Whats up with my VLSD?

[orange-grey]

I just bought a used s13 VLSD from Phase 2 and installed it Saturday. It has a VLSD sticker, but doesn't seem to behave like one at all. When the back of the car is jacked up and you turn one wheel by hand there is no delay before the other side starts turning, almost like the spider gears are welded. I'm pretty sure a VLSD takes a second for the other side to start spinning. Turning in parking lots is sorta difficult, but the tires dont squeal until you give it a little gas. Since the tires don't squeal when just coasting, I don't think the diff is entirely locked like it would be if it was welded. It also makes a bit of clunking noise when getting on or off the gas in first and sometimes second gear. Assuming it was a VLSD before I installed it, I put in regular gear oil. Does anybody have any ideas about what is in this thing? Can a VLSD go bad and act like this? Or did the previous owner put in a clutch type? If so, can I put in just any clutch LSD oil or do I have to find out who made the damn thing?  Thanks.

[Steeles]

was it new or used?  if new what kind?  I know they sell Kaaz units did you break it in properly?  I've heard some kaaz units come packed REALLY tight and for them to be streetable you need to remove some clutch disks before install.  thats about all I can think of.

[sanmiam]

someone correct me if I am a dumbass, but there is special fluid for the VLSD, at least this is what I have heard (never done the swap myself)

[Itsuki]

When a VLSD goes bad it should act like an open diff.

Did you put the "Regular gear oil" in the filler hole or did you actually try to open up the Coupling housing and put it in there??? becuase the type of oil you put in the filler hole should not really have anything to do with it locking up the other wheel, what makes them lock up is the clutch disks in the coupling housing, the oil you put in the filler hole will simply just lubricate the ring gear and pinion gear....

(someone please correct me if im wrong its late almost 2)

[sanmiam]

itsuki, you are right that when a LSD goes but it will act like an open diff, but the problem is most likely the lack of a friction additive to the diff fluid.  I did a little research, and yes, you need to either use differential fluid that is deigned for LSD, or put a friction additive into the diff.  They should have it at any auto store (one would hope).

[AKADriver]

You didn't do enough research, apparently.

A VLSD does not ever require the friction modifiers.  As Itsuki correctly noted, The gear oil in a VLSD is only there to lubricate the ring and pinion, bearings, and spider gears.  The actual limited slip action is achieved by plates spinning in their own sealed chamber of silicone fluid that becomes viscous when heated.  This fluid isn't serviceable, you can't open up the viscous coupling and change it.

Back on the original topic, it doesn't quite sound like a fully locked diff, but it doesn't sound like a VLSD either.  Try running it with clutch LSD oil (yes, any will do) and see if it loosens up.

[philipwight]

this is the same thing that happened to me.  It turns out that i had a KAAZ lsd and i had synthetic oil in it and that is not correct.  So i bought some of KAAZ oil and i an in the process of putting it back together, i will let you know how it turns out.  You need to crack the casing and see what type of unit you have.  Then go from there.  

philip