Rear Diff Noise

[TheWedge]

1973 F-100 302/C-4 9" Rear

I changed out my 325 rear gears to a set of 389 gears and have a noise coming from the rear end now. When ideling along it is a low growl, sort of like a granny 4 speed creeping along in low gear. When you get more speed it becomes a loud high pitch whine, nothing sounds like it is grinding just making alot of noise, any suggestions to as where the noise might be coming from??? Thanks.

[BobbyFord]

Sounds like gear whine. Sounds like it maybe ran low on gear oil at some point.

[ultraranger]

Did you swap gears into your truck's existing 3rd member or just swap out the entire 3rd member?

If the ring gear had surface rust pitting on the teeth, the noise may be coming from that. Antother possibility is the driving pinion bearing races/bearings need replacement.

The gear teeth of a 3.89 ring and pinion will be quite a bit larger than that of a 3.25 ring and pinion set. More tooth contact surface area is prone to generating more noise.

[Donnie]

Bearings tend to growl---------------improper gear set up tends to whine..........Donnie