C-2 Body/Frame shimming??

[Kurt K.]

I will be replacing the frame on my 67 Coupe this winter. What suggestions do you guys who have done it, have shimming the body/frame. I noticed from pictures at the St Louis plant, the frame shim markings were on the frame long before the body was put on. They must have had some sort of guide that they laid on the frame to identify the shim count. I can only assume it was the frames that were not all the same, thus needing the shims.
In my case, I am putting another frame under the car and the factory shim count will not work. What is the best way to shim??? Thanks, Kurt

[Michael H.]

Re: C-2 Body/Frame shimming??

Kurt,

You are correct. The shim count has nothing to do with the body. It's the frame that was shimmed to conform to the original design specs. If you are replacing your frame with a used one, try to find the original shim markings on the replacement frame if possible. If the original markings are gone, you may be able to very carefully measure the mount pad dimensions (from a datum plane) and roughly calculate the shims required to conform to design but that would be a complex system of measurement and not likely to be at all accurate in your garage with an uneven floor. Unfortunately, you may have to "trial and error" adjust the body on the new frame.

Using the original shim count from the original frame as a starting point would likely be worse than just starting with a random number (3?) at all locations and then adjusting from there. Good luck,

Michael

[Stephen W.]

Re: C-2 Body/Frame shimming??

Today we have many laser levels out on the market at very reasonable costs. yes your garage floor will be uneven but you can set up the frame by using the level to creat the level datum plane.With some careful measurements and use of the frame specs you should not have a problem. If you know a body shop with a frame system they can do it as well but at a price.

[Kurt K.]

Re: C-2 Body/Frame shimming??

I work at a Dealership so, I can do the measurements there. My next question is, where do I get the correct specs? I have a 63,67 and 79 shop manual and a restoration book. All have specs that are different for the frame ?? Which are the most correct?? Kurt

[Wayne W.]

Re: C-2 Body/Frame shimming??

Other than a quick check of the frame mounts, why waist all of that time. Set the body on the frame and shim for door fit. Its about that simple. After this many years and water over the dam, there is no guarantee that the frame or the body is going to be close to original specs. Start with a two or three in every position, and shim as required. You can get to all of them without removing the body. The factory proceedure was always interesting to me. They couldnt build a steel frame to spec. but they could a fiberglass body?

[John H.]

Re: C-2 Body/Frame shimming??

Wayne -

The underbody was bolted down at the mount locations to machined pedestals on a precision body build truck, and remained bolted down all the way through the body build process, so there was very little variation either to specs on any one car or from one car to the next.

The frame, however, was a different story - between dimensional distortions introduced by extensive welding and relatively primitive fixturing through the frame assembly process at A.O. Smith - Granite City, there was significant dimensional variation from frame to frame. I spent a fair amount of time at Granite City, and the best way to describe the place was "medieval". That's probably why Granite City lost the C3 frame job to A.O. Smith - Milwaukee (where they made the C1 frames).

[Joe R.]

Re: C-2 Body/Frame shimming??

Kurt,

I'm with Wayne on this one. After doing several my method is to use the four central mounts with four shims to each mount. If the body sits down, then I shim the rear until the doors fit. Line up from top to bottom on the rear. Then I go to the front, install the radiator support and shim until I have contact with the lower valence with the inner brackets and 3/4 inch clearance with the two front lower-inner bumper braces. Everything else will fall right into place.

Regards,

JR

[Irby G.]

Re: C-2 Body/Frame shimming??

Hi, I may be way off base here, but water would provide a large enough level datum plane if you could find something 3' x 12' to hold an inch or two and use the Corvette Chassis Restoration Guide pg. 6 to use for measurements of the frame above the datum.

[Wayne W.]

Re: C-2 Body/Frame shimming??

I still think its funny that the frame(the foundation, a piece of steel) is less acurate than a fiberglass piece. Its especially funny that the underside of the body is so precise when the top( the part you see) has horrible fit and finish. Kurt, the measurements are these. The center box 4-6 mounts depending on coupe or convertible are all on the same plane. The front two at the radiator support are 7/8 inch low. The rear two are 7 inches higher. Thats it, all you need to know assuming the frame is straight down the centerline.

[Kurt K.]

Re: C-2 Body/Frame shimming??

Wayne, Now thats simple.. Thanks for the info. You must practice the K.I.S.S. method...Kurt

[Wayne W.]

Re: C-2 Body/Frame shimming??

When you work on these things for a living, K.I.S.S. is the only way.