in 2009) about wheel diameters. That if they are too large, the a arm angles at normal ride heights become too extreme harming the handling.

Just a guess here but changing the ride height, can affect the bump steer significantly. If you have a completed car and it does not feel "stable", I would check the bump steer (both front and rear) before going to any extreme static settings.

[The Stig]

I don't think you can describe it as "should be", just a compromise. I am going with solid, teflon lined, spherical rod ends or needle/roller bearings at all inboard suspension pick-up points.....I am making all my control arms from scratch. Very little deflection under load but the "ride quality" suffers. Not something I would suggest for a daily driver. My car is intended for track days with occational street use so I can live with the harshness. As a compromise some people replace the soft rubber bushings with a harder plastic (usually urathane) but I dont like that option because they tent to stick if you dont grease them often. Pfadt (sp?), the Corvette racing guy has a spherical replacement kit I believe for the stock Corvette control arms. For a daily driver, I would stay with the Stock Corvette bushings and play with the alignment untill I got something comfortable.

Thanks Joel. That's what I've been thinking as well. I don't plan to have this car on the track very often at all. But I definitely want to do whatever I need to make sure that it is stable and handles well (and safely). There are lots of bumps in the roads around Charlotte, and I don't want to end up in someone's flower bed.

For my purposes, I agree that the softer (stock) bushings should be fine. If I find later that I need to, I'll look into replacing them.

[The Stig]

I know this is not a donor thread but if you are only using the suspension components and the steering column, would you change your mind about going the donor route?

No. I think that the donor route is still very valid. Especially where budget & keeping costs down are concerned. In my build, I just found myself making decisions to change one thing and then another, until I got to the point that there wasn't really much left to change.

I absolutely think that it makes sense to use donor cars with these builds though.

[JCHRacer]

I have had good luck with setting the rear bump steer to produce loaded tire toe-in when the car rolls under cornering loads. This combined with static toe-in produces a very "stable" feeling car. The opposite is also true….if the rear loaded tire is experiencing toe-out under cornering loads (either from bushing deflection or bump steer) the car will feel “wickedly unstable”. Maybe someone with a completed car can check it out.

[Ron565]

Just a guess here but changing the ride height, can affect the bump steer significantly. If you have a completed car and it does not feel "stable", I would check the bump steer (both front and rear) before going to any extreme static settings.

Hey guy's, Just for reference My ride hight is 4.5 front and 5.0 in the back. I thought it is a good compromise regarding road conditions and speed bumps. I don't have any issues with bump steer.

Happy Building, Ron

[spytech]

Hey guy's, Just for reference My ride hight is 4.5 front and 5.0 in the back. I thought it is a good compromise regarding road conditions and speed bumps. I don't have any issues with bump steer.

Happy Building, Ron
Ron-

Random question - did you have to compress your springs or anything to get the ride height up to 5" in the rear? I'm at 4.25" right now and I could get maybe one more turn out of the collars on my koni coilovers on the driver's side, and I can't get any more turns on the pass side. If the sleeves didnt spin freely it probably wouldn't be an issue, but as a result I have to figure out a way to compress the springs a bit so I can get those remaining turns.

[Roger Reid]

Spy

Ron may be using a different type of Koni (from the PDG racecar) with different external threads on the body.

Would a spring compressor tool help you preload your spring to get a higher ride height?

Here is a tool from Eastwood.

http://www.eastwood.com/external-coil-spring-compressor.html

[spytech]

Spy

Ron may be using a different type of Koni (from the PDG racecar) with different external threads on the body.

Would a spring compressor tool help you preload your spring to get a higher ride height?

Here is a tool from Eastwood.
http://www.eastwood.com/external-coil-spring-compressor.html
Roger-

Thanks for the feedback. That should work perfect. I just wasn't sure if compressing the spring/preloading it more, is the optimal way of adjusting ride height with the FFR black konis. Other coilovers I have used in the past had 2 collars - one for adjusting the spring perch, and one for lowering/raising the actual sleeve that the perch spins on. Obviously the Konis only have the perch and the sleeve just floats, but wasn't sure if I had overlooked something.

[spytech]

If this comes up as a duplicate, I apologize. I posted this response before and it disappeared.

Roger-
Thanks for the reply. That compressor should be perfect :)

With the black FFR konis, is adjusting the spring perch collar to preload the springs more the optimal way/actual way of adjusting ride height? On other coils I've had there were 2 collars - one for the perch to preload the spring, and another for the sleeve itself to raise/lower it on the shock body, which raised/lowered the ride height. The koni sleeve just spins freely, so wasn't sure if I was missing something.

