This season we downgraded our autocross car from Street Modified to Street Prepared, and because of the stricter modification rules, some new parts have been appearing around the mc²racing shop. One new part we had to produce was a rear subframe bushing. In Street Modified we could weld our beams solid, but in Street Prepared the bushings cannot have more metal than stock. So, I basically just picked an uber-high-durometer non-metallic material that is readily available, tough, resistant to the elements, and reasonably priced. That material would be Delrin, and these are the resulting solid rear subframe bushings:
The center sleeves were machined out of 7075 Aluminum. The material doesn't give at all, so there's no way to use a traditional bushing design that involves being pressed into the beam. Hence the two-piece threaded-body design. I fabricated a special tool that grips the bottom half, twists, and squeezes the crap out of the beam. The beam may as well be welded solid.
These items are not available for purchase, but I figured I would at least share the pics.
