My Z has a loose steering rack, again.

The first time it happened in 2005. You would turn the wheel and the rack would move 1/4" one way or the other. I noticed it in a race and the steering wheel would end up 5-10 degrees left or right after a turn in order to get the car to go straight.

Nuts and bolts on the bushing were tight as tight can be. So, bushings were replaced, problem was solved.

Now, with only about 6 race hours on the bushings the rack is doing the exact same thing again. Bolts are absolutely tight, rack moves 1/8 to 1/4 inch. Is there something about the bushings and rack I don't know? Does it need some sheet steel shims in the bushing material to hold up well?

Thanks,
Ron