[Made_In_America]

Here is a tool from Eastwood.

http://www.eastwood.com/external-coil-spring-compressor.html

Rent one for free from your local autozone

[Roger Reid]

Spy

There are 2 grooves and 2 snap rings per shock. My black Koni's are using the upper snap ring as a seat for the threaded sleeve. Do your sleeves go down to the lower groove and is that why you can't get a 5 inch ride height?

[spytech]

Spy

There are 2 grooves and 2 snap rings per shock. My black Koni's are using the upper snap ring as a seat for the threaded sleeve. Do your sleeves go down to the lower groove and is that why you can't get a 5 inch ride height?
The sleeves sit on the 2nd groove of the shock, so there is plenty of thread left on the sleeve (right now the perch is maybe halfway up it?). I just cant turn the perch/collar anymore without turning the sleeve at the same time, since the spring is now constantly pushing down on the collar that I'm trying to turn.

[crash]

I am not a spring/shock expert, but I know a couple people who are and they all have told me that too much preload on a spring is NOT a good thing. You should up the spring rate when excessive preload is required to get the car where it needs to be.

[Roger Reid]

The sleeves sit on the 2nd groove of the shock, so there is plenty of thread left on the sleeve (right now the perch is maybe halfway up it?). I just cant turn the perch/collar anymore without turning the sleeve at the same time, since the spring is now constantly pushing down on the collar that I'm trying to turn.

Perhaps drill a 1/4" hole in the sleeve near the bottom and use a spanner wrench like this one.

http://cgi.ebay.com/ebaymotors/SPI-Shock-Adjustment-Spanner-Wrench-Tool-Yamaha-Ohlin-/190504613265?pt=Motorcycles_Parts_Accessories&hash=item2c5af5b591

[mmaragos]

Ron-

Random question - did you have to compress your springs or anything to get the ride height up to 5" in the rear? I'm at 4.25" right now and I could get maybe one more turn out of the collars on my koni coilovers on the driver's side, and I can't get any more turns on the pass side. If the sleeves didnt spin freely it probably wouldn't be an issue, but as a result I have to figure out a way to compress the springs a bit so I can get those remaining turns.

I'm scratching my head on this one...are you adjusting the coilovers with the car on the ground (opposed to on a jack with the weight off the wheels)?

[Mike Downs]

No, I have the same problem as spytech. The car is in the air and wheels at droop and there is still preload on the spring. The front springs are loose when the wheels are at full droop.

[crash]

Are you guys saying it is difficult to adjust to proper ride height when trying to turn the spring collars by hand, or with a spanner wrench?

[Mike Downs]

Are you guys saying it is difficult to adjust to proper ride height when trying to turn the spring collars by hand, or with a spanner wrench?

I have a spanner on the nut/collar and holding the threaded sleave with large channel-loks and it is still difficult.

[mmaragos]

No, I have the same problem as spytech. The car is in the air and wheels at droop and there is still preload on the spring. The front springs are loose when the wheels are at full droop.

I'll have to see how much more room I have to adjust up. Mine are loose in the rear (and the front) with the car off the ground, but I don't know how much I have left...I thought quite a bit. That is with 4.5" of clearance.

[spytech]

I'm glad I'm not the only one with this problem.

I am trying to adjust with the wheels in the air, suspension 'unloaded'. This just seems like a half-assed coilover design, lol.

[spytech]

I had the wheels off tonight to do the FFR shock mount 'safety recall' fix and messed with the shocks a bit, or tried to rather. The driver side has a few more turns left - I could get it to 5" ride height if I wanted to. I turned it up once more so now it sits at 4 5/8" or so. The pass side is immovable, at a hair under 4.5". I just don't get why that side is so much different.

[Mike Downs]

I had the wheels off tonight to do the FFR shock mount 'safety recall' fix and messed with the shocks a bit, or tried to rather. The driver side has a few more turns left - I could get it to 5" ride height if I wanted to. I turned it up once more so now it sits at 4 5/8" or so. The pass side is immovable, at a hair under 4.5". I just don't get why that side is so much different.

How tall are your rear wheels?

[LS MAN]

I had the wheels off tonight to do the FFR shock mount 'safety recall' fix and messed with the shocks a bit, or tried to rather. The driver side has a few more turns left - I could get it to 5" ride height if I wanted to. I turned it up once more so now it sits at 4 5/8" or so. The pass side is immovable, at a hair under 4.5". I just don't get why that side is so much different.

