Gearbox noice issue

[knissen]

Hi,
I have a Studebaker M35A1, w. sprag type transfer case.
Driving in high gear (4 & 5th), high range I have excessive gear noise.
Worst in 5th gear, and increasing w. rpm.
In low range no noise occur, even if I run it at max rpm in 5th.
I checked and changed gear oil on main gear box.

Any ideas?

 

[whyme]

high and low are a function of the transfer case. id check the fluid level in that for starters.

 

[clinto]

Although it's difficult to diagnose, every deuce I've had that has had a noisy gearbox was the transmission.

If so, at a minimum it's a set of bearings (input/output).

 

[knissen]

I will check the transfer case next - my other 3 deuces are w. air engaged frontaxle. They do not have the same noise. (I also have a transfer case in stock, if the old sprag type should be the problem)