Well....here we go. A couple weeks ago, I felt a hard clunk when my 1998 XJ-8 shifted into 4th. gear, otherwise, everything else was normal. My car has 140K miles and I have driven it for about 5 years with no transmission problems. I have not changed the fluid and filter yet, but I did check the fluid level with the car running in park, and it only took about 4 ounces to top it off. I have the OEM ZF fluid and a filter-gasket kit ready to install. Now, I have also noticed that on occasion I am having a problem when I put the car in reverse. It feels like I am trying to back up with the emergency brake engaged. It takes a bit of accelerator to get it to move, and when I let off the pedal, there is no coasting..the car stops moving instantly. Connected to my scanner, I am not showing any codes. Also, if I anticipate the shift into 4th. gear and let off the accelerator pedal, it shifts smoothly and no clunk is detected.

One time while I was waiting for the traffic light to change, it felt like the car shifted into reverse and back to drive all while I sat with my foot on the brake...very strange feeling.

Should I go ahead and change the fluid and filter or is it a waste of time ?

I suspect a problem with one of the solenoids or pressure regulators, but I'm not a transmission expert. The car shifts great on all other gears, there is no slipping or other problems that I can feel . I called a transmission shop that has worked on these but he had never seen this problem.

 

Conclusion to the problem is as follows: Transmission suddenly started slipping when I left my home one morning so I returned the car to my garage. Had it taken on a rollback to a transmission shop in High Point, NC, that specializes in ZF transmissions. Got a complete rebuild for $2500.00 with one year parts and labor warranty. Picked the car up yesterday. Hope I'm trouble free now for a while.

 

Sounds like the torque converter clutch isn't properly locking up. That is a pretty common failure on that torque converter. Rebuild was a good idea anyway though, seeing as the transmission was out and set up for failure anyway.