I thought I had it figured out.
Seasoned, used 73-76 Disc A body UCAs go for at least $125 a pair around here. Tubular aftermarket ones are well over $400 so I thought I was smart by buying the adapter setup from Dr Diff for a measly fifty bucks or so.
I had several pairs of the 64-76 small upper ball joint upper control arms and thought I’d be able to use them. I replaced the bushings but the upper ball joints in them were still good. I gave them a cursory coat of semi flat black paint….
Rick Ehrenberg has written several times that the upper ball joints in these cars are often still in good condition even after many, many miles of use. I’ve found that to be true too.
The Dr Diff kit is simple but smart…
The 73-89 front disc knuckles use the big shank upper ball joint so this kit uses tapered spacers to allow the smaller shank ball joints to fit and work. He includes two nuts to fasten it together. In theory, it goes like this:
The spacer just slips on.
No adhesive, no lubricants either. Just assemble like any other time…
Here is where I encountered trouble.
The shank does not stick through the knuckle very far.
Can you put a nut on the end and pull the ball joint shank deeper in?
Not really. I used a clamp to compress the ball joint into the knuckle and didn’t get far. I ended up stripping the last two threads on the nut trying to draw it in. It gets worse though.
My first attempt was on a UCA with a ball joint that was threaded all the way to the end. A quickie look at other ball joints I have here show this:
Threads that start above the cotter key hole. The fully threaded shank was bad enough… this one couldn’t thread on at all.