High pitch whine coming to a stop

[asymptonic]

Generally happens when having driven a whole lot of miles at highway speed, say 50+. As I come to a stop, just in the last couple miles per hour (<5) there is a high pitch descending whine from mid to rear vehicle. Given how slow I'm going it's puzzling. It sounds like something doing 100-200 RPM but it's in the last moments of stopping.


Garage thinks it might be the rear diff, which is original, but I can't imagine any of the gear ratios are high enough for that pitch of noise.


Manual transmission (AX-15), 3.07 rear diff fwiw.

 

[TheXJDrew]

Very likely that it is the rear differential. Sounds like pinion bearings. To be sure, best thing to do is put it on jack stands, and have someone run it up and get the noise to happen while you listen to it with a mechanics stethoscope. Also, check the pinion yoke for play and for a leak at the seal. That’s usually a give away as well.

 

[kastein]

does it do it, possibly intermittently, for a minute after you come completely to a stop? If so it might be fuel pump noise getting louder and quieter from the fuel sloshing forward (and then back and forth) in the tank on a stop.

 

[asymptonic]

No, it stops the moment the vehicle does, so I'm leaning pinion bearings as well.

 

[kastein]

I would agree with that assessment then. Try jacking the rear up and letting it idle in gear then have someone step on the brakes while you listen. A mechanics stethoscope will help narrow it down a lot. Also bear in mind if it is damage to the pinion bearings it can easily be at the speed of rotation of the rollers themselves rather than the driveshaft.

 

[chris420]

Mine makes a winning sound after being driven a lot at high speed but it stops when it cools down. I think it’s the transmission overheating.