'91 silverado question

[brikeas]

I've got a '91 1500 4x4, 5speed manual trans. At about 10-15 mph from take off, I get a thumping noise from the tranny/transfer case. The noise also speeds up when acceleratng. I removed the driveshaft, locked in 4hi, and the noise was gone. I checked the u-joints and all is tight. I also checked the splines on the yoke and the output shaft. All look fine. Any suggestions?

[ChevyTech007]

Might be in the rear diff. Maybe a tooth broke off ring and pinion. There is a snap ring in the back of the transfer case on output shaft that I have seen break causing loud noise.

[brikeas]

I will take a look into that. It's a 241c transfer case. I hope that is all it is.

[gjohnston]

I just had my transfercase rebuilt and the mechanic didn't put a snap ring back on the out put shaft. It made the same type of noise you described. Those noises are hard to trace as they are conducted up and down the drive train.

 

Good luck