Topic: The Humming Continues

[DanMarino]

The humming continues.  The spider gears are fixed and the car drives fine.
When I coast there is a humming noise.
I noticed that the humming noise gets louder if I press the clutch in and hold it.

Any ideas what could be going on?

Thanks,

13

[DanMarino]

I removed the rear drive shaft and the u-joints seem fine.
I put the Jeep in 4 hi and drove it around with the rear drive shaft out of the car.
It was raining out, but it seemed like the humming noise was not happening.

So does that mean the problem is the rear driveshaft u-joints, or is the problem something in the rear differential?

Thanks for any help you can offer.

Tom

[Jeffy]

Unfortunately it could be either.  How old are the U-joints and what angles are they at? Are they in phase?  Is/was there any play in the pinion?  Did you rotate it by hand when you had the spider gears out by any chance?  If you did, did the bearings feel smooth?

[DanMarino]

Hi Jeffy,

The pinion seemed ok when I had the spider gears out.  Since the wheel bearings are cheap, I'm going to go ahead and replace them to see if that makes any difference.

The suspension is flat and stock, so the driveshaft angles aren't severe.  Not sure what you mean by the u joints being in phase.  They swivel around fine and the bearing caps are not loose with needle bearings missing.

I'll report back after doing the wheel bearings.

Tom

[Jeffy]

If it's the differential, it's probably going to be the pinion bearing or the carrier bearings.

<a href="https://www.youtube.com/v/Idk3BVDVHq4" target="_blank" rel="noopener noreferrer" class="bbc_link bbc_flash_disabled new_win">https://www.youtube.com/v/Idk3BVDVHq4</a>

[bootguy]

Do you think a CV driveshaft cure that?

[DanMarino]

I got the old wheel bearings and seals off last night and put in the new wheel bearings and oil seals.
Got the axles back in and the differential spider/side gears back together.  On the plus side I'm getting good at breaking down the differential and putting it back together.  haha.

I'm taking this a step at a time trying to eliminate the source of the noise.
If the noise continues, I guess the next step will be replacing the u-joints on the rear drive shaft.
After that, the pinion and carrier bearings.

I noticed the transfer case rear tailshaft oil seal is leaking, so I'll have to pick up one of those too.

[Jeffy]

Do you think a CV driveshaft cure that?

Not if it's the pinion or carrier bearings.  You don't need a CV driveshaft to fix it either.