Oddjob

Because a lot of the synthetics have a lower friction coefficient, some do recommend and use friction modifiers to help with the synchros engaging on down shifts and the clutch discs to grap in the LSDs.

I have used Mobil 1 and Amsoil series 2000 trans fluids w/o modifiers.

I think Redline offers some modifiers that are recommended with their fluids.

Oddjob

This is a very repeated thread topic here on rennlist. LSD or no LSD?

LSD was a rather expensive and not a real common option, especially on N/As. Not that common even on 951s and S2s.

So unless you have the 220 option code, or if the car was previously owned by a track, auto-x, or gear nut who installed an LSD trans (which is a somewhat expensive upgrade, and the PO would often have receipts for it and use it as a selling point for the car) its probably reasonable to assume that the car probably does not have LSD, until you prove otherwise.

As mentioned above, its not uncommon for the other wheel to not move when one is spun by hand. Likely that there is enough friction from the wheel bearings and brake pads dragging, that it overcomes the internal friction in the diff, so the opposite side does not move. This can occur whether the diff is an open diff or an LSD. And does not indicate there is a problem with either. I would guess that if you pulled the wheels and pulled the pads out of the calipers, the opposite side hub would then start to turn.

Not an easy way to see the differential, w/o pulling off the diff side plate on the trans case. You dont need to look for a part number, the open diff and LSD cases look completely different. But definitely do not go to the trouble of doing this, as you should be able to figure out by other, easier means.

86 951 Driver

My car is a 944 Turbo it has an oil cooler. Now the guy who had it before me bought a used transmission to put in it that had the cooler on it.

So my test with one wheel on the ground and one wheel in the air i put it in gear and the wheel was locked(wanting to spin, but needed the other one to as well). But If I had both wheels in the air in gear they would spin opposite directions.

Yobtar

Where do you jack the car Up in the rear? I only have two jack stands.

fasteddie313

Ok, all cars have differential gears because the DOT says so. All cars rear wheels will move in opposing directions when forced..

So if you put the car in neutral USUALLY the path of least resistance for an open diff is to rotate the opposite wheel in reverse instead of spinning the drive shaft/pinion. If the other wheel doesn't spin at all and just the pinion turns it's still probably an open diff with dragging brakes or other wheel friction..

What an LSD does it make it harder for the wheels to spin separately from one another (backwards) so more power goes to both wheels especially around corners where the inside wheel gets a lot of weight taken off of it.

If you do have LSD, both rear wheels off the ground, in neutral, both wheels should rotate in the same direction as the one you're turning and the diff will spin the pinion shaft.
In gear (pinion locked) the rear wheels will still rotate in opposite directions but you will have to overcome the force of the LSD to do so, it should require some force..

With one rear wheel on the ground in neutral an open diff should be easy to turn the lifted wheel spinning the pinion, like you should be able to spin it and it have some momentum and not just stop.
With an LSD with 1 wheel on the ground in neutral you should still be able to turn the lifted wheel but again you will have to overcome the LSD in order to do so, and you are not going to be able to just spin that lifted wheel and it keep going, if you have an LSD in this case you'll know it because it'll be hard to turn..

My cars G31 LSD takes 75 ft/lbs of torque to break the LSD and make the wheels rotate opposite directions, with straight MT90, as tested by yours truly..
FSM spec is actually half that torque so I probably need a modifier, it chatters some on tight turns on pavement sometimes and you can hear the inside wheel skid on tight turns on dirt.

But I like it super stiff and it isn't causing any problems so I think I like it that way, if I come into full boost in 1st both rears let go and I bounce off the rev limiter anyway

Tiger03447

If you have the half-shaft undone at the trans, undo the allen bolt out of the center of the c-v receptical and undo the side plate to check the R&P. Drain the oil first, BTW. Check the pinion for wear, chipped teeth etc.. No telling what Le Junque yard trans shape was. Clean the magnet while you're in there. You might want to refit the seal around the R&P and the output shaft WYIT. If all looks OK with no major chips or crap on the magnet, and it was running fine prior to pull-down, then button it back up and run it. If there were shift problems prior to this, or your shifter was sloppy, the go to Only 944 and get their 20.00 shift assembly and check the linkage. You'll have to use a VERY short wrench for the install (or buy one of theirs) if the trans is still in the car. Hope this helps some.