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Unread 08-23-2014, 04:02 PM   #1
EvilM0nkey
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2002 TJ Wrangler 
 
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My rear end is making funny noises. Need help figuring out why.

So here is the story.
I installed a used S35 kit with a Detroit locker it drove nice and quiet. No gear whine at all. A few months later wear showed up in the locker cogs as ratcheting while driving forward.

When it was installed I used all new bearings on the locker and my pinion with a new crush sleeve.

It made zero noise when I put it up on the lift to tear it apart.

My Fix:

-Took locker out, set all of the parts on my cart the same way they came out.
-Took the locker guts out flipped them over and put it back together
The three center cogs in the picture (ignore the rest, not the same as my locker)

(So when driving forward I would be using the cogs that were originally used in reverse). The locker operation is 100% normal, except it ratchets when I decelerate, which I expected to happen. I'll replace those eventually.
-I put it all back together the same way that it came apart (the orientation of the locker case was not affected by my fix, just the internals).

Immediately after I put it back together I have pretty intense gear whine that gets worse while cornering.

I have pulled it back apart and the mesh pattern seems the same, even swapped the shims around just in case I messed those up and no change.
I'm 100% sure the bearing caps are correct.
I've been back inside of it several times since trying to figure it out and I can't.

The noise ONLY happens under load. If I'm coasting in neutral at any speed it's nearly silent.

What in the world could have gone wrong? I'm tired of the nose and I have to open it up to replace a bent shaft soon anyway. Just want it to be quiet!

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Unread 08-25-2014, 09:15 PM   #2
Evildriver-3
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sounds like a depth issue
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Unread 08-26-2014, 04:52 PM   #3
EvilM0nkey
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Any idea what could have caused it?
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Unread 08-26-2014, 05:54 PM   #4
BlueRubiconrich
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solve it with a Dana 44!
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Unread 08-26-2014, 06:53 PM   #5
rjbruzan
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At some point the shims(cast iron ones) got mixed up. Or the bearing caps or bearing cups. The ring gear needs what is called backlash. A tiny amount of play between it and the pinion. The carrier needs to be installed in the axle housing with preload to keep it from expanding or wobbling in the housing. One or more of these setups is not correct any more causing your noise. Without being there no one can tell whats wrong only make educated guesses.
I believe there are Dana manual available at the top of one of these sections. Study them and it will help you understand how each of these help to make a quiet differential.

Ron
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Unread 08-27-2014, 05:50 AM   #6
Evildriver-3
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The pinion depth is wrong. Did you have the depth setting ? Do you have the tool for it to check what the height was ?
Usually the scenario you have is the pin is running shallow.

.
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Unread 08-27-2014, 06:03 AM   #7
EvilM0nkey
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Quote:
Originally Posted by rjbruzan View Post
At some point the shims(cast iron ones) got mixed up. Or the bearing caps or bearing cups.
I know all of this is correct. I swapped the shims in one of my tests just to make sure, they are so close in size I didn't see it making a difference anyway. (I did put them back)
Quote:
Originally Posted by rjbruzan View Post
The ring gear needs what is called backlash. A tiny amount of play between it and the pinion. The carrier needs to be installed in the axle housing with preload to keep it from expanding or wobbling in the housing. One or more of these setups is not correct any more causing your noise. Without being there no one can tell whats wrong only make educated guesses.
I believe there are Dana manual available at the top of one of these sections. Study them and it will help you understand how each of these help to make a quiet differential.

Ron
Ok then. Preload, that might be what I did wrong. I knew you were supposed to preload the pinion, but not the carrier. Took 4 years of asking the question to get an answer, but I finally got it. Now I know where to look for more information.
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Unread 08-27-2014, 06:16 AM   #8
EvilM0nkey
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Ok so carrier preload is done with the shims? So Basically I need to re-shim the carrier. For whatever reason the shims are no longer the right size. I know zero about differentials so I'm just trying to figure all this out. I did notice it felt like there was a good amount of end play. But since I didn't change the shims I assumed they were ok.
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Unread 08-27-2014, 07:38 AM   #9
Evildriver-3
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Carrier and pinion both need preload.

At this point you should get professional help.

A shim at .0015 is a world of difference in differential set up.

.
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Unread 08-27-2014, 11:31 AM   #10
EvilM0nkey
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I've been asking professionals for years and nobody will give me a straight answer. For some reason people are afraid of lockers and non stock axle shafts.
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Unread 08-27-2014, 02:58 PM   #11
Evildriver-3
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Then they aren't professionals and you need to find one. You'll find lots of "professional" people that haven't a clue how it really is, unfortunately you're to far for me to help, you definitely have a depth issue and carrier preload issue.
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