Hey Spytech, the reason you can't tighten the rear springs anymore is that the rear shocks don't have enough rear droop - the shock is topped out. You are pushing against the shock, & without compressing the spring you can't tighten the spring adjuster anymore. These cars need a slightly longer shock in the rear.
The ride height problem in the rear may be an adjustment problem in the front. Try raising the RF 1 or 2 turns, & lowering the LF the same, & see if that doesn't even out the rear.

[spytech]

How tall are your rear wheels?
Mike - diameter is 25.91" (335/30/18)


Hey Spytech, the reason you can't tighten the rear springs anymore is that the rear shocks don't have enough rear droop - the shock is topped out. You are pushing against the shock, & without compressing the spring you can't tighten the spring adjuster anymore. These cars need a slightly longer shock in the rear.
The ride height problem in the rear may be an adjustment problem in the front. Try raising the RF 1 or 2 turns, & lowering the LF the same, & see if that doesn't even out the rear.
Ted - can't hurt to try that, I'll give it a go and see what happens. The front is level right now, so this might help.

[spytech]

Ted - can't hurt to try that, I'll give it a go and see what happens. The front is level right now, so this might help.
Gave this a try but to no avail. No matter how much I tweaked the corners the rear stayed the same. I figure I will only need to compress/preload the spring a quarter inch or so to get the turns I need out of it - is that something to be concerned with?

[JCHRacer]

Gave this a try but to no avail. No matter how much I tweaked the corners the rear stayed the same. I figure I will only need to compress/preload the spring a quarter inch or so to get the turns I need out of it - is that something to be concerned with?

No. A small amount of spring preload at full droop is actually preferable.

[crash]

No. A small amount of spring preload at full droop is actually preferable.

Joel- He's saying that he can no longer turn the collars to get the needed height out of the spring. From what I understand, this is while using a spanner wrench. IMHO, this is definitely too much preload. When you have to use spring compressors to get the collars where they need to be, there is too much preload.

[spytech]

Joel- He's saying that he can no longer turn the collars to get the needed height out of the spring. From what I understand, this is while using a spanner wrench. IMHO, this is definitely too much preload. When you have to use spring compressors to get the collars where they need to be, there is too much preload.
Yeah I had to use a clamp on the sleeve and a lot of elbow grease (while pinching the spring at the same time) to get that last turn out of the collar on the pass rear coil.

Longer rear shocks, is that the answer? A slightly shorter spring at a slightly heavier rate?

[JCHRacer]

If you need to compress the spring 1/4 inch in addtion to using the spanner wrench.....yeh, I agree...too much preload.

Shorter spring but the same rate won't help....you will still need to a compressor. Higher rate spring will solve the preload problem, but change the handling characteristics.

Taller tires?

[crash]

Yeah I had to use a clamp on the sleeve and a lot of elbow grease (while pinching the spring at the same time) to get that last turn out of the collar on the pass rear coil.

Longer rear shocks, is that the answer? A slightly shorter spring at a slightly heavier rate?

Unless your shock is bottomed(extended all the way, or nearly all the way) then this wouldn't be a factor in adjusting your rear ride height.

You should go to a heavier spring that is the SAME length. This will mean that with the collars in the same position, the vehicle will ride higher because the "rate" (lbs per inch of compression) is higher. Conversely, the spring will compress less to give the same height distance at the frame, and you should be able to make your adjustments without using a spring compressor.

As witnessed on the FFR PDG GTM, the higher rear spring rate may also be beneficial to the GTMs performance. Just don't go too much or the ride will get rough. For fine tuning I usually change by no more than 50 lbs in spring rating, but it really depends upon the situation and the lever ratio of the suspension system.

Probably the best thing to do is to let Ted and Ron figure out what they think works best on a street GTM and use them for a "benchmark". :)

[spytech]

Thanks for the responses guys. I technically did not use an actual spanner wrench. I had a long handled allen that fit in that I used to get the last turn out of the thing, close enough I guess though? I appreciate the education on how the spring rates, etc would affect things.

I've been contemplating the change to 800# rear springs for a while so I might be doing that sooner than later now.

[Cooluser23]

Do you guys put a sand bag in the driver's seat, to account for the weight of a driver?

[crash]

It all depends. If you know what setup you want and has been proven to work on the track, it is an easy enough process to measure what those numbers are without the driver, and then set the car up to those numbers...assuming the drivers weight doesn't change much.

