I was going to have my B-body ball joints machined down to 2.010, to fit in my 66 lower control arms. I was told that I should never machine these down as it would take off all of the hardening and could lead to premature failure. Can anyone tell me if there is a danger of this happening? So many people have done this conversion that I thought I would have heard of this problem.

Thanks in advance.

There is a case hardening on the ball joint but once it's pressed in where is the wear happening? Don't worry about it. Many places sell the joints already turned down and if it was a problem, they wouldn't risk the liability issues.

You can hit the ball joint housing with a hand file and shave off some metal...so while the actual tapered stud probably has some heat treating, the housing doesn't appear to. I think the spec is .080" off the diameter which should leave you with plenty of material.

Summit sells Hotchkis turned down balljoints.
As stated above, if this was a problem I dont think manufacturers would risk the liability

Thanks for the info. That's just what I thought.