Flickery's GTM #72 Track Performance log

Hey Fickery.

I am willing to bet that your issues are due to lose cam adjusters or lower probability another loose part.

you should not have ANY movement in the rear suspension.

What you describe is very much like what if feels like when the cam adjusters are loose.

Trust me if one of your rear tires is pointing randomly based on the torque applied to it the car will be un driveable.

I dont think you could install the tie rods incorrectly unless the hole in the upright was rounded out and the pressed in stud was wobbling around.

However I have had my cam adjusters loosen up and its pretty terrible. I thought something broke on the car it was so bad.

In a pinch you can just put a ton of torque on the nuts, but it does not hold for long. Corvettes have the same problem on the track. The removal of the rear adjusters is actually more important then the front adjusters.

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Originally Posted by kabacj

Hey Fickery.

I am willing to bet that your issues are due to lose cam adjusters or lower probability another loose part.

you should not have ANY movement in the rear suspension.

What you describe is very much like what if feels like when the cam adjusters are loose.

Trust me if one of your rear tires is pointing randomly based on the torque applied to it the car will be un driveable.

I dont think you could install the tie rods incorrectly unless the hole in the upright was rounded out and the pressed in stud was wobbling around.

However I have had my cam adjusters loosen up and its pretty terrible. I thought something broke on the car it was so bad.

In a pinch you can just put a ton of torque on the nuts, but it does not hold for long. Corvettes have the same problem on the track. The removal of the rear adjusters is actually more important then the front adjusters.

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I believe I have about 30 sets of the shim kits, http://www.myraceshop.com/Alignment_Shims.html, in stock. :)

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Originally Posted by flickery8

I am certain I will need to install Crash's shims on rear (only put them on front).

At this point I am pretty sure the issue is rear steer. I had several mechanically inclined racers at Autobahn check out the play on my tire (wiggling laterally with hands) and all said it was way too much. This is the case on both wheels. They also crawled under the car while I wiggled and they all pointed to play in the new tie rods. Unfortunately it is unclear what part is moving (well it all moves but not sure why). I tried to tighten everything, but the chassis mount is hard to reach and it spins (though it did tighten more). Also, someone suggested the bolt may be smaller than the hole (where it mounts to chassis) and therefore has some play.



Also was asked if the kit included any bushings for that joint. Were there instructions? I will have to ask the shop.



Does the orientation of the ball joint matter? I can rotate it so the bolt is at a 3-9 o'clock orientation or any other.



As u can see in this video with car on ground I can rotate tie rods. http://youtu.be/IyCVhOedy8A

Is that normal?

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Just watched your video. wow! I'm not surprised. That clicking when you pull on the tie rod should NOT happen. That's an insane amount of play.

The stud in the upright should fit very snugly on the rod end. Zero play. None. Not at all! Wow those are not installed correctly.


Send me a personal message. Happy to discuss this with you. That much play and I'm not surprised you are having issues.

John

We also sell aircraft grade rod ends...http://www.myraceshop.com/NHBBNMB_ART.html

:)

Crash may be right, could need more chassis support. It is hard to tell what is allowing the movement. Please watch the video, at the end you can see more.

https://youtu.be/IJya14niX6k
__________________
Facebook.com/FastGTM

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Originally Posted by flickery8

Crash may be right, could need more chassis support. It is hard to tell what is allowing the movement. Please watch the video, at the end you can see more.

https://youtu.be/IJya14niX6k
__________________
Facebook.com/FastGTM

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Can you take some pictures of where the tie rod mounts to the frame? Also see if you can mount the camera on the ground so it's not moving when you move the car. I would agree that it looks like the frame is bending.

But it wasn't till I mounted full slicks and started pushing hard that I got any flex on that mount. I measured the frame flex pre beefing it up. It bends thousandths of an inch. You def can't see it without a dial indicator.

I drove a full season with r compound DOT tires without issue.

Do both wheels move that much?

I remember you said you went off track a few times?
I would very closely inspect the frame side tie rod mount for cracks.

Good video. We are close.

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Originally Posted by kabacj

Can you take some pictures of where the tie rod mounts to the frame? Also see if you can mount the camera on the ground so it's not moving when you move the car. I would agree that it looks like the frame is bending.

But it wasn't till I mounted full slicks and started pushing hard that I got any flex on that mount. I measured the frame flex pre beefing it up. It bends thousandths of an inch. You def can't see it without a dial indicator.

