I am in the process of replacing my old frame (71) with a new one. As part of this project, I am doing away with the old aluminium mounts and installing poly bushing. The new poly bushings appear ever so slightly thicker(Maybe 1/16 or 1/32 thicker) - Because of this i decided to set the 4 main mounts under the rockers with out shims, then will shim the most outer mounts based on door gaps and such.

I just tried this approach and after setting the body on the 4 main mounts with out shims, I am and getting about 1/32" gap at the very forward mount and about 1/4" at the very rear mount. The 4 rocker mounts otherwise feel sung. Before i go any further, I looking to confirm my approach makes sense and will work.

I welcome and other thought ideas or techniques. Trying to avoid unnecessarily setting the body too high.

Thanks!
Agaon

 

When you torque the bolts it will compress the poly bushings a little.

 

Hi Folks,

Any other thoughts, techniques I should consider? Hoping to hear back from a few more on the topic.
-Thanks

 

Did you happen to take notes on the number of shims at each mount before you removed the body off the old frame?
If not, I would think that at this point, you'd want to add shims at each of the outer corner mounts as they require to fill the gaps you mentioned.
Tighten them all up, lower the car to the ground, and see where your door gaps are at.
Then make shim adjustments accordingly.
The #4 mounts are the easiest to access for adding/removing shims later in the process.
#1's are not too bad either.
Good luck and report back!

 

I just tackled the body to frame shim process.

I pulled the body off the frame a couple of years ago for my restoration (1971 Coupe). I made note of the body mount shim counts (bagged and tagged). The aluminum spacers (mounts 68-72) were pretty much powder and disintegrated during disassembly.

The #1 and #4 mounts that are riveted to the body were in pretty rough shape with the aluminum rivets either disintegrated or loose. I ground off the rivets, removed the mounts, media blasted and powder coated the ones that were salvageable and ordered new ones for the ones that were rusted, thin and had lost their integrity. I used stainless, large flange, pop rivets (Albany Fasteners) to re-install all of the new mounts. A Milwaukee M12 Rivet tool was my best friend.

Mounts #2 and #3 caged nut assemblies on the frame were somewhat eroded and the steel flanges that stop the nuts from turning within the cage were so thin that if there was any resistance with the mounting bolt and nut, the nut would spin in the cage so I replaced the cage and nut assemblies (grind off and weld on).

At this point, knowing the shim count from original didn’t matter anymore, the gaps were now going to be different.

I decided on poly bushings rather than aluminum after seeing what happens to aluminum and rubber parts around the vehicle over the years.

I read several posts around body shimming from Roger68, 7T2vette and other senior members that have a wealth of knowledge. The only part that I couldn’t wrap my head around was reading that the front door gap was set by the #1 and #2 body mounts... If you install the door and hinges, that’s static, and thats what sets the front gaps and the overall door height. I noticed that shimming #1 and #2 sets the height of the rear of the door.

I set the body on the frame and aligned the body using the alignment holes in the door sills using 5/8 wood dowels. The body door sill alignment holes are slightly smaller than 5/8 so I had to shave the dowel slightly on the one end. The body alignment holes in the frame fit the 5/8 dowel just fine.

1. I installed the doors and hinges and aligned them for height and gap on the front and tightened all of the hinge bolts.
2. I then tightened all body mounts down in the sequence #2 and #3 then #1 and #4 (inner then outer).
3. Once all the mounts were tight, I noticed that both of my doors sat high on the rear so I added shims to mount #1 until the doors dropped down at the rear to level with the body. The front gap didn’t change because that gap is set by the hinges.
4. I now worked on the gap at the rear of the door because it was a bit too wide at the top so I added shims to mount #4 to bring that gap in.
5. I then added shims to my door hinges to set the door’s in and out gap.

All of the gaps around the doors are almost perfect now.

It sounds easy but it took a lot of time. Keep in mind that mounts #3 are in front of the rear wheel and are hard to get at without pulling the wheel. Keep in mind that the vehicle needs to sit with all tires on the ground to be accurate because that is how the vehicle will live.
The process to add a shim to a mount was tedious and took me a very long day. I did one side of the vehicle at a time:

1. Jack up under the frame to remove the rear wheel.
2. Loosen all body mount bolts approximately 1”. Don’t pull the bolt out and maybe have mounts #2 and #3 or their washers fall out unless you need to add shims to those mounts.
3. Raise the body up off the frame slightly (the 1" bolt play) with my engine hoist and straps.
4. Add a shim to a mount.
5. Lower the body down on the frame.
6. Tighten #2 and #3 then tighten #1 and #4
7. Install rear tire.
8. Set vehicle back onto the ground and check the gaps.
9. Repeat 1 to 8 until gaps are to your satisfaction

That’s what worked for me. Anyone chime in to correct me and or add anything in that I may have missed

Cheers,
Richard