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

If you want to slide/drag/burnout I recommend an LSD. I have a 7 with an LSD and a miata with a torsen, and I've owned a quaif'd SHO, and a GTI with a Peloquin (both Torsen types).

Here's the deal, when LSD's break due to burnouts and such it's clutch plates slipping. On a torsen it's worm gears shattering. Miata torsens are not the strongest units and while stout, it is not unheard of for them to explode, so if you're doing something that's hard on the diff. I'd stay away. Rebuilding an LSD is cheap and easy. Not to mention that torsens behave like an open diff when one wheel looses traction all together (which is why for off-roading and burnouts that are not highly recommended).

After-market Torsens are pretty bullet-proof and I would not worry about a quaife or anything like that no matter what you threw at it, but the miata unit is not one of those.

That said, my 200whp turbo miata cuts nice SMOOTH 2nd gear fishtails that are beautiful to control, but that's all the abuse I throw at it. To really understand why you want a torsen, step on the gas hard, just before the apex to a corner. I'd swear the damn car rotates AROUND the apex. Definitely a track/grip racing type of diff.

Hope that helps.

anyone can tell if this is from gsl-se?the guy who is selling that says it is from 85' model but he is 600km away from me...

GSL-SE has studs on the axles, all the others had bolts. Thats the easiest way to tell.

I'm working on this. I'm looking for the torsen and the 4.44 ring & pinnion to make a complete rebuild. My next rack day is on June 13 with new wheels and tire for complete the package. So I'm againts the clock!!! let see

so this is not from gsl-se,right?

no, solid discs = gsl

no

-Ted


the rx8 is an 8" ring gear, the SA/FB/93-05 miata are 7"

Ya thats another way to look at it.

I ran a type 1 torsen for a while. It was phenomenal on the track. I was able to apply power way before I was with the clutch type LSD. my roommate's Miata has a type 2. It's a completely different driving experience. When you get on the power with a type 1 only one tire spins until the final exit of a turn. You get the good of an open diff and the good of a clutch type but you also get the bad of an open diff. A type 1 is not drift friendly. Type 2's kick so much more ass. My type one was only in my car for maybe 5 weeks before it started howling so loudly it was unbearable in the car. We tore it apart and couldn't find one thing that was causing the howl...

Were you saying that type two is just a better overall, or just in drift?

I found a local torsen 2. I will be pick-up on wednesday afternoon. I got the other parts (bearings, seals, etc) I still need a 4.44 ring & pinnion.

Racing beat sell the pinion and bearing if you want to spend the money through them.

I'm looking to find it on the internet. If by the end of the week I don't found it, I will call racing beat

If you are concerned with performance, you want a type 2. What changes is the amount of lock up, or how aggressive the diff behaves. Torsens actively bias torque to the wheel with traction and the type 2 does this with more authority.

Simply, any serious performance app: get a type 2, but again, for drifting torsens are fragile compared to clutch LSD's

I don't drift the car, but it definitely does see some power over steer a bit on the track in some tighter turns.

Anyone know what come in the 3rd gen type?

Also why is the first type more expensive than the second type?

You can get the 4.4 from the >front< differential from a rotary 4 X 4 pickup. That's what I put in mine.

or the 4.77 lives in the FRONT of a kia sportage`

:nod::icon_tup::icon_tup::nod:
the problem with the torsen is that once traction is lost it will transfer power to the wheel with no traction. so if you pick up the inside rear wheel through a turn it will spin in the air freely. That's one problem I was having in my car with my suspension. I took off the rear bar and that fixed it, but the $350 torsen only lasted a few weeks.

I dunno, i think i'm still going to go for it. So what exactly went on the torsen you had?

First what type of torsen did you have?

Second. I know that your comment is from your experience but does the LSD are supposed to do the opposite that you mentioned? From waht I know the LSD should sent the power with the tire with traction.

LSD's do not "send" power anywhere. They simply prevent power from taking the path of least resistance. "Slip" is when the right and left wheels rotate at differing speeds. So by logic a "limited slip" differential is one that tends to keep both wheels rotating.

So in an open differential you do a burn-out and all the power goes to the wheel that starts spinning first. In an LSD they both spin regardless. More and more aggressive LSD's will behave closer to a locker or spool, but they are all designed to disengage at some point, it depends on how they are setup.

A torsen on the other hand DOES send power to the wheel with the most traction, the problem is that this is only when both wheels HAVE some modicum of traction. If one wheel looses traction ENTIRELY (like in the example of lifting the inside tire) the torsen will behave like an open diff. So in the case of tire lift, the LSD is better, but because it will keep both wheels spinning, not because it sends anything anywhere.

Good clarification Thanks!!

i can't find a gsl-se axle to fit the miata torsen...:(any other options for axle?aftermarket?i also can get my hands to a kia sportage 4x4 axle with the diff and everything for 200$ but don't know if will work on my little fb...:scratch:

You dont need a gslse rear end , you can use any 84 or 85 big bearing rear end for this.

Got the Torsen 2 yesterday. still loking for the 4.44