Help Lowering My Z - ZR-1 Net Registry Forums

zrss · 09-13-2014

I'm lowering my '94 using Vette Brakes & Products kit which, for the front, consists of wedges that I am supposed to glue to the stock spring in place of the factory rubber pads. I have a few questions.

1. The factory rubber pads are about .9" thick, and the VBandP replacements are wedge shaped, varying from .5" to .7" thick. Does that mean the car will only be lowered by .2' to .4'? The instructions with the kit say the car will be lowered about 1" but I don't see how that's possible.

2. The instructions also say that removing the 2 shims on each side, which are 1/8" thick each, will lower the car about 1/2". So same question, why is the car lowered more than the amount of height removed from the spring/shim combination?

3. The spring retainers (aluminum C shaped brackets) which fit tightly around the original rubber pads are too tall with the VBandP replacements and don't "retain" the spring, which is loose and slides back and forth in the retainers. Do I need to shorten the retainers? VBandP's instructions don't mention shortening the retainers. If I don't shorten the retainers, I don't think they will do anything and don't see why I should install them.

Thanks for any help. As you can tell, this is the first time I've done this.

USAZR1 · 09-13-2014

Here's a couple of links to help you out. I'm going to lower our 94 at a friend's shop next week and will be installing a VB&P adjustable front spring. In the rear,we're going to install a pair of 11" long 14mm bolts to replace the oem 9".
I'm looking to drop the car 1.5"-2" at both ends.

http://zr1.net/forum/showthread.php?...light=Lowering

http://forums.corvetteforum.com/c4-g...-my-96-c4.html

zrss · 09-13-2014

Thanks. I'm hoping to finish mine up next weekend. I'll install the aluminum shims and see how if I like the height and then make changes as needed.

mike100 · 09-14-2014

To answer why the math doesn't add up on the wedge and shim thickness- it is because it isn't just a spacer--the preload or initial tension of the transverse leaf is greater with the stock bushings and shims pushing the center of the spring closer to the ground. There is no lowering of the car per se, as the spring pad on the a-arm and ball joint never move and you always will have the same travel as stock, but all you do is unspring the spring a bit to reduce the spring effort against the a-arms and therefore it drops about an inch.

You might be lowering the CG of the car a bit, but for the most part you are actually reducing the performance of the spring as you now have to compress the car down on it even further to get back to the tension you had stock. The VB&P straight/adjustable spring might be a better choice. Additionally, hacking the bushings off of your hard-to-find ZR-1 stocker is kind of a one way irreversible mod.

As a compromise, I would only remove the shims which will drop it only .5 inches. Don't forget to have the brackets machined shorter if you cut the bushings

USAZR1 · 09-25-2014

How did the lowering on your 94 work out,zrss? Here's a pic of our 94 before I filled the fuel tank & raised the rear ride height another 1/2" to bring the rake angle back to where it needed to be. Will take another pic soon.
(I need to learn how to take better photos)

5ABI VT · 09-25-2014

Zrss you don't need to cut the retainer. Rebember the spring can be moved higher up in it's location so just put the stock wedges under the spring to take up the slack and then the retainer will hold the spring. Hope that makes sense , just remember that you are raising the spring in it's mounting location so adding underneath the spring only fills space.

PhillipsLT5 · 09-25-2014

Call VBP, always helped me over phone

Racinfan83 · 09-25-2014

Where are those "two shims" at on the front? Can those be easily removed and if removed do you have to do anything to compensate?
I wouldn't mind dropping the front of mine 1/2" if it is a fairly simple process...

USAZR1 · 09-25-2014

Quote:

Originally Posted by Racinfan83

Where are those "two shims" at on the front? Can those be easily removed and if removed do you have to do anything to compensate?
I wouldn't mind dropping the front of mine 1/2" if it is a fairly simple process...

zrss · 09-26-2014

Lowering didn't work out quite as I hoped. The nose is a little less than 1/2" inch lower. I removed the factory rubber pads, installed the VBandP pads, and reinstalled the shims (my car has a green spring), which the instructions said would lower it about a full inch. If I get ambitious I may remove the shims to get more drop and see if that gets me close to the 1" drop I was looking for.

I like the look of USAZR1's car but wonder if that's not a little too low, at least for the washboards they call streets where I live.

