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Hey everyone, freshly rebuilt my rear axle and changed gear ratios. I had never done this before and just got back from my first test drive. I noticed a slight howl while driving and now I am starting to second guess myself. I don't know if it is my T5 transmission that I could never hear over my failing original wheel bearings, or the new ring and pinion. It only happens while coasting and goes away when I clutch in or put the vehicle in neutral. Are new gears a little noisy? Should I go through the 500 mile breaking in period before I worry too much? Below is what how I set the ring and pinion up.

Pinion preload: 25 in/lbs
Pinion depth to that specified on the new pinion
Backlash was .009" (.008-.012" range)
Ring gear preload was set up by feel like seen in many videos online.
All new Timken bearings

Marking compound coast side
755884


Marking compound drive side
755885
 

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Discussion Starter #3
The markings look nice
That's what I thought, comparing it to the pictures in my factory repair manual. Maybe i'm just being paranoid.....
 
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If this is only your very first test drive I’d give it some more miles for sure,......how many miles are there, 50?
 

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Discussion Starter #5
Manufacture calls for about 500 total during break in, a few short drives initially allowing the diff to cool, before going on continually longer ones. I've gone about 5 before bringing it home worried about it.
 

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I think that howl is kind of normal. My last gear set did it, new my 3.55's gears do it a little bit, and I've heard Happystang's car driving and hear the same howl in it as well.

What gear oil are you using?
 

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Discussion Starter #7
I think that howl is kind of normal. My last gear set did it, new my 3.55's gears do it a little bit, and I've heard Happystang's car driving and hear the same howl in it as well.

What gear oil are you using?
I'm using conventional 80w-90. I forgot to mention that it is a 3.80 set of gears.
 

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I'm using conventional 80w-90. I forgot to mention that it is a 3.80 set of gears.
And you have friction modifier added as well right? I'm assuming it limited slip? Maybe you said that originally.
 

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Discussion Starter #9
Yeah I have the friction modifier in. I took it for a second drive last night, and it started to make a "whining" noise almost like a jet turbine starting up. Its a real high pitch noise, and what little I can find online points to pinion bearings being too tight. Guess I'm gonna have to pull it out and recheck some stuff just for piece of mind. If everything checks out, I guess I'll just run it and see what happens.
 

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some ratios are more prone to noise than others , hunting versus non hunting. Which is yours ?
 

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some ratios are more prone to noise than others , hunting versus non hunting. Which is yours ?
Mine is a non-hunting.
I would pull it and look at it, because if it’s whining, it isn’t going to stop at the end of its “break in.” It will only get worse.
Yeah that's what I've read unfortunately.... Any chance it could be the pinion pilot bearing? I probably had to seat and unseat that bearing from the pinion a few times trying to get the depth right.
 

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Discussion Starter #14
Well thanks to the simplicity of the axle and only needing a 9/16" wrench and socket, I have it back apart. I will clean it up and re measure my tolerances and report back here.

Usually a pinion bearing will be worse on deceleration.
The noise seemed to be pretty consistent through out acceleration and deceleration. but would vanish when I clutched in.

I built a whole new center section for the 3:80 ratio, so I might throw my stock center back in it and see if the noise remains. Maybe this would be better than chasing my tail? And would only cost me so gear oil and gaskets.
 

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Some manufacturers gears are just loud and are never quiet..... even when perfectly set up. Nothing was as quiet as Ford OE,
that much I will say. We sold Richmond and Zoom and a couple of others.Fairly common to have those two not QUIET.

Your pattern looks ok.
 

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Discussion Starter #16
Here is what I have to report so far after disassembly for re-checking.

Backlash: Was 0.009" Now 0.011"
Ring Gear run out: 0.001"
Pinion Depth: unchanged
Pinion Pre-load: Was 25in/lbs is Now 10in/lbs (Could this be my issue?)
Ring-gear Preload: Seems the same (I don't have the tooling to measure case spread so I have to use the "feel" method)

The Ford manual calls for 17-32 in/lbs of pinion pre-load. Can being off by 7in/lbs really make the noise I am hearing? or should I go off of the "used bearing" specs since I drove about 10 miles on this setup? it calls for a range of 8-14 in/lbs.
 

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IMO the pinion needs to be deeper, based on the pictures. As for the noise it could be because of an incorrect setting but like others have said it may just be the gear set you bought. I can tell you for sure the noise will not go away from break in miles.
 

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Discussion Starter #18
-Update-
It took some time, but I went back and re-set up the rear end, I installed a new crush sleeve and reset pinion pre-load to 25 in/lbs. While in there I also installed a new pinion pilot bearing, as setting pinion depth made me wonder if pressing the pinion in and out of the bearing might have possibly caused some play in it. Even with all of the work, I am still getting the high pitch "whine" or "whirling" noise.

The noise seems to be the loudest when power is applied, and all but disappears when I clutch in or shift to neutral.

Is it possible I got bad pinion bearings and need to go back in and replace them? I also Installed new axle wheel bearings on the rear while I had it apart. Could the noise be from them?

I am at a loss here, and just about to throw the original 2.73's back in and be done with it.... Any one have any ideas?
 

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At this point, I would look around for an experienced ear to listen and tell you if it really sounds like a problem or just something that comes with the gear set. If it is something that is not unexpected for that gear set, then comes the decision to live with it or think about OEM or such.
I remember my first fuel injected motor, I worried like crazy when I noticed a little ticking noise under the hood. Ask someone that knew what they were doing and they just laughed and assured me that was injection pump. That was many years and many miles ago and I squirm to admit it....but hey, I was carb man.
 

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If the pinion depth is off it will cause a whine. I forget which goes with which but if the pinion is not deep enough then it will either whine on the coast or drive side. You can look that up.

What brand gears did you buy? Some lower quality gears will make noise no matter what you do. I got a killer deal on a set of lower quality gears for my truck and they whine. My research said they would whine but for a $50 gear set I thought I would give it a shot.

I literally just got a set of ford gears for my truck in the mail today. I could have kept driving my truck like it was and I have well over 5000 miles with the whine but I couldn't pass up on such great deal for the ford gears, so I bought them. It may be a month or two before I get to replacing them but the whine I have should go away with the ford gears.
 
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