alik

iTrader: (3)

First one I swapped for a newer one. The replacement already had been stressed, and broke under normal conditions (at the notch).
The current one is simply going. There's a noticeable play between the driveshaft turning and rear shafts engaging.

Even though my mechanic says not to worry, I know this play didn't exist before, and RX7 clutch diff seems like a worthy investment of my time.

Savington

iTrader: (31)

If you want a car that pushes horribly on turn-in due to excess preload and then spins the inside tire on corner exit due to insufficient preload, the Rx7 diff is definitely what you want.

alik

iTrader: (3)

Andrew, I know your dislike of that diff.
I'm curios. Do you not like it because it's a clutch diff, or is it just because of that particular diff?

Braineack

iTrader: (62)

the rx7 diff is a perfect diff to recommend to someone on CR.net or roadsterdrift. nuff said.

alik

iTrader: (3)

Fair enough. Let's rephrase the question, then.
I'm not happy with my '96 Torsen. Very often it behaves just like an open diff. I'd love to be able to put the power down from both wheels coming out of the turn.
Is there another version of a rear end that's cheaper than Kaaz or Quaiffe or OS Giken?

Savington

iTrader: (31)

Nope. Change your car setup to take better advantage of the Torsen (more rear shock droop, more helper spring rate, more spring rate in general, more FSB), change your driving style, or pony up for a real diff.

It's that particular diff. I grenaded a Torsen while drag racing in 2007 or 2008 and I had similar inside rear wheelspin issues on autocross courses so I decided to try the Rx7 diff. My car at the time was a ~210whp GT2554R, ~2500lbs w/ driver, 700/450 KONI RACEs, RB tubular FSB, MSM RSB. At the time, Father Leadfoot was still autocrossing his black Ubercharged '94 and he had done a bunch of testing with coke can shims to preload the diff, so I went the same route and preloaded to ~90ft.lbs. The results were abysmal - the car refused to turn in like it did with the Torsen, and it spun the inside tire just as badly on exit unless the front wheels were pointed dead straight. I tried unhooking the RSB and the push got worse without having any effect on the IR wheelspin on exit. 90ft.lbs was too much preload for entry and too little preload for exit, which means there's no way to set one of those diffs up correctly.

QED, they are garbage and should be discarded for a Torsen as soon as possible.

I love the OS Giken I have now. It retains all the turn-in smoothness of the Torsen, but lets you jump back on the throttle so much earlier and harder than a Torsen ever would. It's one of the few mods that directly translates to lower lap times.

sixshooter

iTrader: (12)

Sav was pretty darn specific about the corner entry and exit issues. What part of his explanation do you not comprehend?

fooger03

iTrader: (2)

Did you drop the rear bar yet?

Savington

iTrader: (31)

He asked the question before I answered it, not after

Joe Perez

iTrader: (8)

Yay. Something I wrote six years ago on another forum which I no longer frequent has value.

Leafy

iTrader: (1)

Yes. Mainly fix that front sway bar, run the RB race bar. And run more spring rate if you can get away with it. My car does still exhibit some of the torsen idiosyncrasies but I have tuned some out (like the lift off torsen hop). It will not spin the inside rear exiting corners, unless its quite bumpy, and even then its just skipping, I actually still need to work on turning out the on throttle torsen push, that'll be solved by moving my roll couple rearward, adding more front downforce, or making more powah.

What my car doesnt have is the OS Giken surface dependency, the diff works more or less the same no matter what the wheels are on. If you're willing to have 3 or 4 completely setup and tuned Gikens in the trailer it is the better diff for auto-x. But otherwise the setup that works great at lincoln in the warm and dry will suck if you're running in the cold or the wet at lincoln and will suck at all asphalt sites. I guess you could just get away with having one and pulling it apart and changing the setup before you pack the car for an away event, or even change the tuning at lincoln once you have a better weather report, but you'd need to do it inside an enclosed trailer with the doors closed or in the hotel room to avoid getting the lincoln dust on everything. I think you run with the devens crew, devens is pretty lenient on OSG setup, but a good lincoln OSG setup is going to have too much lockup for Devens and will be pushy on throttle.

Failure

As I understand it, you can use the LSD from an S2000 in a Miata housing, but you'll need MSM axles. It's a clutch-preloaded Torsen and you can find them for fairly cheap because the S2k guys all swap in Ford 8.8s when they shred their R&P.