Lower Control Arms - I Feel Like I'm Taking Crazy Pills

[Parklife]

Correct me if I'm wrong here, but the purpose of coarsely-threaded caps that retain the lower pin into the control arm is that they're supposed to thread themselves into the steel of the lower control arms, so that when they're tightened up the caps have torqued up to the control arm, thus allowing the center pin to turn freely inside.

If I have my understanding correct, then there's no way this - on a set of NOS control arms with no threading in them whatsoever - should happen?

The ID of the bore on the control arms is 1.140" using my $8 Amazon digital caliper, while the OD of the threads ~1.136", giving me a nice four-thousandths slip-fit.

[Zedman]

Send 'em back- The holes are way oversized. 😬

 

[Randy Atkin]

Either the holes are oversized or wrong bushings. It takes a LOT of torque to thread the bushings into an NOS control arm when everything is sized correctly. With a new control arm the bushings form their own threads as they are tightened down. 

Edited May 8, 2023 by Randy Atkin

[brad]

There are different size bushings. Inner and outers are different as well as upper and lowers. Before everyone gets in an uproar about that statement, I'm just relaying that there were early 51 and 52 a-arms that had solid bushings, and also R3 and taxi upper inners were solid. Those were different sizes than outers too.

[Leo B]

My 1963. Upper and lower are different but same outher thread size Lower Threads circa 1.134" Upper Threads circa 1.134". Inside thread is different.

[Leo B]

How about upper one? Same problem? Should be same thread. 1.134 - 1.136

 

Edited May 10, 2023 by Leo B

[Parklife]

15 hours ago, Leo B said:

How about upper one? Same problem? Should be same thread. 1.134 - 1.136

The uppers were a much tighter fit - just large enough for the tip of the caps to pilot in, but they required cranking them in the rest of the way with some determination. The bores on those were 0.020" to 0.030" smaller diameter than the lower control arms.

The lowers, well, that's a story.  The first set - the originals on the car - were slightly bent.  The second set were NOS replacements, that FedEx managed to lose somewhere as they transited through Portland.  This is the third set.  But now needing a fourth set? I'm getting a real black-cat, Friday the 13th kind of feeling from this. The universe wants this car off the road and is prepared to do everything in its power to make it happen.

At any rate, thank you everyone for reassuring me that I haven't lost my mind.  Perhaps about other things, but definitely not about this, at least.