Maybe problem with Carrier bearing, feel thud under truck
 

When ever i accelerate from a stop, or if i turn the steering wheel all the way, i feel a thud, knocking on the bottom of the truck, I'd describe the feel and sound as if someone is hitting the bottom of my truck with a mallet, and it feels as if something in the rear end is slipping and not grabbing right away. I'm not mechanically gifted, and i don't know much about cars, but a few of my friends think the problem has to do with either the carrier bearing, u-joints, or the rear end. A friend told me that when looking at the drive shaft, when I go from park to drive and reverse, the drive shaft will turn 180 degrees before the truck starts moving, so i'm guessing that there's a lot of play in the drive shaft. The thud/knocking sound doesn't happen when the truck is cold, and it gets worse when driving up and incline. Does anyone know what the problem could be, or maybe suggest the best way to troubleshoot this problem? My truck is a 97, 2 wheel drive, automatic, club cab. Thanks so much for the help

William D

that sounds to me like the rear end is the culprit. with the truck off, parking brake on (or block the tires) crawl under the back of the truck and turn the driveshaft by hand. listen for the clunk, this should give you a better idea of where the sound is actually coming from. you might have to spin it back and forth quickly to make the sound. hope this helps

thank you CMAC, I'll try trouble shooting it tomorrow and hopefully i can get it figured out. If it is in fact the rear end, how much does it normally cost to get fixed/rebuilt?

Thanks Again,

William D

i really couldnt give you a good idea of how much it could be. the biggest rear end i have had to work on was a dana 60. i didnt have to pay labor and i got the parts used for real cheap from my uncle. sorry i couldnt be more help

Do you have a limited slip diff? It may be something as simple as adding friction modifier to the oil.

While you're under there- check the transmission mount.
I got similar thing from the drivetrain bucking. The torn mount allowed the tranny to hit the cab floor.
Cheap fix if it is...