STAR57

Please translate into newbie Porsche lingo LSD=Love SEx & Drugs or Low Slip Diferential !? maybe

1999Porsche911

Limited Slip Differential.

TheOtherEric

Thanks for the explanation Chris. It sounds like the measure of torque that is of interest would be the torque applied from the engine that locks up the differential. If that's the case, then it sounds like it would be difficult or impossible to take that measurement without removing the LSD. I hope I'm wrong. Did you get a chance to check out the manual?

STLPCA

These links may help:
Differential (mechanics) - general discussion
How Differentials Work (incl. LSD)-More Detailed

chris walrod

Just looked it up. Break away torque should be anywhere from 3.5-11.0 ft/lbs across the diff.

In other words, with the driveshafts disconnected, you hold one side stationary, and with a torque wrench, set to a starting point of 11.0 ft/lbs., and attempt to brake free the diff, overcoming its preload. Of coarse, this isnt REALLY accurate as seal and bearing drag comes into play. Then, slowly work down the torque setting until the torque wrench 'gives' while overcoming this preload.

The manual calls for the diff to be reoved and tested by itself. I assume this is because of the seal and bearing drag when in situ. Also, with the diff out, its much easier to adjust preload

Edward

Just to chime in that the "in the air and turn one wheel" check is unreliable. My 993 is an open diff, and the rears spin in the same direction when in neutral (the tranny is definintely not an LSD). But I thought, "what if I put it in 6th..." Sure enough, I spun one wheel and the other moved in the other direction. My recollection is that the torque on the flange method is the most reliable with the trans still inthe car.

Edward

orcfromthesouth

Find a secluded and ample parking lot. Avoid tarmac surfaces and look for one with concrete surface, ideally the shiny one preferred by Hipermarkets and Malls. Get car in first, start moving slowly and as you turn about 30 degrees, accelerate gradually until you feel the rear spinning. Stop and check the tire marks. You should see both if the LSD is working. Make a note of how soon the wheels break contact, as it will give you a way to check for wear later.

Orc

TheOtherEric

Chris,
Thanks a ton for finding it. Can you point me to a section and page number? I want to make sure I understand it.