In for updates.

There doesn't seem to be shit in the NorthEast concerning reasonabley priced Torsens.

No yards have them and every add is directed towards the spec crowd:

"freshly rebuilt [pulled from a yard car with 140k] Torsen - $1400"

-Zach

1995
Carrier
Mazda Miata MX5 NO ALUM. COVER, GEARS ONLY $250 Best Foreign Auto Salvage USA-PA(Aliquippa) E-mail 1-800-370-6002

1996
Carrier
Mazda Miata MX5GOOD LOCKERA4879$550Beasley Foreign Parts, Inc. USA-MI(Holly) E-mail 1-248-634-8681

So far so good after one track day, it survived a full days abuse, no odd noises and operates smooth. It wasn't my car, but I did get to drive it for a few laps, and my opinion is it's very similar to the oem unit, the track was a new configuration and i didn't have my miata with to actually do a back to back comparison.

Bottom line is, it works as an lsd, and it didn't fail in any manner.

That one in Aliquippa is about 3 miles from my house.

That is good news but what are the specs on the car that was running the diff? Stock?

The 4.3 7" open diff sitting in my garage is getting tempting to mess with now.

Bust-the one in Aliquippa turned out to be an open.

(zack morris's phone)

So what's the torque ratio of these obx diffs? Type I or ii?

I've read elsewhere that the ratio is about 2.1:1, but it depends on which quaife this is a copy of. Quaife isin't very forthcoming with this info for whatever reason.

Here are a few neat reads on the obx diffs:

http://rbryant.freeshell.org/obx_washers.htm

http://forums.clubrsx.com/showthread.php?t=520556

I just read this one...

http://forums.hybridz.org/index.php/.../page__st__180

Lots of really good info in there.

Also this one. I'll be doing this to my casing as well...

http://forums.clubrsx.com/showthread.php?t=520556

In the first link they discover that a lot of the times the gears are installed the wrong way forcing the gears to the middle under accel instead of the outer side of the casing. This causes huge force to be put on the washers.

So the 3 (or 4 if you're ---- like me) things to do.

1)replace washers
2)replace bolts
3)ensure the gears are installed the correct way
4)optional... clean all the burrs and glass bead the casing. I may even cryo the gears.

I ordered all the stuff i need including the diff.



http://batou1.googlepages.com/obx_gears.JPG

are there two sets of gears or do you have to recut the helicies?

No you just flip them over to make a right hand helical a left hand helical.

Same way you can make a right hand tap a left hand tap by tapping a part from the bottom.

OK after reading through that new stuff, I just tore open the obx diff again. I flipped the gears by taking the ones from the bottom and putting them on top. I'm going to trust that internet forum in that these units sometimes are assembled backwards.

Very funny haha. Even funnier that I just tried to figure out how to flip the gear in my head.

There are two sets of gears in there that make up the torsen, basically one for each axle and some units come with them in the wrong orientation. The rsxforum thread that falcon posted is great

Yeah no problem. Seems there are a bunch of guys running this in the Nissan R200 diff with 350ft'lbs and doing track days with no issues. And Honda guys with 600whp drag launching on them.

As much as it pains me to run an OBX product... the forums back it up as a decent budget diff if the few things I listed are corrected.

Dustin, were yours backwards?

The best way to really check it is to orient the diff as though it is sitting in the housing and mentally "turn" the input shafts. If you turn it that way, do the gears move outwards? OR inwards? You want outwards. And approx .090 of compression on the washers. That, along with 12.9 bolts should give you a fairly clunk free and good diff.

Ah, so there is two sets of gears, one left hand helix, one right, and the left hand little gears and right hand middle gear is supposed to be on top when looking at it with the above orientation?

Is there a way to put preload on these so it does not go open when you lift a tire?

I believe that's the point of stacking the washers in such a way to increase the height when stacked. they have to compress down when installed, and that provides some preload.

So the washer tension determines preload, and possibly lock ratio?

The washers only offer a small amount of preload just enough to keep the guts from rattling around.
There is a Torsen called a Type 2 R that uses clutch packs to provide enough preload to prevent the diff from turning into an open on wheel lift.

The T2R is used in the s2000 and based on indirect evidence I'm willing to bet the MSM Miata has one as well.

My car's been in the shop since 9 this morning. I rode my motorbike by on my way to work around 12:30 and it was parked in the same spot but the hood was open. Obviously ogling my turbo and not working on car :p Hopefully I can get it back tomorrow, and hopefully it doesn't grenade on me.

I'm doing this all for MT btw. :p

I will have results in a few weeks too. I am going to be running mine at a hill climb pretty much right out of the box. With hopefully 300whp +-.

Washers control noise, not preload.

Bad news so far. The surface that the ring mounts on was not flat, and was out 10,000. They are sending it to a machine shop right now to get it made true. It was causing the ring to rotate out of the pinion.

Oh oh

This is not good news, you mean .010", when you say 10'000 right?

Yes. This thing better work well once it gets machined.

Good thing that was checked, otherwise you would have been finding out it wasn't correct the hard way.

How did they find this out? Just by chance or is it something they check?

They put it in with bearings any everything, and were checking the rotation and noticed the pinion kept coming off the ring. They tried a few things and then checked the measurements of the diff and found out it was out of whack.

