Nitro gear humming

So i had my nitro 4.54 front and rear gears done about 1 1/2 years ago. Do to my job i never had time to take it in to the people who installed them to re check. But ever since the gears have been in, the truck hums when letting off the throttle at almost all speeds. Only time it doesn't is if the rpm"s are above 2,800 rpm or so. I use 85w140 fluid in it. Trucks had 5,000 miles on it since and still runs good just still hums. I figured it was because they were heavier duty gears, but finally felt like asking after still being curious. Any input would be great. Thanks

 

So, it's got new fluid in it?

 

The coast side of the gears isn't set up right. Could be pinion depth. Does it have a crush sleeve between the pinion bearings or a solid bearing? Either way, you should pull it and slap some gear pattern compound in there and check the mesh. Do some googling to see what right looks like. If you do nothing, it will not last as long as properly set up gears. Get a good neodymium magnet and let the gear oil drain across it. See how much metal comes out...

 

So now I'm curious as well. Have you ever taken them out to check the wear pattern? (can't remember if you have to reset the backlash if you take the third member out.) I had the 4.56s in my jeep that never hummed. I mean even changing the fluid would have excess metal shavings in it. Did you notice any if you changed it?

I could be way off, but maybe the backlash was just a little bit out of tolerance enough to wear a little harder once you let off. I mean it would have to be looked at to tell for sure.

 

Ive never messed with diffs and gears so probably wont take apart. But ive changed fluid twice now once at 500 miles the second at 2,500 miles. First change looked cruddy due to break in but second change looked fine.

 

Run 'er till she blows and order the next one from ECGS. They know how to set up gears right, and have a warranty that's hard to beat. If you can change the batteries in a remote you can change a third out. You could do it with a single crescent wrench in about an hour if you had to, but jack stands and a socket set will make it go faster. I'm also sure there are some TW members that would give you a hand for a beer and a couple slices of pizza. http://eastcoastgearsupply.com/c-1065072-assembled-3rds-clamshells-05-tacoma.html

 

Lmao that's where i got the gears from just not the built kit. And how long do u think i have till they go out. If its not gonna be long i'd rather not. But if i can get 10k more miles out of them before it happens, ride or die i guess, atleast that would give me time to save for the replacements. Anyone else got any other thoughts. I hate that the only shops that specialize in this are like 4+ hours from me.

 

Anyone?? I mean even if fluid looks good is this still extremely bad?

 

Gears shouldn't need "break in" if installed properly. The cruddy oil is from the gears not being set right. Also will create a hum.

Like he said

 

Thread Rez:

So I had ECGS build me a diff. ARB locker and 4.56 gears. Had a bad seal in the locker. Local shop was paid by ECGS to fix it. Ever since the gears made noise (especially on coasting). As time went on the noise got louder and i could feel gear slap. Drained fluid and had lots of metal. Turned out to be a failing pinion bearing.

ECGS sent new gears, seals, etc. Local shop agreed to warranty since presumably they fucked it up. Instantly same noise. 4k miles later... lots of metal in the fluid again.

So the shop bought me a new, rebuilt, ECGS diff again. ARB locker and 4.56 gears. Instantly quieter. Smoother.

However, this morning at 130 miles into that break in I can tell I'm beginning to hear some coasting noise again.

In theory the shop literally just dropped the 3rd member in and filled with fluid. Not much they could have fucked up this time.

Found this thread while searching because I want to find out if others with Nitro 4.56 hear coasting noise like I do... But haven't had issues.