SO! I have been doing a tiny bit of research about how miata guys use our differentials in their cars.. but havent been able to find if miata differentials fit in our cars!

I have found an open diff from a 1990 miata and before buying it would like to know if it will work in the GSL housing and carrier.

Will it??

 

Early miatas used a 6" ring gear. Later miatas had the Rx-7's 7". Anyway, the '90 is most likely a 6".

May I ask why you want an open diff? I live in the same city as you, so I may be able to shake a suitable one out of my parts tree.

 

Yeah, if you are going through the trouble to swap out the diffy, you should at least be making an upgrade. Better yet, get the entire rear end from a GSL and that will get you not only limited slip, but rear disc brakes as well.




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need an open so i can weld it for track days and such. The stock LSD is nice for daily driving, but sucks for the track

 

You want a welded diff for track use? You must either be a drifter, or insane! (curious to find out which, btw)

 

Stock LSD sucks on the track when it's clutch plates are worn and need replacing. You can add a thicker clutch plate which greatly tightens up the limited slip to the point it puts a ton of power to the ground.

I wouldn't use a welded diff unless that was the only option due to class rules.

Your best bet is to use a torsen from a Miata in your 1st gen. Now there's current technology and they never wear out or need rebuilding.

 

Didn't dj55b just do a writeup on the Miata torsen install?

 

im running a 1995 Kia Sportage with a welded diff... 4.78 gears stock...the complete pumpkin bolts right in with no changes to the mounting spots...

the gsl-se comes stock with 4.11 the kia sportage jumps up to 4.78's

runs great, and feels great...I do drag racing, thats why my diff is welded, but then again i don't daily her anymore, she is a trailer queen

 

Ya i drift haha.. and might be a little insane.. time can only tell i guess.

Would i need to change axles or anything like that for this swap??

The Kia thing interests me.. my friend works at a wrecking yard with a TON of sportages.. hmm

 

I am using a 4:44 ring and pinion from a late 90's Miata using the stock RX7 LSD unit and carrier. It works very well , very tight , but I change the oil once a year and always use the recommended GM oil additive. I have heard the 4.625 ? gears from the late 80's Mazda 4x4 can be used also. Any idea ?

 

https://www.rx7club.com/showthread.p...t=miata&page=3

Here's my contribution to that

 

1990 to 1993 model year are the 6" diff. its useless. its common for endurance race miata's to spit the teeth out of these....

1994 to 2005 model year are the 7" diff which interchanges with the 84-85 (big axle) Rx7's. the miata limited slips are all torsens. the miata also uses 3.9, 4.1 and 4.3 gears depending on the year/transmision.