M925A2 Front Driveline Vibration

[74M35A2]

Seeking similar cases of front driveline vibration at higher speeds (>40mph), which disappears if the front drive is switched on, and what your resolution was.

I'm so far guessing a U-joint or knuckle joint in one the front axle shafts, but also wondering if back-dating the front driveshaft to the previous generation front driveshaft with a carrier bearing would help resolve. The truck did not have this issue until recently. May just be time to pull the front hubs down to the bearings and see what we have.

Thanks in advance.

 

[Jeepsinker]

Pull the front driveshaft and see if it stops. The slip joint in the shaft wears out and causes this, when you engage front drive, it takes up the slack and it goes away. Also will stop if you go fast enough, just like an unbalanced tire.

 

[Jason O]

74-

Take a look and test for any slop in the front output bearing of your transfer case. I have a 931 with the symptoms you describe. I'm able to notice a slight amout of play in the bearing the driveshaft installed. I'm assuming the transfer case has to be removed and split to change the bearing, but I havent reasearched it yet. Driveshaft if removed for now.

Hope you get away with an easy repair.