[Z06] 2004 rear shock upgrade for 2001?
Thread Starter
Drifting
Joined: Nov 2011
Posts: 1,279
Likes: 18
From: Oklahoma
2004 rear shock upgrade for 2001?
Any of you guys done this upgrade and seen a profound improvement? I know my rear end breaks free really easily. I have read this is because the 2001 shocks were too stiff and didn't allow weight transfer properly to the rear wheels. Looks to be about a $250 cost and two hour job to swap them out. I will be road racing my car so I am thinking this is a no brainer, but I would also think that you drag racers would benefit a bunch from this as well.
Melting Slicks
Joined: Aug 2004
Posts: 3,003
Likes: 89
From: Indy IN
The Bilstein sport shocks (not the HD, the Sports) have almost identical valving to the fronts and rear in the low speed regime, and are a softer (more comfortable) over small harsh impacts in the rear. In terms of a performance shock and lap times they are every bit as good or better than the 04Z shocks and cost a bunch less.
More importantly they will last forever, as compared to the life of the OE shocks.
Most serious track folks go for the Bilsteins before the stock shocks because the stock shocks are more expensive and don't last as long, and aren't as fast on the track.
After the Bilsteins you could go for Koni sports, if you want something adjustable, but frankly, the 04 z shocks aren't worth the extra $.
More importantly they will last forever, as compared to the life of the OE shocks.
Most serious track folks go for the Bilsteins before the stock shocks because the stock shocks are more expensive and don't last as long, and aren't as fast on the track.
After the Bilsteins you could go for Koni sports, if you want something adjustable, but frankly, the 04 z shocks aren't worth the extra $.
Melting Slicks
Joined: Aug 2004
Posts: 3,003
Likes: 89
From: Indy IN
If your are feeling the car is loose you need to look at your ride height, if it is lowered too much you will run out of travel before the front runs out of travel and that will absolutey cause the car to be loose
Race Director
Joined: Jan 2008
Posts: 16,027
Likes: 170
From: oregon
with the age of your fronts i would do all 4. the rears are the more expensive of the 2, fronts are only 100 each
part numbers are
F ac delco 540-146 GM 10339944
R ac delco 540-137 GM 10339945
i'm ordering the same set for my 02. these are the sachs 2004 shocks that were actually designed for the c5z and had the best valving
i do agree with solo on his ride height comment, but as for the shocks. bilstein sports are $350, OE sachs 2004 z06 shocks are $450, not a huge difference
part numbers are
F ac delco 540-146 GM 10339944
R ac delco 540-137 GM 10339945
i'm ordering the same set for my 02. these are the sachs 2004 shocks that were actually designed for the c5z and had the best valving
i do agree with solo on his ride height comment, but as for the shocks. bilstein sports are $350, OE sachs 2004 z06 shocks are $450, not a huge difference
Last edited by racebum; Apr 8, 2013 at 03:04 PM.
Thread Starter
Drifting
Joined: Nov 2011
Posts: 1,279
Likes: 18
From: Oklahoma
The Bilstein sport shocks (not the HD, the Sports) have almost identical valving to the fronts and rear in the low speed regime, and are a softer (more comfortable) over small harsh impacts in the rear. In terms of a performance shock and lap times they are every bit as good or better than the 04Z shocks and cost a bunch less.
More importantly they will last forever, as compared to the life of the OE shocks.
Most serious track folks go for the Bilsteins before the stock shocks because the stock shocks are more expensive and don't last as long, and aren't as fast on the track.
After the Bilsteins you could go for Koni sports, if you want something adjustable, but frankly, the 04 z shocks aren't worth the extra $.
More importantly they will last forever, as compared to the life of the OE shocks.
Most serious track folks go for the Bilsteins before the stock shocks because the stock shocks are more expensive and don't last as long, and aren't as fast on the track.
After the Bilsteins you could go for Koni sports, if you want something adjustable, but frankly, the 04 z shocks aren't worth the extra $.
