Differential question

[techghost]

Hi all

I have a sc400 with 2jzgte and turbo tt differential on it along with supra rear brakes and I also have a 95 supra 6speed which was auto tt before. Now my question is that both car when lifted works differently, if I roll one wheel of sc400 the other one moves in opposite direction however in supra if I move one wheel on lift other one doesn't move at all.

 

So which one has LSD? I'm sure both have tt rear diffs but why both are diff? Supra vin says that diff is a01d. I need help to understand which one is better for 6speed

[Chris Wilson]

The one that has a wheel turning backwards is definitely an open diff. the stock LSD is a Torsen type and it's hard to tell from your test if a car has one fitted. An endoscope down the level plug hole would show it. Proper plate type LSD's would make both rear wheels turn in the same direction, off the floor, in neutral. In Park, or with the prope held still, a plate type would exhibit the need to really turn either wheel hard to turn one at all, as you'd need to break the torque holding of the plate preload. As The Torsen is pretty much a gimmick I wouldn't worry much either way

[techghost]

thanks.

 

but something which has really twisted my mind is that i came across original 6speed supra diff (with ears/cooling plates) and when u turn one wheel on it the other moves in OPPOSITE direction!!!! i had an impression that all 6speed supras are LSD from factory. So if their diff moves in other direction then is mine torsen or that diff torsen?

[David P]

These old Bessies have been tinkered with so much over the years, the only way to know for sure is to look inside.

[Chris Wilson]

A Torsen needs torque differential between the output shafts to start to lock (TORSEN means torque equalizing). As such it's all but impossible to tell if it's a Torsen short of taking it apart or having a means to provide input torque and measure output torque variations under individual output shaft load, which means a complex test rig. Just look inside to be sure. IMHO they are pretty useless LSD's and a plate type or cam and gear diff is much better for true performance applications. Even better is the GTR V-Spec rear LSD which has hydraulic control of plate clamping pressure, so with a relatively simple control circuit you can play with plate preload from a knob on the dash, or for the really adventurous, under ECU control as per the original application. For the best off the shelf JZA80 LSD look to the OS Giken plate type diffs with some nice additional trickery. these have made big inroads in International motorsport in the last few years, for good reason.