#4 Body mount shim stack for 63's

[Tracy C.]

I'm in process of establishing how many body mount shims I need on my 63 and I'm a bit perplexed on the #4 mount location behind the rear wheels. The AIM shows usage of the same type of shims used at the other mount locations, but I seem to have almost a 1/2" gap at the #4 mount. This is more gap than I would expect to fill using a stack-up of 1/16" shims.

I'm looking for some input from others 63 owners regarding the #4 mount shim stack on their cars. This mount is easy to view from the rear wheel well.

My car was built on July 24, 1963 (203xx) during the last few weeks of production. Is it possible that the new 64 floor pan configuration had already made it's way into production and a thicker spacer was used at this location until the rubber spacer change came into play with the 64 body mounts?

thanks for the help,
tc

[Joe R.]

Re: #4 Body mount shim stack for 63's

Tracy,

It looks like you did not save the shims when you removed the body from the frame. Your first mistake!

To lower the number of shims needed for the #4 position you will have to remove shims from the #2 and #3 position.

I hope you have shims in the #2 and #3 positions. About 1/2" all around to begin with.

The number of shims needed in the #4 position is usually regulated by hanging the doors and shimming until the door gap is satisfactory.

Hope all this makes sense. When shimming the #4 also check and make sure that the gas neck is reasonably positioned before tightening the body down.

JR

[Timothy B.]

Re: #4 Body mount shim stack for 63's

Tracy,

Is the car frame supported with weight on the suspension,(tires)? If the frame is supported with jack stands the rear portion will flex and bend down allowing a gap like you report.

On my 63 coupe, I had to establish a new shim count and FWIW the passenger side mount #2 (front of firewall) has no shims as this is the high mount. If you locate the highest mount this will enable you to get the box section of the frame as low as possible which in turn will lower the core support and rear mount.

It's my understanding that in 1963 these frames were shimmed while upside down using a hand held guage to establish gap between mounts and flat surface underneith. The bodys were assembled on a "truck" and considered flat, and looking at a pic of that body truck on the line it makes sence.

[Timothy B.]

Re: #4 Body mount shim stack for 63's

There is another pic of a 63 coupe showing the shims or lack of on the passenger front box mount. It's the same mount that's high on my coupe FWIW.

This pic was posted here before but for some reason I can't figure out how to post because the KB limit is too high, maybe someone else can post it.

[Tracy C.]

Re: #4 Body mount shim stack for 63's

Here is some more info....

The frame and body were already separated when I bought the car. There were no disernable chalk marks remaining. The bare frame is on jackstands located at the front coil pockets and the rear sombrero fittings to represent proper load distribution with the weight on wheels when the car is on the ground.

There are NO shims at any of the other mount locations and I still have the gaps at #4. I know that adding shims up front will close this gap some, but it just seems a little extreme.

Could others with late 63's take a peek in the rear wheel wells of their cars and give me an idea what they have at the #4 body mounts?

thank you,
tc

[Timothy B.]

Re: #4 Body mount shim stack for 63's

Tracy,

These pics are from a late 63, (I think) July build roadster. I think you need to get the wheels on the ground before doing any shims other than the box section.

[Tracy C.]

Re: #4 Body mount shim stack for 63's

Thank you Tim, here is a shot at where I am on both sides. I seem to remember looking at least one 63 that had some thicker spacers here. Maybe I'm dream'n again.

Additional shiming will be needed here to close up the gap between top of the rear fender and the trailing edge of the door, so it's only going to grow wider.

tc

[Andy C.]

Re: #4 Body mount shim stack for 63's

Hello; I just went trough the shim process on my 63 coupe and found that the right rear mount had been welded 3/8" lower on the frame than the one on the left side. The left side needed only 2 shims while the right side needed 8 shims! So I removed the mount and moved it up 3/8" so that the number of shims needed was reasonable. I have heard of cases where GM messed up causing a need for many shims on certain mounts. When shiming the body the following in important. You must support the frame front and rear where the axles would be and then level the frame side to side. Then start in the rear and work you way forward. One mount may need ZERO shims while the others may need 1-5 shims typically held in place with tape. Good luck! Andy

[Tracy C.]

