Replace rear spring on 73
Thread Starter
Intermediate
Joined: May 2010
Posts: 40
Likes: 0
From: San Antonio Texas
Replace rear spring on 73
My 73 sags toward the drivers side. I suspect the rear spring needs to be replaced. Is replacing it with a composite spring something I can do at home?
Last edited by gcarpenter; Jul 22, 2011 at 03:17 PM.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Not difficult, but could be dangerous so if you don't feel confident take it somewhere. I normally rec. guys do their own work, but not w/ springs. Do a search for other tips.
Burning Brakes
Joined: Sep 2008
Posts: 805
Likes: 5
From: Naperville Illinois
Not difficult. jack up the rear and put it on stands. jack up the spring near the trailing arm-- you will need to clamp a pair of vice-grips on the spring to keep the jack from sliding up the curve of the spring:
Raise the jack until the tension is just off the bolt connecting the spring to the trailing arm. Carefully remove the bolt and slowly lower the jack. Same for the other side, and reinstallation is just the reverse.
Raise the jack until the tension is just off the bolt connecting the spring to the trailing arm. Carefully remove the bolt and slowly lower the jack. Same for the other side, and reinstallation is just the reverse.
Melting Slicks
Joined: Apr 2001
Posts: 2,030
Likes: 363
From: Lubbock Texas
I just did this swap recently on my '73 and it was not bad at all. I didn't even pull the wheels, I just put the car on wheel ramps and used the floor jack like Rally68's pic shows.
I initially had issues getting the old 7 leaf spring out. It looked like I was going to have to remove the exhaust but I figured out an easier way. After unbolting the old spring, I took it apart and was able to remove one leaf at a time without taking anything else apart. The composite spring slid into position with no issues.
You may have issues with this next suggestion given that your spring may be sagging but to maintain my rear alignment, I measured the ride height before I put the car on the ramps and then kept adjusting the nuts on the new spring bolts until I had the same ride height. You'll need to drive it after installing the new spring and before measuring the final ride height and again after each adjustment. In your case, you might just need to re-align the rear after installing the new spring.
Hope this helps.
DC
I initially had issues getting the old 7 leaf spring out. It looked like I was going to have to remove the exhaust but I figured out an easier way. After unbolting the old spring, I took it apart and was able to remove one leaf at a time without taking anything else apart. The composite spring slid into position with no issues.
You may have issues with this next suggestion given that your spring may be sagging but to maintain my rear alignment, I measured the ride height before I put the car on the ramps and then kept adjusting the nuts on the new spring bolts until I had the same ride height. You'll need to drive it after installing the new spring and before measuring the final ride height and again after each adjustment. In your case, you might just need to re-align the rear after installing the new spring.
Hope this helps.
DC
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Some have said the jack flew out from under & some use a chain around the spring- connecting the chain to the jack might help some guys.
DC3
Most of these guys will be much better off jacking it up to take as much tension off the springs as possible before ...
DC3
Most of these guys will be much better off jacking it up to take as much tension off the springs as possible before ...
Melting Slicks
Joined: Apr 2001
Posts: 2,030
Likes: 363
From: Lubbock Texas
Ganey is correct in suggesting caution. You can't be too careful with springs. The main thing on this job is to make very certain the spring can't slip off the jack saddle. I actually clamped a 2x4 to the bottom of the spring end. I practiced taking tension off the spring and then releasing the tension before I actually removed the bolt.
It really helps to have a jack that can release itself in very small increments rather than too much at once like some jacks. You might want to practice with your jack to make sure you can release tension on the spring very slowly.
It's not a bad job at all, just go slow and think it through. Took me longer to set things up and clean up afterward than it did to swap the springs.
DC
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Drifting
Joined: Mar 2011
Posts: 1,886
Likes: 9
First, make sure the problem is the spring and not a rotten #4 body mount.
If you do put in a new fiberglass spring (get a soft one for the street- maybe 300 or 315 lbs), when you are all done and the weight of the car is back on the wheels, to set the ride height, make sure that your half shafts are pretty close to parallel to the ground. You can get a spring mount kit with extra long threaded bolts from any of the major restoration houses to make that adjustment. If you put a steel spring back in, the factory bolt kit will work just fine. IMO, you don't need poly for the spring bolts. For the exact rear suspension ride height, Chevrolet specs a difference in height between the CL's of the inner and outer lower strut rod bolts of 2 1/8", but that just confuses most people.
If you do put in a new fiberglass spring (get a soft one for the street- maybe 300 or 315 lbs), when you are all done and the weight of the car is back on the wheels, to set the ride height, make sure that your half shafts are pretty close to parallel to the ground. You can get a spring mount kit with extra long threaded bolts from any of the major restoration houses to make that adjustment. If you put a steel spring back in, the factory bolt kit will work just fine. IMO, you don't need poly for the spring bolts. For the exact rear suspension ride height, Chevrolet specs a difference in height between the CL's of the inner and outer lower strut rod bolts of 2 1/8", but that just confuses most people.
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
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Before you switch out the spring there are a few other things to check so you can be sure instead of just changing parts.
Are both spring bolts the same size and adjusted the same?
Are the cushions in place and in good shape?
Any history on the front strings?
Are both spring bolts the same size and adjusted the same?
Are the cushions in place and in good shape?
Any history on the front strings?
