Turn where one of the axles bolts up while holding the other one. If it lets you, it's open.

 

If it is the factory torsen there is no way to tell externally. The Torsen diff requires it to be loaded to function. The method described by DNM works if it is a clutch style differential.

 

Hmm, I just bought a factory lsd diff, I mean at least the seller said so. And i went online to see how to make sure if it s a lsd or not, most people said the same as DNM. I am freaking out now, trying to see if i was scammed or not.
Are you sure about that? Cuz i hold one side of the axle bolt and turn the other side, it let me. I have no idea...

 

just open it carefully and look. The factory torsen will let you spin one side unless its under actual load. You have to pull the cover off and look.

 

Just open it up... re seal it correctly and new fluid. This way you not only know what you have but you know when the seal was done and when the fluid was replaced.

 

http://www.clublexus.com/forums/per...orums/performance-and-maintenance/203834-lsd-help-how-to-tell-if-its-a-lsd.html

this shows the internal differences between the open and LSD.

 

I have a torsen LSD in my car and I was easily able to test it without any load.

I turned the input shaft and tried to hold a tire in place. It insisted on turning the tire I was trying to hold.

 

I've never once seen that kind of behavior from a factory Torsen LSD. Their behavior on a lift is indiscernible from an open diff. The only way to know for sure is to pop open the back cover and look.

I ve seen people said the lsd has cooling fins while the non lsd diff does not, is that true? Mine has fins all over any way.
And defi, if i am able to open the case i probably can be able to tell if it s lsd or not, but i am not able to open at the moment....

Nope. Every Supra's pumpkin has fins along the bottom side of the housing itself, while Lexus/Aristo pumpkins are smooth regardless of LSD or not. All pumpkins have a finned differential cover plate, too.

However, the 'big' diffs found on TT 6-spd models have a cooling fin array that sticks out from either side of the diff cover. If you have one of THOSE diffs, with the large array of cooling fins sticking out on either side of the diff cover, it's a 99.9% bet that it's a factory Torsen LSD as the big-diff 6-spd cars never came with an open diff.
I only say 99.9% chance because a few European and GCC cars of different configurations also came with the big diff, and they might have been available without the Torsen.

Torsen=torque sensing.... are you able to apply 200 pounds of torque by hand?

I bet I could have when I was 17 - but once I started getting laid I fell out of practice. :wackit: :run:

 

I ve seen people said the lsd has cooling fins while the non lsd diff does not, is that true? Mine has fins all over any way.
And defi, if i am able to open the case i probably can be able to tell if it s lsd or not, but i am not able to open at the moment....

 

I was able to keep the tire still on my LSD but I have verified on the track and by opening mine up that it is a torsen LSD.

 

Torsen=torque sensing.... are you able to apply 200 pounds of torque by hand?

 

You have to be "creative."

Need to hold one of the axle outputs snug, provide some resistance on the other, and spin the prop input at the same time. If it applies a crap ton of torque to the side you're holding snug (and tries to rip your hand off in the process), it has the Torsen in. If it doesn't feel any harder to hold the one axle fixed while applying more input, than it's open.

It's difficult to understand if you just have the one in front of you. If you have an open and a Torsen to test side by side, it becomes very apparent.

Or the best method? Put it in the car and give it a clutch kick in a corner.

 

I always checked by turning the input shaft of the diff and if both axle output turn in the same direction it has LSD and if one axle turns one way and the other turns the opposite way then its open diff.

 

if you turn the input shaft on the diff and one tire goes forward when the other turns backwards i think you have bigger problems than finding out if its an open or LSD.......

 

I know this is an old thread but another way to check it is to pop out one of the axle hubs and look inside if you see the spider gear pin then it is open. if it is a closed end then is more than likely is a lsd. not sure how to id if TRD or Plain LSD though.