Engine/Transmission (1998.5 - 2002) Thud during acceleration

[damon]

A few times recently when I'm driving at freeway speed and hit the throttle hard, I feel and hear a thud somewhere in the drivetrain. The rpm's don't change like the transmission is slipping, and the truck accelerates as expected. It feels and sounds like there is something heavy in the bed that is sliding back and hitting the tailgate (yes, I checked for that. )



And now for the first time it happened the other day when running hard from a stop when another CTD pulled next to me and wanted to play. It seems like in this case it was in second gear, although hard to tell since the shift points are so short.



I have never felt any slipping of the transmission, even when recently towing 12,000 +.



Any ideas ?

 

[Rattlin_Ram]

Is your spare under the bed up tight? I had one in the trunk of a car drive me nuts before I finally figured out what was clunkin around back there.....

 

[tgee]

Mine does this when coming to a stop. or sometimes just as I start moving. It is the driveshaft slip yoke behind the carrier bearing that is worn. Also my carrier bearing is good, but the rubber supporting it is loose.

 

[damon]

thanks guys, I'll check both those ideas.

 

[damon]

found it !

I found the culprit, and luckily this time it was simple and cheap.



Of the four bolts/nuts that attach the driveshaft carrier bearing bracket to the underside of the bed, one of the back bolts did not have a nut at all and the other was spun halfway down the threads. Kind of odd since the locknut that was there was difficult to even thread back on by hand, but it got rid of the "thud" once I tightened everything back up.