Rear suspension geometry question
 

I have a '79 RX7 I have set up for autocross. I also have an '84 which is stock. I seem to recall reading somewhere that the '84-'85 cars have a different rear suspension geometry that decreases roll oversteer. Since oversteer is an issue with my current setup, is it worthwhile to swap all my stuff from my '79 to my '84?

Maybe. I think they relocated the pickup points for the control links. How much difference is there in weight?

According to the GCR, all '79-'85 12A cars share the same minimum weight, and since I'd be doing IT prep, (moving my cage/seats/suspension/etc.) it wouldn't be an issue at this time. The later car has aluminum bumpers instead of steel, which should change the PMOI for the better (centralize weight). I understand the rear arms got dropped 20MM to change the roll, which I would really like to do if it's worthwhile.

The later cars also have larger front wheel bearings. They last longer than the older ones.

-Trent

If you want to reduce oversteer, you can change your rear sway bar to the later model one. The later model bar is softer, and will make the car more neutral. If your autocross class will allow it, you may want to remove the rear sway bar completely.

Either way, you will be doing yourself a favor by getting a stiffer front bar. Many aftermarket companies make them. Don't get a later model bar from Mazda for the front.

I would check this out.

For IT or Street Prepared AX this is legal.

http://www.gforceengineering.net/products.htm

Specifically look at the Tri-Link. This is THE setup for the rear suspension in conjuction with the Panhard bar. All of the other stuff is excellent also. The turn-in spacers are not legal for AX though.

It would work on both cars.

I would almost reccomend keeping the 79 and doing some updates from the newer car...such as brakes and rear end and a few other parts/pieces.