damn ... guess its an open :(
 

Oh well at least it was free, 7", and has more options for the guts. I just dont understand, i thought all miata's 94-97 with manual transmission and non base model recieved the torsen, well I guess i was wrong. Didnt make the car not fun to drive though. So should i go with the rx7 diff guts?

Attachment 216943

Attachment 216944

yeah buy a rx7 lsd to throw in. it's what im doing. just make sure to buy the right one ;)

i have a few sources once i figure out mine i can throw our way.

cool, your awesome man. Im really in no rush right now and im installing it as an open diff for the early autocross season.

The Torsen is not very good anyways. You got exactly what you need - the 7" diff housing and gearing. Now go grab the LSD guts from an RX7 and you are good to go. I'd go with the 4.1 since you are only at 4psi... if you plan to up that a bunch the 3.9 may be better.
Great find though! Howd you get it for free??
-Ryan

Ya im not too pissed because i figured eventually i would have prefered to have the clutch LSD instead anyway. I am only 4psi now, but my megasquirt is sitting next to the monitor as i type along with 550cc injectors. So hopefully 15psi is not too far off, id go with the 3.9 ... actually i didnt even know that the gearing ratio was dependant on the guts of the diff, thought that the pinion gear and ring made that.

i'm sort of in the same boat... i'm in the process of turning a stock open 1.8 diff into something i will like. except mine wasn't free =( at least my stock diff hasn't blown up yet.

plus Torsens are running $600-800 for just the LSD. 86-88 RX7 Clutch-type LSDs are in the $150-250 range, and are superior for our applications (Torsen might do better at an autox, however).

just this morning my KAAZ saved my ass from gettin stuck on ice. half the alley was covered in ice. right wheel spins, left wheel grabs for traction and I drive to work. I might still be there pushin my shit without that.

interesting sidenote, the KAAZ stacked for 100% locking (all opposing plates) still allows quite a bit of differential action. If I had to guess the power was 66.66/33.33 in favor of the slipping wheel. still enough to move easily though.

Plus another ~$200 for rebuilt parts.

I feel the stock RX-7 LSD might have a little bit too much lock-up for such a light car. It's fun, though :)

You are correct. I mean that you can choose a different gearing if you want while the diff is out of the car. The RX7 diff will come with a 3.9 so if the open diff you have there is 4.10 you can choose to use one or the other when you swap the guts.

A stock clutch type RX7 diff will outperform the Torsen in an autox - I've tried both in different cars... most autocross cars use the Torsen because they are allowed update/backdate between miatas but they can't use stuff from the RX7.
Guys in SM2 with boost however much prefer the Clutch diff...
-Ryan

thanks ThePass, thanks for letting me know i have the choice to swap pinion gears as well because i did not know that. In that case, i would almost be tempted to run the 3.9 gear as Im planning on 15psi down the road ... hmm so many options.

i just broke off a bolt in my miata ring gear and now hope to use my rx7 ring gear instead it seems to be workable we'll see ill keep you updated on how it sets later today if you like.

dude that would be awesome to be able to confirm this. 80mph@ 3500rpm would be a dream come true once im putting down 220+rwhp

Well my guy gave me relay falckey directions to find him spent about 1 hr looking for his place and no luck so im gonna need to find someone else to do it. ill get back to ya.

From everything I've read it's the opposite. Since the way the clutch engages, responding to driveshaft torque, it is not perfered in low-speed autox corners. It's typically the reason there is such an availibilty of rx7 LSDS, since they all tend to upgrade to a miata/s2000 torsen. Road courses and Drag events on the otherhand....


http://members.aol.com/solomiata/RingandPinion.html

The RX7 "short" pinon, will work, but it needs to be a matched set to the ring-gear as the each have different teeth.

im not swapping pinions just the ring gear i believe it had 41 teeth so it should be all good. looks to me like the 3.6 3.9 miatas use the 11 tooth pinion from the rwd 626, and rx3 hmm maybe someone could put a 30 tooth in there and get a 3.6 ratio not bad

But your 1.8 miata pinon should have 10 teeth, correct? if you put your RX7 ring gear on there with 49 teeth you'll have a 4.9 end-ratio.

It really as easy as counting the teeth and dividing (ring / pinon = end ratio). Just double-check and make sure. I'm thinking of using the RX7 ring and pinon to achieve a 4.08 end ratio.

Interesting statement.
To be honest, most people who think they need a Torsen wont realize any real benefit over a 1.8 open diff...other then a psychological one. ;)

That is not to say there isnt any performance gain to be had from torsen in a specific circumstance, its just that MOST people rarely drive at a level where they will really benefit from one.

Actually looks like:
the 84-85 GSL is a 3.909.
the 84-85 GSL-SE is 4.08.
the 86-88 BASE ,SPORT, SE and GXL is 4.10 w/manual, 3.909 with auto.

All of my friends who have auto-x RX-7 either have, or want the miata LSD...and look at me like I'm crazy when I say I want an RX-7 clutch type.

On this note, I found a guy w/ a complete torsen w/ hubs on the axles locally!