L98Terror

It's that time of year, I haven't driven my car since Nationals and I really need to get the suspension straightened out before next season.

History: it's an ST2 car with T1 Springs & sway bars with Penske 3 way shocks.

When I got the car, it was way to low and it was bottoming out the shocks and completely blow the rears. I sent the shocks away and had them re-valved only to have them returned to me to soft. I spent a over $1000 last year on the shocks to get them rebuilt only to be told they weren't happy with them when they sent them to me. Now the question is what do I do now? Get shocks revalved again? Replace springs? Goto Coilovers? Which Coil Overs? Fit my Penske with Coil Overs? ????

My A-arms are modified to fit the Penske so if I change shocks I'll need new A-arms.

Thoughts on what is the best set up, it's a C5 Z06 @ 3100# and 344 HP with areo.

I've talked to a few people and have a few ideas but want to hear what you have to say.

Z06Fix

Get ahold of Gary at Hardbar. If I'm not mistaken most of the Penske shocks can be made into coil-overs. That would be the route I would take.

gonzalezfj

Who did you have rebuild your shocks? Penskes are completely rebuildable by people that know what they are doing. Contact Joe Stimola for top notch rebuilding at a reasonable price. $250 per shock sounds way too high.

If you are happy with your existing T1 spring rates, forget the coilovers and their added expense.

Frank Gonzalez

0Randy@DRM

Take a tape measure, check body width. I know some larger Penskes have clearance issues in the back when used with coil springs (Gary???). You would need to buy modded rear toe rods $$$$$ 1000 dollar shock rebuild will look like peanuts compared to PandM toe bars.

Penskes can be a good shock, if you have the right valving and spring rate. Most of this will be found testing, which can be big $$$$ too.

Randy
Raise your car up!!! I saw a couple times in your incar "off the bump stops."

L98Terror

The car is now at the correct ride height, the first couple video's was driven as delivered "Fully sorted car"

Aaron Pfadt

Ken,

In your first paragraph you talk about the car being too soft and bottoming out. Rebuilding the shocks 'stiffer' isn't necessarily going to solve that problem. The damping will have some control on the amount of bump compression you get, but the major factor is spring rate. Your choices are (as you have obviously discovered and corrected) to raise the ride height or go to stiffer springs.

The T1 springs you have are 10% stiffer than the C5Z springs. That is all. If you compare that to any coilover set on the market, you will find that they start at around 30% stiffer and some of them are more than 100% stiffer than Z06 springs. I, like many others on this forum, can make spring recommendations to you all day long. The important thing to keep in mind is that the T1 springs are soft and coilovers will put you in a different realm. They also give you the flexibility of quick and inexpensive spring changes. Hypercoil coil springs are $150 a set. If you have to swap a couple of sets to get the car dialed, you will not break the bank.

Remember that damping is there to control the springs and body, not add rate to your suspension.

You have some good choices available because you have a set of shocks that can probably be converted to coilovers. They are probably also valuable re-sale wise, so you could easily sell them and go to a different set of coilovers. That way you would get a set that the damping and springs will be matched well and should work with less futzing around.

If you need new a-arms, you can talk to Corvette Recyclers and they can hook you up with a set of used ones.

Give a call if you would like to talk some details.

-Aaron

ghoffman

For once I agree with the opinion above. The T1 springs are not the answer, they are for the restricted SCCA T1 class just as the Spec Miata package is not the best, only equal. Your 8760 shocks are superb (the best), have a tremendous adjustabilty range (2:1 force on rebound). The Penskes you have are coil-over ready, you only need the spring hardware and the springs themselves. Springs are only $75 a corner, and although you can get recommendations from any/all of us, it is a starting point and you need to do some testing to get what you want.

RogueVette

Ken,

There is a guy in your region in NASA that set up the fastest Corvettes in ST1, TTS, TTU, TTA and the ST2 Vette that went from last to 2nd at Nationals.

I'm pretty certain he would be happy to help you figure this out. He's pretty good at setting up what's fastest from a suspension standpoint.
Give Danny a call and listen. I didn't, and spent lots of money of worthless crap only to be forced to change my set up again because I thought I, and others knew better. I was wrong.

L98Terror

I've already spoken to Danny, trust me he's in the loop.

gkmccready

If only we could all drive each vendors "optimal setup" to see which one we liked the best, eh? I sure wish I could have a shot at a RAFT, Pfadt, LG, ATI, MTI, and HardbarUSA set up and work my way through them to see what I liked or didn't.

As you know, I picked the HardbarUSA Penske 8100 Dual-rate Coilover set up. For me it sounded like a great street/track deal. I tried KONI 3013s, with and without Pfadt Pfatty bars, and stock C6 Z51 with and without Pfattys, and with a softer rear bar. Kind of wish I could go back and try all that again knowing what I do now about alignment and ride height. I still think I'd hate the 3013s, but I bet I could have been a lot happier in general, even with the stock suspension.

The Hardbar Penskes work very well for me although it's clear that I, personally, can tolerate quite a bit of bump damping but I'm not a big fan of "too much" rebound -- especially on the street. As such I really wanted a double-adjustable shock that's easy to adjust. You quickly get into 2812+VBP or Penske+Hyperco and you're looking at $4k for the system.

From other cars I learned that coilovers are great if you want to experiment with spring rate, and I suspect you'll want to do that with aero on the car unless you can come real close real quick as at $500 for a VBP spring can add up quickly vs the $150 for Hyperco coils.

I assume your modified A-Arms actually allow you to run double eyelet shocks, and if that's the case you probably have a lot more options than the average guy. Ohlins TTX36, and just about any other shock you like are available double eyelet.

No matter who you turn to, you're probably going to have to experiment a little with spring rates and shock valving to find the sweet spot for your car, with your aero package, so whoever you pick make sure you're happy working with them!

sleeper02Z06

As Aaron has stated above, your car bottoms due to not enough spring rate. T1 springs are not that stiff although they still work pretty well. The big problem is those rates were developed years ago before this age of A6 hoosiers. The grip modern tires are producing has put more pressure on the entire suspension setup. Every T1 car bottoms but when the shock rule was opened in T1 it allowed everyone to actually try to "band aid" too soft springs with a ton of shock valving. Trying to simulate stiff springs with super stiff shocks is like I said, a band aid. If you don't have to run T1 rates there is no reason to. The big issue is you can still go too stiff on a spring, you have to find that line between too stiff yet stiff enough not to bottom. Testing in your particular car is the only way to do this, at different tracks, with consistant driving and data, with a boatload of time/laps. Unless you can do this, and many of us don't have the time, money or talent to, go with a proven package.

Joe

rustyguns

i vote T1 + leaf springs and Koni shocks! Plus an alignment from a track God!