915 Transmission --- LSD

[83_Silberpfeil]

I was reading the "Swepco vs Kendall" transmission oil thread got a bit tired after a few pages.

What kept my mind wondering was the LSD.

Which model years had LSD and which didn't? Or, was LSD an option?

I have an 83 SC (US/Calif). Does my car have LSD? If it was option, where do I look to see if I have it or not.

Thanks!

[GrantG]

LSD is an option (look for "220" on your white sticker in the trunk with the VIN, Paint Codes, etc. to see if your car has it).

[djcdmv]

Jack up the rear so both tires are up. Then spin one wheel and see if the other spins in the same or opposite direction. Same direction=LSD. Opposite direction=no LSD.

[Tyson Schmidt]

Originally Posted by djcdmv

Jack up the rear so both tires are up. Then spin one wheel and see if the other spins in the same or opposite direction. Same direction=LSD. Opposite direction=no LSD.

Just want to add that the trans should be in neutral for this test. If it is in gear, then the other wheel will turn in the opposite direction, but with a lot of drag from the LSD clutches.

[83_Silberpfeil]

Thanks for chiming in everyone! You guys ROCK!

I'll try GrantG's easy method first, then dj's. TS --- thanks for that extra clarification.

[Bill Verburg]

Originally Posted by 83_Silberpfeil

I was reading the "Swepco vs Kendall" transmission oil thread got a bit tired after a few pages.

What kept my mind wondering was the LSD.

Which model years had LSD and which didn't? Or, was LSD an option?

I have an 83 SC (US/Calif). Does my car have LSD? If it was option, where do I look to see if I have it or not.

Thanks!

Most likely you don't have an lsd, as noted they were optional

another way to check is to get under the car and look at the transmission type & serial number
this is a 915/63 w/o lsd


this is a 915/73 w/ lsd, the 12 stamped between the type and serial # indicates lsd

[larrym]

i understand the posts above, as pertain to an oem LSD - but what if a non-LSD (unmarked) trans was rebuilt - and especially if it got a Torson or viscous LSD instead of an oem unit

- i am aware that some Torson units do not behave as described above

[jibmaster1]

Car is a 85' Euro 911. OK, wanting to change my tranny fluid soon I found this thread to determine whether I had LSD or not. I jacked the rear up, in neutral (as suggested), and both wheels didn't spin at all. Well, duh I thought if the car is in 'neutral'! So, placed it in gear and noted the wheels spun opposite direction. I re-read this thread (and others) and it is ambiguous still whether I have LSD or not! Any ideas from anyone? I just want to order the correct fluid

[GrantG]

Spinning in opposite directions means no LSD (or not working LSD anyways).

[Porchcar guy]

Originally Posted by jibmaster1

Car is a 85' Euro 911. OK, wanting to change my tranny fluid soon I found this thread to determine whether I had LSD or not. I jacked the rear up, in neutral (as suggested), and both wheels didn't spin at all. Well, duh I thought if the car is in 'neutral'! So, placed it in gear and noted the wheels spun opposite direction. I re-read this thread (and others) and it is ambiguous still whether I have LSD or not! Any ideas from anyone? I just want to order the correct fluid

Did you have the E brake off ?

[agfours]

Plug in your VIN into this decoder - i was going through the same question - this answered it for me.

Porsche VIN Decoder, VIN Lookup, Decode VIN

[83-911SC cab]

Originally Posted by jibmaster1

Car is a 85' Euro 911. OK, wanting to change my tranny fluid soon I found this thread to determine whether I had LSD or not. I jacked the rear up, in neutral (as suggested), and both wheels didn't spin at all. Well, duh I thought if the car is in 'neutral'! So, placed it in gear and noted the wheels spun opposite direction. I re-read this thread (and others) and it is ambiguous still whether I have LSD or not! Any ideas from anyone? I just want to order the correct fluid

you were spinning by hand??

[Peter Zimmermann]

Engine off, handbrake off, trans in neutral, and rear wheels off the ground;

1. Turn RR wheel, if LR turns the same direction you have LSD. If the LR turns the opposite direction you do not have LSD.

[jibmaster1]

Originally Posted by Peter Zimmermann

Engine off, handbrake off, trans in neutral, and rear wheels off the ground;

1. Turn RR wheel, if LR turns the same direction you have LSD. If the LR turns the opposite direction you do not have LSD.

That's what is stumping me here. BTW, yes I had the engine off, e-brake off, jacked up rear and when I spun the wheel by hand the other wheel didn't move at all. However, when I spun the wheel while I placed the car in 1st gear (off the ground) when I spun one wheel the other spun in the opposite direction!

[Jon B]

Originally Posted by jibmaster1

That's what is stumping me here. BTW, yes I had the engine off, e-brake off, jacked up rear and when I spun the wheel by hand the other wheel didn't move at all. However, when I spun the wheel while I placed the car in 1st gear (off the ground) when I spun one wheel the other spun in the opposite direction!

With your axles in "full droop", a CV may be binding on the othe side. In neutral, an open diff might then only turn the pinion, having less resistance, and not the other axle. In neutral, an LSD would turn both, same direction, and overcome the CV resistance if less than the LSD preload (most likely).

With an open differential and transmission in gear, turning one rear wheel would turn the other in the opposite direction, without much effort. With an LSD, the effort would be much greater, as you'll either turn the engine or overcome the LSD preload, whichever takes less force. If engine, both wheels in same direction; if LSD preload, wheels in opposite directions, but with far more effort than an open diff.

It sounds like you have a standard, open differential.