A few months ago, I had to make a hard stop from about 25mph. When I started moving again, I noticed a whining noise coming from the drivetrain. The noise starts being noticeable at 10mph and the pitch goes up as the speed increases. The sound does not change with the changing of gears in the tranny, so I don't think that is the problem. There is no noticeable vibration, only the noise. I've had all of the fluids changed (tranny, rear diff, front diff, etc.) but it made no difference. The overall volume does seem to be increasing over time. This past weekend, I put the truck in the garage, chocked the wheels, and put the tranny in neutral. Slid under the truck and check the drive shaft for play. I did notice a little play in both the front and the rear of the shaft. Is there a bearing in the front or rear that could be causing this?

I've attached some pics of the drive shaft. I also took a couple of short videos but I can't figure out how to load them.

Any ideas as to what the cause is?

 

So you are saying that the noise doesn't change when accelerating or decelerating?

 

The pitch of the noise goes up as the speed increases, but at a constant rate. In other words, it doesn't "reset" when the transmission switches gears.

 

Could possibly be the pinion bearing.

 

I second the pinion bearing... time to freshen up the rear end...

 

How many miles on the truck?
I had whining from the rear at around 120k miles and had the diff reworked which helped a while, but it is coming back now at 148k miles. But it is not too bad on our truck (2006 F-150).

 

I would first inspect the rear brakes. You said it began when you made a sudden stop.

My one experience with a bad pinion bearing that was the outside bearing is that the noise was constant and it sounded more like a roar or grinding. In fact I thought it was bad tires that were roaring. Back then in the 70's there were a lot of defective belted tires because American tire manufacturers had not mastered the art of making belted tires. A whining noise sounds more like a gear noise but that would change when stepping on the gas and letting off.