UMI Front frame brace install

edfiero1

Member
Joined
Apr 6, 2017
Anyone out there install one of these?
It came with 3/8 bolts for the rear cross member connection, but instructions include a note saying that come cars may required 10mm bolts.

Well, on my 84, the 3/8 bolts don't fit in the existing frame holes. And even if they did, these holes are not tapped, and there is no way to get nuts on the other end of the bolts, since this area is 'boxed' in. And, the bolts supplied weren't the 'self-tapping' kind either.

What is the suggested way to install this thing? I thinking that its going to be hard to find self tapping 10mm bolts at home depot, and even if they have them, that isn't going to support the kind of torque you'd want to have on a frame component.

Thoughts?
 
Factory braces used 10 mm x 1.5 thread forming screws. They are discontinued at GM, and I have not been able to find them anywhere. The frame holes are made to be tapped to 10 mm, so use a 10 mm x 1.5 tap, and bolts with lock washers (I used NordLock washers). If you use 3/8” self tapping screws, there is a good chance they will pull out.
 
I ended up tapping these holes with a 3/8 FINE thread tap. Hopefully the fine threads will get a couple of extra threads to bite with compared to a course thread, and I bought some matching fine thread bolts at the hardware. Guess it worked out OK, but sure wish the instructions told you up front the holes had to be tapped.
 
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