C5_Z06

(I posted this in the C5 tech section but was advised to go here)

Hi,

First of all im new to the forum but I've been hanging around here searching all old old threas for a while. Great information source. especially since the Z06 is quite a rare animal where I live (Scandinavia). Unfortunately I haven't found the answers to all my suspension questions, hence this thread. I hope you all can guide me in the right direction.

My car ia an 2002 Z06. For now all stock with 29000 miles. I bought tha car a while back to have it as a weekend car / track day car. I.e it's not a daily driver. Up til now I've attended some track events, that is road corse tracks, and I'm quite surprised that the car handled that well being all stock. My impression of the car was that the grip was quite good but the chassis felt soft and unresponsive compared to my previous cars (European cars). The stock Good Year Supercar tires was ok for a while until they overheated and became slippery. Power was quite good though, having all that torque makes it easy to drive and modulate the power. I'm more than happy with the power train.

My goal is to make the car more responsive and direct in it's behavior. E.g I wan't to have a better feel of the car, it feels to soft/sluggish now, and that makes it hard to drive it on the limit. I've looked into what's available and would like to keep the mono springs and not go to coil overs. Mainaly because I don't want to "slam" the car and I'm a bit concerned that the shock mounting are not designed to take also the weight of the car. Some tracks I attend have uneven surface (e.g like Nürburgring) so I like to have proper suspension travel retained and a decent ground clearance. I have no problem with the suspension being hard and uncomfortable.

The obvious choice is the complete T1 kit.
Pros: GM-enginered. Made to work together.
Cons: Made for SCCA T1 class, that is being limited by their rules. A bit old, but perhaps that's not a bad thing. A bit expensive. No adjustments possible.

Other alternativre would be for instance Koni FSD shocks, Hyperco or VBP springs with track spring rates, Pfadt swaybars. VBP poly bushings.
Pros: A bir cheaper compared to the T1 kit. Newer design. Shocks adjustable, swaybar adjustable. Shocks rebuildable.

It would be great to get some input to the chocies above. I found some info here: http://forums.corvetteforum.com/c5-g...or-the-c5.html

Some questions then:

* How do the FSD's compare to the T1 shocks, high (damper)speed vs low speed performance? Compression and return damping? Quality? Koni also make Sport shocks, how do they compare to the FSD? Are the FSD comfort oriented?

* T1 vs VBP vs Hyperco springs. The spring rates are mentioned in the link above so they can be compared. How do the FSD work with the higher rate springs? Obviosly the T1 shocks are tailored to the T1 springs so that shouldn't be an issue I guess.

* Ride height, T1 seems to be about 1" lower on the highest setting based on the info I gather here. that's about as low I want to go. How about the VBP and Hyperco springs?

* I'm most concerned how the parts work together as a kit. Any specifc combo that works well?

* Spring rates are available, but I couldn't find any specs on the shocks. Anybody got some info there?

* Hyperco and T1 have a higher rear spring rate compared to the front spring. The VBP are the other way around, any input on the reason for that?

Many questions, I hope to get some feedback from useres who have pratical experience from the parts above. Any input appreciated, good or bad. Shoud I aim for somethign else or are the kits above the cure for the chassis in the C5. As of now I'm not interested in going to a full race setup, e.g move suspension mounting points and such, tailor made spring rates and so on.

Gray Ghost GS

My current setup for the road courses are T1 springs, T1 sway bars and Pfadt Adjustable Sport Shocks - the cost is very reasonable and performs great (very predictable). The Hyperco springs are a great alternative to the T1. I tried the VBP springs and sold them, but that was my experience - others may vary. Poly bushings and the right tire pressure really help too.

I'm sure you already read several CF threads about the many coilover options available for the C5 and the fact that shock mount can sustain the weight of the car, etc. for those applications. For example, a friend of mine is running the LG coilovers on the road courses and praises their performance (there are fans of Pfadt and others too). Also consider a good track wheel alignment and corner balancing.

C5_Z06

Thanks for the input. Why did you choose the Pfadt shocks over the T1 shocks? What was wrong with the VBP springs, was it the street or track versions?

Gray Ghost GS

I like the adjustability of the shocks over a fixed rate for shock and rebound, and the VBP spring problem was more of a fitment issue on the C5 (probably a rare occurence) than actual spring rates, which I prefer with the T1 and Hyperco.

C5_Z06

Ok, thanks again.

Does anybody know if there is any difference between T1 springs and Hyperco, apart from the spring rates? For some reason T1's are about twice as expensive. ~$500 vs ~$1000. Other T1 parts are more reasoanble, the shocks for instance.