Generally speaking though, especially for an initial setup when you are just trying to get a baseline, the car is usually measured and setup with the driver in the car. Requires more people to do this, but is much more accurate. If you are in a pinch, the sand bag thing, or anything else of weight to compensate, works, but is not ideal.

Again, for a street car, it is highly unlikely you will even notice the difference between a real body and sand bags, so it should work just fine. :)

[The Stig]

Bump! This is an important thread that needs to be kept in view for everyone to read at least a couple of times.

[VD2021]

Here is a video on using HP Tuners - scanner.


http://www.youtube.com/watch?v=h9ii-DOhd3c

Ted and Ron,
I really eager to see some tuning. Any ideal when you Guys will be able to continue educating us? Thanks.

[LS MAN]

Hey Vidal,
Ron is working on his new engine, should have it running soon.
We will get back to some engine & chassis tuning then.

Thanks,

[The Stig]

Bump! Any new updates on Suspension Tuning?

[mendo]

I got to ride in Ron's Car today. (he did not get it sideways!) I am VERY impressed at how nice it rides. I fully expected it to be harsh and jarring, not even. He and Ted showed me all the components and part and talked about what they are doing and where they are going. They are all over this, I got more information than I can remember! I am lucky enough to be close to them and will be leaning on them as I build mine. Then, as a bonus, a very nice Daytona Coupe showed up! I then learned about assembly tips as this is an extreamly clean build and he was very gracious to patiently answer all my questions and show me whatever I asked about. Ted and Ron are great guys and the stuff they create is excellent!

[LS MAN]

We have been testing one of our new shock packages from Genesis Shocks.
These are really high quality racing shocks with advanced features.
Really happy with the results.

[The Stig]

We have been testing one of our new shock packages from Genesis Shocks.
These are really high quality racing shocks with advanced features.
Really happy with the results.

I'm looking forward to hearing more about this.

[LS MAN]

I am very impressed with these shocks.

The adjustable models feature an indicator to show the setting, no more "counting sweeps"
They have a unique spring hat, it installs at an angle, then locks onto the shaft.
The shock body & spring adjusters have a small groove, just slip in a small tie wrap to lock the adjuster, no set screws to damage the threads.

770977107711

[rev2xs]

Cool, what model of shock are you guys running? Is it the GB3?



I am very impressed with these shocks.

The adjustable models feature an indicator to show the setting, no more "counting sweeps"
They have a unique spring hat, it installs at an angle, then locks onto the shaft.
The shock body & spring adjusters have a small groove, just slip in a small tie wrap to lock the adjuster, no set screws to damage the threads.

770977107711

[Ron565]

Thanks David,

It was a pleasure meeting you. I can remember the learning curve when I first started my GTM endeavor. I still have the old LS6 tune in my PCM. I have lost a lot of power. That's next on my things to do list.

Don is a skilled craftsmen and it shows on his Daytona coupe.

Welcome to the family, Ron

[Ron565]

Cool, what model of shock are you guys running? Is it the GB3?

Hi Revxs,

They are custom valved and so far I am very impressed. That's one of the things about Ted he gets it right the first time. Lots of homework and testing.

Ron

[sk7500]

Hi Ron:
Frank said that he got a ride in your car and it was awesome. He also said you wouldn't turn the heater on for him and he almost froze. He didn't know you could ride in a GTM at less than 140 degrees. Next time he'll bring a coat.;)

[rev2xs]

Hi Ron,

I'm just asking out of curiosity, would you recommend these shocks for street use as a possible replacement for the black Koni's people are having so many issues with?

Thanks, Tom



Hi Revxs,

They are custom valved and so far I am very impressed. That's one of the things about Ted he gets it right the first time. Lots of homework and testing.

Ron

[LS MAN]

Hi Ron,

I'm just asking out of curiosity, would you recommend these shocks for street use as a possible replacement for the black Koni's people are having so many issues with?

Thanks, Tom

Hey Tom, these shocks are tuned specifically for the GTM. They solve all the issues caused by the Koni's (black or yellow).
Along with the sway bar & spring package, they provide excellent handling, ride quality, & street/track performance. We will offer 3 different shock packages, to meet different budgets, chassis/tire combinations. We will have more info by next week.

Another note, we have Ron's car set with stock Gen1 caster, about 2 deg, so don't assume that just adding caster will make theses cars stable by itself, our experience is that it won't.

