Help - Tried to Lower Rear
Thread Starter
Racer
Joined: Jan 2001
Posts: 322
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From: Liberty Township OH
Help - Tried to Lower Rear
I tried to lower the rear end of my C4. I bought the rear lowering bolts (10" bolts?) w/ the poly bushings from Corvette Central. There were no instructions, but it looked simple enough. Anyway, after installing them, my car sat 2" higher. I tried a range of 'settings', from the nut being barely on to the nut threaded all the way up. Did not seem to make a differance - car was 2" higher on any setting. finally went back to the stock bolts & the car still sits 2" high.
Could the spring have moved? I'm afraid to move the car because I don't want to break something in the rear spring, differential, etc. Is there something that needs to be done when these bolts are replaced? Does the ride height 'settle' on in?
[Modified by Polar LT4, 11:39 PM 4/13/2002]
Could the spring have moved? I'm afraid to move the car because I don't want to break something in the rear spring, differential, etc. Is there something that needs to be done when these bolts are replaced? Does the ride height 'settle' on in?
[Modified by Polar LT4, 11:39 PM 4/13/2002]
Melting Slicks
Joined: Aug 2001
Posts: 2,047
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Re: Help - Tried to Lower Rear (Polar LT4)
The ride height perception of "no change" could possibly be because the car is holding itself up. By that I mean, you've gotta roll the car several feet before it'll settle. Why? When you lift the car, the rear wheels/suspension will sag. The rear wheels basically end up sitting at almost full positive camber while either side is in the air. Dropping the car, then, causes the wheels to become pinched (per se) under the vehicle. Move it back and forth a couple feet, and I think you'll be fine.
Also, you're doing the right thing if you want the car to sit lower by threading the nut very far up on the new bolts. You're compressing the spring, thereby decreasing the effective ride height. Get your alignment checked after performing said operation! ;)
Also, you're doing the right thing if you want the car to sit lower by threading the nut very far up on the new bolts. You're compressing the spring, thereby decreasing the effective ride height. Get your alignment checked after performing said operation! ;)
Melting Slicks
Joined: Aug 2001
Posts: 2,516
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From: Lockport NY
Re: Help - Tried to Lower Rear (EricVonHa)
Also, you're doing the right thing if you want the car to sit lower by threading the nut very far up on the new bolts. You're compressing the spring, thereby decreasing the effective ride height.
...If shortening the bolt lowers the car, why are the "lowering" bolts longer???... :confused:
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Re: Help - Tried to Lower Rear (Polar LT4)
The longer bolt lowers the rear but indeed you need to drive the car a little after each adjustment before you take a measurement again.
If you measure the length of the stock bolt and set the new one say 1 1/4" longer the rear will set about 1 1/4" lower.
If you measure the length of the stock bolt and set the new one say 1 1/4" longer the rear will set about 1 1/4" lower.
Melting Slicks
Joined: Aug 2001
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Re: Help - Tried to Lower Rear (Rich B.)
The bolts being longer, may still have more thread to them. They should be threaded a good inch or better and closer to the bolt head than the factory ones. Definitely, thread those puppies all the way up, and the car should come down a little. :yesnod:
Team Owner
Joined: Oct 2000
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St. Jude Donor '03-'04
Cruise-In 1-2-3-4-5 Veteran
Re: Help - Tried to Lower Rear (EricVonHa)
Polar, the guys are right on here.
When you lifted the car, the rear suspension relaxed. All of our cars sit higher for a while after being up up jacks.
If you had lef it alone and gone for a drive over to the alignment shop, the ride height would have settled out just fine...
Sorry, neighbor. Go for it again, it's an easy adjustment.
When you lifted the car, the rear suspension relaxed. All of our cars sit higher for a while after being up up jacks.
If you had lef it alone and gone for a drive over to the alignment shop, the ride height would have settled out just fine...
Sorry, neighbor. Go for it again, it's an easy adjustment.
Drifting
Joined: Nov 2001
Posts: 1,783
Likes: 2
From: Latham NY
Re: Help - Tried to Lower Rear (65Z01)
The longer bolt lowers the rear but indeed you need to drive the car a little after each adjustment before you take a measurement again.
If you measure the length of the stock bolt and set the new one say 1 1/4" longer the rear will set about 1 1/4" lower.
