what is the difference with the na and turbo diff. is it just cause the miata torsen cant handle the turbo motors extra power?

No, they are different sizes. If I remember correctly the N/A uses a 7" ring and the Turbo uses an 8".

ok this just confused me..

its just a ring gear swap, correct?

Yes, and no

Its a diff swap keeping the existing FC ring and pinion.

If you changed the ring, (effectively changing the gearing) then you would have to re-space the pinion.

Yes, this is true. And I think that setting the pinion depth for a new ring and pinion set is something that is beyond most people's abilities (mine anyway). There are many special tools needed, and you really need to understand what you are doing.

well the only tools really needed are a dail indicator to check backlash and some anerobic paint to check pinion depth.

here is the FD/FC turbo Torsen diff:
http://www.valley.ne.jp/~sirogane/2961d.jpg

What year of Miata did you use?

94+ 1.8 Miatas use the torsen LSD. But not all of them, you just need to get lucky I guess ;) Seriously though, I have no idea on how to tell if the miata will have the LSD or not. One method Ive heard is that if it is a 5-speed and has cruise control, it will have LSD. Im not sure how true it is, but every one Ive seen with cruise has had LSD.

Just a small update for anyone interested. I was having problems with my diff at 1st. One thing, is that on S5 LSDs, the rear end uses un-equal length axle stubs. When using these on a torsen, or clutch unit, the longer stub will cross over and cause the LSD unit to be "fused" together, making it impossable for both wheels to spin at anything other than the same speed. I got a set of S4 axles stubs and it corrected that problem. Another thing, the backlash will need adjusted properly to spec. My gears were whirring when I put the rear end back in, so I needed to drop it again and adjust the backlash. It is a faily simple procedure, although you will need a few special tools (dial indicator and something to turn the things on the side of the bearings. Mazda calls for a differential wrench, but anything you can turn them with will be fine) The procedure to set backlash is explained in chapter 9 of the FSM, pages 9.43-9.45. Hope this helps..

I thought this was an n/a housing-you were using tII axle shafts? Will the shafts from an n/a housing work? Or do you need the tII shafts? :scratch:

I never said anything about a Turbo2 housing. I was using a S5 N/A housing, but with the viscous LSD the axle shafts are unequal lengths... T2 and N/A rear end pieces are not compatable.

Archive material. Great job!


PS you let that viscous LSD go for only $99?

OK, Guys i read this whole thing and just ended up getting lost in the process!! OK, can i do this on My 91 Vert. Its n/a. Also will that make my non LSD into an LSD?? And in simple tems for us non mechanical guys explain it to me.
Example: "u take the roung thing and put it in the other round thing" thanks hehe

Yeah, I meant doing it on a non-lsd n/a housing...

umm clutch lsd's are much stronger than torsens!!!!

This is true, but considering the GTUs unit originally had a viscous, and the rear end is going in a car that will never see over 250rwhp, its not much of a problem. If I was building a higher HP car, clutch type would be a much better option...

i could break a torsen in a T2.... never broke a VLSD though

You can't break a VLSD unless you open it up or are in a accident that distroys the rear end.

Yes, but you can't really break a VLSD, being that there are really no parts in it. It just uses the resistance of the fluid to bring the wheels to the same speed. You cant break fluid ;)

i bet i could twist the diff if i tried :)

Rxmfn7. Did you adjust the backlash with the diff case out or did you adjust the backlash by removing the rear half of the case? I need to adjust me rear end and i really hate taking the whole thing out. Thanks!

I'm posting here just so I can search and find this awesome thread easier. :D

sounds great. i should start finding a miata's torsen when mine goes out.

I just went through the FD torsen install into my TII diff.

https://www.rx7club.com/vbgarage.php...ype=im&id=1452