I got hired as an instructor/driver coach for a TEAM HPDE yesterday which meant I was in the same car for all 7 track sessions.
This was the first time I had a chance to ride in a coilover car.
The car was an '03 Z06
Pfadt coilovers with the single adjuster for both bump and rebound.
Stock motor except for LG Long Tubes
T1 sway bars
Sparco seats with 5 point harness
Hoosier slicks

The coilovers were just impressive. The handling compaired to the C5/6's with stock springs was really better, flatter in the corners and generally had a much more predictable feel on the track.
Just felt like a different car.

I can only imagine what Gary's setup with the Penske 8700's would be like to drive.

It was also one of the few times I've been in a racing seat with full harness as an instructor. Most times doing a full day in a C4,5,6 with stock belts, you feel a little beat up at the end of the day. At the end of the day, yesterday all I felt was pumped up. It didn't even bother me that I missed Indy. Great day.

cool!

I have never been a fan of the transverse leaf spring. If it was such a great idea, why don't others use it? Oh, that's because they gave up on the idea 40 years ago...

Sure, the C5 does an ok job with TLS, but the end result, to me, is a rather jittery ride and less than stellar dynamics.

To tell you the truth, this whole subject has me eating a little bit of crow. For years I maintained that spring rate was spring rate, independant of leaf versus coil. When I had driven coil over cars, yes, they were better but what was not clear to me was why. Was it the better dampers, or the different spring rate? A couple of years ago I bought a used set of Penske 8100 doubles and after a much needed rebuild and revalve (that is a totally different story, man they were in bad shape)put them on my C6Z with the stock leafs. They difference was dramatic even with the stock leafs. What was obvious was the springs were too soft for both New England roads Lime Rock and NHIS (now NHMS) so I decided to go to coils since the Penskes were all set up for coilovers already. Richard Strout at LEMD.com and I really wanted to develop the dual rate setup and we went through many combinations to get it right. One day we had the rear leaf spring on and the front was off and we were not there yet with the dual rate spring setup and it was getting late on a Saturday night. I said to Richard I got to get home, just give me some big single spring just to hold the front end up. He tossed me a pair of Hyperco 850 Lb/in linear springs so I put them in on the front only with the leaf on the back, both ends with Penske 8100 shocks. What I expected was to lose my dental fillings on the way home but what happened was the opposite. The front end was more compliant than the rear, especially on expansion joints and pot holes! The coil overs simply work better and I think it is mostly due to the friction of the leaf adjusters, but it is not conclusive.
Now, the 8700's with the dual rate setup is so first class, even compared to the 8100's. I will be instructing at NHMS tomorrow, and if anyone wants, I will be giving test rides!

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I've thought about this over the last couple of years. With the Corvette being a world class sports car, why the TSL's?
Probably uppermanagement being pigheaded, sticking to "tradition" and thinking that "we can make the TSL work as good as any suspension out there".
Nobody would be selling coilovers if that was totally true.

I instructed in a '08 C6 ( with the sport suspension, Z51 if they're still using that RPO). So I got to compare the stock C6 with the '03 Z06 coilover car. The '03 was better.

I've never wanted or even thought about owning a C5 but, after a day in that Z06..............

I've never wanted or even thought about doing big suspension mods to the '92 since I don't drive it on the track. But, after driving a coilover car................

I'm still not convinced, but I'll admit that there is some pigheadedness in there somewhere.

Let me pose this question: was this car simply set up better because the coilovers allowed it?

I've learned over the last 3 years since I got competitive that parts do not make the car faster until the driver can't.

Unless there's some poor quality control or unexpected dynamic spring rates on the leafs, the only difference I can fathom is the way the leaf springs jam into the lower control arms. Not exactly a low-friction setup. Maybe that's causing a little binding on initial movement.

It's more than that.

There's cross coupling that goes on with the leafs due to the twin mounts.

