4X4 noise/vibration - having trouble pinpointing

[maxtrax]

So with the recent snow I have been using the 4x4 more often. I have noticed however that it feels like maybe a vibration/bearing out. Because I drive the truck often I notice it slightly by sound but more so through feeling in the floorboards. Trying to pinpoint it is tough and seems like the transfer case-front diff-left front tire. Here is what I have come up with:

Noise/vibration not evident when hubs locked and not in 4x4
Noise/vibration more evident when decelerating
T-Case output shaft doesn't seem like the bearing has any play

I thought if it was a wheel bearing then it would be present all the time.
Also thought that if it was the front diff it would be evident if the T-case was not locked in.

Crawling under the truck it seems like I need to take the front drive shaft from T-case to diff apart to grease splines as they seem to have a little play. Not sure if this would cause the vibration or not.

Any advice is appreciated

[NoRalPh]

Originally Posted by maxtrax

Noise/vibration not evident when hubs locked and not in 4x4

But if the hubs are LOCKED and you engage 4x4 the noise returns?

See, what it is you're describing is classic symptoms of bad needle bearings in the Ft hubs (NOT wheel brgs, just the needles that support the stub axle when in hubs are UNLOCKED) but that wouldn't involve taking it in-out of 4WD.

So, forget for a moment the application of the TC and engaging 4WD. Manually LOCK both hubs and drive around listening for the noise. If it doesn't happen you can UNLOCK one side at a time to see which side it's coming from (you should probably do 'em both, if one's bad the others not far behind)

A cheap fix that's done in an afternoon.

Welcome to guzzle's 4x4 Needle Bearing Maintenance Web Page

[maxtrax]

TC=4x4 Hubs=locked -->Noise
TC=2x4 Hubs=locked -->No Noise


Going to check this weekend with
TC=4x4 Hubs=unlocked to see if there is noise.

Wouldn't the hub needle bearings make noise even if my TC was in 2x4 and the hubs were locked?

[NoRalPh]

Here's what happens, when the hubs are UNLOCKED the wheel is spinning and the axle is Not. That axle (short stub axle from the U-Joint into the hub) is stationary and has to be supported by the needles as it's not spinning with the rest of the assembly. Bad needles (and they fail ALL the Time) cause noise.

BUT when the hubs are LOCKED, everything spins together and those needles aren't needed. At that point they are stationary and cause no noise.

Double check, be sure this is involving the TC position..... You're going from an easy fix, to something more complicated because, the entire Ft end, U-Joints/axles/diff, are spinning with those hubs locked.

[maxtrax]

So I should put the TC in 4x4 but don't lock the hubs? I'm going to try that and also check my front drive shaft between the TC and diff.

There is no noise when the hubs are unlocked and TC is in 2x4. From what you are saying it sounds like if the needles were bad I would have noise in the front with the truck in 2x4 only - making me lean toward the u-joints on the TC-diff shaft

[NoRalPh]

Originally Posted by maxtrax

From what you are saying it sounds like if the needles were bad I would have noise in the front with the truck in 2x4 only -

WOW, I don't know how you got that!

FORGET the 2x4 -vs- 4x4, the Only thing that indicates bad needle brgs is whether or not the hubs are Locked or Unlocked REGARDLESS of the TC position....

[maxtrax]

^^^ precisely. That is what i was trying to say just couldn't put it into words. I am only experiencing the problem in 4x4 with the hubs locked. Guess that rules out the needles and points more towards u-joints (or that other sliding joint) on the TC-diff shaft