Independent Suspension Setup

[METAL C6R]

So.... due to recent events, I haven't been too active on the forums. A general lack of motivation for all things.
I thought I had given you guys a long enough break from my crazy ideas so... fair warning, I'm back! LOL ;)

I was researching and budgeting parts for the 'donor'. Initially, I started looking at this as, "lets try to utilize as many parts as I can from the donor as possible." I thought that in some way I might be able to utilize the suspension geometry of a Viper with the mounting locations, control arms, spindles, wheels, rotors, calipers, and all. that and a vast amount of time making sure I didn't royally !@#! things up. <- hence research.

http://assets.nydailynews.com/polopoly_fs/1.2215387!/img/httpImage/image.jpg_gen/derivatives/article_635/2016-dodge-viper-acr.jpglink (http://www.edmunds.com/car-reviews/track-tests/2013-srt-viper-gts-suspension-walkaround.html)


I noticed a few things though. The Vipers control arms are both at an angle, for both front and rear. Supposedly, providing both anti-dive and anti-squat. Neither arm is truly parallel to the ground.
OK, I can understand the whole anti dive and squat thing. However, to me this still doesn't seem right. (something seems crazy to METAL??, WHAT!?!!?!? lol) I don't have a suspension calc program to verify any of this and I am sure that's what the engineers at different car companies get paid to do this sort of thing. Yet for some reason I feel this is an overlooked factor, because I believe the original concept for the anti squat comes from solid axle geometry. Not double wishbone.

http://jddracing.com/images/chevelle/IMG_2153%20copy_edited-1.jpghttp://www.how-to-build-hotrods.com/images/rearsquat.jpg


Yes there are some diagrams that show a-arms, but with the travel of the arms being perpendicular to the direction of travel that this diagram is aiming for. it's my assumption that the A-arms actually amplify the % of anti squat you get. not only that but it adds caster to the equation, as well as taking the circular pattern that the arm's take relative the the front of the car, and making it more elliptical. Thus decreasing the amount of travel that the A-arms can take to maintain near proper camber. hence it is in a very extreme way of looking at it working against the whole concept that the double wishbone suspension is working towards. yes you can reduce the amount of spring travel and the subsequent consequences of the angled arms by increasing your spring rate and making the car stiff and quite a car to handle. again. working against what suspension is intended for. Admittingly, caster doesn't mean anything to the rear wheels with cv axles but that can't be said for the front end.

Take this comparison video. 2 very similar cars, yet one is noticeably better.
Laguna Seca - Viper GTS VS C6 ZR1 (https://www.youtube.com/watch?v=ExgJxgNSWtk)
here is a pic of the vettes "newer" suspension. Sorry for lack of better picture, or actual year relative to the video, but it seems that there is no anti squat built into this irs. .. and it handles better.. hmmm.
http://blog.caranddriver.com/wp-content/uploads/2013/07/2014-Chevrolet-Corvette-031-626x352.jpg


Additionally, with the A-arms being pivoted this solidifies the "%" of anti-squat or dive that you get. not easily adjustable without taking off everything to get to that .58" spacer that others have used to align the arms. FFCARS:anti-dive-why-uca-angled (http://www.ffcars.com/forums/35-autocrossing-prosolo/43552-anti-dive-why-uca-angled.html) That, and re-aligning everything after you re-assemble it.

On a more absurd note ( and METAL way of thinking!! ) , Koenigsegg, I feel came up with a pretty unique and ingenious Idea to go about providing anti-squat yet keeping a truer suspension geometry.
/Inside Koenigsegg Triplex Suspension Video Explanation (https://youtu.be/bbgjRBT4ltM?t=55s)

http://www.blogcdn.com/www.autoblog.com/media/2011/03/43-koenigsegg-agera-r-geneva.jpg



So in general, donor car and parts aside,
What are your guys general opinions, point of views, experiences, thoughts with anti dive and anti squat?

Ideally I think I would want to run absolute 0%, both arms parallel to the ground. If I am really ambitious at the time, I would like to experiment with the Koenigsegg design. But I feel that's out of my league at the moment.
Conclusion, I'm insane. ;) lmao

[crossle45f33cf]

You're absolutely right!

[GThompson]

My thought is that, by the time you've invested all of the time and money into completely re-engineering and fabricating everything required to make the suspension what you seem to want it to be on a Coupe, you could have bought a Viper or Corvette and been enjoying driving it, most likely for a good period of time.

The suspension in the Coupe isn't that high-tech, it's 20-25 year old passenger car tech at best. In my mind, comparing the stock Coupe/Roadster suspension to a Viper or Corvette suspension is like comparing an IBM 486 computer to an iPhone. Will it work and can changes be made to improve it? Yes. Are there less-expensive options available immediately at lower cost? You betcha'!

That said, good luck with your project! I'm 8 years into my build and the end is not yet in sight...

[edwardb]

The newly released 2015 Mustang IRS is also available in the Coupe. This is a significant upgrade from the previous IRS option. http://www.factoryfive.com/whats-new/factory-five-launches-2015-independent-rear-suspension-option/ I like mods as much as the next guy, within reason I guess. If you want a Viper or Corvette suspension, then I agree, buy a Viper or a Corvette.

[CraigS]

I just checked my Carroll Smith Tune to Win book to refresh my memory on IRS anti-squat. He says a max of 20% can be used. Going for more than that will result in power on oversteer exiting a corner. Anti-dive also causes problems if excessive. It causes the suspension to be stiffer w/ brakes applied which can cause problems over rough surfaces/ bumps. I see it used more in standard cars w/ soft springs which I assume allows them to get away w/ it. Note that the old SAI mod for our FFRs changed the SAI and also reduced the amount of anti-dive. I think that is because we are in the stiffer suspension range compared to a lot of street cars so anti-dive plus stiff springs is thought to be too stiff. Note the change has been incorporated into the current FFR chassis.

