Rear spring Question..shims
Team Owner
Joined: Sep 2003
Posts: 25,381
Likes: 2,735
I finally had some time to swap out my Z51 spring for a softer base spring (NYR I think). It has a MUCH bigger arc - my Z51 spring is almost flat.
I installed the "2 above, 0 below" shim setup on the new softer base spring and put the brackets back on the RH and LH side and guess what happened....the brackets bottomed out when I tightened the bolts and there was still space left in the spring / shim area.
Basically, the NYR spring I used must have a certain shim count that is required to fill the finite space that the brackets provide. How do I find out what that is? My 1984 factory manual (purchased with the car in 1984) does not call out any differences in shims, etc.
It makes sense, the Z51 spring is much thicker than the base softer spring. When you put the NYR softer spring in place you need extra shims to take up the space. Just need to find out what that is. Anyone have any idea? This must be documented somewhere easy to get. Also, where do I buy shims? I'll look at cc and a couple of others. Thanks in advance.
I installed the "2 above, 0 below" shim setup on the new softer base spring and put the brackets back on the RH and LH side and guess what happened....the brackets bottomed out when I tightened the bolts and there was still space left in the spring / shim area.
Basically, the NYR spring I used must have a certain shim count that is required to fill the finite space that the brackets provide. How do I find out what that is? My 1984 factory manual (purchased with the car in 1984) does not call out any differences in shims, etc.
It makes sense, the Z51 spring is much thicker than the base softer spring. When you put the NYR softer spring in place you need extra shims to take up the space. Just need to find out what that is. Anyone have any idea? This must be documented somewhere easy to get. Also, where do I buy shims? I'll look at cc and a couple of others. Thanks in advance.
There are 4 thickness shims. 2 are in my post above and the other 2 are
14084056 - 1.72mm and 14093185 - 4.39mm
OR measure the gap that you have and fill that dimensionally. If you have to shuffle the stack to adjust height then do that.
You'll need to probably find these from a WTB in the parts section. You might try "indianavette" - I would think he should have! VanSteel - maybe?
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
It's looking like my RR is sitting 1/2" lower than the other side. Unless [bad] shocks can make that much difference, could you adjust one side accordingly? (move shims top to bottom)
I will look for evidence of de-lamination and I need to install new shocks that I've already bought.
It's a really annoying situation because of how often my left side pipe is touching the ground. It's gonna tear the cover up one of these days!
You guys probably tilt them anyway for circle-track racing, right?!
I will look for evidence of de-lamination and I need to install new shocks that I've already bought.
It's a really annoying situation because of how often my left side pipe is touching the ground. It's gonna tear the cover up one of these days!
You guys probably tilt them anyway for circle-track racing, right?!
Team Owner
Joined: Sep 2003
Posts: 25,381
Likes: 2,735
I have a "new" NYR and a "new" BMF and the difference in the cushion thickness at the mounting pads is something right at 7.14mm. The BMF isn't a Z51 early but it should be something very close I would think to what you need to get a correct attachment.
You should I guess be prepared for a dimension close to that when you're checking your parts for thickness.
You should I guess be prepared for a dimension close to that when you're checking your parts for thickness.
Team Owner
Joined: Sep 2003
Posts: 25,381
Likes: 2,735
It's looking like my RR is sitting 1/2" lower than the other side. Unless [bad] shocks can make that much difference, could you adjust one side accordingly? (move shims top to bottom)
I will look for evidence of de-lamination and I need to install new shocks that I've already bought.
It's a really annoying situation because of how often my left side pipe is touching the ground. It's gonna tear the cover up one of these days!
You guys probably tilt them anyway for circle-track racing, right?!
I will look for evidence of de-lamination and I need to install new shocks that I've already bought.
It's a really annoying situation because of how often my left side pipe is touching the ground. It's gonna tear the cover up one of these days!
You guys probably tilt them anyway for circle-track racing, right?!
Last edited by WVZR-1; Sep 8, 2013 at 04:48 PM.
7th Gear
Joined: Aug 2013
Posts: 7
Likes: 0
That is very close to the gap I see right now. I will probably measure the "stack" of my original set up and do the match with the new NYR to see what shims I need.
I'm surprised information like this isn't in a matrix somewhere for folks to swap different springs in and out quick.
Now to start the shim search....
I'm surprised information like this isn't in a matrix somewhere for folks to swap different springs in and out quick.
Now to start the shim search....
I have a "new" NYR and a "new" BMF and the difference in the cushion thickness at the mounting pads is something right at 7.14mm. The BMF isn't a Z51 early but it should be something very close I would think to what you need to get a correct attachment.
You should I guess be prepared for a dimension close to that when you're checking your parts for thickness.
You should I guess be prepared for a dimension close to that when you're checking your parts for thickness.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
7th Gear
Joined: Aug 2013
Posts: 7
Likes: 0
I measured the current Z51 setup including all the shims, isolators, etc. Then measured the thickness of the softer NYR spring at the mountings. Looks like I need about 6.5mm based on my non digital calipers. The 7.11mm measurement was just about right on the money.
I found shims on Ebay and have them ordered. Hopefully this week I can get this buttoned up.
Thanks for all the great input!
I found shims on Ebay and have them ordered. Hopefully this week I can get this buttoned up.
Thanks for all the great input!
