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anyone have any ideas how to quiet down a noisey front differential?

 

Figure out why it's spinning in 1st place

Check that your hubs are unlocked

Check your u-joints aren't failed

 

the noise is coming from the gears when in 4 wheel, u-joints and axle joints are fine, sounds like a gear lash problem

 

That sucks

Once gears start making noise, they stay noisy and get worse. Killing the noise will require new gears and bearings

 

Way back in the olden days, car dealers/sellers used to put sawdust in the diff to make them quiet.......not recommended of course, just reminiscing...

 

Have you checked the fluid? What kind of sound is it making?

 

pulled the front cover off and the spider gears look to have some play in them, not sure how much is normal or if this is even the source, the ring and pinion look good but I didn't check the backlash, oil was full and clean, no metal shavings

 

You are going to hear some gear noise when in 4x4. Over the net its impossible for us to tell if yours is normal or excessively loud.

 

turns out that the pinion bearing is bad judging by the amount of heat in the housing around the pinion shaft after a few miles

 

They get warm under normal use, especially front riffs that haven't broken in fully. During break in, my rear diff was too hot to touch at times, around 180f.

 

truck has 95k on it, rest of the diff was cool just hot around the pinion bearings and the noise is getting worse, definetly sounds like a bearing

 

It can be possible to change the pinon bearing fairly easily. The carrier bearing shims are captured and its fairly easy to remove the carrier once you get the axle shafts out. The toughest part is the crush sleeve if you elect to do a new one. that is the ideal way to do it however, you can check the preload prior to removal (which will probably be pointless if the bearing is bad) and tighten up to the crush sleeve without over torquing it. You should check the final preload, I would guess with a new bearing it should be set to 20-30 inch lbs.

If you elect to do the inner bearing it will be a little more difficult as it needs to be pressed off. It may not be damaged however. Sometimes the outer pinion bearing doesn't get sufficient lube if the level drops but the rest are ok. It's also more susceptible to dirt contamination and there is less mass to keep it cool back there.