Ramo7769

I have recently picked up a 1999 FRC to use it to it's full potential on track and autocross. I will need to drive it on the street, but I am looking to make zero compromises for the street in terms of comfort. That's what the Volt is for. Over the winter I plan on doing some track prep, changing all the fluids, adding oil cooler, and swapping the seat and adding a 5-point. I'm also going to tear apart the suspension down to the hardpoints to go to polyurethane bushings.

I have a lot of faith in the OEM which has compelled me to stick with leafsprings. The big wild card is that there are not many published spring rates out there. Even looking at VBP, they only show a range of rates for their springs. While I understand that measuring the effective rate on a leafspring is not as simple as with a coil, why not just stick with wheel rates?

Anyway, I'm a bit skeptical of going to coilovers, but leafsprings do not have the adjustability of coils. On top of that, upgrading leafs along with buying high quality shocks looks more expensive than a set of coilovers. Because of this, I'm still trying to keep an open mind to coilovers.

Any suggestions, technical info, or even pitches from Pfadt, VBP, DRM, etc. are very welcomed by me! I'm a 23 year old engineer with decent competitive driving experience for my age with some LeMons racing, autocross, and karting under my belt. But, I understand that I am still an amateur and I'm looking to get more seat time and learn a lot about vehicle dynamics with my Corvette. And yes, I've referred to the sticky on lessons learned with a Corvette track car and will continue to do so. Thanks for your time and input.

crimlwC6

I did the samething. Got a 99 FRC about a year and half ago. It is a pure track car. I've stuck with leafsprings and I've had good success with them after removing a few hundred pounds from the car. PM me and I'll answer any questions I can for you.

Bill Dearborn

Maybe stick with the leafs and a good set of shocks until you can get a feel for what the car can do. Coil overs have a lot of adjustment that can be beneficial but if you don't have a baseline based on how the car handles with leafs and don't understand how to adjust the COs for the handling you want you could spend a lot of time sorting things out.

Bill

fatbillybob

If you are new to the game IMO the best and cheapest thing you can do is set up the car like a 2012 SCCA T1 car or a 2013 SCCA T2 car. Then you can compare laptimes over just about every track in America. When you get close then start playing games. Until then you have no clue if you got to the car's potential. You might be surprised. There is more T1 data than T2 since the T2 formula for C5's has been around only for 1 year.

Solofast

What he said...

This way you get a known, fast proper setup for a very reasonable price and you can go from there...

el es tu

aftermarket:

for the front Hyperco makes a 579 and a 641
for the rear they make a 785 and 873

they also supposedly do a higher rate set for for aero cars (1000+)

VBP will make any rate spring you want and I believe they give forum member discounts

2MCHPWR

I'm running the T1 suspension and love it. Only change from the T1 kit is I use a stock z06 rear bar instead of the T1 rear bar.

FYI is you lower the weight of your car, the springs act stiffer on a lighter car.
If your car was 3400 total race weight with the T1 springs, if you lower it to 3200 lbs, the springs act like a stiffer set.

I wonder if anyone has kept the T1 springs but swapped out to spherical bushings and high-end shocks. I'd like to do that experiment over the winter.

hklvette

If Van Steel's information is correct, the Hypercoil 12407HPT and 12408HPT leafs are roughly equivalent to T1 leafs.

el es tu

van steel lists those as 10% over t1 setup, and rates the springs at 641 and 873

not sure why they decided not to get a little more aggressive with the design over t1...

geerookie

That should make a huge improvement. The weak point will be the spring pads as they will still have a lot of stiction. I would suggest delrin pads, polish the landing area and use some high pressure silicone grease on the polished landing area.
Also 2 or 3 way adjustable Penske's so if you decide the T1 springs aren't working it will be an easy upgrade to coilovers.

Scooter70

How much open track experience do you have? My suggestion is to make it track worthy (fresh fluids, oil cooler, brake ducts, good pads), maybe a good set of shocks since yours are 14 years old, replace the plastic sway bar end links, get a good alignment, and then come play with us at 3BallsRacing. There are usually 8-10 of us in C5s and C6s at any given event and have lots of fun running laps together. Once you have a bunch of events under your belt and you'll figure out where your car (or "the nut behind the wheel") needs help to keep up. Most of us live in the northwest Detroit suburbs so there are plenty of us around to help you out.

