whinding noise...
SteveCooke101
02-12-2008, 12:18 AM
I own a 1996 Dodge Ram 1500 4x4. I have noticed when i let off the gas and coast there is quite a loud whinding/groaning/grinding noise. It sounds like when the truck is gearing down but alot louder. I just had the rear pinion bearing replaced but i dont quite know if it is comming from the rear of the truck or right underneath me.:banghead: Any ideas?
kevinb70
02-13-2008, 03:58 PM
I got the same thing. I'm suspecting pinion bearings, due to sound causes when ring and pinion gears dont mesh well.
I have a bit of gear whine on decelerate, sound goes away when I press the clutch (for AT, would go away in neutral). I believe there is a whine on accelerate, I just can't tell over the [fairly loud] exhaust. Sound is at all vehicle speeds (well I have to be going at least 10-15mph for it to be loud enough)... sound is not dependent on which gear I am in [sound that varies with engine RPM not road speed would point to the tranny].
I'll be checking inside my pumpkin soon as it gets a bit warmer (just bought this truck, first checking to see if I have a LSD, gear wear, etc) Luckily I put very little miles on this truck (like only 120 miles in the month I've owned it)
first thing: sound travels up and down the driveline, hard to pinpoint the sound from the cab. Being able to run it on a vehicle lift would be the safest way to pinpoint the noise.
why was pinion bearing replaced? were you getting the same noise prior? and the fix didn't help? is the sound new after replacing the bearing?
can you isolate the sound to only 4x4 mode? then consider the transfer case on up. I have never owned a 4x4 can't help you there.
road test: if the sound gets louder when turning to either side at fairly high speed, it's axle bearings. (basically you are trying to shift the load to the left and right axles, just dont flip the truck trying it!)
easy stuff first:
proper oil level in the diff - if you have a LSD, was the right amount of friction modifier added? (if you jack the rear with the wheels off the ground, when spinning one tire by hand, a properly working LSD will spin the other tire in the same direction... an open diff or a bad LSD will spin the diff in the opposite direction). If both wheels spin same direction, friction modifier MUST be added.
transmission fluid/oil level ok?
transfer case oil level correct?
any play in your u-joints?
might have been a bad pinion bearing replacement. if you had it done professionally, have **someone else** other than the shop that did the work to check it out and see if that's the problem.
BTW, there are TWO pinion bearings on the pinion shaft. No idea why only 1 would be replaced. Maybe you just misstated. when replacing only the pinion bearings, the original shim must be reused, bearing cups seated correctly, and pinion preload checked with a in/lb torque wrench... diff should be removed for the test.. should get 15-35in/lb [NOT ft/lbs!!] STEADY turning resistance as you rotate the pinion round and round using the torque wrench... if the preload friction varies as you turn the pinion, you've got something binding, like a bearing cup not seated correctly. if during preload adjustment, if the pinion nut is ever backed off once you have it tight, you need to use a new crush sleeve. basically that crush sleeve is there to allow you to tighten the pinion nut around a steady 210 ft/lbs so you can fine tune the proper preload on the pinion bearings - you dont want the pinion resting in the bearing cups too loosely nor too tightly.
The more you tighten and crush the sleeve, the pinion moves toward the front in very small increments until you got just the perfect amount of play in the bearings. If the pinion was removed, a new crush sleeve must be used.
I have a bit of gear whine on decelerate, sound goes away when I press the clutch (for AT, would go away in neutral). I believe there is a whine on accelerate, I just can't tell over the [fairly loud] exhaust. Sound is at all vehicle speeds (well I have to be going at least 10-15mph for it to be loud enough)... sound is not dependent on which gear I am in [sound that varies with engine RPM not road speed would point to the tranny].
I'll be checking inside my pumpkin soon as it gets a bit warmer (just bought this truck, first checking to see if I have a LSD, gear wear, etc) Luckily I put very little miles on this truck (like only 120 miles in the month I've owned it)
first thing: sound travels up and down the driveline, hard to pinpoint the sound from the cab. Being able to run it on a vehicle lift would be the safest way to pinpoint the noise.
why was pinion bearing replaced? were you getting the same noise prior? and the fix didn't help? is the sound new after replacing the bearing?
can you isolate the sound to only 4x4 mode? then consider the transfer case on up. I have never owned a 4x4 can't help you there.
road test: if the sound gets louder when turning to either side at fairly high speed, it's axle bearings. (basically you are trying to shift the load to the left and right axles, just dont flip the truck trying it!)
easy stuff first:
proper oil level in the diff - if you have a LSD, was the right amount of friction modifier added? (if you jack the rear with the wheels off the ground, when spinning one tire by hand, a properly working LSD will spin the other tire in the same direction... an open diff or a bad LSD will spin the diff in the opposite direction). If both wheels spin same direction, friction modifier MUST be added.
transmission fluid/oil level ok?
transfer case oil level correct?
any play in your u-joints?
might have been a bad pinion bearing replacement. if you had it done professionally, have **someone else** other than the shop that did the work to check it out and see if that's the problem.
BTW, there are TWO pinion bearings on the pinion shaft. No idea why only 1 would be replaced. Maybe you just misstated. when replacing only the pinion bearings, the original shim must be reused, bearing cups seated correctly, and pinion preload checked with a in/lb torque wrench... diff should be removed for the test.. should get 15-35in/lb [NOT ft/lbs!!] STEADY turning resistance as you rotate the pinion round and round using the torque wrench... if the preload friction varies as you turn the pinion, you've got something binding, like a bearing cup not seated correctly. if during preload adjustment, if the pinion nut is ever backed off once you have it tight, you need to use a new crush sleeve. basically that crush sleeve is there to allow you to tighten the pinion nut around a steady 210 ft/lbs so you can fine tune the proper preload on the pinion bearings - you dont want the pinion resting in the bearing cups too loosely nor too tightly.
The more you tighten and crush the sleeve, the pinion moves toward the front in very small increments until you got just the perfect amount of play in the bearings. If the pinion was removed, a new crush sleeve must be used.
SteveCooke101
02-13-2008, 06:46 PM
Thanks for all the great help. Had it diagnosed and fixed today! Turns out that the pinion nut which faces the driveshaft was comming loose. going through the bearing process i guess the threads on it was getting loose but the noise is gone! I had to replace the bearings due to an MVI (Motor vehicle Inspection) wasnt a fun experience... hope this helps your issue too! Let me Know! thanks again
Automotive Network, Inc., Copyright ©2026