I'm not really up to speed on diff theory. So please educate me.

The last time I was at the track I had a fright: one time while staging, the water dude yelled at me to stop my burnout. He told me that one of my wheels was not turning. My heart missed a beat; I thought I had snapped a halfshaft(only a matter of time right?) - but I hadn't heard anything. I pulled up a little further, and nothing seemed amiss, so I just had a normal run.

When I told one of my buddies about this later, he said "Yeah, I've noticed that several times. I thought you knew" Thanks man.

Anyway, what's the deal? And what's the harm? I read recently in another thread that the fluid within the VLSD brakes down over time, and is sealed/self-contained, so that it cannot be changed. I gather that as this occurs, the diff becomes more and more of an open diff. If this is true, the question becomes: if my diff is acting up and/or breaking down, is there a problem with doing one-wheeled burnouts?

 

Yeah, it looks ultra gay.... and if you're doing 1 wheel burnouts your not really helping out the other tire right? All my burnouts in, or out of the water pit I've had both wheels spinning. Something could be wrong with your car.. I too have VLSD if you were wondering.

 

Yes, the VLSD does wear out over time and will eventually become an Open diff.

Please keep in mind, the VLSD does not kick in until AFTER you lose traction; a gear/clutch type will kick in BEFORE you lose tracion.

 

you can do a burnout???

 

VLSD = Viscous Limited Slip Differential.

The clutch mechanism inside the diff is a fluid clutch, much like a torque converter. I'm guessing over time, heavy usage will wear out the clutch. Maybe the fluid gets thinner or the tolerances between the vanes are widening so you lose the friction? Not sure why. Actually, i'm not even sure if that's how the vlsd works, but that would be my guess.

But the waterbox guy told you to stop because the more you do a one wheel peel, the more you wear out the clutch, but my guess is that it doesn't matter at that point because the clutch is already worn out.

Anyways, one wheel peels are.

1. Gay looking
2. Hurts your launches because you'll have uneven grip between the wheels.
3. Add wear to your diff bearings because it was never designed to compensate for wheel speed differences of that magnitude.

 

With all the racing you do, I'd say you're VLSD is toast due to mileage and lots of racing, especially if you've done prolonged (2 second+) burnouts with only one wheel spinning. The VLSD's wear out and they're only good for 60-70K miles and if you race, you'll kill them much quicker.

As for potential damage, yes, you can literally blow the diff up if you do really prolonged burnouts on one wheel. I suggest that when you go to the strip, put the DRs in the water box and have the tires just inside the box and start your spin and come out of the water box spinning. That way you'll be pretty certain both wheels are spinning.

 

Thanks Dave. That's the info I've been looking for.