Had the truck in a garage tonight to diagnose my humming noise in turns that remains after replacing my hub bearings.

I only hear the noise at a decent speed (40 to highway speed) and only in turns (which was the original reason I thought it had to do with the front end).

Preliminary diagnosis was actually in the rear of the truck. Mechanic brought me in to hear what he found. Had the truck up on the lift and the another lift under the rear diff so he could spin the tires. He said there's a possibility that the ring and pinion are shot, possibly chipped teeth, etc. I DID NOT have him pull the cover because I need the truck tomorrow. The other possibility he gave was something with the parking brake, said it could possibly be hanging up. I told him I set the e-brake every time I park the truck so pretty sure it's not hung up.

The options he gave me WITHOUT pulling the diff cover were a new ring and pinion or to put a whole new (used) rear under it. He said a new rear might be the more cost effective route. My ever-knowledgable mechanic Brother said to pull the diff cover myself, check the fluid, check for metal shavings and/or obvious signs of damage. He also said as a mechanic he'd rather change a ring and pinion than replace a whole rear because there are less things to change (brake lines, etc.) and there's no guarantee that the used rear will be in any better condition than the one coming out.

SOOOO, which would be cheaper? New ring and pinion or whole new rear?



CLIFFNOTES: My humming/whirring sound was diagnosed as coming from the rear. Might need a new ring and pinion, won't know for sure until rear diff cover is removed. Mechanic said it might be cheaper to put a whole new rear in, which is cheaper?

EDIT: Also, since this sound has been present for a couple months now and hasn't gotten any louder, can I assume I still have a little time to replace? Like, say until Easter?

 

Yea I don't see how a new rear end is easier/cheaper..

Then again I was told by my mechanic neighbor that re-doing the ring and pinions and getting the shims and splines and what not all perfect is a PITA.

I'd guess it's all about cost! Good luck sir!

 

Speculation... You really need to pop the cover and have a look inside.

 

Just to add my .02 cents worth.
Ring/pinion/bearing noise would be constant, either in drive/coast or both and diminish/increase with speed. not on cornering only.
spider gearscould cause noise as well as outer wheel bearings on cornering.
droping the cover would be a good place to start as mentioned, again this is all speculation
Also it could be as simple as a splash shield rubbing the rotor,and the little endplay in the axle allowing it to do so,
again, speculation with out hearing it first hand.

 

In the middle of rear axle service. Pics and vidz to follow to prove that it actually happened.

I do have some shavings. No chipped teeth. Some scoring on the innermost gears. What does this mean for the condition of my rear? Definite replacement?

Also, the new cover came with a magnet but the old one didn't have one. It had the little indent for the magnet to fit around but alas, it was not there.

 

I just did my rear axle and went to synthetic. The cool thing was the clunking I had in my driveline which I had always thought was the tranny...turns out it was the rear diff. After the cleaning and fluid swap to synthetic, it's perfectly smooth, no clunking, and hard acceleration does not give me a jolt-clunk sound!

I had a tiny bit of shavings as well, but I figured with 100k miles on it, some shavings would be present. No markings or anything, so I deemed it ok. Do scorings mean the rear end is toast?? That's unfortunate [&:]

 

Good, or I was gonna call BS.

Weird that the magnet was missing, they usually hold quite a bit of filings etc. Just clean it all up, put on the new cover with magnet, fill up the fluid, and hope for the best.

 

Correction, teeth don't look so good.

The sound remains, heard most prominently in somewhat sharp turns at speeds 35MPH and up. Good news is I got new fluid in the rear diff so that should be set for a while. Bad news is I'm flustered and don't know what this sound is. Pics and vidz as promised:



Popped the cover-click for video



Here's the closeup of what the teeth look like:

Turning gears VIDEO Slop in driveline VIDEO



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that is not as bad as i thought it was going to be, no doubt the shavings were small, considering what ive seen, unfortunatly it all looks like it came from your spider gears, in this situation your going to need to rebuild the entire deal, one for safety and two if we only replace the spiders now it doesnt mean the ring or pinion gear wont go further in the future from shaving contaminated fluid, and that fluid was burnt to a crisp i might add, and three im your bro better safe than sorry a full rebuild will guarantee worry free driving for another 80k,when you change the fluid again, soid say replace w a new ring and pinion, along with new spider gears, the carrier should be fine, so heres your list - if moneys a big deal, we would have to eliminate new ring and pinion gears -

ring and pinion set- comes with new shims and bearings and races
spider gears
rear diff fluid - might want to think bout synthetic
lucas rear diff fluid - recommended
new gasket

 

Hrm...my diff cover didn't have a magnet on it either..And I tried to save money and not buy the new cover...what a mistake. Took me as long to clean off that stupid old cover as it did cleaning the entire differential!!!

And man does that old fluid stink. Sucks about your gears though...maybe you should look into a G80 from a junkyard