Rear Axle Whine

[David63]

Recently my 1977 rear axle (9" BB) started to make a noticeable whining noise when its put under a load (ie accelerating, running through gears from a stop, etc.) I checked the fluid and its clean and full. Before I pull the diff, I thought I would check to see what folks think. Is this indicative of a bearing going out?

 

[Speedrdr]

Before I pulled the 3rd member, I’d consider jacking up the rear end and running through the gears and checking to see if it’s an axle bearing going out…lots easier to replace. Is your rear axle a posi or limited slip? If not, you only have to jack up one side at a time.
There are more members with more experience and smarts than me, so hope they post as well.

Randy

 

[okie4570]

Definitely jack it up and listen. It may or may not make the same noise or whine with no load on it though.

 

[73azbronco]

Unless its making a howl decelerating 55 to say 45mph, its probably an axle bearing, something inside tranny/transfer case?. Oddly, in my experience, Rear ends usually dont make a noise if they are bad during accel.

 

[Glass Pony]

Back in the day I watched my dad troubleshoot an axle bearing on our station wagon. He jacked up the rear axle and while idling in drive he took a length of 2x4, put it under the tire and stopped one side at a time so he could listen to each side.
Although I don't think I would try that with a posi or locking rear end.

 

[bigmuddy]

Not saying this is your issue, but when I had a howling rearend it ended up being abnormal wear on the gear teeth. So sharp you could shave with them. Bad set up? I really don't know what happened.

 

[David63]

Thanks for all the replies! I have twin sticks and when I disengage the rear axle and drive only using the front axle the noise disappears. This leads me to believe the noise is rear axle related since the transmission and transfer case were quiet. Guess I need to just pull the rear axle apart and check everything to be sure.

 

[Broncobowsher]

I would start with checking for excessive play at the pinion. Rear axle in neutral (eliminate the false solid feeling that a loaded driveshaft may make) and check for play at the pinion. It may help diagnose what is going on.

 

[Yeller]

If it goes away in front wheel drive it is either a bearing or a ring and pinion. Bearings are replaceable without a complete rebuild. Hard to describe the difference but an experienced ear can tell you which.