[jogasz28]

We are going to start on repairing both #1 body mount pads today on the '69.
Questions: What is the exact dimension between the center point of each #1
body mount hole?
Is there another dimension to triangulate to assure proper alignment?

The original #1 gage holes are in great shape, but the body mount holes are rusted so I cannot know for sure there exact original position.
Is there another way to assure proper mount hole placement?
I've read where guys have welded in an 1/8" plate and hole sawed the mounting hole. How did they spot the hole?
Any replies are greatly appreciated.

 

[HwyStarJoe]

That was a difficult one for me as well. I had to totally remove the mounting surface on mine, they were so bad.
Once I made the replacement plates, I just centered them on the remaining portion of the mount as best as I could and welded. I had already bored the mounting holes in them. There's still plenty of play once the sub is under the car. I used much larger mounting bolts than original and I still had plenty of slack to move the body around on the frame to align it.
I didn't use the alignment holes at all. They're drilled, but I didn't use them. I just measured, measured, measured and measured some more until I was happy with the sub placement.

I'd get you that measurement you want but the body is in the way.

 

[jogasz28]

That was a difficult one for me as well. I had to totally remove the mounting surface on mine, they were so bad.
Once I made the replacement plates, I just centered them on the remaining portion of the mount as best as I could and welded. I had already bored the mounting holes in them. There's still plenty of play once the sub is under the car. I used much larger mounting bolts than original and I still had plenty of slack to move the body around on the frame to align it.
I didn't use the alignment holes at all. They're drilled, but I didn't use them. I just measured, measured, measured and measured some more until I was happy with the sub placement.

I'd get you that measurement you want but the body is in the way.

Thanks for the quick reply.
After reading your post, I'm wondering if we should just weld in the plate, drill only the alignment holes for now. Then when we're installing the sub frame later, after it's in final mock-up position (all front end sheet metal lined up), thread the #1 bolts down from inside the car to mark the proper hole center. Then remove sub frame and drill the mounting holes.

 

[HwyStarJoe]

That's an idea. Or use a snap punch instead of the bolt. One of those spring-loaded punches. Get the frame where you want it, snap punch a marking hole on the plate from above to mark where to put the center drill for the hole saw. You'll be as close as you can get to the correct center.

 

[Johnny B]

Jogasz28,

Here is what I used to locate the body mount holes. This is in the "1969 Chassis Service Manual". Joe is right...there is plenty of room for lateral adjustment in the body mounts. Look at the caged nut in the body and you will see how much play there is.

I laid out the dimensions from the frame drawing on a sheet of plywood. Then I set the frame on the plywood and transfered the points to the subframe using string lines and plumb bobs. (actually to locate the templates I made but really didn't need after all)......Jb

 

[CDJr]

Maybe this will help...

 

[HwyStarJoe]

Not only do the caged nuts have room to move, but the bolts are also a smaller diameter than the holes in the bushings themselves, giving you some more play room.

Excellent drawing CDJr.

 

[jogasz28]

Thanks for the great replies.
We've got the #1 body mount plates welded in. I'll post pics later.
And thanks for the great drawing CDJr. I will layout the body mount hole center according to your drawing and see how it lines up during mock up.

 

[CDJr]

Always happy to help :thumbsup: I forgot to mention that those measurements are from the outside edges...the steel is 1/8" thick IIRC, so make sure to measure from the outside.