The other night I was driving home and there was some snow on the ground. I got to a place where there was dry pavement where the tire tracks were and snow on the side. I put the right side of the car in the snow and left side on the dry pavement and hit the gas a little. The engine revved way up and the car didn't really grip much. I thought I might have gotten both wheels in the snow a little, so I tried again and the same result. The rear end didn't slide around at all, so I'm pretty sure only one wheel was spinning.

My car has 59K miles on it, mostly highway. It did have the dreaded rear end groan for the first 15K miles until I fixed it by putting in an extra bottle of XL-3 in the diff. I did not take any fluid out though, only added the 1 bottle.

Temps outside were around 10F, but I had been driving the car for about 25 minutes at 75mph so I know the rear end was warmed up. I didn't get to try it any more since the snow melted the next day. Any ideas??

 

You need to try on dry pavement to confirm.....

 

It would be a lot easier to see the equal black marks if I had an extra 150hp like some people here...sheesh.

Just joking, I have never had any problems with only one wheel spinning when taking off hard on dry (or wet) pavement. I just figured that the whole point of a limited slip was to...limit slip from one wheel. It didn't do that the other night. I think I was in 2nd or 3rd gear and the rpms went from 1500 up to about 3500 when I hit it. That should be more than enough difference for the limited slip to engage.

 

If your car is able to normally spin both rear tires, then it's possible that both of them were also spinning when you conducted your experiment the other night, even though one tire was on snow and the other was on dry pavement. The reason that may have happened is because traction on dry pavement is greatly reduced when the ambient temperature is extremely cold(10 F in your case) due to the tire tread getting stiff, and the road surface losing its stickiness(Plus, it may not be as dry as it looks). My S197 has a much easier time spinning its tires when the temps drop only into the 40's. And when it drops into the teens and lower, it feels like I'm launching on ice.
The best way to find out if both tires are spinning under those same conditions is to have someone else check them.

 

Yeah, I had thought of that, and it is possible the other wheel was spinning too, just not getting any traction. It sure spun easily though, I only gave it about 1/3 throttle. It is also possible the road was not totally dry like it looked like. It could have had some ice on it that I could not see. I will try again some time soon when we get more snow. I'll also investigate later this week when I have the rear end in the air installing my new LCA's.

 

I think that's normal for almost any factory type limited slip. That's why they're called a limited slip. It is possible though with 59k miles the clutch plates in the diff could be worn some. I remember seeing a car/truck show on tv a while back where they installed an eaton posi in a truck. They showed how bad the factory limited slip performed by driving the truck up a ramp. One side of the ramp had some steel rollers on it. As soon as that side's drive wheel hit the rollers that tire just started spinning, and the other drive tire didn't. I would check it with both wheels on dry pavement.

 

When it's cold out I've noticed it can be tough to get traction in dry pavement with well warmed tires. Could be the dry salt layer on the road that lets the tire on the dry patch spin....

 

The extra bottle of XL-3 may have caused the clutch plates to have worn out prematurely due to extra slippage afforded by the friction modifier (reduces friction). How well does the Stang drive in snow? If it feels like it constantly swings to one side (like a one wheeled wonder) the clutches may be toast.

 

Everything feels fine about the rear end. It doesn't seem to want to spin just one wheel, both spin at the same time. The only thing that got me wondering was the lack of acceleration when one wheel had traction and the other did not.

 

That is normal with a limited slip differential. Remember that a Traction-Lok is similar to an open differential, except it has a spring for preloading the clutch/steel packs to keep the 2 axles/side gears spinning at the same speed as much as possible. It is possible to overcome this preload with 1 wheel on a slippery surface. If you increase the pre-load, you wear out the clutches faster and the rear end tends to make weird noises. Adding more XL-3 can result in faster wear of the clutches or it reduces the efficiency of the lock up/biasing.