88 Dodge Ram D100, 318, Automatic Transmission: some vibrations occurring while maintaining speed - dissipate when accelerating and deceleratiing. Got under the truck and tried to wiggle the front (closest to the tranny) u joint - I can hear (not even really see any movement, or if there is, it is imperceptible) what sounds like bearings in grease, so I'm guessing the u joint bearings are starting to go bad - here is my question, though - are there bearings on the transmission side that could be making this noise??? I'm 90% confident the answer is no, but since there is little visible evidence of movement in the u joint (only the sound), I thought I would bounce this off the forum.

While I'm at it, let me ask another question: when I put the tranny in Drive (or 2 or 1), it really goes in abruptly, with a noticeable thunk noise and the entire truck lurches a bit. Goes into reverse very smoothly. Shifts fairly well after it gets going.....any thoughts on this?? could it be a rear end issue possibly?? Any thought on how to troubleshoot??? Thx, Mike

 

I can't hear the noise but I can tell you that there is a bearing in the transmission tailpiece that supports the shaft. If it goes bad (very unlikely) it will make the seal leak before it gives any other problems. Really bad u-joints can be spotted by hand manipulation. Early u-joint problems may need the use of a large screwdriver as a pry bar to find free play. The screwdriver also allows you to better isolate the pressure to the u-joint itself and even individual bearing cups.

Clunks and bangs during gear engagements usually are drive shaft or differential noises and not transmission related. Put the transmission in neutral and manipulate the drive train to look for excess free play in the u-joints or in the differential gears.

 

have you check the fluid level in your rear end? the rear fluid being low can cause a clunk when shifting into gear. if your universal are shot you can hear and feel it when you go to take off in drive or reverse. the vibrations could be caused by the tires. they could need to be balanced or one of the belts in one of the tires could have broke.

 

Many thanks....esp. for the screwdriver tip. Also, if memory serves, when putting the truck in Drive with the parking brake on, I could see the drive shaft move quite a bit (like maybe 1/8-1/4 turn)...so possible something is amiss w/ the differential. Per other post, I will check the fluid in the differential first. No leaking tranny seal (thankfully), so hopefully this is just the early stage of a u joint failure....as always, many thanks!!! If I can get the u joint fixed (and it fixes the problem!) I'll feel a lot better about driving this beast on the highway. Will investigate differential once I get the u joint resolved. thx, mike

 

I had the clunking too when going into gear from park or neutral. My problem was motor mounts. The rubber was completely gone on one side and all but gone on the other. Changed them out and not only is the clunk gone, with the a/c and stereo on, if I'm in park I can't even tell if the engine's running anymore.