unklej

iTrader: (1)

I'm having a problem with a low humming noise coming from my diff. I installed a TT with my factory gears that came out of the truck and I set the lacklash to within .0005-.001" of stock (.0065 stock, now set at .007"). I broke-in the diff in with Conventional 80/90 gear oil for 500 miles and she was quite. I then changed the fluid with Mobil 1 75/90 and now I have a low hum (not whine) between 35-40 mph when I let off the gas. The noise is not super loud, you need to have the radio off and the windows up to hear it.

The noise is worse when cold and then gets a bit quiter when the diff warms up. Do you think the rear shifted or settled causing the lash to change. I only get the noise between 35-40 and the diff/gears are dead quite everywhere else.

Or do you think the noise is coming from the mobil 1 gear oil?

CHEVY6000VHO

iTrader: (2)

Sounds like you have too much backlash.
The humming noise you explain usually means it may have placed wear marks onto the gear teeth now. You may not get the noise to stop now even if you put the backlash where it should be.

Jim

8MC

iTrader: (3)

I 2nd the backlash. Mine has done the same since new. But if you just add a little gas while coasting to load the drivetrain it goes away right? I'm just going to deal with it until I lift the truck and swap the gears.

LS1TRUCKGUY

iTrader: (7)

i 3rd the backlash. i was told also if it is a low hum, then the backlash is not correct. it will wear a pattern in the gears, so if you reset the backlash, the hum will most likely not go away.

unklej

iTrader: (1)

I hear you guys, I know I'm in spec with the gears (.003-.010"), I guess it just doesn't like the differance between stock. There were 35,000 miles on the gears before I did the diff install. Also, the noise does not change with throttle in that 35-40mph zone. Weird right. I can be on the throttle lightly or coasting and the noise is the same. I guess I should have said that before.

So, other than a new set of gears, there is nothing I can do about it? The noise is super low, I mean you really have to listen for it over the tire noise.

Jeff

CHEVY6000VHO

iTrader: (2)

An abnormal wear pattern in the gear teeth will cause the noise.
There is nothing you can do to quiet it down anymore.
Maybe some sawdust and a few fresh bottles gear oil............ J/K!
You would need a new set of gears and a professional installer to cure and prevent anymore diff noise.

Jim

Blown02Sierra

all annoyances aside, will that cause any less durability / expected life?

unklej

iTrader: (1)

I just spoke to a guy at Randy's ring and pinion and he said that the only reason or way a rear will make noise during decel is because of a loose pinion bearing. The thing is that I didn't touch the pinion, I guess I could take a look.

unklej

iTrader: (1)

Ok, I figured out why the rear was making noise. The answer is kind of stupid, but here is some info. I installed the TT and broke it in for ~550 miles. At that time I changed the rear fluid with mobil one and I installed my 07 yukon 17" wheels and new tires (goodyear triple treads). After that I started to hear the noise.

So, to rule out the tires reinstalled my old stock 16" wheels and general tires and drove on them yesterday and today. With the old tires the noise didn't exist. Everything was dead quiet. I reinstalled the new rims and tires, the noise returned. So, the Hum was from the new tires. I'm just glad the noise wasn't from the rear, it was starting to drive me crazy.


Also, the 17" 2007 Yukon wheels with 275-60-17 tires weigh 63 lbs each vs. 50 lbs each for the stck Aluminum 16" wheels with 255-70-16.

Jeff