NV 5600 gear noise at cruising speed

[Brett Maverick]

2003 Dodge Ram 3500 4x4, Long Bed Ext. cab, 5.9 w/ NV5600 4.11 rear.
106K, ALL STOCK (It does have a pacbrake), original owner.
I've always used AMSOIL and my towed load is within specs (13,500 LB 5th wheel)
No racing or off roading, no mud-bogging, out of spec towing or other "Accelerated wear" type of useage.

I have started getting a "Gear noise" at cruising speed from the transmission area.
Partially pressing the clutch pedal doesn't seem to change the noise so I don't suspect it's a clutch or throwout/pilot bearing issue,
backing off the throttle makes it quieter.
There's no banging, squealing rattling or screaming, just a slight "sloppy bearing grumble or rattle" type noise at cruising speed.
It happens while towing or running solo.
21 years of Navy machinery rooms has left my hearing a little "High mileage", since i've only noticed the noise over the last year or so, that tells me it's getting louder/worse.

If I have to pull the transmission/transfer case it might be wise to replace the stock clutch while I'm in there, even though it only has 106K.
Other than the "Bearing noise" at cruising speed, the transmission shifts and acts normal, I recently added an extra quart of fluid through an upper bolt giving it a bit of an overfill.
Since it seems to be getting louder, I imagine a failure is coming, I'd rather do some preventative maintenance on it than have it fail while pulling the toyhauler.
Anyone have an idea on where to start, other than just replacing everything?

Thanks,
Brett

 

[Tuesdak]

Possible the damper springs on the clutch have one broken etc. Supposedly the syncro life is 200K. That said the syncro's were shot (flat) in mine at 120K as the PO abused it like didn't stop moving before jamming it into reverse and this also tore up the reverse slider. No clue other than shifting slow and notchy when cold.

You have a transfer case that could be the source of noise. Do you have a drive shaft center/carrier bearing? (Those can get loud when failing.) Wheel bearing and u-joints are always a good thing to check including the fun ones behind the front wheels.

 

[NIsaacs]

I would drain the transmission and pull one of the pto covers and inspect it, maybe the t-case too and the rear axle cover, noise can travel when it is drive train related.

Nick

 

[Tuesdak]

You can jack the rear end up and wind things up to 65 and see if you can get a general idea where the noise is coming from from outside the truck. Strapped down on a dyno is a good safe way to do this.

 

[GCroyle]

You can jack the rear end up and wind things up to 65 and see if you can get a general idea where the noise is coming from from outside the truck. Strapped down on a dyno is a good safe way to do this.

I can't comment on the effectiveness of this as a diagnostic, but this technique CAN damage the drive straps of the clutch cover IF done incorrectly. It has been documented high rpm engine test drives and a sudden deceleration with the tire in the air (on a lift or just raised up) or even on a possibly on a dyno if not controlled correctly. If you choose to do this, accelerate slow and decelerate even slower.

Drive straps are the 3 or 4 sets of stamped spring steel straps that are riveted between the cover stamping and pressure plate casting. They pull the pressure plate back for release and are the only mechanical connection to rotate the casting. IF you kink one, the clutch will not release. IF you really do a high RPM job on it (gas engine) the straps kink, then crack and the failure can get really ugly.

 

[S.Morris]

I'd be inspecting the hangar bearing closely. I put my $ on this one.