[METAL C6R]

My thought is that, by the time you've invested all of the time and money into completely re-engineering and fabricating everything required to make the suspension what you seem to want it to be on a Coupe, you could have bought a Viper or Corvette and been enjoying driving it, most likely for a good period of time...

Currently I am trying figure out decisions with my life in general. So, for the mean time I am just biding my time the best way I know how.... "re-inventing the wheel" ..because I'm weird like that.
And yes I could be in a C6 or 7 right now, but I set a goal to build something better for a cheaper $ amount and I feel that a project like this is well within a base price of ~$65k-80k of a Z06. And You are absolutely correct, No doubt if I was to put a $ amount on the re-engineering and R&D that I will put into this, It wont be worth near as little as a Vette or Viper. But I am fine with that you can't put a $ amount on enjoying what you do.



The newly released 2015 Mustang IRS is also available in the Coupe. This is a significant upgrade from the previous IRS option. http://www.factoryfive.com/whats-new/factory-five-launches-2015-independent-rear-suspension-option/ I like mods as much as the next guy, within reason I guess. If you want a Viper or Corvette suspension, then I agree, buy a Viper or a Corvette.

Yea, I am really interested in the new IRS package. I haven't looked into the rear-end just yet.. Just trying to go slow and go one element at a time.
I forgot to mention your thread in here, I was in a bit of a rush when I posted this, my apologies. I am very interested in it as it's likely that I will use it in my build. I am leaning in the direction of a complete kit with the new IRS package and making modifications to it from there.

At this point I feel like buying one of those cars is 'giving-up'... yea.. I am not going to lie, once the C7 came to the market I was on the fence for quite a while. Hell, I still am, That car is nice. I have always liked corvettes, therein lies the method behind the name. Go Jan Magnussen! :cool:
I just feel that the hands-on experience of building one, and the technical know-how that I will gain once I do it, is something I can't replace.



I just checked my Carroll Smith Tune to Win book to refresh my memory on IRS anti-squat. He says a max of 20% can be used. Going for more than that will result in power on oversteer exiting a corner. Anti-dive also causes problems if excessive. It causes the suspension to be stiffer w/ brakes applied which can cause problems over rough surfaces/ bumps. I see it used more in standard cars w/ soft springs which I assume allows them to get away w/ it. Note that the old SAI mod for our FFRs changed the SAI and also reduced the amount of anti-dive. I think that is because we are in the stiffer suspension range compared to a lot of street cars so anti-dive plus stiff springs is thought to be too stiff. Note the change has been incorporated into the current FFR chassis.

So.. I'm not crazy?!?! lol
I am not familiar with the SAI mod. I haven't looked to far into it at the moment. Definitely on my radar now though Thanks!
FFCARS:274139-sai-mod-done (http://www.ffcars.com/forums/21-ffr-type-65-coupe/274139-sai-mod-done.html)
TFFF:SAI Mod or Not (http://thefactoryfiveforum.com/showthread.php?10356-SAI-Mod-or-Not)
IMSASUPERS:Suspension Geometry Relations (http://ismasupers.com/downloads/tech-talk/Tech-02%20Suspension%20Geometry%20relations%204.pdf)

[HCP 65 COUPE]

Metal,

Correct me if I'm wrong but does the c6 zr1 not have magnetic shocks with active computer control an active suspension can be tuned for anti squat and anti dive, it is constantly changing wheel rate at all 4 corners of the car depending on driver mode and a million other variables it maybe how it over comes the lack of mechanical anti dive and anti squat.

[METAL C6R]

Well, I learned something.
The magnetic ride control was an optional feature for the base model C6's and the Z06 and ZR1 had them standard.

They have kind of a weird set up were its actually cross leaf spring suspension. you get a few benefits from it, IE: lower center of mass and a sway bar effect.
Left is C7, Right is a cutaway showing leaf spring set up this is similar for C5-C7's

http://image.motortrend.com/f/roadtests/convertibles/1307_2014_chevrolet_corvette_stingray_z51_first_te st/54993555+w644/2014-chevrolet-corvette-stingray-z51-suspension.jpghttp://www.westcoastcorvette.com/images/Product/medium/5046.jpg

[mstephenson51]

I'll tell ya my $.02 worth.... and its worth just that but might give you a little perspective on what you propose attempting.

I come from working on Indycars, and when it comes down to it all of these systems are fundamentally the same. They all have in essence a double wishbone setup, springs, shocks and an anti-roll device. With the exception of the Koniggzegigzegigzegigzeg. They run whats usually known as a third spring setup. There are advantages and disadvantages, but in my opinion a setup like that makes geometry change a nightmare. With a standard double wishbone and roll bar setup, it makes a very simple task out of designing simple parts that can allow geometry change easily. Anyway, back on topic: If indycars and F1 can achieve massive cornering speeds with simple double-wishbone and roll bar designs, then a type 65 coupe can do it too. These cool cars with cool setups do it that way for sever reasons, including packaging/size constraint, cost to manufacture, serviceability, etc. The trick is all in how you set it up. So if you get something fab'd up that you can change geometry around (instant centers, camber, anti's, etc) then you can tune it to drive how you want it to.

I recommend you get a book called "racecar vehicle dynamics" by Miliken and Miliken. They go over all of these types, advantages, calculations, etc.

What indycars did was to have a-arm pick-ups that move around in order to change the anti's, and heims to change kingpin angles and caster. You can also do a block that you can shim away from the chassis to change those geometries.