09-13-2014	#1
zrss Join Date: Dec 2006 Location: Montana Posts: 64	Help Lowering My Z I'm lowering my '94 using Vette Brakes & Products kit which, for the front, consists of wedges that I am supposed to glue to the stock spring in place of the factory rubber pads. I have a few questions. 1. The factory rubber pads are about .9" thick, and the VBandP replacements are wedge shaped, varying from .5" to .7" thick. Does that mean the car will only be lowered by .2' to .4'? The instructions with the kit say the car will be lowered about 1" but I don't see how that's possible. 2. The instructions also say that removing the 2 shims on each side, which are 1/8" thick each, will lower the car about 1/2". So same question, why is the car lowered more than the amount of height removed from the spring/shim combination? 3. The spring retainers (aluminum C shaped brackets) which fit tightly around the original rubber pads are too tall with the VBandP replacements and don't "retain" the spring, which is loose and slides back and forth in the retainers. Do I need to shorten the retainers? VBandP's instructions don't mention shortening the retainers. If I don't shorten the retainers, I don't think they will do anything and don't see why I should install them. Thanks for any help. As you can tell, this is the first time I've done this.

09-13-2014	#2
USAZR1 Join Date: Oct 2013 Location: Wichita Falls,Tx Posts: 594	Re: Help Lowering My Z Here's a couple of links to help you out. I'm going to lower our 94 at a friend's shop next week and will be installing a VB&P adjustable front spring. In the rear,we're going to install a pair of 11" long 14mm bolts to replace the oem 9". I'm looking to drop the car 1.5"-2" at both ends. http://zr1.net/forum/showthread.php?...light=Lowering http://forums.corvetteforum.com/c4-g...-my-96-c4.html

09-13-2014	#3
zrss Join Date: Dec 2006 Location: Montana Posts: 64	Re: Help Lowering My Z Thanks. I'm hoping to finish mine up next weekend. I'll install the aluminum shims and see how if I like the height and then make changes as needed.

09-14-2014	#4
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,786	Re: Help Lowering My Z To answer why the math doesn't add up on the wedge and shim thickness- it is because it isn't just a spacer--the preload or initial tension of the transverse leaf is greater with the stock bushings and shims pushing the center of the spring closer to the ground. There is no lowering of the car per se, as the spring pad on the a-arm and ball joint never move and you always will have the same travel as stock, but all you do is unspring the spring a bit to reduce the spring effort against the a-arms and therefore it drops about an inch. You might be lowering the CG of the car a bit, but for the most part you are actually reducing the performance of the spring as you now have to compress the car down on it even further to get back to the tension you had stock. The VB&P straight/adjustable spring might be a better choice. Additionally, hacking the bushings off of your hard-to-find ZR-1 stocker is kind of a one way irreversible mod. As a compromise, I would only remove the shims which will drop it only .5 inches. Don't forget to have the brackets machined shorter if you cut the bushings Last edited by mike100; 09-14-2014 at 01:23 PM.

09-25-2014	#5
USAZR1 Join Date: Oct 2013 Location: Wichita Falls,Tx Posts: 594	Re: Help Lowering My Z How did the lowering on your 94 work out,zrss? Here's a pic of our 94 before I filled the fuel tank & raised the rear ride height another 1/2" to bring the rake angle back to where it needed to be. Will take another pic soon. (I need to learn how to take better photos) Last edited by USAZR1; 09-25-2014 at 06:08 PM.

09-25-2014	#6
5ABI VT Join Date: Jun 2013 Location: Toronto Posts: 780	Re: Help Lowering My Z Zrss you don't need to cut the retainer. Rebember the spring can be moved higher up in it's location so just put the stock wedges under the spring to take up the slack and then the retainer will hold the spring. Hope that makes sense , just remember that you are raising the spring in it's mounting location so adding underneath the spring only fills space.

09-25-2014	#7
PhillipsLT5 Join Date: Aug 2005 Location: Scottsdale, AZ Posts: 2,446	Re: Help Lowering My Z Call VBP, always helped me over phone

09-25-2014	#8
Racinfan83 Join Date: Apr 2013 Location: Eastern Missouri Posts: 773	Re: Help Lowering My Z Where are those "two shims" at on the front? Can those be easily removed and if removed do you have to do anything to compensate? I wouldn't mind dropping the front of mine 1/2" if it is a fairly simple process...

09-26-2014	#10
zrss Join Date: Dec 2006 Location: Montana Posts: 64	Re: Help Lowering My Z Lowering didn't work out quite as I hoped. The nose is a little less than 1/2" inch lower. I removed the factory rubber pads, installed the VBandP pads, and reinstalled the shims (my car has a green spring), which the instructions said would lower it about a full inch. If I get ambitious I may remove the shims to get more drop and see if that gets me close to the 1" drop I was looking for. I like the look of USAZR1's car but wonder if that's not a little too low, at least for the washboards they call streets where I live.