Race Director
Joined: Aug 2004
Posts: 14,639
Likes: 39
From: Winston-Salem North Carolina
St. Jude Donor '08-'09
Any of you guys done this upgrade and seen a profound improvement? I know my rear end breaks free really easily. I have read this is because the 2001 shocks were too stiff and didn't allow weight transfer properly to the rear wheels. Looks to be about a $250 cost and two hour job to swap them out. I will be road racing my car so I am thinking this is a no brainer, but I would also think that you drag racers would benefit a bunch from this as well.
Melting Slicks
Joined: Aug 2004
Posts: 3,003
Likes: 89
From: Indy IN
Here's the link to a source, for the Bilsteins $326 for the set. Shop around and you might be able to do better, I just did a quickie search...
http://www.eshocks.com/bil_veh.asp?M...tein&SubChar=Q
Fronts 24-029773
Rears 24-029780
The C5 never had Bilstein's, as OE shocks. The 04Z shocks were made by Sach's, I don't know who made the earlier ones. Bilsteins will last as long as the car, most OE's won't. If you google "far north racing" and look through their stuff there is a set of shock curves for the 04Z, the Bilstein Sports, and the Bilstein HD shocks, so you can see what the differences are. In short there's no reason to spend $450 + shipping for the Sach's. No doubt they are a good shock, but I wouldn't pay $125 more for them.
http://www.eshocks.com/bil_veh.asp?M...tein&SubChar=Q
Fronts 24-029773
Rears 24-029780
The C5 never had Bilstein's, as OE shocks. The 04Z shocks were made by Sach's, I don't know who made the earlier ones. Bilsteins will last as long as the car, most OE's won't. If you google "far north racing" and look through their stuff there is a set of shock curves for the 04Z, the Bilstein Sports, and the Bilstein HD shocks, so you can see what the differences are. In short there's no reason to spend $450 + shipping for the Sach's. No doubt they are a good shock, but I wouldn't pay $125 more for them.
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Thread Starter
Drifting
Joined: Nov 2011
Posts: 1,279
Likes: 18
From: Oklahoma
Here's the link to a source, for the Bilsteins $326 for the set. Shop around and you might be able to do better, I just did a quickie search...
http://www.eshocks.com/bil_veh.asp?M...tein&SubChar=Q
Fronts 24-029773
Rears 24-029780
The C5 never had Bilstein's, as OE shocks. The 04Z shocks were made by Sach's, I don't know who made the earlier ones. Bilsteins will last as long as the car, most OE's won't. If you google "far north racing" and look through their stuff there is a set of shock curves for the 04Z, the Bilstein Sports, and the Bilstein HD shocks, so you can see what the differences are. In short there's no reason to spend $450 + shipping for the Sach's. No doubt they are a good shock, but I wouldn't pay $125 more for them.
http://www.eshocks.com/bil_veh.asp?M...tein&SubChar=Q
Fronts 24-029773
Rears 24-029780
The C5 never had Bilstein's, as OE shocks. The 04Z shocks were made by Sach's, I don't know who made the earlier ones. Bilsteins will last as long as the car, most OE's won't. If you google "far north racing" and look through their stuff there is a set of shock curves for the 04Z, the Bilstein Sports, and the Bilstein HD shocks, so you can see what the differences are. In short there's no reason to spend $450 + shipping for the Sach's. No doubt they are a good shock, but I wouldn't pay $125 more for them.
Melting Slicks
Joined: Aug 2004
Posts: 3,003
Likes: 89
From: Indy IN
The link in the above thread had them for $326 and free shipping, so that's what I'd do, but I'm cheap...
Race Director
Joined: Jan 2008
Posts: 16,027
Likes: 170
From: oregon
i would go {actually am going} for the 04 shocks all else equal. #1 sachs is every bit as high as quality as bilstein and #2 GM did a lot of testing at the ring to get the valving dialed in on the OE 2004 shocks. bilstein as far as i know did none
there's a really trick dampening curve on the 2004 shocks that's firm at the ends but softer in the middle. increases compliance with uneven terrain and at the same time gives you that planted feeling in corners.
there's a really trick dampening curve on the 2004 shocks that's firm at the ends but softer in the middle. increases compliance with uneven terrain and at the same time gives you that planted feeling in corners.
