With the cooler weather, my car has been acting quite beastly. Low speed WOT always results in going side ways. Well, this aftenoon, I noticed that I am leaving only a single patch of rubber vs. two. I know this sounds quite childish but ... is my limited slip working or not?? Shouldn't the differentials lock up and both tires should spin? On a side note, this was with competition mode on. Now, I am scared to do WOT b/c the rear end is sliding out on me.

Secondly, what is wrong with these Micheline Pilots! I still have at least 60% of tread and I am not getting any traction. They are now worser than my previous run flats :( Is this because of the cooler weather and car having more power or is it b/c Micheline pilots are bad in cooler weather? BTW, I have 11" rims in the rear with 295/35/18's.

Thanks




[Modified by sbkim, 3:06 PM 10/27/2001]

 

Yes, the cold weather brings out the beast in all our vehicles :reddevil

The Vortex gets a snout-full of cold air increasing your low end, the ground is cold, the rubber is cold (and hard). This combines to make a once "locked down" car in 70+ degree weather a "street salmon" in -50.

That said, it is also possible your differential plates are wearing out, and they are less likely grab and bring the other tire into action. Torque is still probably going to the other wheel, but not enough to spin it (though it is still probably helping you move forward). Strange, if only one was spinning the car should not fishtail in a straight line (b/c one tire is still holding the rear in place-when both spin the rear is free to move)

I've had this problem before on 'stangs. The mechanic will lift your car, turn the right wheel and you'll see the left wheel move either with it, or the opposite way. They'll then say there is no problem.

Mayber a differential fluid change, or a sympathetic Chevy Dealer. I'm almost positive they'd have to change the whole rear for that though.

Did you beat on your car a lot? Long burnouts, track time, line loc, doughnuts, powerslides, etc all wreak :reddevil on your diff...

 

DAP,

THanks for the info! You gotta love the cooler weather. As you had noted, it's a combination of all those items that makes the car more difficult to handle. What surprises me is overall performance of these highly rated Micheline Pilots. It's a night and day performance between cold and warm/hot. When the weather is warm, these are extremely sticky...

Back to your comment, I just got a new diff put in. Could you expound on your diff test -- lifting the car and turning the rear wheels. Should both be turning at the same time? I recently changed the fluids and diff is quiet around turns and etc.

BTW, I typically do not abuse my car. i.e., no donuts and burnouts. Typically it's just aggressive stop and go.


ThankS!


[Modified by sbkim, 10:42 AM 10/28/2001]

 

SB: The Powerloader isn't programmed for cold weather...... :jester Such a problem! :D

 

Isn't the diff test a specific torque? You jack the right wheel, put the car in neutral, and then measure the torque required to turn the lifted wheel?

The right kind of use can burn up the clutches pretty fast. Put that right wheel in a situation where it can spin freely while the left is planted.. ALL of the torque to the left wheel has to go through the clutch pack.

If you allow that right wheel to spin, you will quickly damage the clutches. You can either re-shim to compensate for the wear and tighten the stack back up, or you can just replace the clutches.

But since you just had a new diff put in, something else is going on here. How many miles since it was installed? Where did the diff come from? Who did the work? What fluid did you put in?

My guess is the pre-load on the clutches was wrong, or the fluid wasn't right. Too much friction modifier can cause this problem. Too little friction modifier can cause the friction material to rip off the plates. Also, when the diff gets hot, the clutch pack tightens up.

 

When you changed the Diff fluid, what kind did you use? Did you use friction modifier, too?

I have Amsoil in mine and even though they say you don't have to use the friction modifier, I still put it in.

 

You said that you "slide sideways" and that you are in competition mode which means the Active Handling is on and the Traction Control is off.

Given that scenario, it is possible that you are activating the Active Handling when you get sideways and it is applying one of the rear brakes to "assist you" in regaining what it thinks you have lost control of.

Try it in a safe situation with the TC AND AH off on nice even pavement. If it then still leaves one scratch, you may have problems with the diff.

Hope this helps!

Karl

 

wow, thanks for all the input guys! I am using GM non-synthetic lube with friction modifier. I did figure 8's for about 20min. after the fluid change and all seems good. I only have about 1000 miles on the new diff.

Well, an update to my story above: Went back to another intersection where I left my other "signature" yesterday (I think it's mine), and I saw two tire marks. I could be wrong but I did leave quite a burnout yesterday and the width of the rubber marks resemble mine. I am not going to any forensic examination to be sure but I will just assume I have no diff problems :D