I am putting together a 71 chevelle project car that I bought disassembled. I am working on the front suspension. I have brand new upper ball joints that were just dangling on the upper control arms when I got it. One side had 1/4 bolts holding them in which are sloppy in the holes, the other side has nothing. I just helped a friend replace these on a 67 camaro and they came with 5/16 bolts and we were told to drill the holes out on the comtrol arm to fit. (His old ones were rivoted in)
My question:My ball joint holes are too small for 5/16 bolts. should I drill them also or just go with the 1/4 bolt and tighten them good. Why would my ball joint holes be too small? Is it possible that these ball joints were desinged to be rivoted. Thanks in advance.

I just replaced, in March, a riveted set on my 70, 71 should be same. The bolts, can't be sure of size now, were not sloppy but not tight. They appeared to be correct size, I didn't notice anything. You could always go buy a new ball joint and see what it looks like, holes and bolts, then take it back if not needed. Or take the one you have to the parts place and compare. Doesn't seem like should have to drill out any holes. The holes in the control arm aren't worn are they?
Edit: bolt in or rivet in should both work with the same size hole in control arm and balljoint.

Some replacement brand ball joints come with bolts that require drilling. Can't remember which brand Kragen (CKS) sells but the holes need to be opened up to get the bolts through on theirs.

Originally posted by John_Muha:
Some replacement brand ball joints come with bolts that require drilling. Can't remember which brand Kragen (CKS) sells but the holes need to be opened up to get the bolts through on theirs. So maybe his controls arms were drilled from a previous set and the ones he has now don't require drilling? Makes sense, didn't know they ones that you had to open the hole up.

it makes sense to me that I would have to drill the control arm...I just don't know why I would have to drill the ball joint holes.

The only holes I've ever drilled are the 4 mounting holes for the ball joint. Perhaps they used cheaper steel bolts. Perhaps they (the replacement company) determined that smaller bolts lacked the sheer and tensile strength needed to hold them together.
I just drilled the holes and put the joint together.

ok...thanks John. That's really what I wanted to know. (Drill the ball joint)

the new ball joints in my uppers are moog and they 5/16 grade 8 bolts
the holes in the ball joints where the proper size for the 5/16 bolts
the important thing though is that they are grade 8 bolts and wether they are 1/4 or 5/16 I would definately use the grade 8's

Replaced mine a couple of years ago with Spicer# 500-1009 and they fit fine with no drilling of the ball joint. Tight fit, but ok.

I wouldn't hesitate to put 5/16 grade 8's in even if I had to drill the joint and arm to make them fit. In fact, by doing that, you eliminate any slop.