If you measure the length of the stock bolt and set the new one say 1 1/4" longer the rear will set about 1 1/4" lower.
The bolts being longer, may still have more thread to them. They should be threaded a good inch or better and closer to the bolt head than the factory ones. Definitely, thread those puppies all the way up, and the car should come down a little.
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Melting Slicks
Joined: Aug 2001
Posts: 2,047
Likes: 0
Re: Help - Tried to Lower Rear (Bluevette85)
These two posts contradict each other. I believe that if the distance from the top of the bolt to the nut is longer, then the car will be lower.
Take the nut closer to the head of the bolt (closer to the top of the hub assy knuckle) this will "Compress" the spring thereby lowering the ride height. Kapeicsh? The more the spring is compressed, the lower the ride height. Get someone to push down on the car as you watch how the geometry of the suspension moves... no, I did not drink heavily tonight...
Pro
Joined: Feb 2002
Posts: 596
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From: Tollhouse Ca
Re: Help - Tried to Lower Rear (Polar LT4)
sounds like some knowledgable people out there, so maybe you can help with this ...
I recently had my front spring (I think it was a Z51) replaced on my 84. The shop put a Vette Brake standard spring on it. Now the front fenders sit 3" above the tires which I think is too high .. the rear fenders sits 2" above the tire. I have called and emailed Vette Brake, but so far they haven't really told me anything except their springs are top quality.
How can I get the front lower? Should it sit this high? I was told taking the shims out will only lower it 3/16" and it's not recommended to cut the rubber blocks off and use the lowering blocks.
Any way out of my dilema?
I recently had my front spring (I think it was a Z51) replaced on my 84. The shop put a Vette Brake standard spring on it. Now the front fenders sit 3" above the tires which I think is too high .. the rear fenders sits 2" above the tire. I have called and emailed Vette Brake, but so far they haven't really told me anything except their springs are top quality.
How can I get the front lower? Should it sit this high? I was told taking the shims out will only lower it 3/16" and it's not recommended to cut the rubber blocks off and use the lowering blocks.
Any way out of my dilema?
Melting Slicks
Joined: Aug 2001
Posts: 2,047
Likes: 0
Re: Help - Tried to Lower Rear (84FromHell)
The ride height in your car is up to you! If it looks good to you, go for it! If it doesn't, then cutting out the block that cushions the spring, may be the way to go. I'd give VB Products a call and tell'em your scenario. It's more in the spring than anything else. I had a "sport" spring at one time that gave the car about a 2" drop. Killer kidney killing ride with that setup, so I did away with it... Hopefully they can do one better for you. :yesnod:
Drifting
Joined: May 1999
Posts: 1,697
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From: Joliet IL
Re: Help - Tried to Lower Rear (Polar LT4)
I noticed the same thing when I lowered mine. I did the poly bushings at the same time. I sat there in the garage for about half a day trying to figure this out. Then I took the car for a ride and then the car was lower then before. Now everytime I jack the car up, it looks like a 4x4. I could almost slide under the car and change the oil without driving it up on the ramps. When I'm done with the car, I just take it around the block and it's back to normal.
Melting Slicks
Joined: Aug 2001
Posts: 2,516
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From: Lockport NY
Re: Help - Tried to Lower Rear (maduraj)
I sat there in the garage for about half a day trying to figure this out..l.
...This Forum is starting to affect me that way, too... :crazy:
Safety Car
Joined: Dec 2000
Posts: 3,767
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From: Jacksonville Fl
Re: Help - Tried to Lower Rear (Rich B.)
HAHAHAHAHA.....
Ok, longer bolts let the suspension move further AWAY from the spring ( the spring maintains the same arc regardless ), thereby bringing the wheels closer to the frame. This causes the car to sit closer to the ground.
When replacing the spring bolts, most people usually replace the spring cushions as well...which will have to relax under the weight of the car before final ride height will be achieved ( may take some time driving for this to occur )
Ok, longer bolts let the suspension move further AWAY from the spring ( the spring maintains the same arc regardless ), thereby bringing the wheels closer to the frame. This causes the car to sit closer to the ground.
When replacing the spring bolts, most people usually replace the spring cushions as well...which will have to relax under the weight of the car before final ride height will be achieved ( may take some time driving for this to occur )