I have a 89 GXL, and a few months ago I swapped the open diff for a S4 LSD. I started noticing a klunk coming from the drivetrain when I gave it throttle, but didn't think too much of it. After a weekend of racing my S4 LSD was leaking badly from the front seal, and it looked like the driveshaft flange was pulled forward from the diff body by about half an inch.

Thinking that something happened to the S4 LSD internally, I had my old open diff swapped back in yesterday. The klunking didn't go away though. Now my open diff is leaking from the front seal as well.

The front diff mount was replaced two years ago, and inspected upon each swap, so it is not the source of the klunking. Any ideas what part of the drivetrain could cause the differential driveshaft flange to be pulled out exposing the oil seal?

 

The transmission end of the driveshaft is free to slide in the spline, so if the diff has any end play in the pinion, you should be able to push it in & out.
You don't want that.

Any end play in the other diff?

Any chance the front pinion nut has come loose?

 

did you look at the sub-frame mount? two bolts of hell... they like to break through the poorly manufactured mount.. haha. easy fix though. well in some cases...

 

I'll check the other diff today. As for the front pinion nut, I'll ask the installer.


I'll lift the car and check.

 

The rear subframe bushings are in good shape.

I was unable to push or pull the driveshaft in or out of the differential. However, there seemed to be some rotational play in the driveshaft. I could twist it almost half an inch back and forth. The sound that the diff made when I twisted the shaft hard was very similar to the klunking sound that I hear when first applying throttle.

 

your u-joints are worn out.... or you ring and pinion backlash need readjusting.... or both

 

got to it before i did.... i et its the u-joint