Hi Cecil,

Looking at the picture above, the lefthand end is a ball joint.

The vertical threaded rod you can see ends in a ball which can swivel in a socket.

Over time, the movement of the ball in the socket

(every time the rear wheel goes over a bump) causes wear, so the two parts of the joint can wobble about relative to each other.

The right hand end is a rubber mounted bush or bearing.

This is designed to give a certain degree of compliance, but the rubber perishes with age and use and gets too soft.

When either of these things happen, the rear wheel can wobble in and out

(toe in and out) as you are driving, giving an unwanted and unpredictable rear wheel steer effect.

Therefore, if you can use a prybar or something similar to wobble either end of this link while it is in place, it's probably causing some strange handling issues.

I guess you could also check it by jacking the rear wheel and trying to to pull it

(hard!) to see if it wobbles in the toe direction.

A more likely cause of replacement is that the three pieces of the bar

(ball joint, tube, and rubber bush parts) are all rusted together in one big lump.

This means that you can't adjust the rear toe if you have a wheel alignment done.

Hope that helps!