C2 Rear Cross Member Bushings

[Joel T.]

I've just finished replacing the rear end on my 1963. As part of this swap, I pressed out the old cross member bushings and replaced them with new reproductions from LI Corvette. That swap out was actually fairly easy. When I got the new rear/cross member up there and in place the new bushings would not fully seat on the frame mounts.. there is about 1/4" of daylight between the cross member and the frame mount seat. I've got the bushing bolts as tight as I dare make them, and I did put some grease on the bushings and mounts before installation.

My question is, will the bushings seat further as I place the car back down on the floor, or should I be doing something else to get those bushings seated all the way?

Thanks!!

Joel

[Timothy B.]

Re: C2 Rear Cross Member Bushings

Joel,

I don't think it's supposed to be flush in the area you describe. If you take the bolt out can you look and see if the inside parts are pulled together.

[Irby G.]

Re: C2 Rear Cross Member Bushings

Added question.....when should you replace this bushing? The one on my cross member still look really good, no cracks, not compressed. Should I replace it anyway?

[Alan D.]

Re: C2 Rear Cross Member Bushings

Chev had trouble with these cross member isolation mounts for 63-65 and came out with a TSB, 11/29/65, to replace them with a different design which is available from the repro houses.
I've often wondered about the same thing on mine - see photo.
If I look at the cross member cone area the mount appears to be bottomed out, however the rubber does not seem to be correct. Perhaps somebody can tell us more.
PS, when not at a show I attach a round metal plate against the mount and use a longer bolt to secure, got from a second hand mfg back in the 70's along with a plastic spring for street use.

[Joel T.]

Re: C2 Rear Cross Member Bushings

Joel,

I don't think it's supposed to be flush in the area you describe. If you take the bolt out can you look and see if the inside parts are pulled together.

Tim;

I'll check it out as you suggest... Based upon how tight the bolts are, I gotta believe that the bushings have bottomed out. I tried jacking the cross member a bit with no appreciable difference... Guess I did a better job than I thought!

Thanks!!

Joel

[Joel T.]

Re: C2 Rear Cross Member Bushings

Added question.....when should you replace this bushing? The one on my cross member still look really good, no cracks, not compressed. Should I replace it anyway?

Irby;

I'm not sure what constitutes worn out for these bushings.. perhaps someone else will know. Mine were reasonably well cracked from age and rusted in there fairly well. I guess they might have been the "old" style.. in that they only had 4 small tabs on each one.. the new ones have 8 larger tabs.

In my case I figured that I would swap them while I had the rear end out.

Regards,

Joel

[John H.]

Re: C2 Rear Cross Member Bushings

With the car up in the air, the bushing rubber is unloaded with the crossmember, diff and spring hanging from them; when you get the car back on the ground, the weight of the body and frame will compress the exposed rubber at the top somewhat, but there will always be a significant gap between the top surface of the crossmember and the frame. You do NOT want to over-torque those two bushing bolts and strip them - then you get to pull the body.

[Wayne M.]

Re: C2 Rear Cross Member Bushings

..... If you take the bolt out can you look and see if the inside parts are pulled together.

Tim -- that's what I do. Just a note for Joel and others; if the X-member already has the diff and maybe more suspension components attached, the downward force is tremendous, so have it well supported before removing the bolt. In the bolt hole, you'll see if the metal of the bushing leaves no visible gap with the metal of the frame 'hat', wich means it's fully in place.

Also, the bolt torque for these 2 frame mounts are NOT what is shown in the '63-5 AIM's (20-30 ft.lb); TSB was issued revising it to 55-65 ft.lb.

[Joel T.]

Re: C2 Rear Cross Member Bushings

Wayne;

Thanks! I will block up the X member when I pull the bolts (one at a time). I've learned to respect the weight of that assembly.. I saw the lower torque ratings in the AIM but they candidly did not seem reasonable... I will torque the bolts to 65 lbs once I get done looking inside.

Thanks again for your input!!

Joel

[Timothy B.]

Re: C2 Rear Cross Member Bushings

Joel,

One final thing to remember, use a grade eight bolt. The originals are grade eight, the same bolt as the four crossmember to differental bolts (the ones you can't get to) except those use a flat washer and the bolts in question use lock washer.

Also, grade eight on the snubber bushing and front bracket bolts that thread into rear housing for 63-64(not the through bolt) I put a smear of silicone grease inside and out on frame and bushing and never seize on the bolt.

Assemble the spring loosely to rear cover and bounce it around with car weight before tightening the four spring bolts... I remember back in the seventies my friend owned a repair shop and those cars came in constantly with broken rear covers.