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#4 Body Mount - 1" Gap - Shim help

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Old Dec 27, 2023 | 05:03 PM
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Default #4 Body Mount - 1" Gap - Shim help

Today I finally put my body back on my restored frame and everything went well. When I got to the #4 Mount, there is a 1" gap between the frame mount and the body mount on the driver side and 3/4" on the passenger side. I noted the shims and put everything back how it was from the factory, but obviously something is out of whack here. Below are some notes:
  • #4 Body mounts are original and I didn't remove them from frame, only new reinforcements on the body.
  • crawled all under the car and I can't find any interference that would be holding the body up higher on the frame
  • I can feel the #3 BM properly seated to the bird cage.
  • If I tighten the #4, it results in the doors not being able to open.
  • The front clip is bonded to the body, but front brackets/supports aren't installed yet
  • Door gaps are close to what they were before I removed the body - still needs some fine tuning.
It seems like something is causing this and shimming the 1" Gap isn't the correct answer. Any advice?



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Old Dec 27, 2023 | 11:09 PM
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Arg0413

Any work done to #2 body mount? e.g. rusted out and repaired with insert?

Mapman
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Old Dec 28, 2023 | 02:51 AM
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This came up not very long ago. So I'll tell you the same thing I did to the last guy. (Worked for him as well).
these cars flex a heck of a lot when we lift them.
SOOOOO, set it down on the frame, with mounts and shims in place. Don't get concerned with the number of shims. Be concerned with the thickness of shims. New replacement shims tend to be thinner than the originals. Go with measurement. Not count.
set it down. Get your alignment holes lined up on both sides. Just start the bolts. Don't tighten anything.
Let it sit for at least 24 hours. Tighten numbers 1 and 2. Let it sit and rest another 24-48 hours. Tighten number 3. Now look at your number 4 gap. Bet it's down to 1/4 inch or less. Let it rest. Allow the body to S L O W L Y drop back into place.
now, if you have door issues, shim as required. Tighten down number 4. Spend a week. It's amazing how much these bodies flex. Give them time to settle back. No cracks that way.
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Old Dec 28, 2023 | 10:06 AM
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Originally Posted by mapman
Arg0413

Any work done to #2 body mount? e.g. rusted out and repaired with insert?

Mapman
No, I never touched the #2 mounts. I did do rust repair on the rear frame rails and had to cut off then weld back on the #3 mounts.
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Old Dec 28, 2023 | 10:07 AM
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Originally Posted by 4-vettes
This came up not very long ago. So I'll tell you the same thing I did to the last guy. (Worked for him as well).
these cars flex a heck of a lot when we lift them.
SOOOOO, set it down on the frame, with mounts and shims in place. Don't get concerned with the number of shims. Be concerned with the thickness of shims. New replacement shims tend to be thinner than the originals. Go with measurement. Not count.
set it down. Get your alignment holes lined up on both sides. Just start the bolts. Don't tighten anything.
Let it sit for at least 24 hours. Tighten numbers 1 and 2. Let it sit and rest another 24-48 hours. Tighten number 3. Now look at your number 4 gap. Bet it's down to 1/4 inch or less. Let it rest. Allow the body to S L O W L Y drop back into place.
now, if you have door issues, shim as required. Tighten down number 4. Spend a week. It's amazing how much these bodies flex. Give them time to settle back. No cracks that way.

This does make sense and I didn't have the best body support when I had the body sitting. I was also told to remove all the shims, and snug the bolts and let it sit. Going to do that as well as let the body relax.
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Old Dec 28, 2023 | 03:18 PM
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Originally Posted by 4-vettes
This came up not very long ago. So I'll tell you the same thing I did to the last guy. (Worked for him as well).
these cars flex a heck of a lot when we lift them.
SOOOOO, set it down on the frame, with mounts and shims in place. Don't get concerned with the number of shims. Be concerned with the thickness of shims. New replacement shims tend to be thinner than the originals. Go with measurement. Not count.
set it down. Get your alignment holes lined up on both sides. Just start the bolts. Don't tighten anything.
Let it sit for at least 24 hours. Tighten numbers 1 and 2. Let it sit and rest another 24-48 hours. Tighten number 3. Now look at your number 4 gap. Bet it's down to 1/4 inch or less. Let it rest. Allow the body to S L O W L Y drop back into place.
now, if you have door issues, shim as required. Tighten down number 4. Spend a week. It's amazing how much these bodies flex. Give them time to settle back. No cracks that way.
My Dad would let his C2 bodies sit on the mounts for a week before he tightened them down.......valid advice.

Jebby
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Old Dec 28, 2023 | 03:51 PM
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Well folks I went out today to lift up the body to inspect and remove all the shims and found some serious user error: The fender washers and lock washers were sitting on top of the #3 body mounts!!!! Explains why I couldn't find them!!! So that's why the #4 was so high! I put the body back down with no shims and only finger tight. The PS #4 took one shim and the DS #4 took three to make it touch the mounts.
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Old Dec 31, 2023 | 12:02 AM
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Glad you found the issue. A lot of things going on when redoing a C3.
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