Can you circle or show the part that was actually not flat? I'm having a hard time figuring out which piece needs to be perfectly flat.

It's the big flat ring around the diff housing that the ring gear sits on.

It's fairly simple to detect, when you're setting the back lash between the pinion and ring gear, if the ring gear is not running true, it'll be loose on one side and tight on the other. What's OEM spec? Couple .001"? .010" isn't a lot, but definitely towards the high side of gear mesh tolerance, and I'm only used to straight or helical gears, not ring/pinion.

Backlash is supposed to be within plus or minus .002 IIRC, so the .010 out means it would never be within spec.

Success! Shop just called to say that it's installed and working great. I will pick it up around noon.

Sweet, are they going to give you a spec sheet with the install info/measurements?

This sounds interesting. Not a replacement for the Type II in the MSM, but it would be a damn nice budget 3.6/LSD in an open diff for about the price of a stock 4:10/3.9 lsd.

BTW, someone mentioned they think the MSM is a torsen type II, which it is. The S2k actually uses the Mazda 7" ring gear and the mazda uses the S2k diff. A guy with an MSM replaced his diff with an OSgiken, found this out.

Isnt the Type I better for accel locking, and Type II for decel?


but the Type II is quiter and smoother in operation?

I could have sworn the msm diff is a torque sensing unit made by bosch that is something like a hybrid type two (that is also sprung). Is that not correct? If not is there a link for msm diff knowledge?

nothing special about the MSM torsen, same as S2K. there was some POS Fuji Super LSD in whatever '03 miata...

OK i have the car back, and it actually drives!!!! The machine shop measured how far it was out, and it was out .007, not .010, but enough to cause massive problems. They said it appeared that it just missed that part in manufacturing or something. Anyways the differential is super quiet and very smooth, I've done a couple of boosted pulls from 3rd and 4th, but no launches yet. But so far it's doing great.

And it turns out my old differential was in fact an open diff. It's just an open piece of crud with the spider gears. So this should allow me to have way more traction in drag racing, and I'm expecting some good things. It cost me $100 worth of machine labor to make it perfect, so if you want to go this route, consider that cost.

On my way home tonight I'll do a launch and see what happens.

technically an open diff gives 50/50 torque to the rear wheels when driving straight.

the torsen operates pretty much the same in that condition.

Right up untill one tire breaks grip and you do a one wheeled burn-out for 100 feet...

true, but on a torsen, if the one wheel starts to spin it has zero traction and cannot transfer torque to the other...one wheeled burned out?

Open diffs supply torque to the wheel with the least traction

Torsen diffs transfer torque over to the wheel with the most traction. It's impossible to transfer torque that's not there (tire off the ground).

I guess in the least you'll have 50% traction as opposed to zero?

Theoretically what you're saying is right. But these diffs have been a pretty hot thing with the big HP (500-600whp) Honda guys for a few years for drag racing and they all seem to love them.

I will be using mine on the track, where helical/torsens are best suited.

clutch diffs are best for drag, but I'd rather have one wheel with some power, than 1 with zero (no drive) and the other with too much that just spins.

If i'm not mistaken, yes. The type II also has nice cornering benefits, but at the limits it apparently has issues with the inner tire slipping too much, which is why the one guy switched to the OSgiken.

As far as I know, its not a hybrid of one type or the other, its pretty standard stuff....

TI = hexicoil gears
TII = plane gears

Well at the end of the day, the diff is $260, washers and 12.9 bolts cost $35 and install varies depending on your know how. So for some it will be a good upgrade from an open diff for under $300. I'd love to buy a osg but the bank account does not agree.

Holy fuck, the OBX diff is definitely working. I was turning right down a road and slowed down to low first. I turned the wheels and decided to give it some gas. Couldn't believe how sideways the car got... Then a little farther up the street I came to a stop and turned launch control on. Just as a refresher my car holds at 4500rpm with launch control on and makes 5psi of boost. Sweet monkey jesus I've never laid rubber down like that. There was a party going on in the rear end.

If you have an open diff, buy this. Do it now.

Fuck you and your convincing review. My credit card is trying to bounce out of my wallet.

Dooo eeeet.

By the way, I've updated the very first post of this thread with the useful information.

What did it cost for installation?

It was 4 hours of labour at a transmission shop. With that, the machining, and taxes, it came up to $600.

So did you do the polishing/deburring of the case or no? I'd be so interested in buying a few of these and polishing/glass beading and doing the washer mods and reselling them to interested parties. Pretty easy for me to do and I can charge less than a machine shop /etc for labor.

I'm more interested in hearing about your car after 5k miles. Also, what diff fluid are you using?

I did not do the polishing/deburring because I did not think it was necessary. I used Royal Purple Max Gear 75w90 gear oil.

Cool and cool. It seems it was a discretionary thing, if you saw a lot of burrs/imperfection fix it is what i read. Sounds good, hope the long term test goes swingingly.

I'll buy one.

Got one sitting on the floor right next to the computer. Guess I'll have to get off my lazy ass and get it torn down.

Somehow I 100% believe you. maybe i will seriously do this starting next week... :idea:

nothin better to do.