best rearend advice
 

hey guys im selling my rearend off my 85 gsl (guy that owned it before me said it has been rebuilt and certified by Mazda) and i want to replace it with the best one possible. after doing a search i have found that some think the ford 9" rearend is the way to go when others think it is too heavy or some other reasons. my car is only a drag car which will never be driven on the normal roads so i am maxing it out all the way. i am staying 12A because i just want to stay carb and want the experience working on one. also if you need to know about transmissions i have no clue what i want to replace mine with (stock one also for sale) i want both to be able to withstand my launces with the biggest most traction loving tires i can get on them. any advice or opinions would be great. thanks for your time :D

you must really be making some power to need a 9" a good lsd rear out of gsl and gsl-se is good for about 220fwhp is what ive heard. after that you really get into trouble, if you use good wrinkle wall tires and a decent clutch you shouldnt have any problems. but if you want you can get a 2000$ + custom 9" rear and drop it at redline all day but there no point unless your got alot of HP

Re: best rearend advice
 

You were that guy who was going to run a peripheral port weren't you?

As far as gearbox's go the best option is to just drop in a Series 4 Turbo box. There are people runing low 10's with them so it should be able to handle anything an n/a 12A can throw at it.

Personally, I would stay away from the 9" though as there's lighter differentials that will do the job. A lot of people here use Toyota Hilux or Borg-Warner setups but I'm not sure what the availibility is like in the States.

An other option would be to just install an SE rear end (they came with larger axles standard) and just hope for the best.

It's hard to say though... riceracing on this forum is running over 500hp through a stock S2 rear (albeit with a factory race centre and billet axles) so in the end it comes down to how much abuse you're going to give it.

Ford 9" rears are very commonplace here. There are many companies making housings for them, and in many cases it's cheaper to buy an entire aftermarlket rearend than it is to buy a junkyard housing, have it gone through, shortened, and everything!

Series 3 rears are apparently weaker than Series 2. The story goes (I haven't had opportunity to, ah, TEST my S3 rear yet :) ) that while the axles themselves are stronger, the housings are weaker and can distort more, and this distortion can cause the axles to fail even more rapidly than the "weaker" axles in the S2 rears.

Because of this and the fact that S2 rears are loads lighter, I might almost want to trade the S3 rear for an S2 rear. Only thing holding me back is that FCs and '94-up Miatas use the same axle spline size/count and thus the diffs can freely interchange.