Modified Body Mounts?
Thread Starter
Racer
Joined: May 2007
Posts: 391
Likes: 2
From: NC
Modified Body Mounts?
The basics:
68-72 have solid (aluminum) mounts.
73-82 have thicker cushion (rubber) mounts.
Question:
I'm not able to find a poly cushion conversion for the 68-72, so has anyone modified a poly set designed for the 73-82? Is all it would take is to trim 3/8" off the cushion so the body height will remain the same?
It's hard to imagine a conversion is not available. Maybe I'm missing something.
Tnx!
68-72 have solid (aluminum) mounts.
73-82 have thicker cushion (rubber) mounts.
Question:
I'm not able to find a poly cushion conversion for the 68-72, so has anyone modified a poly set designed for the 73-82? Is all it would take is to trim 3/8" off the cushion so the body height will remain the same?
It's hard to imagine a conversion is not available. Maybe I'm missing something.
Tnx!
Le Mans Master
Joined: Apr 2001
Posts: 5,941
Likes: 281
From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
I think if you search you will find some topics on it. If I remember correctly most people were just placing them in the car without modification. I think they need slightly longer body bolts, and in the end it is something like a 1/4 inch difference in body height.
Team Owner
Joined: Sep 2006
Posts: 31,218
Likes: 4,302
From: Westminster Maryland
Hi ncv,
I wonder why there's a difference in the cushion's height. Perhaps to get the squish the engineers wanted the rubber needed to be that high. Would you defeat the purpose by milling them down in height?
Many people seem to live with the 3/8" difference. Would you notice the 3/8" in the distance from the top of the tire to the fender lip? It would bother me, but I'm pretty nuts about how the tires fill the wheel openings.
Regards,
Alan
I wonder why there's a difference in the cushion's height. Perhaps to get the squish the engineers wanted the rubber needed to be that high. Would you defeat the purpose by milling them down in height?
Many people seem to live with the 3/8" difference. Would you notice the 3/8" in the distance from the top of the tire to the fender lip? It would bother me, but I'm pretty nuts about how the tires fill the wheel openings.
Regards,
Alan
Thread Starter
Racer
Joined: May 2007
Posts: 391
Likes: 2
From: NC
Yeah, I suppose the height difference was to have enough rubber mass to act as a cushion. I have read where the mounts on the 73+ were adjusted by 3/8" because of the height issue. I'm like you, Alan 71, and would cringe at the height difference. I guess somebody has to be the first one to cut up some mounts, right?
Melting Slicks
Joined: Jul 2002
Posts: 3,000
Likes: 22
From: Boulder Creek California
Anyone know if you can go below stock body-mount thickness without having anything collide? That would be the best way to lower the car without compromising suspension geometry. Not much there but may be worth doing to eke out a bit more.
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
I did some research into this since I was replacing my 72 frame with a 73 frame. I had read and believed that the frame mounts were lowered on 73+ frames to accomodate the rubber mounts. Comparing the frame drawings of pre-and post 73 frames it turns out that the difference is less than 1/8" at best. The aluminum mounts are ~1/2" thick and I'm betting that rubber mounts are about the same thickness when torqued down. Poly mounts are a unique breed in that they are usually made to be the same dimensions as a rubber mount yet they don't compress much at all, so you can expect a higher body height. Since poly mounts probably aren't much of an advantage over solid mounts, I'd either use the solid aluminum mounts or OEM-style rubber mounts.
Rick B.
Rick B.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Might want to pick up a copy of the 1968-1982 Corvette Parts Interchange Manual, but note it's not big on info for non-OEM combinations.
FWIW, lowering doesn't necessarily compromise suspension geometry, as road race prep heights recommended by Chevy Power are 1-1.25" Z and 1.25" D (full tank and driver aboard).
