Rear differential whine at 30-40 MPH '14 RAM 1500

[pb379]

I drove the truck for the first time yesterday following the fluid change in the rear differential. Still a little bit of whine, even when it was heated up. Seems a bit quieter, but hard to say. I mailed off the sample for analysis yesterday so should have the results mid week.
Today I put the truck on jack stands and put it in drive. I used a broom stick to push on the brake and turn the selector to Drive through the lowered window. I used the same broomstick to my ear searching for noises. The loudest was near the input pinion but it wasn't what I would consider alarming. The driveshaft carrier bearing was very quiet. The center section was a bit louder than the pinion, but quieter than the axle ends. The axle ends were pretty quiet as well. Of course this is just at idle with no weight on the wheels so I guess I wouldn't expect much noise from the axle end bearings. Of course I have no frame of reference as to what 'normal' sounds like.

This seemed strange to me-
With the rear end on jack stands, rear wheels in the air, the front wheels on the ground, 2WD selected on the dash and the truck in drive, the output shaft to the front axle was turning. Is this a traction control thing?

 

[Snagglefoot]

I seroiusly doubt your frankenbrew would cause any problems with your differential.

I'd second that. Firstly, its a 1500, secondly it's an Eco diesel not a big dog 1,000 lb ft Cummins Turbo diesel. Take a kid out for ice cream instead.

 

[pb379]

I'd second that. Firstly, its a 1500, secondly it's an Eco diesel not a big dog 1,000 lb ft Cummins Turbo diesel. Take a kid out for ice cream instead.

Sure. I never stated I thought it would cause any problems. I just said I planned on changing it.

 

[Oliveoil2]

If it was mine, I’d just change it in the spring. And then maybe test that fluid too, depending on what your UOA looks like.

 

[50yr Street Mech]

Good job ! At least you narrowed it down a bit. I can't give you an answer, but I did blow a center section on a utility truck I used at work. I was towing a trailer with a small backhoe with it for a year. It was not rated for that. This area I'm not familiar with, maybe someone else can help in the forum, sorry

 

[clinebarger]

I'm going to go against the grain here & say you should have the differential tore down & inspected to see if all new bearings is a viable repair.

 

[Snagglefoot]

I drove the truck for the first time yesterday following the fluid change in the rear differential. Still a little bit of whine, even when it was heated up. Seems a bit quieter, but hard to say. I mailed off the sample for analysis yesterday so should have the results mid week.
Today I put the truck on jack stands and put it in drive. I used a broom stick to push on the brake and turn the selector to Drive through the lowered window. I used the same broomstick to my ear searching for noises. The loudest was near the input pinion but it wasn't what I would consider alarming. The driveshaft carrier bearing was very quiet. The center section was a bit louder than the pinion, but quieter than the axle ends. The axle ends were pretty quiet as well. Of course this is just at idle with no weight on the wheels so I guess I wouldn't expect much noise from the axle end bearings. Of course I have no frame of reference as to what 'normal' sounds like.

This seemed strange to me-
With the rear end on jack stands, rear wheels in the air, the front wheels on the ground, 2WD selected on the dash and the truck in drive, the output shaft to the front axle was turning. Is this a traction control thing?

This is similar to Chevys. The front driveshaft always turns and then if four wheel drive is selected electronically a solenoid shifts to lock in the front axles.

 

[pb379]

I'm going to go against the grain here & say you should have the differential tore down & inspected to see if all new bearings is a viable repair.

That may be what ends up happening.

This is similar to Chevys. The front driveshaft always turns and then if four wheel drive is selected electronically a solenoid shifts to lock in the front axles.

Gotcha. I guess I thought all the gear switching was in the transfer case.

 

[D60]

This is similar to Chevys. The front driveshaft always turns and then if four wheel drive is selected electronically a solenoid shifts to lock in the front axles.

What year(s) GM? This sounds wrong to me if it's a true part-time 'case (read: not AWD)

Still, there's potential drag on the 4wd sprocket on the mainshaft, so it might lightly spin the chain and thus the front output.

GMs with a CAD are more likely to spin the front d/s when rolling because you're still spinning one side gear in the diff (the CAD only discos the right axle). Systems like Ford's IWEs truly disco BOTH front wheels AT the wheel -- same as true manual lockouts in the good ol' days

 

[Snagglefoot]

What year(s) GM? This sounds wrong to me if it's a true part-time 'case (read: not AWD)

Still, there's potential drag on the 4wd sprocket on the mainshaft, so it might lightly spin the chain and thus the front output.

GMs with a CAD are more likely to spin the front d/s when rolling because you're still spinning one side gear in the diff (the CAD only discos the right axle). Systems like Ford's IWEs truly disco BOTH front wheels AT the wheel -- same as true manual lockouts in the good ol' days

I'll gladly look into this, but only with the Magna Power Train transfer cases. GM switched over to Magna Power Train starting in about 2008. All the models, including those for the 1500, 2500 and 3500 utilize a heavy duty chain, and a front axle release. Some were electronically actuated and some had a manual lever at the floor level. The auto track versions had a clutch pack so one could keep it in 4 wheel auto and the front wheels would only receive power when slippage was detected between the front and rear wheels. A quick search of the net has plenty of examples of front axles turning in 2WD, but like everything One has to be specific. You mentioned the one side axle turning with the diff. It may be the source of the turning of the front drive shaft, and the drive shaft is not receiving any torque from the transfer case.

 

[pb379]

A friend of mine has helped me with some diagnosis. His first thought was that it was stuck in 4WD but I've had it up on Jack stands and put it in 4WD Auto, 4WD low and back to 2WD and the transfer case seems to shift properly. In 2WD the rear wheels spin but the fronts don't.
I'll be taking the truck to a shop in Killeen Texas called Sunshine Performance. I fella I've known for many years recommended the shop because they have worked on a few of his friends rear ends with good results. If anyone else has a recommendation for an awesome gear shop in central Texas between Waco and Austin, please let me know. Thanks

 

[Snagglefoot]

A friend of mine has helped me with some diagnosis. His first thought was that it was stuck in 4WD but I've had it up on Jack stands and put it in 4WD Auto, 4WD low and back to 2WD and the transfer case seems to shift properly. In 2WD the rear wheels spin but the fronts don't.
I'll be taking the truck to a shop in Killeen Texas called Sunshine Performance. I fella I've known for many years recommended the shop because they have worked on a few of his friends rear ends with good results. If anyone else has a recommendation for an awesome gear shop in central Texas between Waco and Austin, please let me know. Thanks

Did you happen to turn a front tire with your hands to see if the front drive shaft turned? That is one condition you couldn’t mimic with the truck on jack stands.

 

[pb379]

Did you happen to turn a front tire with your hands to see if the front drive shaft turned? That is one condition you couldn’t mimic with the truck on jack stands.

Yes I did and when I turned the wheel, the front DS did not turn.

 

[pb379]

Well here's what the lab sent.
I have driven this truck on the sand at the beach several times. Never buried in the sand though. When I changed the front diff fluid, I did notice some grit, probably sand in the bottom of the pan when I transferred it but I just figured it was from having the pan under the diff when I cleaned up the exterior surface around the plug before I removed it removed it.

 

[pb379]

I was informed on the ecodiesel forum that the RAM 1500 rear end is known for having crazy high silicon from the factory and it takes more than one drain and fill to get it all out. Never hear or read that before. Is that the case?