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Since I'm redoing my corvette more or less from top to bottom I would also like to change my body mounts.
The current ones are so so. They are not rusty but they do start to show their age.
Should I go with stock aluminum or should I go rubber or poly?
Can I change them without pulling the body completely off? I mean change them one by one or in any other way.
Last edited by Primoz; 11-26-2016 at 08:34 AM.
Reason: adding pics
To the best of my knowledge, the OE body mounts were rubber, not aluminum. When I replaced the mounts on my wife's '79, about 20 years ago, I installed polyurethane mounts.
To the best of my knowledge, the OE body mounts were rubber, not aluminum. When I replaced the mounts on my wife's '79, about 20 years ago, I installed polyurethane mounts.
Hi PAK,
The original body mounts through 1972 production were solid… an aluminum puck was used. 1973 production and beyond used rubber mounts.
Since the later rubber mounts are slightly thicker the body will need to be loose enough for it to be raised 'slightly' to get the old mounts out and the thicker mounts in place.
How people seem to do this on 68-73 cars with out loosening all the bumper brackets (and many other things) I don't know.
Regards,
Alan
I'm from Europe and every purchase must be well thought of because of the high shipping costs and customs and taxes.
I've seen those discussions, and can certainly understand your concerns. When I was doing a LOT of upgrading to my wife's C-3, which has since been sold, I installed numerous polyurethane bushings. I also used polyurethane bushings in several other cars that I've owned, over the years.
What I've seen is this....On the Corvette project, I purchased the poly bushings in conjunction with several other suspension parts, from a well-known Corvette supplier. Their parts appeared to be rather generic, sold in unmarked, plastic bags. I also used poly parts obtained from Energy Suspension, a well-known, long time manufacturer of polyurethane parts.
I can't vouch for the poly bushings I installed on the Corvette, as we sold the car 3-4 years after I installed them. (as I'm typing, I seem to recall, however, that the body mount bushings I used were from Energy Suspension) Therefore, I don't know how well they held up, in the long term. They were OK at the time we sold the car, and the person who bought the car, has since left this area. What I can say, is that any of the Energy Suspension parts I've ever used, have held up well. I even installed their control arm bushings in a couple of cars that were driven through several road salt filled winters, with no problems.
Hi PAK,
The original body mounts through 1972 production were solid… an aluminum puck was used. 1973 production and beyond used rubber mounts.
Interesting.....I haven't worked on any Corvettes older than a 1976, hence my earlier statement. I'm kind of surprised, though, as I would have thought that GM would have considered the chemical reaction of dissimilar metals (aluminum pucks/steel frames), especially considering that some people drove their Corvettes through the winter, therefore they saw road salt, which might have even sped up this corrosion process.
Interesting.....I haven't worked on any Corvettes older than a 1976, hence my earlier statement. I'm kind of surprised, though, as I would have thought that GM would have considered the chemical reaction of dissimilar metals (aluminum pucks/steel frames), especially considering that some people drove their Corvettes through the winter, therefore they saw road salt, which might have even sped up this corrosion process.
Well GM didn't consider that. I removed the headlight brackets when I was redoing them and they were quite damaged because of the chemical reaction.
Hi l4,
The aluminum pucks DID degrade as time went by.
Whether it was due to the material or the elements I'm not sure.
On my 71 which had 35000 miles and 2 winter's (salted roads) worth of driving, the pucks were still in good condition around 1990 when I began to take the car apart.
I have seen photos of cars on which much of the puck appears to have disappeared for the reasons you cite.
Regards,
Alan
I remember a forum member discussing using poly to get all the deflection out of the chassis.
Since the body is FG he suggested using the stock rubber mounts to reduce vibration on the body.
That makes sense to me.
I put 73-up rubber mounts on my '71. It made a big difference in ride quality without hurting handling. Getting the bumpers to line up is a bit tricky as the body sits a little higher on the rubber mounts but it's doable with some shims on the bumper brackets.
I put 73-up rubber mounts on my '71. It made a big difference in ride quality without hurting handling. Getting the bumpers to line up is a bit tricky as the body sits a little higher on the rubber mounts but it's doable with some shims on the bumper brackets.
That would actually cure an issue I have with front end sagging a bit. And I'm pretty sure the front body mounts are gone.
Well my brand new rubber mounts in the rear 2 mounts only split up badly just by using the recommended 45 ft-lbs torque. So I replaced them and only torqued down until I could see some deflection in the rubber mount. I think the poly mounts in the pictures may have been over torqued also but who knows?
I once put solid poly body mounts in my GTO and regretted it. Car felt more like a tank. Now the front and rear body mounts on the corvette see the environment where the ones protected under the passenger compartment don't. IMHO the best of both worlds is to use rubber under the passenger compartment and poly mounts out on the front and rear mounts. This should give you stiffer mounts at the suspension ends while a softer ride in the people compartment. Also use minimum torque meaning torque the rubber only until I starts to bulge and torque the poly mounts a fraction of a turn past snug.
Well my brand new rubber mounts in the rear 2 mounts only split up badly just by using the recommended 45 ft-lbs torque.
Something was seriously wrong with those mounts then. They're supposed to have steel sleeves so that the rubber only can compress a certain amount before the steel sleeves contact.
Something was seriously wrong with those mounts then. They're supposed to have steel sleeves so that the rubber only can compress a certain amount before the steel sleeves contact.
Not mine. I'll see if I can find the order document.
Had the same problem with repop A body rubber bushings think they wound up around 25-30 or as you said just where they start to bulge a hair. They really dont need heavy cinching at all
Dont know if theres difference between the two but some kits will specify to reuse the old steel sleeves some come with new ones.
Prefer polygraphite (graphite imregnated usually black) over polyurethane. Seen too many use the usually polyurethane suspension bushings even with grease they squeaked that was many yrs ago though maybe the compound is different now.
Susp-graphite
Body rubber
Good ride without everything transmitted inside.
If you use poly engine mounts use rubber on the trans when you can
I put 73-up rubber mounts on my '71. It made a big difference in ride quality without hurting handling. Getting the bumpers to line up is a bit tricky as the body sits a little higher on the rubber mounts but it's doable with some shims on the bumper brackets.
OK! Then there is no issue with rubber body mounts from 73 onwards if fitted to 71?
OK! Then there is no issue with rubber body mounts from 73 onwards if fitted to 71?
Rubber mounts work fine on earlier cars. I was able to do it without lifting the body completely off. I lifted one side at a time just enough to get the mounts in place.
Rubber mounts work fine on earlier cars. I was able to do it without lifting the body completely off. I lifted one side at a time just enough to get the mounts in place.
I will try to use the same process.
How did you lift the body? With lift from the bottom? Did you have to remove the bumpers before changin the mounts?
Everything has to be disconnected as you need to lift it more than you might think for mount 2 & 3. Bumpers, steering shaft, seat belt safety cable (easy to forget!), etc.
I used a couple floor jacks to lift. Take it slow and listen for creaking noises indicating you forgot to disconnect/remove something.
11-26-2016, 08:12 AM
71 body mounts stock or not
