Help diagnosing a rhythmic thumping noise when driving.

[fatmonk8]

Recently noticed a rhythmic thumping noise when driving. Sounds almost like I'm going over a very subtle rumble strip.

Checked under the car and took a look at my u-joints, couldn't see or feel any play.

Lifted each wheel off the ground and checked for any play, front wheel bearings were just replaced not to long ago.

Lifted the back two tires off the ground and spun the tires, couldn't bear anything.

All front ball joints are new, cv's are new.

Anything I may have missed? Hoping it's not coming from the transfer case or tranny.

Oil was replaced in the transfer case not long ago, and tranny had the filter replaced recently also.

 

[B-train]

The only time I've experienced that was a bad u-joint. Usually the one at the rear pinion. Did you remove the shaft and manipulate them by hand? They can be sneaky to diagnose by spinning wheels, etc.

 

[fatmonk8]

The only time I've experienced that was a bad u-joint. Usually the one at the rear pinion. Did you remove the shaft and manipulate them by hand? They can be sneaky to diagnose by spinning wheels, etc.

I did not remove the shaft yet, I'll do that today and check them. I suspect that u-joint also. Would just suck because I just replaced them.

 

[B-train]

Is it possible a needle bearing fell down into the cap during assembly? That will also cause what you are explaining.......I know from experience.

 

[fatmonk8]

Is it possible a needle bearing fell down into the cap during assembly? That will also cause what you are explaining.......I know from experience.

Could be possible, but It has been fine for a while. I would assume it would have been rough right after install.

 

[B-train]

Yes, that was my experience. So I got the joy of doing it twice. I would assume that's not the case for you.

 

[fatmonk8]

Yes, that was my experience. So I got the joy of doing it twice. I would assume that's not the case for you.

Pulled the rear shaft, u-joint are good

 

[Joseph Garcia]

You said that you checked the tires. Did you look at the entire tread to be sure that you don't have a stone or similar embedded in the tire's tread?

 

[fatmonk8]

You said that you checked the tires. Did you look at the entire tread to be sure that you don't have a stone or similar embedded in the tire's tread?

Yes, nothing I could see.

Was thinking maybe I could rotate and check the balance on my tires just in case. Probably not a bad thing to do anyways.

 

[Doubeleive]

Yes, nothing I could see.

Was thinking maybe I could rotate and check the balance on my tires just in case. Probably not a bad thing to do anyways.

have you tried jacking it up and putting it in gear to see if you can find the source?
it can be done within reason I just wouldn't try to rev it up much usually with wheels off the ground it will spin up to a slow speed like 10mph or so without even applying any pedal.
that might be enough to determine if it is transmission, transfer case, rear diff, etc
if you don't hear it then it might only be doing it under a load
if is awd then all 4 wheels need to be up
i have done it with wheel chocks and jack stands or just jack stands if all wheels need to be up
and these trucks are tricksters, the sound can carry might sound like it is coming from one place and actually be coming from another......