For those of you who think that a viscous lsd will always be good are smoking crack. You can't "break" the fluid but it sue as heel will break down. If the lsd fluid has ever been overheated (by hard use) or is old (as is the case in almost every rx-7 out there, then it will act alot like an open diff. The chemical molecules in the diff are very complex and break down over time and with heat. I doubt that any of the stock fluid lsd's are still very good at all. The miata guys figure that if the cars more that about 5 years old or so, or if it's been used hard often that their viscous lsd's are esentially open lsd's.

If you don't beleive me read this.
http://www.sportcompactcarweb.com/pr...8scc_proj350z/

MM torsen LSD..... But can i adjust the black lash by removing the rear diff cover instand of removing the whole thing? It takes me a long time to get the sub frame back in place. Thanks!

intresting so should i not get a lsd off an rx7 for my vert and just try to finde a miata lsd

If you road race or autox I would recomend the miata Torsion Unit. If you mostly just straight line from a spot sign rebuild an N/A clutch type and drop that in there.

As far as adjusting the backlash:

I have built 3rd member style diffs a couple of times though not an RX-7 one.

RX-7s have 3rd member style diffs.

The proper way to install a new gear set or used carrier from a different car into your RX-7 should include the following if you want to avoid problems and premature failures.

1. Replace all the bearings including pinion bearings and carrier bearings. To do this you must remove the pinion which reqires point 2....

2. Use the proper shims from an install kit to set the pinion depth correctly (THIS IS VERY IMPORTANT).

3. Use the proper tools to set the backlash to spec. Installing a carrier into a third member housing without doing this is asking for a loud rear end and premature failure especially with a torsion unit.

None of this is terribly difficult but reqires some proper tools, and some knowledge of how to do it. With good mechanical apptitute a home mechanic with a vise should be able to do this. I personly think it is futile to try to do this with the unit still in the car as you would have to remove the center section of the rear axle from the car and disconnect the driveshaft. 1 more bolt and its out anyway.

I will be rebuilding my N/A unit with a miata torsion this winter...

That is a great write up man. I think I'll start looking for a miata lsd rear end now...sweet

hello,
can anyone tell me the number of splines on the shafts that go into a FC non turbo diff head please

thanks

Would the miata Torsen be more desirable than a TII stock diff?

I installed my Miata Torsen a couple months ago and am very happy with it. I've got a couple additions:

The S5 non-LSD axles are equal in length and work.

To not have to reset backlash, mark the locations of the adjuster nuts and put them back that way, be sure to check it though, as they could be out a full turn or more. I didn't have to change anything on mine and the backlash was good, no noise then and still none, so it must be good.

That is not necessarilly true. If you are installing a different carrier, even if you swap over the bearings the backlash will change, as will the pinion depth.

If you keep the pinion bearings. You might get lucky and be fairly close on pinion depth but both are related to a certain extent.

It is best to check and adjust both.

And, honestly, i dont know why anyone would put a diff back togeather that is 15+ years old without new bearings.

ALL bearings have a finite life. Regardless of how you take care of them or what they are made of.

...the bearing on this one is different from the one I'm looking at...which does the rx7 take?
http://cgi.ebay.com/ebaymotors/ws/eB...MEWA:IT&ih=009

other than that, will this fit?

I used the bearings that came on the Miata Torsen, and by a close visual inspection they looked great.

The pinion and the carrier are all bolted to the same piece, so unless the bearings a different diameter or you install it out of position laterally the backlash and depth should remain the same.

I checked my backlash and checked the gear contact and both were perfectly acceptable.

right...but...the one on ebay i'm looking at has a standard bearing on each end, and the one in this write up has one standard bearing and one slanted bearing.

oops, i'm an idiot, it's just the race that's on there. ok i'm gonna take it, hope it works out.

I know this thread dates back a ways but I've got other questions. I have an '89 gtus lsd w/ the 4.30 and I want to run the 4.85 ring and pinion that is available for the 1st gen and the '94 Miata. (difference is pinion gear length) 4.11 and 4.30 are the only availble ratios for the s5 lsd. I run 3rd gear at the track and I need more rpms.

Is it possible to swap the '94-'97 Miata diff. into my s5 rx7? Sounds like mounts are the same just use the rx7 bushings but what about axles and drive shaft? The drive line shouldn't be a big deal but the half shafts seem to be the unknown for me.

Any info or direction would really be helpful here.

if you need more rpm wouldn't you want the 4.10 ring gear?

I suppose it'd be entirely possible to use the Miata 7" housing from a 94+ 1.8l car, but you will need to custom fabricate some sort of solution for the front diff mount and you'll need a longer drive shaft. All in all, if you're not class limited to running the stock diff case, that's probably the better way to do it, as you're not cutting and welding the pinion shaft. It might just be cheaper too.

Pistones - A numerically higher final drive ratio raises rpm. Less top speed but I'm looking to get the rpms up.

Black91n/a - You suppose the half shafts will work?

Use RX-7 stubs and halfshafts and it'll work out just fine. Since you'd be needing to change the bushings anyway, I reccomend the Mazda Comp ones, I've got them and I like them. It'll be a good idea to open up the diff (won't mess with backlash or anything) to inspect everything if you're buying a Miata diff with those gears in it already (beware, that's not a stock Miata gear ratio you're talking about).

can you reupload the pictures

Some thoughts on this. I'd probably do something like a Y shaped mount that goes back and ties into the rear diff mounts so that at any point on the mount it's only having to deal with vertical forces, and not any twisting forces that'd be there if you just made a simple extension for the front of the diff to bolt to the front diff mount. I'd tie it into the stock front diff mount location and use the stock front mount (or the Comp version) as a start, since that'll give you vibration isolation and it'll be easier than doing something else. If you're wanting to do this you've probably got an NA anyway, so the strength of the stock mount isn't so much of an issue anyway.

Thanks for all the input. I'm searching for the Miata diff. at this point and since I only have a couple of races left this season I'm not in a hurry but I'm going to do this forsure. (or atleast try) Just going to wait and find a good deal on one. The Torsen diffs on ebay are like $800 or $900, I'm just going to be patient.

Try the Miata.net classifieds, that's where I got mine for much less than that. I was looking there not long ago and I recall seeing a type I torsen for around $400.

what model miatas have the torsen lsd? any '94 and up?

It's really a crap shoot, any 1.8 could have a torsen, but there's also open diffs. The ONLY way to know for sure is to call Mazda with the VIN, they can tell you, or just buy one already taken out and identified.

I am looking to do the swap, and I found there was two models: type 1 (perpendicular gears) and type 2 (gears parallel to half shafts) helical lsd for +94 Miata. Also jdm trader told me:

"No.no no.not fit both T1 and T2.T2 is bigger than T1.so I cant use T1 gear on the T2 torsen.I have T1 gear.but I cant use this T1 gear on the T2 torsen."

Then, which of them will fit my rx7 s4 na with 4.30 ratio??

Cheers