I have a 1995 ZJ 5.2 and it runs fine when cold but when it warms up I get a thud when gearing down from 3rd-2nd. It gets worse as it warms up. I was driving in the snow and I ran it in 4LOW and it actually made it better but not completely cured. Any ideas to what I'm dealing with? I'm thinking transfer case.

 

eesh, could be a lot of stuff. Id be checking the driveline first, u joints, flywheel bolts, loose harmonic balancer, fan, ...wheels...

 

I was just about to post the exact same thing. Same year also. '95 ZJ. Anyway it makes a noticeable hard "down shift" as I slow to a red light or something and it's going from 3rd to 2nd or 2nd to 1st. As the op described it it's like a thud. Doing a quick Google search I keep seeing transmission control module come up as a likely cause. Anyone have any input on that as a specific cause or experience with changing that curing a similar situation? Thanks in advance

 

Probably broken trans mount. The sudden change of torque lifts the transfer case and then it slams back down. JMHO.

 

I'll check that out. I just got this thing 5 days ago and am still figuring out the various imperfections. I do hear something clunking or loose sounding when I go over a bumpier bit of road.

 

BTW, I believe that was Joe Pesci playing the character Tommy Devito in "Goodfellas" The musician Tommy Devito was a good friend of his. The character was supposed to be Tommy Desimone of the Lucchese family. Good movie!

 

Yes correct. In real life Tommy DeSimone was much younger than Henry Hill. In the movie they have the age difference reversed.

But just to keep the thread on topic. If I start slowing down a ways before a red light and make a very slow gradual stop it doesn't do the hard thud. Even stopping faster it only seems to do the hard down shift after being much warmer. If the weather here ever cooperates I'll crawl under there and inspect everything.

 

You see, I get that thud, but only when I'm starting down a hill and slip it down to 2nd for a little engine braking. At 35 mph, it's going from 4th to 2nd.