Edward

PLEASE forgive the lame-o question but if the rear of the car is in the air and you spin one tire and the other one goes in the SAME direction, does this mean LSD ? No option-codes sticker to check so I'm in the dark as to how to know definitively. Thanks in advance!

Edward

kary993

Edward, I believe the other tire should turn on the opposite direction.

chris walrod

Edward, if your car in in nuetral, wheels off the ground, they should both spin the same direction if equipped with LSD (not the drug)

Now with 993's, just because they dont spin the same direction doesnt necessarily mean the car doesn't have LSD. The G-50 LSD does not have the best reputation for holding preload, in other words they wear out quickly

With LSD installed, the car in gear and both wheels off the ground, they should spin the opposite direction with some resistance..

Jack Ennuste

This happens with normal diff.
In LSD case, other wheel turns in the same direction, if gear in neutral.

kary993

I might be confusing something here; however, when I spun a GT3RS rear wheel the opposite side spun the other direction. I was told that that car had a motorsport limited slip. Maybe it didn't.......I also sem to recall a thread about this a few months back but could not find the thread....oh well.

Edit:

Finally found the thread, yes I was confusing the direction. Sorry about that!

chris walrod

Kary, speaking of diff's, did you ever get a new one installed in your car?

Edward

OK, help me out here guys. I feel lame about this since I've only owned and tracked the car for about 3 years so take it easy on me.

But I just noticed yesterday after swapping back to street brakes/tires, the rears spun in the SAME direction in neutral!! Imagine my excitement to think that I have an LSD ...even if it is shot! I know that open diffs will spin in opposite directions in neutral, but is there any reason that a 993 diff would spin both wheels in the same direction if it DIDN'T have LSD. How can I tell definitively? or do I really have it!! Again, no option codes sticker to go by. TIA, all.

Edward

Steve Weiner-Rennsport Systems

Edward:

All that means is that your LSD is in fine shape and not worn, yet.

chris walrod

Edward,
One way to confirm LSD or not, is to have a look at the bottom of the gearbox casting, near the drain plug. There is a transmission type number that is stamped onto one of the casting webs.

G50-20 01 is open diff
G50-20 02 is LSD

Hope this helps..

Edward

OK, now I'm really confused!!

I checked the number on the tranny (thanks, Chris!) and it is an "01" so this means open diff? BUT, the wheels still behave as I had described. I'd love to think that I have an LSD (and one that's still working would be gravy!), but have never heard of an open diff NOT spinning wheels in opposite directions.

Chris, you sure those numbers are right? Steve, any way that an open diff would do what I'm describing? I'm confused ...and hopeful
Thanks guys!

Edward

Mark in Baltimore

Edward,

Maybe you got lucky and the PO installed one. Or maybe you got really lucky and the PO installed a Guards LSD.

Whichever one it may be, it's adding entirely way too much weight at the worst spot of your car. Better give it me.

Steve Weiner-Rennsport Systems

Edward:

If indeed they rotate the same direction, you have either an LSD or the differential spider gears have a LOT of preload,...

Another (although more time consuming) way to determine what you have would be to unbolt the CV joints from the flanges on each side of the tranny and measure the breakaway torque, flange-to-flange.

Now,.....some folks test this by hammering the clutch at 4000 RPM and watching for 2 black streaks on the pavement, but you'll NEVER hear me recommend or endorse that,...

chris walrod

Thats funny! I have always enjoyed that method of determining what you have Of coarse, my muscle car days are shining through..

Another thought is your spider gears have pitted or worse starting to come apart This would cause resistance in the differential, preventing smooth action.

I dont want to alarm you, but drain your gbx oil and have a look at the oil. Stir a magnet around in the oil and see if you see any evidence of unwanted pieces.. Might save a more costly repair later...

Edward

Ohhhmyyygooodness. Thanks Steve, Thanks Chris ....so much for wishful thinking

I was planning to do my annual gearbox oilchange in a matter of weeks. So two questions:

-- What are spider gears (I am familiar with the general workings of a tranny & diff, but don't know what these are)

--If indeed my spider gears are malfunctioning/disintegrating, what is the best course of action (Translation: can this be put off for a while or do I have to fix this now lest my diff grenade on me).

Thanks ...bummed

Edward

kary993

Chris, I got delayed getting the car to the shop and Steve W and I seemt o missing paths......