i went to the yard today and the guy told me he could order me a r4ear end for $250!!! he asked me though if i had a 12a or 13b which i said 12a does that mean i am getting a gsl rear becaseu he said it had disc brakes and lsd.......which also he said is a 9" and the 13b is a 10" is this true and what is the ups and down of getting the 13b rear and 12a rear i have an 85 gs now and this is a 85 rear......

 

9" or 10" what?? All the first gen rears use a 7" ring and pinion

But eh difference between the GSL and the GSL-SE rear is the GSL-SE rear uses larger vented rear disc brakes, and has a bolt pattern of 4x114.3mm instead of the 4x110mm used on the gsl

The gsl-se also has a ring and pinion ratio of 4.08:1 whereas the the gsl has a 3.909

Higher the ratio, the faster you accelerate and the more torque to the wheels, but lower top speed

 

hmm...i knew about the bolt pattern and gears but didnt know what it meant... if im doing autox and maybe drift the se rear would be better i gusse??......will it install the same? as the gsl?? and what all is needed for the install while im doing it i plan to put new rotors and pads and ss lines and new diff fluid shocks and springs anything else i should know about?????tools......ect..

 

the rear end is basically the same, installs the same. The only differences are the ones I listed above

 

Okay, there's actually a lot more to consider here. If you go with the -SE rear end, you'll need parking brake cable ends from an SE as well. Pre 83.5 cars also have a different driveshaft flange bolt pattern and smaller axle splines as well. If your car is an S3 (83.5 - 85) then your only consideration is the parking brake cables. FWIW, the GSL-SE diff also has one less LSD clutch (3 instead of 4) to make room for the bigger pinion gear.

 

The -SE's rearend is perched 20 mm lower, it's a part of the uni-body design. the rear brake lines have a different thread pitch and don't forget to get limited slip gear fluid
(oil) gotta have-it .

 

GSL SE 4.07.. not 8

When he said 9 or 10 maybe he ment rotor size?

I also have a 84 GS,with the drum brakes.I put on the GSL SE brake booster and the pressure was sooo dam nice..

Since you have an 85, 84/85 DONT need to change the brake booster so you can put a GSL SE rear end in.. also keep in mind of the lug pattern change 4x110 GSLSE= 4x114.3

Im going Ford 9in soon.. I wished there was more first gen gusy here in my area.. someone please move here.. lol

 

Taken from Felix Miata's site:

"4.083 49 12 GSL-SE beginning 84/12
4.077 53 13 GSL-SE thru 84/11"

You're both right, but rounding up I'd say hornbm is more right.

 

Ok I dont know how to edit,yeah im a newbie again.. I put on a GSL SE master cyclinder and increased brake pedal alot.