I drove a full season with r compound DOT tires without issue.

Do both wheels move that much?

I remember you said you went off track a few times?
I would very closely inspect the frame side tie rod mount for cracks.

Good video. We are close.

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Thanks for your help.
It is really hard to see what is moving that should not. Both wheels move like this. I could see better if I remove wheel but then I can't get leverage to wobble the hub much. I don't see any cracks on the inner toe mounting bracket. I am not sure the chassis is moving. The car is jacked up so everything is moving.

There is play in the tie rod. For example, pushing it in and out on its horizontal axis. I stuck my finger behind the ball joint between the ball and bracket. Then I pushed the rod in and I could feel pressure on my finger. I am going to get the huge Allen wrench required to tighten that shaft next. What would allow play in the tie rod? I am wondering if my new tie rods were shot after 5 minutes on the track. I didn't notice this on the two hours of interstate driving after they were installed.

Wow! That is all I can say about the amount of play. I watched the end of the vid several times. It looks like tightening up the bolt through the rod end will take out a little of the play but very little. It looks like the bracket is loose. The bracket moves while other things in the background stay solid. My bracket looks a little light for track work but as John says it might move a few thousandths, not tenths. Tighten up the rod end bolt and then do what ever you need to to find the source of the movement. Get a friend to wiggle the wheel while you feel for movement like you did at the rod end or take the wheel off and bolt something to the wheel studs where you can wiggle with one hand and check for movement with the other. If the bump steer stud on the hub arm is tight (should be!) maybe just put a socket on it with a breaker bar and pry back and forth. The nuts are easily replaced, put a vice grips on them and wiggle away. Anything to get a little leverage on the tie rod; it should not take much.
Ken

I finally got the 3/8" hex to tighten the shaft that attaches the heim joint to the chassis. It was a bit loose. There is now a little less movement at the wheel, but I am considering replacing the hub as there is still play and maybe the bearing is bad (though there is more play horizontally compared to vertically which would indicate tie rod still).

I have read on corvette forums opinions ranging from only use SKF Performance Wheel Bearings (which cost $350 each) to just get the $50 cheap ones as they will all fail after a couple of years. Curious what people would recommend for a car that sees 6 HPDE track weekend per year.

At six "race" weekends per year you are really on the bubble. We got about half a season out of the cheap hubs, which would be roughly 6-8 race weekends. On the other hand, once we went to the SKF 5049 race hubs we have not had any issues since. We replace them at the end of the season for the 25 hour race, and then run the next years season on them as well. This year that is about 12 race weekends plus the 25 hour race which is more than a season of regular racing. Remember that our races are 3 hours long minimum, so just a race weekend for us equates to a few regular race events.

My opinion is that if you are going to keep the car, and if you are really going to do a few track events per year, then the 5049 hubs are worth it. Since the hubs give you lots of warning before they really go bad, on the other hand, it may be cheaper for you to just stick with the cheap stuff. For us, it is a requirement to run the race hubs.

I think by tightening everything AND replacing wheel bearing it is stiffer. Not sure what to expect as perfect. At the beginning of this video when I show the new bearing side I first shake so hard I think the entire car is probably moving on the jack stands. There is a couple seconds where I use less force and compared to the other side with the same force I think there is improvement.

http://youtu.be/-dRGr-TQjcw

Haven't found the shims to replace the cam bolts, but they are tight. Also, I did have the 3 torx bolts (star) come loose once before but they were good.

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Originally Posted by flickery8

I think by tightening everything AND replacing wheel bearing it is stiffer. Not sure what to expect as perfect. At the beginning of this video when I show the new bearing side I first shake so hard I think the entire car is probably moving on the jack stands. There is a couple seconds where I use less force and compared to the other side with the same force I think there is improvement.

http://youtu.be/-dRGr-TQjcw


Haven't found the shims to replace the cam bolts, but they are tight. Also, I did have the 3 torx bolts (star) come loose once before but they were good.

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I hate to say it but something is still not right.

What if you take the wheel off and just try to move the suspension with the brake disk?

Try this. Get four 14 inch leneolium floor tiles should be 99 cents at Home Depot.

Then if you have it make a sandwich of two tiles with glass beads ( for a sandblasting) or you can use grease that's messy however

Put the rear tires on the tiles on the ground. Then try to move the tires.

