Hello everyone I'm new to the cherokee forum and have come across a knocking problem in my 91 comanche, it seems to only do it in drive or reverse, even when I'm not moving. At first I thought it was the transfer case so I replaced the fluid only to track it down to the transmission so the next thing I checked was the flex plate but no luck there. Also the tranny fluid is full. Other than the noise it seems to drive just fine. I don't think it matters but the engine is from a 98 xj with 172k miles currently and the transmission is original with 312k miles currently.

 

Check the engine and transmission mounts. Mine would knock in drive, while moving, and only when the torque converter was not in lockup. My motor mounts looked fine until I pulled the air filter box and saw just how bad it really was. I changed them out and never had a problem since.

 

Check the exhaust pipe where it passes over the transmission crossmember.

 

x2 on checking the exhaust pipe. If the motor or trans mounts are bad, the exhaust can hang low enough to rattle on the cross member. I've never heard of the trans knocking, unless it was a loose or broken flexplate.