HEY, i have a 90 miata with the 1.8 swap done already. I am about to have my turbo kit installed soon but i would like to know what would the best rear end to use? I heard the one off any 1.8 is okay up to a certain point and and rx-7 rear end is good but is not so great for holding up to torque.
So, what would be my best bet for a simple swap into my car? Would the 1.8 rear end be just fine?

 

TORSEN LSD

 

A 1.8 diff with a cheap rx7 clutch type lsd is a very robust setup. But basically anything is better than the 1.6 rear you have now.

 

any LSD in a 1.8L carrier will work. the strength required is in the ring gear itself. so even if you just get an open diff, it wont break.

 

yes, a rear end from any 1.8 car is a recipe for successful living.

 

thank you EVERYONE!
but uh, how well would you say a 1.8 rear end would hold up to a 1.8L engine running about 6-10 lbs of boost? wouldnt be the best idea to rev and drop the clutch i take it?! hah

 

the 1.8L rear is buillet proof more or less. Go ahead and do as many launches as you want... (of course something else might break, but the diff shouldent..)

 

okay great...how great are the 1.8 transmissions?

 

250+ horsepower eaisly. youll only be at 190 ish, you really have no worries with your setup. Of course launching the car all the time will wear stuff eventually, but you should have no worries.

The 1.8 diff has suported over 400 hp before, so it is very strong.

 

oh...sounds pretty good!
i am planning on running around 6-8 pounds of boost to start, then if i feel like i want more ill probably push it to 10! dont think ill need to go more for now.
know of any other ways to get some more power out of the motor without forced induction?....maybe different cams or something?!

 

Dude the 1.8 trannys are the same as the 1.6's there where a few synchro changes etc but other than that they are totally the same.

 

the 1.8 6speed tranny is the same as the 1.6?????

 

No the 6 speed is not a 5 speed. but other than the 6 speed all of the 5 speeds are the same. Don't be silly

 

he he sorry but the 6speed's are much stronger aren't they

 

Yes they have been know to hold on very nicely into the 300-400etc + power ranges very well. Where as our 5 speeds tend to breack past 250 of so lb/ft.

 

where could i find a 6speed tranny?
and what would the best bet for a rear end be?....is there anything better than the 1.8 that can bolt right up? where could i find good "strong" reliable parts???
oh...and does the 6speed tranny bolt right up?

 

Theres some parts you need to get with the 6sp. This info is all listed on m.net "garage".

 

One thing about the RX7 LSD is that most likely you'll need to rebuild it since it's a clutch type. Unless you think you can do it yourself it'll costs more than a torsen.

 

I never broke my 1.8 Diff even at 498hp. Should be fine

 

so...is the 1.8 rear end just a simple bolt in?!
or do i need a driveshaft and other things as well?