Welcome to the Corvette Forums at the Corvette Action Center!

2002 Z06 Rear Shocks for 2001 Z06?

R

rjsmith

Guest
Does anyone know if the improved rear shocks on the 2002 Z06 can be retrofitted to the 2001 Z06? If so, does anyone have a part number? The other rear suspension components are unchanged between the '01 and '02 Z06.

I finally noticed the "twitchyness" in the rear end when I jumped on the throttle during an impromptu stop-light grand prix. It's not life threatening (the car stays pointed in the right direction despite a millisecond sensation that it might swap ends) but it is something I could do without. According to Sports Car International (September 2001, pp58), Chevrolet acknowleded the behavior (which SCI luridly described as "skittering sideways at throttle drop") and fitted new shocks for the 2002 Z06. According to the article's author they changed the compressed disc valving.

ABS and Traction Control Engineer (what a title) Kevin Zelenka of Chevrolet is quoted in the article as saying the "bumpy ride of the previous car is gone. The revised rear shock valving has done away with the jittery feeling on bad roads".

Uh, hello, Kevin? Bumpy ride? Jittery feeling? Have you driven a C4? If the '01 Z06 ride is "bumpy" and "jittery" I can't wait to get my hands on those '02 shocks. Jeez, I am amazed with how well my '01 Z06 handles bumpy roads (i.e., most roads in Southern California) compared to my '92 with Z07. And that baby was a sweetheart compared to the early Z51 cars.

Has anyone out there taken the car out to a dragstrip and performed a 2,500rpm-drop-the-hammer-launch? Does it get seriously tail happy?
 
V

vettepilot

Guest
The 2002 also has aluminum anti-sway bar links vs the molded plastic that the 01 had. Also I believe there was an increase in the rear spring stiffness. The revalved shocks rounded out the remaining changes for the 02 rear suspension. There may be more but I really think I hit them all.
I really know what you mean about the C4 on bumpy roads, I had a 93 ZO7, normally handled like it was on rails, but hit one good bump at high speed, and the rails went in several directions. Had many a good upper body work out with the high speed bump jitters... lol
vettepilot
 
R

rjsmith

Guest
vettepilot said:
The 2002 also has aluminum anti-sway bar links vs the molded plastic that the 01 had. Also I believe there was an increase in the rear spring stiffness. The revalved shocks rounded out the remaining changes for the 02 rear suspension. There may be more but I really think I hit them all.
I really know what you mean about the C4 on bumpy roads, I had a 93 ZO7, normally handled like it was on rails, but hit one good bump at high speed, and the rails went in several directions. Had many a good upper body work out with the high speed bump jitters... lol
vettepilot

I agree with your characterization of the C4 Z07 handling. The rear end would always dance to the outside of a corner if you hit a bump. Unsettling, but as I'm sure you discovered, it wasn't hard to control once you knew it was coming. But it never failed to cause a irregular cardiac rhytms.

I don't know how anti-roll bars came to be referred to as anti-sway bars. Anti-sway bars, or more commonly just sway bars, were used on station wagons in the '60s and '70s to control the side to side movement (sway) of the long body (movement about the vehicle's yaw-axis). Anti-roll bars are used to counteract the movement of the suspension when the car attempts to rotate around the roll axis (hence the term anti-roll bar).

The bar itself is actually a torsion bar. Twisting one end (the side of the car in compression in a turn) forces the other end in the opposite direction keeping that side from lifting the contact patch off the ground. Hitting a bump with both tires forces both ends of the bar to move in the same direction which cancels out the twist.

Normally torsion bars are solid. The Corvette suspension engineers did a nice job making a hollow one to save weight. The bar diameter determines how much force (torque) must be applied to twist the bar.

Increasing the rear spring stiffiness would make the car loose (i.e., tend to oversteer) so it seems odd that they would modify the shock valving to make the car less tail-happy yet increase the rear spring rate which would tend to make it more tail-happy. The reason is simple: softer springs allow more weight transfer to the rear, causing more mechanical downforce on the contact patches, increasing traction. Stiffer (i.e higher rate) springs inhibit weight transfer, so less mechanical downforce, less traction.

