Noisy Front Diffential

[ckt]

In 4-wheel drive, my front differential makes a howling noise and vibrates at a speed of 60 mph. Does anyone else have this issue?

[Mark Rinker]

I wouldn't describe mine as a 'howling' noise - but you can definately hear when its engaged. You can feel the vibration through the floor. Not any more than other Chevrolet 4x4's I've recently owned.

[JohnC]

Don't take this wrong, but does it have oil in it? These tend to develop seal leaks and can over time loose a lot of oil. If you don't check it regularly, the oil level will get dangerously low and the bearings will give up the ghost.

when I traded my '95 it was leaking about a quart in 2000 miles.

[mark45678]

How many miles are on the truck and how many of those miles are in 4x4 mode? I have found my last three HD trucks make more noise then normal for about 300 mile. I think that tire pressure plays into this also , I run 52 in the front and 48 in the rear on my crew cab. Also Like JohnC said check the fluid mine was a qt low after the dealer prep.

[stumo]

In 4-wheel drive, my front differential makes a howling noise and vibrates at a speed of 60 mph. Does anyone else have this issue?

As Mark Rinker stated I too hear a whirring noise out of mine and can feel a slight vibration in the floor as well. Check the fluid level. Your profile doesn't say your location but IF your fluid is low and IF you've used 4WD in cold weather (<32 degrees F) then you MIGHT have a pinion bearing that is toast. And as always, measure tire circumference of all 4 tires and hope they're all within say 1/2 inch.

Let us know,
stumo

[DA BIG ONE]

Did you check the mounts?

On another note there was some posting not long ago with TSB about dyno lube failure in some front diffs in cold weather, synthetic was the cure.

[ckt]

Thanks for the replies. My truck has around 19k on it, most of it in 2wd. The oil level is fine, from the factory it was around a 1/2" low and I topped it off. The noise is still there. My salesman let me drive a new 06' to compare. The 06' did not have near the noise or vibration. The vibration I experience does not shake the truck, it is more high frequency. You can feel it in the pedal and on the floor. Does anyone think that the vibration could be harmful over the long run, or should I just live with it?? Should I change the fluid to synthetic??

[DA BIG ONE]

Because of the mount design there is very little free space between the chassis brackets and the outer sleeve of the mount. When in 4wd one outter sleeve can hit or even rest against the chassis because of torque, and causing the noise and vibes.

The design is such that the inner sleeve is compressed between the chassis mount, the outer sleeve which is pressed into case has maybe 1/8" clearance on each side of inside of chassis mounts top and bottom.

The differential can be adjusted w/o much effort by putting front of truck on horses, then loosen the 2 pass side bolts holding the diff extension (you will see adjusting slots here) and adjusting diff side to side so mounts are centered in chassis brackets. Once adjusted retorque bolts and test drive.

I'd consider a change to synthetic no matter what.

[ckt]

Thanks again for input. I'll see about trying this adjustment.

[Turbo Al]

As you said you do not have a lot of 4x4 miles on the truck. Mine had quite a vibration when it was new. I have a lot of 4x4 miles on the truck now and have syn oil in the front diff and can hardly tell that it is in 4x4 at hwy speeds. But do check your drive shaft clearances as stated by Da Big One --it is a pretty odd set up that Chevy uses.
Al