20-30 mph detectable whirring sound

[Dennis H]

69 Coronet R/T. 3:54 Dana 60. New green rear wheel bearings. Neutral and not under load. Does not increase when turning wheel right or left. Constant and consistant with road speed. Front bearing are next and would like advice before going through the Dana which has been bulletproof since car purchased in 1988. Changed the dana fluid about 5 years ago. Drained brown river water out, put synthetic ina nd it leaked in 100 miles. Changed it again and replaced the seal.

WHat else could it be. It has been doing it for about 900 mmiles with no other symptoms or increase in sound. Sounds like a classic wheel bearing problem, not sure but seems to be on the rear of the car. Right now I am ignoring and driving to see what happens. Need a fix or at least a dignosis befor going to Fall Fling.

 

[68 Sport Satellite]

Dennis, my car has done the same thing since i had the rear bearings and suregrip rebuilt with pinion gear replaced at the same time last year. I keep thinking mine is the setup on the suregrip is too tight. I added a few bottles of the mopar friction modifier from the local chrysler shop, but it didn't fix my issue. I'm thinking of draining the pumpkin and replacing with dino oil 89/90W + friction additive.

If you haven't done so, try adding the friction modifier to see if it improves.
Otherwise, hopefully others will chime in on the things to watch out for when installing new rear green bearings. I posted to a similar older thread today that may have some useful info in there for you.

 

[70rr-brian]

Ok I know this will get a WTF most likely.... but are you sure its not your speedo cable making the noise?

You said sounds rear but thinking of replacing front bearings... Could be right in the middle! Just for grins and giggles disconnect the speedo from the tranny and see if the noise goes away. If not, well it only took a few minutes.

 

[RustyRatRod]

Only one way to know for sure. Put it on a rack, get under it with a stethascope. We do it everyday sometimes. If it does not change with sudden movements of the steering wheel loading and unloading wheel bearings, it is likely an inboard bearing such as a carrier or pinion bearing. When you say road speed, I assume you mean wheel speed? If it sounds like wheel speed, I would think axle or carrier bearing. If drive shaft speed, pinion bearing.

 

[69Bee]

...Changed the dana fluid about 5 years ago. Drained brown river water out, put synthetic in and it leaked in 100 miles. Changed it again and replaced the seal...

I am concerned with the "Brown river water" comment. Did you actually drain water out, or was it just a wierd comment? If you replaced the seal, did you re-torque the pinion nut to the proper torque, or just use an impact? The Dana uses shims for preload, and not a crush sleeve, so you don't have to add any torque when just doing the sleeve. If you actually drained water out, I would expect the pinion and carrier bearings to be rusty and spalling causing the noise.

 

[Hemi Rebel]

I am concerned with the "Brown river water" comment. Did you actually drain water out, or was it just a wierd comment? If you replaced the seal, did you re-torque the pinion nut to the proper torque, or just use an impact? The Dana uses shims for preload, and not a crush sleeve, so you don't have to add any torque when just doing the sleeve. If you actually drained water out, I would expect the pinion and carrier bearings to be rusty and spalling causing the noise.

I agree. If you had moisture contamination you needed more than just a drain and fill. It should have been dissassembled to be cleaned. even the mighty dana is no match for contamination.

 

[Dennis H]

River water described what it looked like while draining. It gave 15 Thousand quiet and trouble free miles of service after that drain. I will pull off the speedo cable, then go underneath.

Thank you everyone.

 

[68 Sport Satellite]

Ok I know this will get a WTF most likely.... but are you sure its not your speedo cable making the noise?

You said sounds rear but thinking of replacing front bearings... Could be right in the middle! Just for grins and giggles disconnect the speedo from the tranny and see if the noise goes away. If not, well it only took a few minutes.

On my car the speedo isn't hooked up.

 

[68 Sport Satellite]

Only one way to know for sure. Put it on a rack, get under it with a stethascope. We do it everyday sometimes. If it does not change with sudden movements of the steering wheel loading and unloading wheel bearings, it is likely an inboard bearing such as a carrier or pinion bearing. When you say road speed, I assume you mean wheel speed? If it sounds like wheel speed, I would think axle or carrier bearing. If drive shaft speed, pinion bearing.

That stethoscope is a good idea. I saw one of my go-to mechanics do that and let me listen to a problem he found on my rear drum brakes a few years ago. It's a viable way to trouble-shoot.

 

[rev.ronnie]

After you drive the car for a short amout of time, get under there with a temp gun and check the pinion bearing area and see if it is hotter than normal. You should be able to check the carrier bearings as well. They all should be the same temp or within reason. This will indicate a bad bearing.

If indeed you had a lot of mud in there, one of the cages may have failed. The whine would be from the bearing itself or the gears from the misalignment.

It's telling you something, for sure...

 

[Meep-Meep]

I suspect pinion or carrier bearings. On a Dana you can pull the cover and have a peek to see if there is any evidence of rust. The "river water" comment has me thinking there may have been some moisture in there. If there was and the rear end sat unused for a long time, it's possible the tapered roller bearings have rusted where the rollers were parked on the races. I have seen this happen. Or it's just a failed bearing. Pinion turns roughly three times the carrier speed so the frequency would be higher. Like Rusty said, drive shaft speed.

 

[Dennis H]

Ruled out the front wheel bearings.