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Thread: 4th gen setup questions. . . don't be stingy!

  1. #1
    Senior Member Carroll Shelby Supercharged111's Avatar
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    4th gen setup questions. . . don't be stingy!

    As some of you may know, I bought the car with 1200ish# front springs and recently ID'd 325# rear springs. Last month Perry donated some 950# springs to the cause, so I threw them on between qual and race (a buzzer beater at that having never done it before). I immediately noticed that the steering wheel would rotate farther before the tires broke loose, so I figured this was a sign that I took a step in the right direction. The front also has a 30mm bar, Z06 wheels, 1/2" spacer, 2 degrees camber, and 1/8" toe out. It seemed less bad, but I still was plagued with a mid corner push and my lap times just weren't as on par with the leaders as they were at Hallett. I simply couldn't place the car where I wanted to consistently because it just wouldn't respond and I'd miss my apex. Turning in earlier was not the fix, I tried it. I also tried all combinations of spacers and dropping tire pressures to no avail. The car did respond to spacer changes, but it never really took the way I wanted it to. So just last weekend I went out for a practice day. I'd raised the car a bit since HPR in July so the tires weren't tucked into the fenders and I'd replaced the swaybar bolts so they weren't shanked out and I got the endlink bushings properly tight. Camber was verified at 2 degrees and alignment still 1/8" toe out so one less variable there. At first the car seemed awkward, but after a couple sessions I determined I was just driving with sledgehammer inputs. Once I settled down the car was predictable, but still suffered from that mid corner push. I added 3/4" spacers to the front of the car as a last ditch effort and the car was amazing! My lap times only dropped a few tenths, but they were so much more consistent. The car went where I pointed it without being overly loose and just flat worked. I'm pretty sure I could have dropped lap times with another session or 2 of wheel time as the car now tolerates throttle input much sooner. Problem: I'm 1/16" too wide here. I'm sure I could grab some 5/8" spacers but I'll lose some of what I gained. I'll likely grab them anyway, but I want to know if the fact that wider spacers worked so well is an indication of something else that needs changed (springs/sways?). I know I need to drop the rear spring rates. Though the car wasn't super loose, as Ryan mentioned it may be causing me to chase my tail. He also suggested more camber. I've started with 2 sets of full tread RA1 this year and what I've noticed is that the outside tapers quite a bit. The shoulders don't take too bad of a beating, but the tread as a whole tapers and wears more on the outside than the inside. Were I to take tire temps, I think that would definitively tell me what the car wants for camber and air pressure, but I'm not there yet. So for next month's race, my intentions are to bump camber to 2.5 degrees and fit 250# springs out back and run the test and tune the Friday prior to feel out the changes. Am I missing anything huge here or does that setup sound like something that will make the car get around a track and not suck? Maybe do camber first, then the rear springs to see how it takes? Rear springs take all of 5 minutes to swap out now.

  2. #2
    Senior Member Carroll Shelby GlennCMC70's Avatar
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    Adding the spacers effectively softened your wheel rate (spring rate). That is a sign your still too stiff. You mid corner push could also be too much camber (or caster - you didn't list it). With higher spring rates (or wheel rates as you need to factor the sway bar too), you need less static camber and less caster as there is less body roll. Less body roll results in less camber loss due to body roll. Running lots of caster just adds to wheel turned camber (thus your mid corner push. If tire pressures were right to begin w/, you likely did see any gain as a result of the change. Lends to you being on the right track. you must run that 32mm bar. The 30 is just too small. That is why some folks liked to run large spring rates - to make up for some of the body roll. A push can be caused by too much or too little camber. My guess is you have too much as the push comes when you are at max wheel input through the corner. Just a guess w/out you providing where it is now.
    A soft car is easier to drive. It can also be driven offline (for making a pass) easier than a stiff car. Softer rear rates will help plant to front some during turn-in, but if the F/R balance is off, it will pick up a push through the corner.
    I still think 700-800F is the sweet spot. 225-275R would match. Depending on your driving style a 3:1 to a 3.5:1 F/R spring rate ratio is the target. If I had made Hallett, I would have let you drive my car to compare.

