Shimming a 69 body

[Greg L.]

I have a bit of a problem that I hope someone can help me with....

In a nut shell how do you properly shim the body to the frame? AND When adjusting the front rad support cross member how do you know how much force to put on the front clip to raise it without putting too much force and damaging it? I don't want to stress it by raising it too much and have it crack on me down the road....

When I took the body off I marked and counted all the shims so I know for a fact that they are all back in their original locations. The rear bumpers mounted up perfect but my problem is the center mount for the front bumper. The cross member that it bolts to(that the rad support sits on) seems like the rear edge of it has to be raised and the front edge lowered because when I try and bolt the center bumper mount to it there is about a 3/8" gap at the rear bolts but the front two bolts mate up nice. If I were to just tighten all the bolts it would be forcing the very nose of the body up with a lot of pressure so I know this is wrong. I can find some adjustment with the brackets that attach the cross member to the front frame horns but not enough so I'm wondering what to do here.

Is this a body to frame shimming issue or something else? Thanks

[Alan S.]

Re: Shimming a 69 body

Hi Greg,
Since the forward cross member mounts to the frame extensions could your situation be caused by the way those extensions are bolted to the frame horns?
Do the extensions need to be tipped a bit?
Since the outer bumper brackets mount to the extensions too, all 3 pieces… 2 outer, 1 center, may all need to be installed and aligned at the same time and the bolts gradual tightened in some sequence.
Regards,
Alan

[Greg L.]

Re: Shimming a 69 body

Hi Alan ,how are you doing?I'm going to try tipping the extensions tomorrow and see what that does. I didn't think there would be enough adjustment but maybe there is. Do you know how much upward force/preload I can put on this cross member to support the nose? I'm thinking that the front of the clip including the hood, rad support and rad with fluid should be around 200 lbs so I'm thinking that anything in about that range should be okay.

[Alan S.]

Re: Shimming a 69 body

Hi Greg,
I'm good, hope you are too!
I'm very concerned about putting any preload on any part that TRANSFERS that load to the fiberglass.
If the front clip is soundly bonded to the cowl I don't think there should be/can be any pressure put on it in order to make something fit.
I think the bumper, grills, brackets, etc., need to be fitted to where the fiberglass is.
I'll be interested in hearing what you discover.
Regards,
Alan

[Greg L.]

Re: Shimming a 69 body

Well... I can't say for sure what it was but after several unsuccessful attempts to make things fit I decided to totaly loosen the crossmember and then bolt the center bumper support to it. I then aligned the front of the bumper support to where it would be once the bumper was installed and then lifted the back of the crossmember and tightened the extensions to the frame horns and it looks like it will workout after all.

However, I now have about a 3/16" gap between the rad support crossmember and the rad support itself. I don't remember having shims there before but it's been about 12 years now since I started the resto. I did notice in the assy manual that there is mention of a "special" shim used here but I'll start a new thread about that.