Gray Ghost GS

Where did you find the Hyperco (front and rear) springs for only $500? They cost $1075 on the LG Motorsports website - the T1 springs from Gene Culley are $922 plus shipping.

C5_Z06

My understanding was that the Hypercos are roughly $500 each, seems to be inline with the LG price, but the T1's are $1000 each.

Gray Ghost GS

Crap! You're right - I forgot I paid that much 3 years ago.

fatbillybob

The local T1 guys in so cal are turning some pretty amazing laptimes. As a whole I think they are faster or just as fast as the guys with the coolest aftermarket suspensions and engine mods. Even the C6Z guys have trouble with the C5 T1 guys. Maybe it is skill but maybe the GM T-1 package was pretty well thought out. And if you are slow with a T1 package then its you not the car. This is a big deal because when we modify stuff as rookies it is hard to know if a product is the problem or us.

sperkins

Am I reading it right that you still run street tires?

rustyguns

my 2002 Z06 was very similar to yours. the existing springs and sways are fine. i replaced the rubber bushings in all upper and lower A arms, shock mounts and Sway bars, with poly and it made the vette feel like my old 911 ( shhh dirty word here )

i could not stand the jittery rear end on washboard tracks coming out of turns ie...Nurburgring

so i went with the Koni FSD. Absolutely amazing shock. it has two frequency controls so it handles small quick bumps and big single bumps in unison absolutely fantastic. the suspension actually dropped 1/2 an inch because the FSD's are not gas charged. i come from the belief shocks should dampen and springs should suspend. call me crazy

the Z06 actually felt softer but hugged the corners in any condition like friken glue.

try it you will like it!

and.............HAUL *** !!!!!!!!!!!!



PS.. IF I WERE TO DO ANYTHING DIFFERENT I WOULD HAVE PUT CONCENTRIC BEARINGS IN THE A-ARM BUSHINGS LIKE ( PORSCHE DOES ) shhhhh!

rustyguns

Michelin racing slicks beat anything!!!!!!!!!!!!

NEWs

Hey C5_Z06..

I am in just the same spot as you are, with a Z06 C5, in Norway, on rough road conditions, and want to attend more tracks.

Having had a couple of Z06, i finally now bought another one with registration in Norway. 02 E/Blue, with only 8k miles.

It rides like crap on our roads, under full load in 4th, in about say, 110 miles, if i release, and mash the throttle again, the car can sidestep about 2 feet, I feel my Audi is more predictable than the Z.

Enough about this, i am also beeing torn between the various suspension upgrades available, up until i started searching, i was pretty set on the complete pfadt upgrade. Agressor 1 or 2..

You mention that the shock mounts wont sustain the coilovers, is that an issue? (havent searched here)..
I would not want to end up in a situation where my mods cannot be unbolted, and undone..

Nils Eirik

rustyguns

you guys really need to buy the Koni FSD shocks!

GrantB

If I'm understanding you correctly, my C5 behaved the same way. I changed a ton of stuff in the suspension all at once, but it mostly solved the issue (which we generally call bump-steer or roll-steer).

I did: Pfadt control arm bushings, 2004 Z06 shocks, Z06 anti-roll bars, Z06 springs and an alignment. I believe the bushings and a decent alignment will have the largest effects.

Granted I live in Florida where the roads are very good compared to most things on the east side of the pond...

C5_Z06

Yep, that was my thoughts. See first post

C5_Z06

Correct, car is 100% stock so far. Depending on how much street drving I'll do I'll either stay with stock-ish tires or change to some track oriented tires. I don't have the possibility to have different sets of wheels at the track. Some tracks are >500 mls one way driving.

C5_Z06

Up til now compromises are usually a bad thing, but maybe the FSD are the exection to prove it's wrong? How are they adjustable? Is anybody using the Koni Sports?

C5_Z06

That could be the issue on the street, where the surfae sometimes is uneven. What's the reason behond the bump/roll steer?

On the track where the surface is even, but the elevation changes, the feeling was still that the car was unresponsive.

Btw some of the roads I've seen in the US has been quite bad as well. So I assume you guys have similar issues. Even in a straight line when going above ~120-130 the car starts to feel a bit loose. In some cases I'll be doing thoose speeds for longer periods of time and then it would be nice to be able to relax a bit as well.

NEWs

But if you end up eventually going with coilovers, you can adjust height, and damping.

The T1 stuff, is that sold in a "T1" suspension package,or is it piece by piece. ?

Is there an issue with bolting coil overs in, and the mounting points?

GrantB, i think you have it right. In some kind of web page i also saw someone selling kits for correcting bump steer, both front and rear. We've been using this succesfully on track day BMWs, i guess it will do the same for this.

C5_Z06, where in scandinavia are you located?

NEW
Nils Eirik Wenaas