I believe Rob has a list of the suspension specifications here on the forum. I tried to check them but the link is broken. Perhaps he is working on the page.

Nice car you've got, BTW.
 
V

vettepilot

Guest
Thank you for the nice car compliment, I'm really enjoying it.
I must have had a brain fart when I referred to the anti-roll bars as anti-sway bars, or the old CRS syndrome took hold. LOL
I'll see if I can locate the thread that has the mods we were referring to, or another reference, like I said I may have gotten them confused.

Like you said too, after the first high speed corner with a well placed bump and the ensueing skitter to the outer radius of the turn, like Pavlos dogs we soon learned to know what's coming, and prepared to compensate.

vettepilot
 
R

rjsmith

Guest
vettepilot said:
Thank you for the nice car compliment, I'm really enjoying it.
vettepilot

You deserve it. I see you're a retired Army pilot. UH-1s, Loaches, Guns, or Hooks? Did you fly in Vietnam? I may have ridden on one of your choppers if you did, was in the Central Highlands.

Enjoy the ride.

Ray
 
V

vettepilot

Guest
I missed the Southeast war games because of schools and other assignments from 1970 thru 77, but managed to get in just about every other conflict between 1977 and 2000 before I retired. I flew UH-1s, OH-58s, OH-6s, AH-6/MH-6, and TH-67s. Most of my time is in the OH/AH/MH-6 in the Army Aviation Special Operations. Nice way to travel and see the world, if you don't mind a steady diet of MREs...lol
Just curious, have you driven a 2002 to compare it against a 2001? Some of the people that have say there is a very noticeable difference. I haven't driven a 2001, so I have nothing to compare my 02 with, (in the ZO6 world that is).
 
R

rjsmith

Guest
vettepilot said:
Just curious, have you driven a 2002 to compare it against a 2001? Some of the people that have say there is a very noticeable difference. I haven't driven a 2001, so I have nothing to compare my 02 with, (in the ZO6 world that is).

No, I have not had the opportunity to drive the 2002 Z06. I suppose I could drive my SUV to a dealer who has one in stock and ask to drive one.

I could have waited for the 2002. I knew they were upping the horsepower to 405 (and that has a certain cachet that 385 does not) but I would have had to wait for the car (an indeterminate amount of time) and I caught Cormier Chevrolet with 13 2001 Z06s in stock (in mid-July). Given that the 2002s would go for sticker or above, and given that I was able to negotiate an obscenely low price for the one I bought there was no way I was going to wait. It has a very late build date so I knew that the running production changes had been applied, and after I drove a different one it took enormous self-discipline not to drool all over the salesman's desk.

I am actually thrilled with the way the car corners and accelerates. The fit and finish is light years beyond any of the other Corvettes I have owned. If the 2002 is even better that's good because by the time I am ready to buy another they may have tweaked it even more.

I did not run out and buy a C5 in '97 because, quite frankly, it took a long time to acclimate to the styling, especially the rear fascia. Even a private tour of the Bowling Green Assembly plant (arranged by one of my Vietnam buddies who works there when we went back to Fort Knox for our regimantal reunion), and the opportunity to drive a fresh-off-the-line 2000 FRC on their one-mile test track didn't move me (even though I had been waiting for a true coupe). What got me moving was when Car & Driver actually had good things to say about the Z06. I figured if C&D is saying something nice about a Corvette, they must have REALLY improved the car.

Just as when I went from a '90 C4 coupe to a '92 C4 coupe with ZO7, it took awhile to adjust to the new body. Now it seems natural. And since the C5-R has the same big butt, if it's good enough for Ron Fellows, I can live with it.

Now if I could only convince Jim Minniker to put the Ferrari-style F1 transmission in the Corvette I would have it all.

