M923, long term storage, went to move.. THUMP, THUMP, THUMP on move.. WTF??

[ke6rwj]

This M923 has sat for about a year. When we bought it, it had sat longer, but got it started, freed the brakes and drove it home... ran great... now when we go to move it.. it has a noticeable "THUMP, THUMP, THUMP" when rolling... it gets faster as we go, but not at the same speed as the drive shafts.. we tried rolling slow, while someone was along side to see if we can see anything hitting..,nothing... looked through the rear channel from the back as we slowly moved it forward, didn't see anything obvious... The tires are all aired up, and not rubbing anywhere...

Im not sure how to troubleshoot this, other than tying someone under it.

I really sounds like its coming from around the tandem axles, any ideas? Any levers or controls animals can build nests on?

Im at a loss..

-- Chris...

 

[Mullaney]

.

This M923 has sat for about a year. When we bought it, it had sat longer, but got it started, freed the brakes and drove it home... ran great... now when we go to move it.. it has a noticeable "THUMP, THUMP, THUMP" when rolling... it gets faster as we go, but not at the same speed as the drive shafts.. we tried rolling slow, while someone was along side to see if we can see anything hitting..,nothing... looked through the rear channel from the back as we slowly moved it forward, didn't see anything obvious... The tires are all aired up, and not rubbing anywhere...

Im not sure how to troubleshoot this, other than tying someone under it.

I really sounds like its coming from around the tandem axles, any ideas? Any levers or controls animals can build nests on?

Im at a loss..

-- Chris...

.
Hi Chris,

So, is it parked on the street now - rather than on soft ground before? The tires... It is possible that it has flat spots from sitting. Your "Thump Thump Thump", could you see the tire rotation timing up with the thump?

 

[gringeltaube]

If dual rears, could there be a rock, stuck in between tires?

 

[ke6rwj]

.

.
Hi Chris,

So, is it parked on the street now - rather than on soft ground before? The tires... It is possible that it has flat spots from sitting. Your "Thump Thump Thump", could you see the tire rotation timing up with the thump?

It was parked on dirt before and is now.. The thump sounds very "Mechanical". it also does this sound at all speeds, on any surface.

Ill take another look at the tires...

 

[ke6rwj]

If dual rears, could there be a rock, stuck in between tires?

I didn't see any when I looked before, but ill take another look at the tires...

 

[juanprado]

Look at hanger bearings and rubber cushions on driveshafts.

 

[ke6rwj]

Update on this...

Spent some time trying to isolate this.. looked very closely at the front driveshafts and nothing is moving out of place that is noticeable.

The tires are not low at all.

I put it in low and the thump got **REALLY** bad.

I still can't see anything obvious at all. We thought maybe a wheel bearing but the thump is closer to a single driveshaft rotation than a tire..

I'm thinking to pull the front driveshafts and see if it changes or disappears..

Not quite sure how to troubleshoot this
..
Thoughts?

 

[Jbulach]

Worse, as in faster? Check the transmission to transfercase drive shaft. Also check for water and condition of fluid in both, especially the transfercase.

 

[ke6rwj]

Worse, as in faster? Check the transmission to transfercase drive shaft. Also check for water and condition of fluid in both, especially the transfercase.

Worse as in louder.. I'll check fluids..