1963-1982 Corvette Body Mount Replacement Part 2

by John Pfanstiehl

This is the second in the series of three articles about replacing body mounts on 1963-1982 Corvettes. The first article, 1963-1982 Corvette Body Mount Replacement Part 1,  started with removing the relatively easy front mount (#1) and the trouble-prone rear (#4). This tech article focuses on the particular problems often encountered with the central body mounts, #2 and #3. If these bolts come out easy, this part of the job will be a breeze.

However, if a bolt breaks, if the caged nut spins or if the cage breaks loose from the frame, much more work will be required to fix this problem. That can involve removing the body entirely from the frame or raising it so high that a new cage and nut can be welded onto the frame.

To avoid those problems, this article will focus on ways to remove these bolts without creating the need for much more costly work.

Step 1

01: Spray penetrant several times over several days before attempting removal of the bolts. The lower cushion and the Body Mount Bracket of the #2 bolt are visible here. Spray penetrant over the top of the outer frame rail onto the nut cage and down onto the bolt’s threads. The thick body mount shield is also visible forward of the #2 mount.

Step 2

02: For the exposed threads of the #3 bolts, spray penetrant up into the frame toward the bolt. The frame has an internal bulkhead-like plate a few inches from its end, but some penetrant may get to the bolt.

Step 3

03: Another access to the bolt’s lower threads is around the fiberglass splash shield. Try several different angles to help get some penetrant through the nut’s cage onto the nut and the bolt’s threads.

Step 4

04: Zip Corvette offers new replacement Body Mount Brackets. They are welded to the frame on two sides but the four corners of their cage that holds the nut are open. The object is to spray the nut cage to get penetrant though the openings and onto the nut and the bolt threads.

Step 5

05: Remove the rear tires and remove the access plates. Zip Corvette offers a set of 1963-1982 Body Mount Access Plates with Screws & U-Nuts. The plate, screws and U-nuts are also available individually.

Step 6

06: Scrape off any old caulk from both the body and the plates. Repaint the plates if needed so they’ll be dry and ready to install later.

Step 7

07: Apply fresh sealing caulk to the grooves in the front side of the plates. Zip offers a large package of Strip Sealing Caulk. If this plate is not sealed properly, water can get into the #3 body mount cavity where it will remain and accelerate rusting.

Step 8

08: This #3 cushion bolt was so severely rusted that a good portion of its head was missing. Normally, a 5/8 socket would fit, but in this case, even a smaller 9/16 socket spun on the head.

Step 9

09: The solution was to clean the bolt head with acetone and then cement a 9/16-inch six-sided socket to the bolt head using JB Weld Steel Reinforces Epoxy. After curing for a few days, the epoxy strongly bonded the socket to the bolt.

Step 10

10: If the bolt doesn’t unscrew easily, cut and remove the upper rubber cushion. This enables penetrant to be applied to the upper end of the bolt and run down onto the nut.

Step 11

11: Use no more than moderate force to turn the bolt back and forth many times and frequently apply penetrant. After removal, we can see how weakened the bolt shaft had become.

Step 12

12: The head on the #3 bolt on the other side of the car was not rust damaged but rust on the exposed lower threads was a problem. Remove the rubber cushion to facilitate getting penetrant to the nut. Tip: If the progress to unscrewing the bolt becomes very slow, apply heat to help the penetrant wick in. Note the aluminum foil barrier to prevent damage to the door ajar wires.

Step 13

13: Remove the sill plates and kick panels on both sides for access to the #2 bolts. The 1968-1977 Corvette Sill Plate Replacement tech article provides more information on that. If the bolt doesn’t break free easily, cut and remove the rubber cushion to enable penetrant to seep down onto the nut and threads. While loosening, these made a nasty crunching noise as the rusty bolts and mount washers broke loose. Other than that, removal was without drama.

Step 14

14: Zip Corvette offers the #2 Body Mount Shield. Consider ordering this because it is much easier to replace when the body is lifted. This is a closed-cell rubber block which goes over the top frame rail between the rocker channel and frame rail at the #2 body mount on all 1969-1975 Corvettes.

Step 15

15: Zip Corvette also offers Body Mount Metal Shims individually. Consider ordering enough to have on hand when the mounts are replaced.

1963-1982 Corvette Body Mount Replacement Part 2

SourceZip Corvette Parts
8067 Fast Lane | Mechanicsville, VA 23111 | (800) 962-9632

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One Comment

  1. Jim Moreland

    Good reminder to count the shims that you remove from each body mount to replace with new later.

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