A chronic problem I've had is the lower ball joints going bad in less than a year. I always
chocked it up to Chicago pot holes, low profile tires and hard driving.
But what I discovered after cutting one open is that it's mostly from bad design.
Instead of a solid ball in the socket, its 2 pieces that depend on springs in the socket to keep
them together. I suppose the idea was that the spring would compensate for wear, but the main
effect is that the assembly has very little resistance to side impact. A fairly minor hit will
cause the upper haf of the ball to slide sideways, wedging the top of the socket upward.
This appears to be a later design, because I found an old original with a solid ball. It was
ruined from rust, so I couldn't use it even if I hadn't cut it open. I figured anything
I buy new will certainly be the louzy split ball design, so decided to make my own parts to
repair an old control arm.
The ball is stainless steel and the socket is 7075 T7 aluminum. I modified the top slide on
my lathe to enable cutting radiuses. Theres alot of set up time, so I made 3 balls out of
the 1 foot of bar stock. I also made the nuts out of 7075 because stainless will weld to
steel under pressure.