Rear end whine goes away in 4wd

[Chris1957]

I have what seems like the classic rear end whine. 3.73 open diff. Worse 55-65 loaded stops when you let off the gas. I found by accident it goes away in 4wd so I thought maybe transfer case. I put another t case in but same result. What gives?

 

[imp]

I have what seems like the classic rear end whine. 3.73 open diff. Worse 55-65 loaded stops when you let off the gas. I found by accident it goes away in 4wd so I thought maybe transfer case. I put another t case in but same result. What gives?

@Chris1957
What gives is the fact that the noise produced is a borderline product of torque applied to the rear axle gears. In 4WD less torque is appliued to those as part of the force needed to propoel the vehicle is done by the front wheels.

Too bad you took the time and expense to mess with the T-case. If the whine is not extreme, you may "leave it go" awhile without serious result. A slight whine, noticeable but not offensively loud, may be allowed to continue almost indefinitely, unless caused by pinion bearings, which are highly stressed, and can fail quickly. imp

 

[Chris1957]

I thought is was a change in torque but this thing is really noisy. I plan on going through the rear end soon. I had the transfer case laying around so I thought I would give it a shot and see. On a side note the t case I used was from an 02. I had to move the ground wire from pin 11 to pin 12 to get the clutch to work on my 04. I just left the speed sensor wiring alone as it doesn't go anywhere on the 04.