With the coil overs you can get progressive rate.
You could do that with a leaf spring, but you'd need to redesign it.

I'll find out how good the coilovers are when I make the switch.

I am just putting in race seats hoping to avoid that beat up feeling at the end of the day and to unlimit my driving. I feel really limited in cornering now with the stock seats, I get thrown around to much.

An article on the leafs:

[IMG]http://i119.photobucket.com/albums/o130/Aardwolfki/spring.gif[/IMG]

Brian, most coilovers I see aren't progressive rate either.

I recall someone out there offers a progressive rate leaf, it uses a bar on top that the spring flattens into, similar to a progressive rate leaf spring on a 3/4 ton truck.

And you're going to have cross-coupling / cross-talk no matter what unless you remove your front sway-bar.

There is no such thing as a truly independent suspension Corvette, nor would you want it that way.

Besides, if the leaf provides some anti-sway, doesn't removing it potentially warrant a larger sway bar?

I'm not trying to defend the leaf spring mercilessly, but I've yet to see much of any legitimate explanation for why the coilover seems to perform better, all else being equal.

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Jon, this guy just installed the coilovers without putting it on scales or doing a realign. he had to change the ride height in the front to get the slicks to clear. Didn't have time before the track day to get it to a shop. And the car still felt better that the C6 i was in the week before.

"parts do not make the car faster ", Yea, Roger Penske said
" if you want to drop your lap times by 1/100ths, work on the car. If you want to drop your lap times by 1/10ths, work on the driver"
Once you're running in the top 3 or 4, you can see the parts taking over. The guys in front of me are more stable in the corners with $3,800 Penskes vs. my $1000 Koni's.

[quote]
Aardwolf wrote:
I am just putting in race seats hoping to avoid that beat up feeling at the end of the day and to unlimit my driving. I feel really limited in cornering now with the stock seats, I get thrown around to much.

You're gonna love it. There's quite a difference. You won't be gripping the steering wheel so tight to hold you in position. You'll feel much better at day's end. Enjoy.

What seats did you get?

CC, I've thought about the way the leafs jam into the control arms too, you may have something there. The geometery on a coilover setup is certainly different.

Yea, a larger bar would be needed but everyone goes to the T1, or larger swaybars anyway.

I think progressive springs for coilovers are out there. I think Gary and I had a discussion on them. Basically running 2 shorter springs on the shock with 2 different ratings. I'm not convinced that this would be a better way to go on the track.

Some Deja vu here.

2 different rate springs stacked on each other does NOT provide a progressive rate, at least on paper. It just gives you a rate somewhere in between. But I recall Gary had more to say about this.

You only get a progressive rate when part of the spring collapses on itself. This reduces the amount of effective coils in the spring, which gradually increases the stiffness.

This is a progressive coil:



I know it sorta looks like two different springs in one, but it doesn't function that way. The spring is the same diameter and stiffness throughout. The close coils simply collapse.

Bill, I made the same choice as my last car. Corbeau A4 seats. I really like to drive the car as much as possible so it will remain driveable on the street. I really needed a non-fixed back seat, due to my back problems more then anything. I considered the new Sparco Steel seat but it weighs more. I got the A4 shaved for more headroom, double locking sliders, and the sub belt hole.

Now I need harness and a harness bar, thinking of making one of those.

Cool, the A4's are nice seats.
I usually run the rather expensive Willins harnesses but lately I've seen some nice harnesses at reasonable prices.
I saw thw new G-Force camlock 5 point at the last SCCA time trials and was impressed. The Z06 with the Sparcos had a new Crow camlock harness which also worked very well.

Good luck on building the harness bar, I like to engineer and build my own things too.
But, sometimes it's more cost effective to buy one, like Hardbar's. Either way, the harness will be as much of an improvement as the seats.

That would definitely change the rate, but not very progressively.

I don't think coil bind was his intention.

I thought VBP had the progressive leafs, but it looks like theirs are just adjustable. Maybe there isn't one.