limited slip question

[rick-z28]

I have a 2000 z28 A4. It has the GU5 rear end. It has 75k on it.

When I bought this car about 10k miles ago it was actually dificult to spin tires. A launch from a stop would produce 5-10 feet of posi marks. Now doing the same launch produces total annihilation of the right rear with a little bit of left wheel spin.

My question: Is this due to fluids or the clutchs?

Thanks,
Rick

[alamantia]

I believe 2000 had a torsen unit for the differential. If thats the case, it does not have clutches. Thus I do not believe fluid is your answer. However, if that rear has a clutch style "posi" unit like eaton whoch I believe came in GM cars or a conical style such as Auburn. Then it does consist of clutch packs or cones and will have a tendency to not lock both spider gears causing the right wheel to spin more than the left. Simply changing the fluid to a hig grade conventional or even synthetic fluid could fix this. I reccomend removing the cover, thuroghly cleening the entire carrier with brake cleaner, letting it dry and refilling the rear with one bottle of the GM posi additive and two quarts of 75w-90 synthetic and see what happens. Good luck

[rick-z28]

Thanks, I will try the cleaning and refilling as you described. I will use synthetic. How can I find out or tell if it is a torsen or auburn?

Thanks,
Rick

[alamantia]

Well an Auburn would have been installed by someone who previoulsy owned the car. You would see conical clutches on the spider gears. Eaton's I believe came in F-Bodies from the factory. Look at a diagram of Torsen carriers on their website www.torsen.com they dont use clutches at all. It also says they started supplying to GM in 1998 so I would venture to say your is a Torsen.