Update 12-15
I still have the same (but worse) whining/grinding noise coming from who knows where now! I just replaced my rear axle assembly and I get the same noise I was getting before. I thought it was a blown pinion bearing so I replaced the whole rear axle assembly and saw no change in noise before/after. I need ideas, I can't get my head around this one....

Original Post: ,

Hello everyone. I have a 2000 Ram 1500 w/5.2 V8 2WD. I recently had a catastrophic highway speed front u-joint failure. My driveshaft hit the asphalt which remained bolted to the rear diff and was unusable after. My transmission broke in half, literally. I put a new 46re in and I've had zero shifting or slipping issues since installation (2500 miles ago/1 month). I picked up a driveshaft/yoke at a junkyard and replaced u joints properly and had the assembly professionally balanced. My fluid levels are perfect in tranny. Enough background, here's my issue...
I noticed recently when I'm coasting, or otherwise decelerating under 40mph, I hear a whining noise. It's pitch/frequency is related to vehicle speed. It goes away (or maybe it's muffled by my FM exhaust) on acceleration. Needless to say, I'm very concerned, especially considering I don't know where it's coming from. I've had nothing but good luck with this forum, Thank y'all in advance!!

 

Pinion bearings may have suffered with the driveshaft let go...... See any evidence of new fluid leaks anywhere?

 

coast/decel is sometimes bad gear mesh. wondering if the incident cause a rear end mishap. You could drop the fluid and do a mesh test on teeth to see.

 

If there was fluid leaking from the rear end where would it be apparent while parked?

 

Right around the pinion seal would be my chief concern.

 

From the 96 service manual:

GEAR NOISE
Axle gear noise can be caused by insufficient lubricant.
Incorrect backlash, tooth contact, or worn/damaged gears can cause noise.
Gear noise usually happens at a specific speed
range. The range Is 30 to 40 mph, or above 50 mph.
The noise can also occur during a specific type of
driving condition. These conditions are acceleration,
deceleration, coast, or constant load.
When road testing, accelerate the vehicle to the
speed range where the noise is the greatest. Shift
'out-of-gear and coast through the peak-noise range.
If the noise stops or changes greatly, check for insufficient lubricant.
Incorrect ring, gear backlash, or
gear damage can cause noise changes.
Differential side and pinion gears can be checked
by turning the vehicle. They usually do not cause
noise In straight-ahead driving. These gears are
loaded during vehicle turns. I f noise does occur dur*
ing vehicle turns, the side or pinion gears could be
worn or damaged. A worn pinion gear mate shaft can
also cause a snapping or a knocking noise.

BEARING NOISE
The axle shaft, differential and pinion gear bearings can all produce noise when worn or damaged.
Bearing noise can be either a whining, or a growling sound.
Pinion gear bearings have a constant-pitch noise.
This noise changes only with vehicle speed. Pinion
bearing noise will be higher because It rotates at a
faster rate. Drive the vehicle and load the differen*
tial. I f bearing noise occurs the pinion rear bearing is
the source of the noise. I f the bearing noise is heard
during a coast, front bearing is the source.
Worn, damaged differential bearings usually pro*
duce a low pitch noise. Differential bearing noise Is
similar to pinion bearing. The pitch of differential
bearing noise Is also constant and varies only with
vehicle speed.
Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changes
when the bearings are loaded. Road test the vehicle.
Turn the vehicle sharply to the left and to the right.
This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise
Is usually not noticeable at speeds above 30 mph.

 

Thank you Ramchu, This is very helpful.

 

Okay, so my problem persists... I've thoroughly inspected my differential for evidence of leakage through the course of my daily travels and have found none. I added let's say 3-6 fl oz of gear oil (until it reached the fill hole) and that only slightly reduced the noise. I performed a quiet road test (finally I had a chance w/o traffic) and brought it up to 35 mph (noisiest speed) and shifted into neutral to coast to a stop. The whining stopped almost immediately all the way to STOP. Does this mean my pinion is damaged?
I have also noticed a Grind/vibration when making sharp turns (parking lot speed or less, i.e. backing a trailer around a corner/up a hill) worse than it used to be. That particular noise (during slow-speed sharp turns) has gone on for years very mildly since I've owned the truck and I've been assured by many that it's just a Dodge thing. I'd definitely like another opinion there as well. Thanks Everyone! It won't be long before I'm answering newcomer's questions

 

Do you have a limited slip rear?

Sounds like pinion bearings are whining. You *might* be able to get away with just changing the outer. That one is fairly easy. If the whine persists though, think I would just do ALL the bearings in the rear.

 

I have seen roller bearings mark the race when they have been subjected to trauma. I think it's time to tear apart the diff.