Thumping Noise

shaun94 · Feb 2, 2004

All right here we go, I have an 88fsb recently I've been hearing a thumping noise under my seat when I hit the gas. It dosen't do it all the time, I have new c6 tranny haven't had any trouble shifting, so I don't know if it is my driveshaft or ujoint. I saw a post were somebody had a thumping noise in the rear but this is deafitly coming from underneath my seat because i can feel it. Any help or ideas would be greatly appriciated.

davids78bronco · Feb 2, 2004

You're going to have to spend time, chasing this one down. Put the truck in N, set the parking brake, and crawl under there. Check for worn/broken motor/tranny mounts, driveline U-joints and the slip-joint, check for work yokes and/or worn bearings in the axles, or Tcase, check the backlash in the rear axle (IIRC, anymore than about 1/16 turn is too much)

shaun94 · Feb 2, 2004

Thanks, I really appriciate it. I was a lost their for a little while.

azrockrat · Feb 3, 2004

if it is under your seat check the tranny cross member make sure it is tight, that is a common thing

Sturgell · Feb 4, 2004

I have a broke axle on the front and it made a bad thumping noise because I left the hub wit hthe good axle locked and it was twisting the other axle. [-X Stupid me lol.

James Sturgell

shaun94 · Feb 4, 2004

I think we all have had one of those day's :wacko:

amcabbott · Mar 3, 2004

chech your radius arm bushing there should be no up down side to side play .

BLADE262US · Mar 3, 2004

I agree with amcabbot my radious arm bushings in my F150 extended cab are shot right now and there a thumping noise under the seat . To look at them they look fine but under close inspection the cone part where it goes in the bracket has worn or broken off and it has been moving up and down and has polished the bracket .