C2 Rear Differential Crossmember Bushing

[Terry M.]

During restoration of my 1965 Coupe we replaced the rear differential crossmember bushings. Available new bushings are not configured exactly like the originals. The first two photos show one of my originals next to a new bushing. The new bushings feature a recessed top and multiple retainer tangs. The multiple tangs on the new bushings are more in keeping with those found in later models, I believe, as catalogs (Paragon) list the same bushing for 1963-1979 models.

My car is being restored in a small shop that is operated by two brothers, Iowa farm boys. They are quite ingenious and very detail oriented. Anyway, using my original bushings and a bit of "surgery" they converted the new bushings to look more "as original". First, they removed the extra tangs on the new bushings and trimmed the remaining tangs (narrowed) to match the originals. Next, they removed a portion of the metal casing on the original bushings (cut off wheel/hand grinder) to expose the rubber. Then they carefully cut the upper portion of the original (razor blade) to the appropriate depth to fit the new bushing. The cut off portion of the original was "glued" into the new bushing with black Plasti-Dip. After curing, they touched up a few imperfections on the old surface with Plasti-Dip. The finished result is shown in the last photo. Turned out pretty good, I think. This may be a bit over the top as the bushing really can't be readily seen. That said, it does show what can be done with a little thought and ingenuity.

[Joe L.]

Re: C2 Rear Differential Crossmember Bushing

During restoration of my 1965 Coupe we replaced the rear differential crossmember bushings. Available new bushings are not configured exactly like the originals. The first two photos show one of my originals next to a new bushing. The new bushings feature a recessed top and multiple retainer tangs. The multiple tangs on the new bushings are more in keeping with those found in later models, I believe, as catalogs (Paragon) list the same bushing for 1963-1979 models.

My car is being restored in a small shop that is operated by two brothers, Iowa farm boys. They are quite ingenious and very detail oriented. Anyway, using my original bushings and a bit of "surgery" they converted the new bushings to look more "as original". First, they removed the extra tangs on the new bushings and trimmed the remaining tangs (narrowed) to match the originals. Next, they removed a portion of the metal casing on the original bushings (cut off wheel/hand grinder) to expose the rubber. Then they carefully cut the upper portion of the original (razor blade) to the appropriate depth to fit the new bushing. The cut off portion of the original was "glued" into the new bushing with black Plasti-Dip. After curing, they touched up a few imperfections on the old surface with Plasti-Dip. The finished result is shown in the last photo. Turned out pretty good, I think. This may be a bit over the top as the bushing really can't be readily seen. That said, it does show what can be done with a little thought and ingenuity.

Terry------


Something to keep in mind: GM did not change the design of these cushions because the first design worked just as well. As a matter of fact, the design was changed because the original design had a way of "working itself out", sometimes at the most inopportune times. So, what has been done here, albeit quite ingeniously and laboriously, sacrifices important functionality for minimal and largely unseen nuances of originality. That would not be the kind of trade-off that I would make, especially for a driven car. But, to each his own.

The original cushion, GM #770447 was used from 1963-65 and replaced for SERVICE in October, 1965 by the 1966-68 cushion, GM #9743971. The latter was discontinued from SERVICE in May, 1969 and replaced by the 1969-79 cushion, GM #9750078.

I might also add here that the reproduction cushion used as the basis for the final cushion pictured is not a faithful reproduction of the GM cushion. It differs in certain elements of configuration and the steel portion of the bushing appears of thinner gauge material than originals.

[Terry M.]

Re: C2 Rear Differential Crossmember Bushing

Thanks Joe. Great information. Had I known this, we may have used the new bushings as delivered. That said, my car is a 17,000 mile fuelie with factory 4.56 gears. It is getting a full frame off restoration. Not likely to see a lot of road miles, at least in the beginning.

[Richard G.]

Re: C2 Rear Differential Crossmember Bushing

Getting any reproduction bushings to fit into the hole is a real PITA.
I would be interested in how others did it.
Rick

[Alan D.]

Re: C2 Rear Differential Crossmember Bushing

Terry,
A number of speed shops make a plate which go over the bushings making that area very firm (not ride wise) that claim to fix the problem so if you are going to use the car a lot could add those. If just a trailer car then you should OK, I used them for years before retiring car.

[Terry M.]

Re: C2 Rear Differential Crossmember Bushing

Thanks Alan. Could send me some info on the plates?

[Michael S.]

Re: C2 Rear Differential Crossmember Bushing

@alan drake. alan can you explain further? maybe a pic. part number? place to buy it? i am starting a ground up on my 64 and i have been reading all the post here on 63-7's. so when i get to that point i have already done my home work and know which way to go. thank you.

[Alan D.]

Re: C2 Rear Differential Crossmember Bushing

Sometime in the 1970's I had 5" round X1/4" plates make, these would cover the bushings use same nuts as the bushings, bolts were longer.
These also came with my fiberglass rear spring, so it was a know problem as Joe mentioned, in fact there is a TSB #1036 for 63,64,65 cars
Just can not find the plates or spring at the mount. Some of the newer JG have TSB in the back.

[Michael S.]

Re: C2 Rear Differential Crossmember Bushing

can any one else help out? pic's?

[Tom E.]

Re: C2 Rear Differential Crossmember Bushing

Here is a set of discs I took off of my 67 from the PO.

DA20DEE6-8CF2-4761-A42E-4E34B4750E9C.jpg

[Tom D.]

Re: C2 Rear Differential Crossmember Bushing

Getting any reproduction bushings to fit into the hole is a real PITA.
I would be interested in how others did it.
Rick

A food friend and I pressed two in today. It's a nice big old press, and we applied some grease in the holes first. Took a few seconds for each one.

[Tom D.]

Re: C2 Rear Differential Crossmember Bushing

1967 biscuit - 1.jpg

This is unrelated to my 1965 comment above. This one is an original on a '67. Shows eight (8) folded over tabs, not the four small ones, like 63-65.

Please ignore the wrong bolt used during an older restoration. Ignore also, the texture of the metal on a chassis driven around Western NY during the winters "in the Lake Erie snow belt".

[Joe L.]

Re: C2 Rear Differential Crossmember Bushing

[ATTACH=CONFIG]99168[/ATTACH]

This is unrelated to my 1965 comment above. This one is an original on a '67. Shows eight (8) folded over tabs, not the four small ones, like 63-65.

Please ignore the wrong bolt used during an older restoration. Ignore also, the texture of the metal on a chassis driven around Western NY during the winters "in the Lake Erie snow belt".

Tom------


Yes, the 1966-79 cushions had 8 tabs and, as I mentioned previously, became SERVICE for 1963-65 in October, 1965.

[Norm B.]

Re: C2 Rear Differential Crossmember Bushing

Getting any reproduction bushings to fit into the hole is a real PITA.
I would be interested in how others did it.
Rick

I just did mine this morning on my '63. I do not have access to a press. I put the bushings in the chest freezer last night. This morning took them out, sprayed them liberally with silicone lube, and drove them in with a ball peen hammer. I don't know if putting them in the freezer last night helped but it probably did not hurt. The whole process took about 15 minutes.

[Norm B.]

Re: C2 Rear Differential Crossmember Bushing

@alan drake. alan can you explain further? maybe a pic. part number? place to buy it? i am starting a ground up on my 64 and i have been reading all the post here on 63-7's. so when i get to that point i have already done my home work and know which way to go. thank you.

I just came across this in the Corvette Central catalogue while looking for something else. It's called "Differential Crossmember Reinforcement Kit", Part #582408 - $44.95. Is that what you are looking for?