Miata Torsen Differential in 85 GSL technical questions?
 

Now i know that these things can be swapped in, but I just need a few technical answers.

First off, contact length of the axles with the differential of stock vs torsen. According to this document "http://www.nellump.net/peri/epi/firstGenTechs/torsenLSD.html" the stock contact of the axles in the diff is at 25mm but with the smaller unit of the torsen it is reduced to 15mm. Can anybody confirm this?

If this is true, what couldn't happen from the reduced contact area? Would I safely be able to push around 300whp through it still?

Are all the bearing the same as the first gen? As in the carrier bearings or does something need to be modified?

Lastly T-1 vs T-2 style, what are your thoughts on both of these? I can't find the link to it but someone mentioned that the T-1 is better suited to a rear wheel drive car and the T-2 to a front wheel drive. Any thoughts on this?

this has been runnign through my head for the longest time. so here is wat ive pieced together. it will fit. ring and pinion i am not sure about. seals. again not sure about. but it will fit. why? rx7 diffs are swapped into miatas often. the miata can take in an s4 7in. ring gear with the miata ring and pinions. even the stub shafts from an s4 will work with some miata axles.

http://www.miataturbo.net/showthread.php?t=4288

look at section 13. rear ends.

ive seen a lot of things done in the 1st gen section so, im sure someone could figure it out.

the miata 3rd member is almost identical to the 1st gen unit, it uses the same bearings, shims, adjusters etc etc. seal and driveshaft flange might be different, but interchange.

really the only thing different is the diff itself, and the gear ratios.

its been so long since i looked at these i forget which one is "better" the t2 is cheaper new and i think its been used longer...

http://rx7-gsl-tii.us/TIIswap/dscn1147(1024).jpg

pic is miata diff in rx7 haus

j9fd3s - what application have you used the car in? I do more road racing than autoX, and according to that miata turbo link posted above, the clutch type is suppose to be better for road race.

I already knew the ring and pinion all fit on and what not, but I'm more worried about the axle contact area at this point. This is not an issue for the miata guys since the bigger diff will give them MORE contact area since the unit is larger. Now I do have the after market moser axles, but I do now recall if they were a bit longer which in this case would help you. Maybe Billy from RE-speed can pitch in on there. I also wonder if I just sell the axles in my car right now and buy another set made a bit longer if that would work out better to play it safe.

As for the T2, I hope you're not refering to the Turbo 2 car but rather just the T-2 style torsen. Here's the links on the differences for the people that look this up:

http://www.torsen.com/products/T-1.htm

http://www.torsen.com/products/T-2.htm

I should probably toss this up in the air also, if anyone know where to get the T-1 unit for cheap from somewhere let me know. Cheapest I found was 500$, ebay has some too but it'll be about the same price as this with shipping and duty.

Lastly if anyone has a quick reference to this, what do the 3rd gens use?

yeah type-1 vs type 2. the type2 is cheaper new, and its probably in more cars.

i know there is a difference, but its been so long i don't recall what it is.

maybe if i actually had one... i had an FD, with a torsen....

Cool.

Still need to know about the axle contact area if anybody has any insight about this.

Others have dealt with the axle length issue. See:

http://www.rx7.org/jes/axles.html

Note the part about the length of the axles. The originals received by Johann and David were 2mm too long and had to be shortened. If you specify "the length of the axle should be REDUCED from 13mm to 11mm longer than stock", they should be just right.

Ya, I don't know. I'm really tempted to just toss it in without changing the axles. Anyone know what they mean about shimming the axles to make it fit though?

the link we keep posting IS a turbo, AND its been running fine since 2004...

Oh, then I'll be fine :)

How do you think drag racing it with semi slicks would be?

I was about to start a new thread about this. My car is an 84. It had drums in the rear and we change it for a GSL-SE rear end because of the disc brakes and the LSD. I don't know much about differencials but my LSD isn't working like it should be. It spins the inside tire at the track. I was looking to the miata torsen and found this :

http://www.mazdamotorsports.com/pdfs...Drivetrain.pdf

It says
"Torsen “Type 1” unit from 1994-95 Miata
can be fitted to 1986-91 RX7 non-turbo
models. May also be used on 1984-85 RX7s
(12A &13B).

Torsen “Type 2” unit from 1997 Miata. Type
2 Torsen unit has a slightly higher bias ratio
than Type 1 units and is less expensive. See
notes for Part #MM01-27-200 above.

But I need to know if it is a direct fit to my GSL-SE rear end

Good link, and yes to the second question. Still not sure whether to get the T1 or T2

I think what I need to do is look up some more miata forums and see what they say about the t1 vs t2

If the swap is easy as change our diff to the torsen I'm also tempted. I'm not very worried about the 10mm lost in the spine since I'm aspirated. The link of jim have the other parts that are needed.

http://www.jimrothe.com/mazda/torsen.html

Ya thats just the regular oem bearings and parts for the clutch type.

Just for the record I plan on ordering all the parts for this swap within a couple of weeks hopefully, and once I do i plan on taking pictures of everything along with measurements of the diff and what not to have a fully documented with picture swap info.

Good!!!!!!!!!!! I thinking about do it too but I have to wait a few months. So probably you will do it first. So I (and so many people ) will thanks you for the pictures

the bearings are the same for both. if you're keeping the FB center section, you wanna order that seal as well.

the kia stuff is the same too, they just add an 0k (generally) in front of the mazda part number

Oh, Is that the pinion seal off the Miata unit? Also is that considering that you're keeping the miata ring and pinion or the FB ring and pinion?

Bump for answer on seal

if i went with a torsen will i be able to get sideways? aren't they more of a grip/track differential?

bump for the seal question as well

i think you use the FB pinion seal, because the case and yoke stay the same

and need also the Ring & Pinion. Any ideas where to buy?? Not from ebay and I don't have access to mazda comp parts

any ideas where to purschase?? I check out mazda trix and ask 1K for the torsen but it's for the Torsen 1 I'm looking for the torsen 2

Online somewhere , local yards, best prices I found. But still around 500$

Any ideas if the ring & pinnion from the rx-8 fit?? They are very cheap and easy to find