Pro Mechanic
Joined: Oct 1999
Posts: 3,915
Likes: 1,450
From: South-Central Coast California
i would go {actually am going} for the 04 shocks all else equal. #1 sachs is every bit as high as quality as bilstein and #2 GM did a lot of testing at the ring to get the valving dialed in on the OE 2004 shocks. bilstein as far as i know did none
there's a really trick dampening curve on the 2004 shocks that's firm at the ends but softer in the middle. increases compliance with uneven terrain and at the same time gives you that planted feeling in corners.
there's a really trick dampening curve on the 2004 shocks that's firm at the ends but softer in the middle. increases compliance with uneven terrain and at the same time gives you that planted feeling in corners.
I have not tested Bilstein's on my '04 Z06 and I'm not trying to slag on that brand--they worked very well on C4s--and obviously must still be good quality-wise as GM went back to Bilstein as the OE supplier for C7, but it is true that the OE '04 shocks were the best street high-performance valving you can get and they are a significant ride enhancement over '01-'03.
Thread Starter
Drifting
Joined: Nov 2011
Posts: 1,279
Likes: 18
From: Oklahoma
"racebum" has the issue spot on. Back in summer '03 I did an interview with the then lead engineer for Corvette ride-and-handling, Mike Neal, and he described exactly what "racebum" says along with telling me about the shock testing they did at Nurburgring. The '04 Z06 was the first car GM developed using Nurburgring as a test venue.
I have not tested Bilstein's on my '04 Z06 and I'm not trying to slag on that brand--they worked very well on C4s--and obviously must still be good quality-wise as GM went back to Bilstein as the OE supplier for C7, but it is true that the OE '04 shocks were the best street high-performance valving you can get and they are a significant ride enhancement over '01-'03.
I have not tested Bilstein's on my '04 Z06 and I'm not trying to slag on that brand--they worked very well on C4s--and obviously must still be good quality-wise as GM went back to Bilstein as the OE supplier for C7, but it is true that the OE '04 shocks were the best street high-performance valving you can get and they are a significant ride enhancement over '01-'03.
Instructor
Joined: Mar 2013
Posts: 135
Likes: 0
From: Peoria Arizona
I would like to add, that Bilstein will revalve/rebuild their shocks. So if you have them and they are getting old or do not perform like you think they should you can send them in to be rebuilt and request that they be revalved and you can match the specs of the 04 C5Z's mentioned above. Assuming the specs are common knowledge.
Only issue i've seen is that the last set I sent out took 8 weeks to be completed and returned.
Only issue i've seen is that the last set I sent out took 8 weeks to be completed and returned.
Le Mans Master
Joined: Apr 2001
Posts: 9,556
Likes: 288
From: Granbury Texas
"racebum" has the issue spot on. Back in summer '03 I did an interview with the then lead engineer for Corvette ride-and-handling, Mike Neal, and he described exactly what "racebum" says along with telling me about the shock testing they did at Nurburgring. The '04 Z06 was the first car GM developed using Nurburgring as a test venue.
I have not tested Bilstein's on my '04 Z06 and I'm not trying to slag on that brand--they worked very well on C4s--and obviously must still be good quality-wise as GM went back to Bilstein as the OE supplier for C7, but it is true that the OE '04 shocks were the best street high-performance valving you can get and they are a significant ride enhancement over '01-'03.
I have not tested Bilstein's on my '04 Z06 and I'm not trying to slag on that brand--they worked very well on C4s--and obviously must still be good quality-wise as GM went back to Bilstein as the OE supplier for C7, but it is true that the OE '04 shocks were the best street high-performance valving you can get and they are a significant ride enhancement over '01-'03.
I concur!