Thumping Noise (1 Viewer)

[80 Cruiser Rod]

I have a thumping noise when I hit a bump in the road coming from my rear and it is driving me nuts. I've been under my truck to see if I could find anything loose. I've removed the spare tire and rear seats and I still have the thumping when I go over something rough in the road. Any thoughts might stop me from loosing it.

 

[-Spike-]

Check the shock bushings, and maybe the exhaust mounts.

-Spike

 

[80 Cruiser Rod]

Check the shock bushings, and maybe the exhaust mounts.

-Spike

Checked them both. Exhaust is tight as all hell and both shock bushings seem to be tight too.

 

[ScottsHZJ80]

I've just replaced the sway bar mounts and rubbers on mine. The silence is almost deafening

It was more of a rattle, but still worth checking.

 

[80 Cruiser Rod]

I've just replaced the sway bar mounts and rubbers on mine. The silence is almost deafening

It was more of a rattle, but still worth checking.

Is this one of the rubbers you mean? There is a little play in the passenger side but the drivers side is tight. The noise does seem to come more from the passenger's side.

 

[MoJ]

Could it possibly be coming from the front? Take a quick minute and check the welds where the front sway bar brackets connect to the front axle.

 

[BrettinSanAntonio]

Interesting. I've got the exact same issue right now but it seems to be coming from the exhaust mount just forward of the rear bumper. The truck handles great but that noise is freaking driving me crazy.

You know, it would be easy to disconnect that sway bar and test the theory. Undo that bolt and take it for a test drive.

 

[Firedog]

Could it be something in the interior, behind the interior panels? The drivers side has the jack and tool bag, the passenger could have anything stashed in the compartment or behind the panel, mine had an old quart of oil back there when I took the panel off.
Also look at the boots on the end of the bumper, mine were broken loose at the wheelwell - it made a bad thump everytime i went over a bump.

 

[ScottsHZJ80]

Is this one of the rubbers you mean? There is a little play in the passenger side but the drivers side is tight. The noise does seem to come more from the passenger's side.

Yep, that's the one. There is a metal sleeve inside the rubber bush which rattles against the mount when the rubber gets worn. I also replaced the D shaped rubbers on the bar, as they were well buggered and it rattled there too.

 

[80 Cruiser Rod]

Yep, that's the one. There is a metal sleeve inside the rubber bush which rattles against the mount when the rubber gets worn. I also replaced the D shaped rubbers on the bar, as they were well buggered and it rattled there too.

How hard where the D shape rubbers and the others to replace? Everything else checks out fine, that has to be were the noise is coming from.

 

[ScottsHZJ80]

The D rubbers are split along the top (straight) side. It might have taken me 30 minutes from start to finish including having to repeat step #6 a couple of times

The only things holding the sway bar on are the bolts in your earlier picture - 1 each end, and two on each saddle holding the D rubbers. The FSM says to have the suspension at full droop when you do this, ie stands under the frame, but I can't see why they wouldn't reseat themselves in the right spot after a while if you did it with the weight of the vehicle on the suspension or not.

 

[Squash]

If you have an under slung spare tire...tighten up the crank.

Easiest way to check is to kick the spare, if it moves fix it.

 

[80 Cruiser Rod]

If you have an under slung spare tire...tighten up the crank.

Easiest way to check is to kick the spare, if it moves fix it.

I did that and I also took the spare completely out and it still made the noise. I think it is the sway bar rubbers.

 

[80 Cruiser Rod]

The D rubbers are split along the top (straight) side. It might have taken me 30 minutes from start to finish including having to repeat step #6 a couple of times

The only things holding the sway bar on are the bolts in your earlier picture - 1 each end, and two on each saddle holding the D rubbers. The FSM says to have the suspension at full droop when you do this, ie stands under the frame, but I can't see why they wouldn't reseat themselves in the right spot after a while if you did it with the weight of the vehicle on the suspension or not.

Great, I'll look into that and thanks.
Rod

 

[80 Cruiser Rod]

One more question. Should I replace the Stabilizer Bar Link too?

 

[ScottsHZJ80]

One more question. Should I replace the Stabilizer Bar Link too?

It wouldn't hurt, that's where some of the noise was coming from on mine. You should be able to check by 'wiggling' the link once you have the bar disconnected.

I have only replaced one of mine so far, as that was all the dealer had in stock last week, but wheeling yesterday it would appear they need to be replaced as a pair. It feels like the back of the car is stepping sideways in relation to the axle at full articulation, but that could also point to the panhard rod bushes I guess. I'll report back if replacing the other side doesn't fix this.

 

[80 Cruiser Rod]

Ok, I replaced all of the rubbers along with both stabilizer links. There is a big difference in the ride for the better but the thumping or banging noise is still there. It definitely is coming from the passenger side, I can't find anything loose in the back of my truck or under it. Still open for suggestions.

 

[ScottsHZJ80]

Rod,

Good to hear replacing the sway bar links has improved things. Sorry to hear it hasn't solved the original problem

You said you have already checked shock mounts, how are the bushes in the suspension control arms and panhard rod mounts? That would seem to be the next place to check. As you feel it's coming from the passenger side I'd be checking out the panhard mounts, as the chassis end of the panhard rod is under the USPS, I guess the 'thump' would trasmit into the cabin via the PS even if both mounts are worn as you would also feel the 'thump' on the axle tube end through the chassis mount as well.

The other thing worth bearing in mind is with the weight of the vehicle resting on the bushes it is hard to detect any play in them, but with the weight of the vehicle moving about on them as it goes down the road, it doesn't have to move far at all to produce a clunk.

When I did mine I had also done the rear suspension bushes the weekend before. It has made a huge difference, but the sway bar links were making 95% of the rattling noise on mine.

 

[xingji]

Did you check the shock cushions at the top mount too?

Checked them both. Exhaust is tight as all hell and both shock bushings seem to be tight too.

 

[chui]

hi did you ever find out the cause for the thumping. im having the same issue now