I'm trying to figure out what rear axle gear ratio I have and if it is a limited slip diff or not. But the kicker is doing it without disassembling the diff. Its a 4 lug, non turbo 1988 Mazda RX-7. Is there any way of telling other than that? Any help would be greatly appreciated. Thanks,
Mike

 

It is a non-limited slip type and 4.10 gear ratio. Turbos and GXLs of those years were the only ones to have limited slip differentials. 4.10 is pretty much standard for the N/A unless it was GTUs.

 

Assuming that it's the original rear end for that particular year/trimline car (i.e., 88 base), then it's a non-LSD. The 86-88 GXL's have LSD, but I believe they also have 5-lug hubs. BTW, the limited production 88 GTU also has LSD. As far as the final drive ratio is concerned, it really depends on what transmission you have. MT cars use a 4.100 final drive ratio, and AT cars use a 3.909 final drive ratio.

Hot_Dog
90 RX7 GXL
02 Acura RSX-S