Hello, I'm looking into swapping the LSD/rear end in my 85 GSL-SE. It has a sreet port and as you know this takes away some of the low end torque. I'm thinking I'd like to compensate by going with a lower gear ratio.
Does anyone have any suggestions on the best way to accomplish this? Not trying to go 150mph but rather 0-100 a little quicker. Thanks everyone.

 

Stock ratio in a gsl-se is 4.1.
Commonly available swaps are a 4.3 (can be found in some 94+ Miata) or a 4.8 (can be found as the front differential on 4wd Kia Sportage)

 

mschiap, thank you for the info. I'll check out the site. Appreciate it.

 

Would I need to change anything to make that set up work? Drive shaft/CV axles? Thanks again

 

The stock GSL-SE differential has a high-quality "clutch-pack" style Limited Slip unit.
If you buy a 4.8 front differential from a KIA Sportage, it will be an "open" differential. Your axles will fit into the KIA differential fine, but you would likely want to have the limited slip unit from the GSL-SE differential swapped into the KIA differential. A shop that specializes in differential repair will charge approx $100 to do this.

 

actually i would recommend properly installing the kia ring and pinion into the rx7's third member. The kia member does bolt up but the input seal is essentially NLA and the mazda one DOES NOT interchange so a leak is repairable. Plus you can set the lashing up better than the sloppy Kia arrangement. New bearings are worthwhile too since everything in the Mazda is likely 31 years or older and the Kia is older and crappier.

 

There is a Torsen unit available for 24 spline axles as well as a 5:38 gear if you really want to wake things up. The car will pull like a freight train and Rotaries love gear.