Back end thud

[bluboti]

Every time I turn a corner, left or right, there is always an annoying thud. It sounds like the tailgate sliding but I have taken off the gate and all of the hardware that belongs to it. Its always done it even when my Dad bought it brand new in '69. Just wondering if it is somewhat common and what some of you have done about it. Thanks.

[blukangoo]

Do you have a C10 or a C20.
Leaf springs or Coil springs with trailer arms?
Are all the bushings in the back nice and tight?
Do you have a spare tire in the back?
It could be lots of things.

[beautimus]

i new of a guy who had a similar noise, not a thud but more of a pop.
the rear axle was a posi that needed posi additive in it. the rear would seem to bind as he turned at slow speed then it would pop and then free up. after he added the bottle of positraction additive, he went to a big parking lot and he drove in lots of circles and figure eights, to distribute the additive and no more problem. i think its about 5 bucks a bottle at a gm dealer. its might be worth a shot.

[blukangoo]

Originally Posted by beautimus

i new of a guy who had a similar noise, not a thud but more of a pop.
the rear axle was a posi that needed posi additive in it. the rear would seem to bind as he turned at slow speed then it would pop and then free up. after he added the bottle of positraction additive, he went to a big parking lot and he drove in lots of circles and figure eights, to distribute the additive and no more problem. i think its about 5 bucks a bottle at a gm dealer. its might be worth a shot.

Now that you pointed that out, I remembered we had the same problem with our Camaro. We didn´t believe it at first but the additive worked. That would be the easiest thing to try.

[68 P.O.S.]

I have a similar problem, but mine comes from the gas tank.

[bluboti]

It's a C20, leaf springs, no spare tire. Not a posi rear end. It is more of a thunk than a thud. Not the gas tank. Like i said earlier it's been doing it since it was new. Thanks for your ideas.

[69halfton]

does the thunk/thud change with speed...I.E slower speeds is louder...or something?

[bluboti]

It seems to do it more on left turns and not as much on right turns. Doesn't really make much difference if it's slow or fast. As far as I can tell, all the mounts and bushings are Ok.

[ProStreet68SB]

Theres always a possibilty your missing a couple teeth on your ring and pinion.... my dads truck was having a loud noise come from the rearend on turns and turns out the ring gears was missing about 4-5 teeth.

[68gmsee]

Originally Posted by bluboti

It's a C20, leaf springs, no spare tire. Not a posi rear end. It is more of a thunk than a thud. Not the gas tank. Like i said earlier it's been doing it since it was new. Thanks for your ideas.

Try this to see if you can duplicate it while parked.

Find you the sturdiest friend that you have, preferably a football lineman player type. Have him push on either side of the bed as hard as he can (without doing damage of course)to see if you can hear it. If you can, then you can isolate it.

If you don't hear it then lift one wheel off the ground and repeat by pushing on one side and then the other.

Lastly, have him grab the wheel that's off the ground and pull and/or push as hard as he can to see if you can duplicate it.

I know yours is a rearend noise but I had my son find a worn lower ball joint noise for me on one of my other vehicles by doing this.

[bluboti]

Thanks for that, I'll give it a whirl. I have tried shaking the bed back and forth while its parked and on the ground. I'll try getting it in the air. To busy this weekend though.