-Matt

rfn026

I didn't notice where you lived. Don't do anything to your car until you talk to Danny Kellemyer at DJ racing. The man is a genius with these cars. Even better he won't run the budget up on you.

Take your car to Danny and tell him that you want to run track days. He'll take care of the rest.

Step 2: Get Danny to coach you at Waterford. That will be far better than spending money on parts you don't need.

Richard Newton
Car Tech Stuff

Racingswh

Have you kept the stock rear bar because of the issue you were having at Thunderbolt? I can't remember what the fix was I just remember watching the vids and the car was being difficult.

Is there a reason why you wouldn't go with Delrin bushings instead of sphericals? Aren't the Delrin bushings good enough in your opinion?

I like the thought of adjustable shocks as well. I have always had some success with them when the car isn't behaving quite how I want it to especially on the rebound side. With the Sachs you're stuck with what the setup gives you. Not that you're stuck with a bad setup by any means but just that the option to adjust would be nice.

2MCHPWR

hi! my issues at T-bolt were due to the rear having toe OUT That was an isolated issue.
I already have poly bushings so I would think the sphericals give better movement on all the axis' versus the poly and delrins. Not sure I'm event gonna do it. Would be nice to be able to sell my poly's in the A-arms to recoup the spherical price. Pretty pricey.

geerookie

Less stiction and much better feel.

Sperical's and Penske's will be the best money you have ever spent on the car

Ramo7769

I appreciate everyone's helpful input. I'm not opposed to running leafsprings, as I said. I have no reason to believe coilovers provide any performance benefit over leafs, rate for rate with all other things being equal. I mostly just want to get the rates right. I am wondering if the earlier posted spring rate table (OEM and T1 leafs) are measured the same way as VBP measures. VBP recommends a higher rate up front than rear. It's also discussed here. http://forums.corvetteforum.com/auto...-on-front.html

Increasing the ratio of front to rear spring rates makes sense to me for a car running a square setup. I have a set of 4 18x10.5 Z06 rears I'm planning to run in spring. I plan on running a good street tire to start off for a while before thinking about slicks. Currently thinking 285 Dunlop ZIIs or 295 Toyo R888s. I know the ZIIs hold up well lap after lap endurance racing (on a 2.8L Chevy S10 at least ).

To summarize, what I would like for next spring as a starting point:

• Higher overall spring rates with overall balance for square contact patches
• Sway bars to fine tune the balance
• Shocks with valving to support higher rates and the adjustability to tune transient handling
• Corner weighting and Alignment
• Oil cooler
• Seat (I think my body rolls relative to the car body as much as the car body rolls relative to the ground in it's current state!)

I can wait to upgrade to poly bushings or spherical bearings. It sounds fairly high maintenance, but should be worth it after the bigger hitter handling items are done and I have some more seat time.

Hi, Bill, this is Endicott native Andrew who moved to MI to attend Kettering University. I'm Jason's brother (he's got the red '02 Camaro that he autocrosses). Thanks for the input!

froggy47

Given you have already decided to give up nvh for track performance, I would skip the poly and go straight to spherical (unless that breaks the budget). I have poly but I street drive it 50% and it's right now to the point that if I do much more it'll just be a pita on the street.

Good luck.

Ramo7769

That's right. I will still have to drive the car on the street, but I don't care about NVH. The only thing I'd be concerned with (besides budget) is longevity of spherical bearings on the track and street. If I knew the price would be swallowed once for a couple years of use, ok. But if I hit a couple pot holes and get some dust in them on the dirt road leading to Waterford Hills (local road course) and they fail after one season of use, then I will cry. Do you have any input on longevity?

froggy47

I would talk to the vendors as I have no experience, my poly's are like new after 3 yrs (and no squeak).

Some (all?) spherical are rebuildable. For a reasonable price so I am told. Define reasonable?

crimlwC6

I have sphericals and the older pfadt adjustable inverted shocks. They work great! (like tony the tiger great)