Lsd

[JJR512]

On the night I was adjusting my parking brake, I had the rear end jacked up and noticed that when I moved one wheel, the wheel on the other side spun in the same direction. I didn't think anything of it at the time.

Tonight I was doing some other 944-related research and came across a comment that if you spin one wheel on a jacked-up car and the other side spins the same way, that means the car has an LSD.

Intrigued, I did some more searching on that, and found a bunch of sources that back that up.

But my car does not have the option code for LSD. On the other hand, it has the option code for 16" Fuchs, which were replaced by cheaper 15" phone dials. So I have a hard time believing that someone swapped an LSD into this car. But who knows.

Anyway, I just wanted to check with the experts here...specifically for the 944...is what I described, spinning one wheel on a jacked-up car (in neutral) making the other side wheel spin the same way, indeed a positive sign of LSD? Could it mean anything else? Is there any other way to definitively confirm or refute the presence of LSD on this car, short of removing and opening the transmission? If I can do it without too much disassembly, I'd consider it.

[944tothefloor]

I've never tried it myself except on a remote controlled car but my understanding is that the other wheel turns the opposite way.

[JJR512]

Originally Posted by 944tothefloor

I've never tried it myself except on a remote controlled car but my understanding is that the other wheel turns the opposite way.

What I'm being told on rennlist is that the other wheel will turn the same way in neutral, or the opposite way in gear. If your remote control car is anything like the ones I've experienced, it probably doesn't have an actual neutral, it's always essentially "in gear" so that would make sense that it turns the opposite way. (I think.)

[944tothefloor]

Originally Posted by JJR512

What I'm being told on rennlist is that the other wheel will turn the same way in neutral, or the opposite way in gear. If your remote control car is anything like the ones I've experienced, it probably doesn't have an actual neutral, it's always essentially "in gear" so that would make sense that it turns the opposite way. (I think.)

Ok, good point.

I looked into it a bit. Seems to me you must do the test is neutral and if the wheels spin the same way it is lsd.

[Lapkritis]

Open diff will spin the opposite direction for an in-air test. A welded diff or spool will also turn the same way as a LSD.

[plyhammer]

Has to be in gear. If in gear and they go the same directions it points towards LSD.

[Techno Duck]

Check the transmission code on the top of the trans bell housing for a more fool proof way of knowing.

[JJR512]

Tonight I wanted to double-check what I saw the other night, and try some other tests I've read about elsewhere.

I jacked up the rear end again. With the gearbox in neutral, if I spun one wheel forward, the other wheel also spun forward. When I had a friend hold the other wheel still, I could not spin mine; I could budge it a bit, but I could tell something was holding it back. At the same time, my friend said he could tell it was trying to move forward.

With the gearbox in 1st gear, I again spun the wheel forwards, and this time the other wheel spun backwards. When I had a friend hold the other wheel, it was just as before, except this time he said he could tell it was trying to move backwards.

From what I've read here and elsewhere, all of this seems to be very much in favor of this car having a LSD.

I wanted to get the transmission code off the top of the housing, to see if just the differential was swapped, or the whole transaxle. Unfortunately, I was not able to find it, but I wasn't really well-equipped to find it, either. I didn't have an inspection mirror, so first I tried my iPhone in "selfie" mode, then I tried a lady's compact mirror. Couldn't find it. I had a rag that I tried to brush dirt off with, but couldn't really get a good angle. Plus, I didn't really know exactly where it was supposed to be. So I wasn't able to get the code, but not a big deal for now.

[JJR512]

Is the stock LSD that's in an NA transmission the same as the stock LSD in a turbo transmission?

[Rasta Monsta]

Originally Posted by JJR512

Is the stock LSD that's in an NA transmission the same as the stock LSD in a turbo transmission?

No, 951 ratios are different, and internals go through different hardening processes dependent on model of 951 gearbox.

Or do you mean just the diff assembly?

[JJR512]

Originally Posted by Rasta Monsta

No, 951 ratios are different, and internals go through different hardening processes dependent on model of 951 gearbox.

Or do you mean just the diff assembly?

I'm not absolutely sure what I mean, but I think I mean just the diff assembly.

Let me put it like this: Suppose you have a turbo transmission without LSD, and suppose you also have an NA transmission that does have LSD. Now suppose you take whatever LSD-specific parts out of the NA transmission, and you want to swap those parts into the turbo transmission, to give it LSD. Is that viable? Are the LSD-specific parts the same between NA and turbo?

[944 Ecology]

Originally Posted by JJR512

I'm not absolutely sure what I mean, but I think I mean just the diff assembly.

Let me put it like this: Suppose you have a turbo transmission without LSD, and suppose you also have an NA transmission that does have LSD. Now suppose you take whatever LSD-specific parts out of the NA transmission, and you want to swap those parts into the turbo transmission, to give it LSD. Is that viable? Are the LSD-specific parts the same between NA and turbo?

Yes, the LSD pumpkin (technical term) is the same between the NA and the turbo transaxles. Unfortunately, you're not going to easily just pop it from one to the other without reshimming some of the bearings in the transaxle, or you risk damage to the transaxle. Best left to a professional with experience and the proper tools.