Going at about 5-10 mph the rear of my 97 A4 made me feel like i was riding a horse,major clunking and hops, I thought the diff was out of fluid but it wasn't,this has happend maybe 4 times in the past 5 yrs but it always goes away by itself. I only drive the car on weekends but don't thinks that has to do with it,any inputs? thanks.

 

 

check the condition of your rear oil - moisture content and viscosity. you may have minor clutch pack problems - not to unusual with limited slip and posi rear ends.

 

When my rear end started doing major clunking and sounding like it was going to come up through the rear floor board I had actually lost about 5 teeth off the gear

 

More than likely the differential.... Pull the cover off and look for broken spider gear teeth...

 

I got a clunking in the rear going at low speeds (no noise at higher speeds) and the backlash was off. Is it really loud, or just like a slight "clunk clunk clunk." Are your gears howling?