Ray

P.S. Stan, if you check out my web site you will find photos of Huey's, Loaches, Hooks, etc., from a variety of aviation units that provided us direct fire and logistics support. The photos were taken out in the field and include a couple of downed UH-1B gunships hit while reacting to an ambush we found ourselves in on Highway 19 near the Mang Yang pass. You will also find photos of my drive at speed on the Formula One circuit at Monza, Italy (in my rental car). Now that was fun.
 
V

vettepilot

Guest
Ha Ha,
I felt the same way about the C5 looks when it first came out, in some ways I still think the C4 looks sleeker. I think it's the long low look the C4 has, the C5 doesn't seem to come across that way. But as far as handling and chassis refinement, there is no comparison to the C5 from the C4. I couldn't believe the difference.
But I still held off, I was really going to wait for the 50th, but after reading such good press about the 01 ZO6, then an even better report on the 02, I couldn't stand it any longer. I built the car on line through the Chevy web site, then went looking through local area zip codes to find one. it took about a month but finally one was built that had everything I wanted. So that spared me the long anxious wait on a special order, I got the car about a week after it was delivered to the Dealer. Exactly what I would have special ordered if my local Chevy dealers could have qualified as a ZO6 dealer. And I got a good deal to boot, no mark up and a good trade in value. I'm happy!!!!
:) :) :)
 
R

rjsmith

Guest
vettepilot said:
Ha Ha,
I felt the same way about the C5 looks when it first came out, in some ways I still think the C4 looks sleeker. I think it's the long low look the C4 has, the C5 doesn't seem to come across that way. But as far as handling and chassis refinement, there is no comparison to the C5 from the C4. I couldn't believe the difference.
:) :) :)

Agreed, IMHO the '91-'96 body was the sleekest, reminiscent of the 1970 Ferrari Daytona.

BTW, the rear transverse composite leaf spring in the 2001 Z06 has a rate of 125N/mm (for comparison the older Z51 rate is 113 N/mm). Do you have a figure for the 2002 Z06 rear spring?

Ray
 
V

vettepilot

Guest
rj,
I think I spoke from the dumb side of my brain in respect to the increased 2002 spring rate. I could not find any reference to an increase over the 2001 spring when I went looking. So I guess what you have is the same as the 02.
Doesn't that make you feel a whole lot better to know that you only have to update a couple of shocks and stabilizer links...
That's a $$$$ saver :beer
 
R

rjsmith

Guest
vettepilot said:
rj,
Doesn't that make you feel a whole lot better to know that you only have to update a couple of shocks and stabilizer links...
That's a $$$$ saver :beer

It does. Thanks to you I am now aware of the stabilizer links. I missed that completely.

I'm off to the Chevy dealer first thing tomorrow to order the 2002 shocks. I'll keep you posted.

Thanks again.

Ray
 
R

rjsmith

Guest
vettepilot said:
rj,
I think I spoke from the dumb side of my brain in respect to the increased 2002 spring rate. I could not find any reference to an increase over the 2001 spring when I went looking. So I guess what you have is the same as the 02.
Doesn't that make you feel a whole lot better to know that you only have to update a couple of shocks and stabilizer links...
That's a $$$$ saver :beer

Stan,

When ordering the 2002 shocks I was told that the other change (in addition to aluminum versus rolled-steel stabilzer-bar end-links) was the substitution of a shorter rear jounce-bumper.

The shock valve change involved making the valve larger for the jounce cycle so that weight could more effectively transfer to the rear making the car squat. Shortening the jounce-bumpers prevents the rear from bottoming out on them under hard acceleration. The bottoming out inhibits weight transfer which causes the "twitchyness" in the 2001 Z06 rear suspension.

This is why the rear spring stiffness remains the same for the 2002 as the 2001.

Ray
 
V

vettepilot

Guest
Ray,
That's right..... I forgot all about the jounce bumper, all that you said is correct.... I remember that specifically being mentioned in the video also.
Stan
 

JBsC5

Well-known member
Joined
Nov 28, 2001
Messages
1,219
Location
Northern NJ
Would you possibly be better off ordering Bilsteins?
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Parts/Accessories:

Vetteskins

Advertise with the Corvette Action Center!

Double Your Chances!

Partners

Top Bottom