Morning all,
My Diff/ pinon bearing and carrier berring all went out... basically cheese grating my rear end. I got new gears installed (900 for gears and labor) I know very little about gears and am terrified of repairing all things driveline related myself.

I got it back and drove it around the block and told him it has some coasting whine, and I was told to give it 3 weeks to quiet down.

Drove it about 50 miles yesterday, and I noticed that as I drive, I have a light hum @ 65, and then as I coast down to a stop, every gear it downshifts I get a "whirrr" noise for about 5-10 seconds. It almost sounds like the rear axles are slowing me down, if that makes sense. If I tap the throttle I can pull it out of the noise.

Is this normal for new gears? I have heard that whine at a slowdown means the pinion nut may have worked loose or be backed off a bit too much. I have maybe put 100-120 miles on the new gears.

 

Is it a steady slowing whirr or more like a "voo voo vooo vooo voooo voooo" (chuckle)

The hum up at 65 I would say is new gears, but the slowing down I'm not too sure of. I'm no expert though so hopefully someone has a better idea

 

yeah???? its like either when I am coasting down a hill I can hit a constant "voooooo" as you say

or I get this when I come to a stop 2500rpm....slow....downshift...vooo 2100rpm .....slow....downshift...voooo 1800rpm......slow... downshift.....vooooooo 1000rpm......

somthing like that???

 

What I meant was more like a sound that would show something was out of round or misaligned. But it sounds like everything is straight if that's the sound you're getting. It seems like the sound is only there when pressure on the gears is reversed, when the wheels are pulling on the gears instead of the motor pushing the gears. pressure here -->/\/\/\ vs /\/\/\ <-- pressure there. If you get my drift.

I'm almost inclined to say wait the 3 weeks to see if it all smoothes out and comes into place.

Or it's possible they got a good contact patch going one way but not the other, but time can only tell.. The shop I used gave a 6mo warranty when I got my LSD put in.

 

He did tell you about the break-in procedure, right? With new gears, you can't just drive like you used to, at least not for a few hundred miles. The below link is a bit conservative on its numbers, but better to be safe than sorry with a large investment like this.

https://dodgeforum.com/forum/3rd-gen...new-gears.html

 

Nope, no break in was discussed...not to that point; So I will follow this from now on... I may have broke a tiny bit of the rules... I drove 40 min within the first 200 miles.. am I screwed?

And it makes quite a bit of noise so I am calling him tomorrow so he can look at them Thursday.


That is the perfect way to describe it... I will see once a few more days if it seems to get better or worse, worst case is I call him and ask if he wants to look at it.


I do have a 12mo, 12,000 mile warranty on the work and parts. so that helps me breathe.

I would assume that @ 500 miles I should change the diff fluid?

 

when I first got my 4.10 installed, I was told to romp the crap out of my truck, it helps seat the gears, if you are whining there is an issue, something isnt messed properly

 

Something else, some gears just have a natural whine. It just depends in the brand.

 

+1. Cheaper brands tend to be noisier.

You aren't screwed necessarily. Romping around to seat gears is incorrect, from everywhere I've read. You don't want them to crash together, you want them to slowly seat together. Once the seat is near perfect, romping won't make them crash together, and you can do that.

What brand of gears did you use DM_kota?

 

I strongly suspect that the backlash is set improperly. This can be adjusted (in a regular old-school differential) by shimming the ring gear carrier to the left or right, or by adjusting the pinion depth (again, via shims).

Generally speaking, the pinion depth is set to spec, then the ring carrier is shimmed for proper lash (using a dial indicator).

The symptom of incorrect lash is exactly as you describe (whine on deceleration).