So guys---if the droop isn't suppose to happen---is it because a weld broke loose?
Yes, I have tied in a metal bar from door post to rear 2x2 and removed the rivets and bolted the Fb to the 2x2 frame already. Stiffened it right up and fixed the door gaps.
But--what is the cause of the rear square framing to have a droop? Can this be fixed or would it require removal of the body---Not even thinking that is going to happen.
David
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The reason that mine was sagging in the rear was not due to the frame. The frame is relatively rigid with only a small amount of flex. The reason for the sag was that the body was not attached securely to the rear frame. The rivets were loose and the holes were worn. This allowed the FG body to sag in relation to the frame. I bolted and bonded the body securely to the frame while supporting the rear of the body. This eliminated the sag. Like you, I also added a strut from the door post to the rear frame to stiffen the rear, but its purpose was not to cure the sagging problem.
I'm pretty sure the subframe used by others is pretty near the same as the FF/CMC sub-frame. It doesn't appear that the welds crack or break. It's just the the fiberglass butt is too heavy for the few 1/4" rivets thru thin fiberglass side panels. When I did mine I also used HD constuction mastic (similiar to lLiquid Nails).
The CMC build manual actually has the builder fiberglassing in the rear engine compartment panel above the exhaust which would, if done, give it more strength. I think most builders just screw/pop-rivet that panel in though.
Here's photo of actual sub-frame:
Butt sag fix: Use a 3' piece of 2 x 4 on a floor jack to support the rear area of the body , then drill out the rivets. Slowly jack up the body until you have an even vertical door gap. Drill new 5/16" holes ...Pry away the fiberglass panel from the 2 x 2 frame filling in that area with exterior construction adhesive or automotive seam sealer slip a fender washer on the 5/16; bolt pass it through the fiberglass panel and the 2 x 2, add another fender washer and nyloc nut.. When you have completed both sides let the jack down and you will probably have to adjust the door latch striker plate.
Alan,
A year ago---Been there did that--door gaps are much better now. But why does the metal 2x2 sag--you can push up on it prior to the fix and it flexes. I would think that if I lift on either side or in the middle it would be like I'm lifting the entire car.
The 2 x 2 does sag a bit , but the real issue is the fiberglass inner wheel well pushes against on the rivets and over time the fiberglass wears elongated holes so the body drops a bit and causes top of door gaps. Both a angle brace, 5 -1/6" bolts and construction adhesive will take care of the sag
Alan
