de_cat55

I had a noise on the back every time I hit a bump. After lots of investigations I tightened the body mount in front of my back tire. The noise stopped for a while but it is back. Do I have to change the mount? How is that mount installed ? If you look from the bottom it is inside the chasis, so I wander how I can replace it. Is the receiving nut welded to the chasis???? :confused:

Thanks in advance.

Easy Mike

Nut is caged. You might be able to replace these two mounts by loosening the bolts and raising the body enough to replace the rubber. Go slowly and be prepared for a weld nut or two to break loose.

While there, you might want to take a break and look for your VIN stamping. If it's still legible (probably filled with road gook), it will be on the top of the rail in front of the #4 mount on the left (driver's) side. You should find the same stamp as on your block since they were both stamped at the same time by the same person using the same stamping tool on the assembly line.

roger68

You might want to also check the rear-most mounts. They're behind the rear wheels, in the rear corners and you can see them by just laying under the car. The entire bolt was missing from one of my rear mounts.

Roger

454Big

If your car is older than ten years (should be for a C3 :D ) or the body mounts haven´t been replaced for about ten years you should face the fact that the rubber of the body mounts sags and detoriates.
I guess you should replace the mounts.
Even if we are talking of the early sharks (they had aluminium shims) the aluminium detoriates and crushes to a powder.
Replace the Body mounts!

The receiving nut is a so called cage nut. It is a square nut, that is able to move forth and back in the cage that avoids spinning of the nut.
If the bolt is rusted to the nut, you will kill the cage when trying to turn with excessive force.
Unfortunately you will need a new nut and cage assembly then (available at Paragon).
Hope this helps!

de_cat55

I agree, it is best to change all body mounts. What's involved in this work? Do you do one at at time or you have to take all of them out to lift the body? Should I leave it to a professional ?

roger68

Just as an FYI, '68s used aluminum body mounts - a one year only thing. I almost ordered poly body mounts, then found out, and verified with my tired ol' eyes, that my '68 has aluminum mounts.

Oops, someone already mentioned the aluminum mounts. As far as the caged nuts, there's a product called PB Blaster (or Blaster PB, I forget) that is the best penetrant I've found. I'd spray the bolts/mounts as best I could so as to do my best to avoid ripping up the cage/nut setup. It would seem like one heck of a job to replace the cages.

Roger


[Modified by roger68, 3:30 PM 9/21/2001]

454Big

roger68, I´m not absolutely sure, but I guess that all sharks from 1968 to 1972 had the aluminium body mounts.
Can we find out what opinion is correct?
Have you found this year-only special in any piece of literature?

Kevin_73

[QUOTE]roger68, I´m not absolutely sure, but I guess that all sharks from 1968 to 1972 had the aluminium body mounts.QUOTE]

1973 was the first year that corvettes used rubber body mounts. I have read that it is possible to put rubber mounts on earlier C3's, but it will raise the body by 3/8".

Kevin

roger68

454Big, I'll have to look for a source for the '68 being the only year for aluminum mounts. It *might* be in Richard Prince's C3 resto book, but I'm not sure - I'm still at work. I know I've read it in at least two places and it is a '68 only thing. It's easy enough to verify on a car - you can clearly see what type mount at the rear-most mounts. I'll dig around and find sources.

Roger

Tahos

"Corvette Chassis Restoration Guide" by Joseph A. Tripoli, Jr. shows on
page 36 a picture of aluminum spacers on a 69 chassis.
Somewhere I have seen that they are aluminum on 68 thru 72 models.
My old 68 rattles in back big time also.

zzrck

My '70 also use aluminiun spacers and I've chek in zip catalog (as I will soon replace them) and all 68 to 72 use the same kit wich is with aluminium spacers