Thanks,

[The Stig]

Another note, we have Ron's car set with stock Gen1 caster, about 2 deg, so don't assume that just adding caster will make theses cars stable by itself, our experience is that it won't.

Thanks,

Great point Ted! Thank you. That was one of the things that I've been curious about as well.

[mikespms]

I recently drove my car for the first time and before doing so I did a quick alignment. I noticed when I set the caster that the passenger side at the limit of the adjustment was about 2 deg. less than the drivers side. On the rear at ride hight the closest to zero camber I could get was neg. 1.5 deg. and almost neg. 2 deg. by going up to 6.5 in. ride hight I was able to get it to zero. I have had to correct alot of things on my car so far, the radiator tabs were reversed the upper shock mounts had to be moved back the trans suport bracket was more thant 2 in. out alignment. Is this a comon problem with the GTM's rear suspension? If so is there an easy fix?

[VD2021]

Ted, Ron,

Its awsome that Ron's GTM is up and you Guys are doing more develpoment. I'm also eager to see the HP Tuner tuning as well. Keep up the Outstanding work.

[Ron565]

Funny you should mention that. I had a tune done a long time ago by another local shop before Ted had HP tuner. The guy locked out my PCM so I had to send it to SpareECM.com. They have special software to get in and unlock it so Ted I can retune for the larger displacement engine. We will post the tuning process.

Ron

[Ron565]

Hi Ron:
Frank said that he got a ride in your car and it was awesome. He also said you wouldn't turn the heater on for him and he almost froze. He didn't know you could ride in a GTM at less than 140 degrees. Next time he'll bring a coat.;)

Hi Steve,

Tell Frank I'm real sorry not getting back to you. No excuses I just spaced it out.

It's really easy to do, especially after the fact. I bought some Keep It Cool 5/8 " jute matting that has an aluminum reflective barrier on one side.
I slid it between the coolant hoses and the rest of the crap that's in the back bone. I just isolated the coolant lines and used some aluminum tape on both sides to hold it in place and to keep hot air from escaping into the tunnel. I left it open somewhat in the front of the tunnel so air could go through the tunnel and escape through the engine compartment. I also bent a 3/4" lip on the belly skin at the seam so it would help move air through the tunnel.


TTYL, Ron

[Kempo]

Guys, any news on the shocks?

[LS MAN]

Hey Hugo, we have 2 more sets of shocks coming in tomorrow.
Should have them tested next week, will post the info then.
We will have 3 different options available when we have completed testing.

Thanks,

[The Stig]

Thanks Ted.

Looking forward to hearing about that as well. Waiting on the shock purchase before I start rebuilding the front and rear control arms and adding the front sway bar kit.

Mike

[LS MAN]

Bringing this up for those that may have some set-up questions - check out the videos for some tips.

[The Stig]

Bump! This is an important thread that needs to be kept in view for everyone to read at least a couple of times.

[narkosys]

This is some very good information. Keep up the good work! I am definitely adding your sway bar kit and genesis shocks with coil overs to my parts list.

P

[VD2021]

Ted and Ron,
I really eager to see some tuning. Any ideal when you Guys will be able to continue educating us? Thanks.


Hey Vidal,
Ron is working on his new engine, should have it running soon.
We will get back to some engine & chassis tuning then.

Thanks,

Ted,
Any chance you can do a MAF tune/calibration video? Preferably without a wide band and dyno. Thanks.

[VD2021]

Bump

Ted,
Any chance you can do a MAF tune/calibration video? Preferably without a wide band and dyno. Thanks.

[flickery8]

Bump, it has been a couple years since this thread was posted. To my knowledge it contains the most precise suspension info on the forum, but I am curious if anything posted in the past two years would add to this great info? Thanks to LS MAN, looks like the shocks are still available? Any feedback from customers? It is almost time to get back on the road and track :)

[The Stig]

Bump! Lot's of great information in this thread.

Mike

[Shoeless]

So this is my first time stumbling across this thread and thoroughly enjoyed every bit of it. Lots of insight on how to set the GTM up for a baseline, and more importantly to me, how to do it myself without having to pay someone to put it on a rack.

My kit should arrive in about 4-6 weeks and I can't wait to dig in.

[kabacj]

Glad to hear it.

Plenty of help here when you get to the tuning part

The GTM is a racecar that you can register. If you plan on driving it on the street at legal speeds very basic setup and you are good to go.

If you are planning on breaking the sound barrier let us know and the forum will provide the setup you need.

I'm excited for you. This build is so much fun.

Keep us up to date on progress.

John