Front Driveshaft or Front Diff Bushing NVH? Opinions welcome

[mercdudecbr600]

Hi All,

Replaced front diff bushings with poly Creative Steel ones as part of regear and now I've got heavy NVH at drivers side floorboard above 60mph. When driveshaft out, no vibrations. I'm on my 2nd driveshaft right now - first one wasn't balanced and had some wear and that one felt really bad. Second is lifetime trakmotive unit, supposedly balanced and brand new. This one has a smoother feel but still rough.

Tires road force balanced, front suspension all new. It's something located in the driveline. I had the rear driveshaft rebuilt and rebalanced as well.

Diff shop seems to think it might be a shifted pinion angle - I started to suspect a pinion bearing but the pinion yoke is tight and everything is smooth and dead silent until 60mph. So does anyone have a good pic of all three diff mounts? I'm suspecting that back rear triangular mount might be rotated incorrectly (or something like that). Appreciate the help.

 

[mercdudecbr600]

Okay some updates. Found that the np242 front output shaft and pinion yoke has a relatively significant (1/16”?) lateral movement and there’s some black grease sprayed around the yoke. More importantly I can feel and hear a “clunk”. By comparison the rear output shaft has ZERO movement with the same tests.

So here’s what I’m thinking: prior front driveshaft was so unbalanced that the after some time It wiped out the output shaft bearing and now no matter how balanced the driveshaft, the wiped bearing is letting the cvs wobble at speed. New tight mounts and increased gear ratio are exaggerating my issue.

So… looks like I’m into this never ending project for a transfer case.