Your car will not shake as much so it's easier to see any movement.

I measured the movement in a healthy stock GTM using a dial indicator just twisting the wheel with the car on the ground.

http://i1073.photobucket.com/albums/...pseberzzmv.jpg

The whole setup only moved thousandths of an inch.

I think the next step is to try to isolate where the movement is coming from.

The tie rods were clicking when you pulled on them. Is that still happening? There should be zero movement in that part of the system

What about your bushings. How old are they?

Try to move the upper and lower a arms back and forth. Any play there?

what about your ball joints. How old are they?

It does not look like the car is shaking in your vid. I think something is still wrong

I agree with John, something is still not right.
My suggestion is to remove all of the suspension components and look for failure points and play in each component.

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Originally Posted by flickery8

Not sure what to expect as perfect.

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With my car supported by its frame on a lift, I have absolutely no perceptible motion when I try to wiggle the rear wheels. None. Zilch. Zippo. They shouldn't move at all - other than spin, of course ;) .

-Michael

Yeah, I'm sure you guys are right. I was just really wishing I had figured this out. I did have someone wiggle the wheel for me today and I could feel movement between the upper control arm bushing and the mounting bracket. I guess 1/100th of an inch there would be 1/10 of an inch on a 26" tire. I took a pic where you can see a gap between bushing and bracket. I ordered the pfadt bushing kit and hope to install it tomorrow night. I would guess they are ten years old.

Tie rods seem good, no movement I can detect. Ball joints are probably 10 years old also. I unseated both and removed knuckle to replace the hub. Didn't see anything odd. I can get a good grip on the upper joint and feels solid. Bottom is hard to get hold of. Any tricks to checking ball joints other than lifting up on tire with a 2x4 and looking for deflection?

So finally got some time to spend on the car and I am still working on replacing all of the bushings. While removing the front cam bolt in the lower control arm on the rear of the car (the one used to adjust the camber) I noticed what may have been my problem. Many people had suggested the bolt could be loose, which it was not. However, you all were correct when you told me to use Crash's shim kit. Despite it being tight it would have had play. Look how the cam has worn and the thread on the bolt has stripped.Attachment 51423

Wow. Well there you go. Problem solved. That setup would not do much to prevent movement

Especially with one loose wheel. Picture the casters on the front of a shopping cart. Not good for high speed stability!

I'm glad you found it.

That will do it right there. Glad that you found the problem.
When you swap over to shims make sure that you have a very honest conversation with your alignment shop.
I just had an experience with a shop that cried an absolute river that I was using shims. They simply could not get their head around something that was different to them.
It made me realize that although they boasted about being experts in performance suspension setups, they were just knob twisters and button pushers.

Well, I am about to have a break down. The rear tire still wiggles when I grab it and move it on its horizontal access (vertical access seems to be less but not sure). I have replaced the bushings, installed the camber shim kit, replaced the hub assembly, replaced the tie rods (put the old tie rods back on to test) and examined the tie rod mount for cracks. The only thing I have not replaced would be the ball joints on the control arms.

It is possible that now that I have replaced the cam bolt with shims that the problem of the car rocking back and forth under hard acceleration will be gone. Maybe the new tie rods, being stiffer, caused the damage to the cam bolt as this all became bad immediately after changing the tie rods (though the new tie rods were an attempt reduce some small amount of bounce). One other idea I have is to increase the rear toe, but that doesn't fix the problem. The only other idea I have is that for some reason the rotor isn't being held properly against the knuckle.

Ok, I think I made some progress this week and I'll update later. For now, rather than whining, I thought I'd share how I solved a problem. Replacing the stock bushings isn't too bad once you have a method. Here is a cheap effective way to press the bushings.
https://www.youtube.com/watch?v=7qyS4_5-tNM

After installing the bushings and putting car back together I saw I was running positive camber on the rear. I had marked the spot, but this just reiterates how bad those cam eccentric bolts are. So, I used Crash's handy shims and they look great. I tried setting toe with my toe plates, but I could tell I was not on center. My rear tires stick out further than the front so I don't think a string alignment would work though I never tried. I took the car to GM shop and got it aligned. The rear camber was right on. I used an app for my iphone to ball park it and my main concern was consistency right to left. Problem one resolved, Crash's shim kit.

