Clutch or LSD (S4)
 

Since both either are or contain clutches, what are the different symptoms for them? I'd imagine they'd be very similiar when they're about to fail. Any way to check them without a visual inspection?

My current symptom is when I get on the gas pedal a little bit I get a free rev of about 500rpm before those revs drop back down to the previous location on the tach. Once there the car accelerates (As of right now I do not have a TPS on the car.. Waiting delivery).

I have owned 2 S4s with both types.

I had a 88 SE with clutch type.

I have a 88 GTU with LSD.

Both have the yellow tag behind the fill plug, however they did not react the same way when spinning the tires.

just my .02 cents.

I think I wasn't clear in my post. Manual trans Clutch, or the LSD Clutch pack. How can you tell which one is going out without a visual inspection?

Sounds like a bad clutch. If it was the reare end it just wouldn't be limited slipping like it should.

you can check your lsd with a simple test leave your car in neutral jack up the back of he car and spin one tire, if they both roll the same way then take of the tires have someone lock the brake rotor with a screwdriver or pry tool so that axle wont move. grab a breaker bar and see how much force it takes you to rotate the wheel you didn't block if it goes easy then your lsd is going bad or needs further diagnosis
however if it takes a substantial amount of force then your lsd is good

It's the clutch. How do you thinks an open rear works if your think the lsd is slipping in a straight line?

IIRC, 88 GTU LSD's were clutch-types....all S4's were, unless you had an aftermarket or miata LSD, or viscous from the GTUs?

88 GTU for the win!