    Pay more attention to tire temps across the face than wear.

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    Senior Member Carroll Shelby Fbody383's Avatar
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    Also:
    http://www.aicmctexas.com/showthread.php?4309-Red-Shift-Racing-82-Set-Up-Notes


    I think Orange is running 750/225 at the moment... ish. Somewhere in that range. Hallett was the second event ever on 17s and I think we were narrower than the limit given the spacers we had on hand. I think the last alignment was around -2 camber, 4ish caster, and a little toe in with the stock bushings. Never taken tire temps but really probably should.

    Yes, Mr. Allford - the Global West bushings are waiting patiently in their little box for installation. Gotta keep up with Ross.
    #39 CMC Camaro
    Orange is Fast!
    CMC-NT01 FTW!

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    Senior Member Grass-Passer Suck fumes's Avatar
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    super soft is fast....just sayin.

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    Senior Member Carroll Shelby
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    I'm running 650F and 200R. I did this because the springs came with the car, I felt like I needed to start my DE and first few races off on a soft spring.

    I started off with 30mm front at the 19mm rear that came with the car, then later upsized to 32/19.

    Overall I the car always felt just a bit more pushy than I'd like, and had always wanted to up to a stiffer a spring and put a little more bias to the back, but constant engine swaps/issues put it on the back burner each time.

    Going up to a stiffer 800F and something stiffer in the rear (keep a few pairs in the 225-275 range to play around) was the plan.

    With the way the car behaved on RRs at Hallett, I'm wondering if I should go stiffer?

    Alignment is maybe around 2.25* in the front, caster is whatever the max is. Need to get a proper camber reading since my readings weren't trustworthy.
    Last edited by Pranav; 08-21-2014 at 05:46 PM.

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    Senior Member Grass-Passer Suck fumes's Avatar
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    Going stiffer in front will not solve your push. The shock travel is what you need to look at. More than likely your car is to low and you are bottoming out.

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    Senior Member Carroll Shelby ShadowBolt's Avatar
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    Don't use Hallett as a guide. My car went from loose to very tight between TWS and Hallett. The new surface had my car different than it had ever been.

    JJ

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    Senior Member Carroll Shelby Supercharged111's Avatar
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    So it's not just me, I thought my car pushed less at Hallett judging by my pace relative to the field. I've felt I'm shooting blindly here without the ability to take tire temps, I know they'll tell me what camber the car wants and which end wants more/less spring. The car currently has 2 degrees of camber and an unknown amount of caster. 2 of the bolts are hogged out to the max and pushed out as far as they'll go and I just used the other 2 to set camber only. I know some people like higher spring rates than others and I figured a heavy spring with a lighter bar ought to get me close to where I want to be. The 30mm bar has about 100# less rate than the 32mm bar (according to Strano's site) and attaches real close to the bottom of the shock, so wheel rate should be similar to a spring change right? So does that mimic an 850# spring up front but with better brake dive resistance? I'm not against going lighter yet to see if I like it, but I'd hate to bail on this spring/bar setup if it can be made to work, or at least work better. Let's also not forget the shocks will probably start making the car act funny too when they get that far out of their range. I don't even know how to identify when a shock is holding me up. So nobody's running more than 2 degrees camber? If not, I can cross that off my list of things to try. First and foremost then is to get a lighter rear spring and 5/8" front spacers.

  9. #9
    Senior Member Carroll Shelby GlennCMC70's Avatar
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    I run about 2.2.

  10. #10
    Senior Member Carroll Shelby AllZWay's Avatar
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    Glenn's information is about dead on to my own as is Dave's.

    There maybe be faster setups for a certain track, but for an overall decent setup follow these guidelines and the car will work pretty well.

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