Now, the other good news, I found something else that was not right. The set screw on the perch of the driver rear spring was loose and that side of car had dropped half an inch. The initial camber numbers were not symmetrical but once we raised the spring back up the numbers did match. I believe this was the second issue, I was rubbing the tire on the fender under hard acceleration. Since I went to sport cup 2 tires I had to use a larger size that leaves little clearance but with the rear set at 5.5" it fits. I really need to get smaller wheels so I have more tire options.

It is very hard to simulate track conditions on the street so I can't say for certain I have it all worked out. Fortunately I am off to NCM (National Corvette Museum) race track for the weekend. I hope the rain stays away because I just don't go in the rain.

alignment for this weekend
Front
camber -2.3 -1.8
caster 4 4
toe 0.09 0.16 degrees
rear
camber -0.8 -0.7
toe 0.09 0.12 degrees

Took the long haul from Missouri to Ohio to visit a great track that makes me a bit nervous, Mid-Ohio. Oddly, second time here and the water pump went out again, just like last time here! Wish I had GoPro of me going sideways past China Beach but not leaving the track as I dropped water in front of my rear tire. I waved at the flag station that something was on the track. The next corner I realized, uh oh, that is me on the track. I was sideways every which way but never left the pavement. I was close to pit out so decided to drive in grass but just couldn't make it as fail mode kicked in and it was just too hot. I decided to add a tow point mounted to the thick metal plate under radiator as a "best for now" a while back. It lasted for a while as they towed me off the track and to the paddock but I didn't keep the line tight and POP busted out the rivets. No big deal, I always carry rivets to the track and it is great to just run to the local parts store for ls6 parts. Only missed two sessions. A young nephew visited me at the track and I explained all of my important tools I carry: rivets, zip ties, duct tape, and a big hammer (and some wrenches). As for the rest of the weekend, I need to write up some info on my suspension changes and what I have learned.

Well, it is never boring.

We headed to Tulsa, OK to run Hallett last weekend. As I got ready to go I realized my battery was bad. I am using an Odyssey battery which is special order only. I decided to get a battery for my truck (which will need one soon) and strap it in to the passenger floor board. Worked well, easy fix.

I had an overheating issue a couple weeks prior and I was worried I may have a problem with the head gasket. Burped the system and didn't run the AC anymore and problem did not come back. However, all weekend at Hallett I was running 220-230 and I was very distracted and concerned. My last track weekend my water pump went out and I had to be towed for the first time and that sucked.

Saturday went pretty well. I was taking it easy and trying to remember the track. I had been here once before about a year ago. It is a nice track with some elevation changes. There are no long straights but the longest is a bit concerning as if you were to not turn at the end of the straight you go into the forest. Most tracks have pavement runoff at the end of the main straight but not here. Also, the tire wall only helps if you turn but don't make the turn. If you go straight you are screwed. They also run this track backwards last session of the weekend. I have always passed on that opportunity.

For the excitement. I had seen cars going off at a high speed turn all weekend. I entered the turn fast (maybe 80?) but all was well. Suddenly I was backwards. I believe I did about a 360 on the asphalt before going into the grass. It was very bumpy and I did another 360+, it was very jarring but I stopped shy of the tire wall which was 50+ yards off the track. Somehow the car didn't die and I drove back on to the track. I had to complete 70% of the track to get to pit exit. I wasn't sure if I damaged anything but I went slow.

When I got back to the paddock I saw my passenger rear body was nearly on the ground. I was able to get a jack under the rear and we discovered the broken suspension mount. I am sure this broke before I spun and was the reason for the spin. It was so sudden and unexpected.

I am now trying to figure out if I have the FFR "fix" or the original part. I called FFR and they were not super helpful. If this is not the fix then my next question is how does the FFR fix compare to the Vendor's fix which can be purchased?

https://www.dropbox.com/s/olgtubrqpm...%20AM.jpg?dl=0

https://www.dropbox.com/s/wt74c3filn...%20AM.jpg?dl=0


Gary

Oh man I stumbled on this thread and got invested in to the story! How does it end? does Flickery8 git it repaired and sorted? does the villain play get found? does the supper hero Crash and the Minions help Flicker8 cross the finish line and tame the beast GTM? I have to Know! What a cliff hanger! From the way back cold case files of 2016! If any body can solve this case, please chime in!