Learn me urethane bushings

So I crunched my RX 7 track toy a month or so ago and have finally picked up a replacement car. My original plan was to just move all of the suspension bits over from the old car to the new car along with some other items that I want to keep. I know rubber bushings deteriorate over time/use, what about urethane? I have had the car for 7 years and put about 4500 track miles on it in that time, the previous owner had all the bushings replaced shortly before selling it. To me it still feels as solid as it did when I first started driving it. I am better off getting new bushings or do the urethane ones last almost forever and I would just be wasting money? If they should be replaced are there other options that would make for better handling?

How's it going Chuck? Pull the suspension pieces out and check the steel sleeve. If its still nice and tight inside the bushing and there is otherwise no obvious damage, just reinstall them. I've seen bushings distort and I've seen the steel sleeve wear out of round. I saw the vid you posted of the car snapping around in that turn. Something looked off about the way it happened. My biggest concern would be the control arms bending from the impact. Do you still have the stock control arms or are they aftermarket race pieces? There are some pretty trick rear toe eliminator bushings, and adjustable camber arms for those RX7s.

Thanks Todd, the control arms are stock and I do have the rear toe eliminator. As much as the hit was hard it looks like the only significant damage was a bent tie rod end and a snapped ball joint. For the new car I'll probably see if I can just move the left front bushings in case the control arm has been damaged. I am hoping to reuse as much as i can to keep costs down. As for the crash I am pretty confident it was total driver error in not holding onto the steering wheel tight enough. Not sure I would have totally saved it but the snap was caused by "letting" the wheel spin by itself. Had I fought to keep it from over rotating I still probably would have gone off track but maybe not caught the wall and certainly not as hard.

Urethane bushings do last many times longer than rubber ones, I definitely wouldn't replace them based on age alone. The only options that will handle better are metal bushings or spherical bearings, and those are extremely noisy and maintenance-intensive.

My experience: If the bushing only moves in one dimension, poly bushings are okay. Otherwise, stick with stock rubber or spherical. Example would be MR2 strut rod bushings, which deflect in two dimensions as the suspension travels and poly bushings make the car vague/loose on-center and twitchy taking a set.

Any bush that moves or that a pivot point moves within it, will wear out eventually.

I keep telling the MGB boys that instead of fitting urethane or Delrin bushes, they should opt for the MGB V8 Metelastic - an inner steel sleeve that is locked in place by the nut, and a fairly stiff bonded rubber outer that is pressed into the eye of the A arm. There is zero wear surface and all suspension motion is accommodated by the rubber flexing. A very long lasting and pretty foolproof set up - although fools can always find failure modes, like tightening the nuts while the suspension is unweighted and then there is a preset load on the bushes when at normal ride height.

I always use this sort of bush on the street and save the solid bushes for the race cars, which get regular inspection for wear.

I've had good luck with Superpro, not good luck with energy suspension.

I had energy suspension black bushings on the front of my FC and they lasted as long as I had the car with no issues, but I didn't use the rears, since I was using individual camber adjusters, which twist that bushing and with a urethane bushing, its more likely to cause bind compared to stock. Something to consider going forward.

I actually used both types of rear camber adjusters, the subframe link for the big adjustments and the individual ones to even it out side to side, trying to make them each equal distances from stock (in opposite directions, obviously), to minimize and equalize any bind.

In my experience, urethane bushings are better than destroyed rubber bushings, but they creep and go loose fairly quickly. Normally the inner sleeve pounds the urethane egg-shaped internally, but I did have one where the bushing was loose inside the outer shell.

I bought two sets of the Energy Suspension rear suspension bushings for my FBs and I went through all of the main links bushings, using them only in the lowers after only replacing bad rubber bushings. I'd get maybe 20k out of a bushing before it was loose again.

If the rubber bushings are good, leave them alone. My butt chassis analyzer says that good rubber bushings feel better.