Re: #4 Body mount shim stack for 63's

Andy,

The pics that Tim posted appear to have a similar condition with the right mount welded lower than the left. If you compare the mount position relative to the bottom of the frame, the right mount appears flush with the bottom while the left is welded a little higher.

I've added a pic of my left mount to my post above. Both mounts appear to be about the same height relative to the bottom of the frame.

[Harry S.]

Re: #4 Body mount shim stack for 63's

Tracy, as Joe Ray said, it's best to count your shims prior to removing them. But sometimes that can't be done!

Sounds like the question is, how do I determine how many shims I need when I have no idea how many were there originally. I seem to recall a post/thread that described that process but I can't find it.

Can anyone else point to that post/thread or a document on how to calculate the number of shims needed?

[Tracy C.]

Re: #4 Body mount shim stack for 63's

Harry,

I have a plan to determine the shim stacks for the other locations, I was just hoping that some late 63 owners would weigh in on the #4 mount shim stack.

A few with cars near mine are Stu, Mikie #14 and Rick A.

thanks,
tc

[Timothy B.]

Re: #4 Body mount shim stack for 63's

Tracy,

On my 63 coupe the drivers side rear mount is welded approx 1/4" higher then left side, I can get you a pic if you want to look. Coupe body's are rigid so as long as there is no hard grounding it's almost a matter of filling in the space for the rear.

As I stated above, my high mount is the passenger front, #2 (just in front of firewall), but also the drivers side rear #5 has no shims and the rt. side rear has three shims.

I believe the best way to shim to get the box flat first then go to the rear and front. I don't understand how Andy can start in the back but he may know better then me..

[Andy C.]

Re: #4 Body mount shim stack for 63's

The reason why I suggested starting in the rear with the shims is because on 63's there are 2 rubber blocks that go between the cross member and the floor pan! If you have to few shims you can't get the blocks in and if you have too many the blocks may fall out. So on my car I started in the rear to satisfy the rubber blocks , then I went to the mounts at the firewall and installed 2-3- shims there, then I went to the mounts in front of the rear wheels, then the mounts under the door sills, then the very front mounts. The center body mounts I did last. If you shim the body too low, there is a possibility that a FI unit could hit the bottom of the hood? I'm new to this , but just saying what I did and got good results. Andy

[Timothy B.]

Re: #4 Body mount shim stack for 63's

Andy,

I think your process is OK. I have read that some suggest a starting point of three or four shims at the box section points.

I wanted to pass along that on my early coupe there was only one rubber cushion on the drivers side. The glue teltale was still on the body where it was slid in.. The rubber fit nice with the floor barely touching.

I installed a second rubber like the book shows but I had to lift the floor pan with my arm to slide it in. I am fairly certain this car only used one..

Tracy, Is your frame a new replacement? By the time you fill the slot then lift the body for the door gap you describe it's way to many shims here. What does the gap at the floor pan look like where the rubber cushions are placed..

[Chuck S.]

Re: #4 Body mount shim stack for 63's

...I seem to recall a post/thread that described that process but I can't find it.

Can anyone else point to that post/thread or a document on how to calculate the number of shims needed?

Over the years, there has been more than one...this is the first one I ran across in a search. It seems like there was an earlier thread that was more complete, with John Hinckley's input on the subject, but I didn't see it in the first cut. It's probably much earlier than the thread below:

https://www.forums.ncrs.org/showthre...+Shim&uid=5104

I believe that Andy is on the right track...I would level the frame suspension points side to side, and make the center box side rails level front to back. If you find the frame is clearly twisted when you try to level the side rails front to back, then keep the suspension points level side to side, and set the side rails as close to level as you can, taking some of the "twist" on each side rail. Then...you have a good excuse to buy a LAZER LEVEL.

The body may have "settled" over the years, but assuming the body is unchanged is a good starting place...you can make final adjustments as required to perfect the gaps.

P. S. I would not make any conclusions about the quality of the shim counts until all the body mount bolts were torqued to spec. This torqueing of the body mount bolts will be a lot of trouble if you get into trial and error, and you surely will, but you want to be sure all the body mounts are fully seated on the shim stacks.