9.25 rear 3.92 differential final assembly.. Finally

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DazSpaz

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Tech questions...

Finally have time to put the diff back today.
3.92 rear 1500 5.9 auto 4x4. New clutch packs, carrier bearings and races.

#1) what has everyone set, or aimed to set backlash to? I've read a span from 0.003 to 0.009...
I have it in my head .005 to .008 is acceptable..

#B) After its reassembled, is there anything I can do to verify its good before I install the axle back in the truck? Or after its back in the truck but before I've started up and test driven? Is there a way to know you're not gonna have carnage in the first drive?

#4) What an I looking for to know I'm safe to take it for a rip? Is it always obvious right away that you've made a mistake, or do some errors take time to present themselves?

#4b) anyone open the diff back up after a few trips to have a look? Any point to doing so?

98 ram 1500 magnum
5.9 gasser auto 4x4

Thanks ahead..again...
 

DodgeDude99

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You should’ve pulled a gear pattern & back lash reading before you tore it apart.
Look on the ring gear, it will have the backlash is was lapped to during manufacture. But it will be in the 006-010 range as you listed.


You need gear marking compound.
 
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DazSpaz

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I did both before I disassembled. backlash was .003
reassembled with a backlash of .007
carrier bearing adjuster cups torqued at 75 ft pounds
bearing cap bolts 100 ft pounds
Gear mesh pattern matches pretty much identical to what i pulled off drive and coast side of ring gear before disassembly.
have already taken it for a tester ...see below

Soooooo...any noise is bad. Took it for a spin around the property. Nothing crazy, just some putting around some figure eights and a little forwards backwards. Nothing over 30 km/h heard what sounded like a metallic clinking. No pattern to it and very very sporadic. Hardly happened but when it did it sounded crappy.
Back on blocks, diff cover off and nothing has changed. No metal bits, retainer clips in place still, Backlash still 0.007 / 0.008. Not brake noise.
Flushed the diff and threw the cover back on. Filled it up, this time adding a lucas diff additive, on top of the friction modifier and Lucas 80 90 diff fluid to full. Ran it around again and same same. Not rotational, no pattern to it. Hear it for a second or three and then its gone. Doesnt happen when i take my foot off gas and coast, doesn't always happen in just forward or just reverse. Not speed related either. Im F*****g lost here.
No damage at all in the diff.
Any opinions or advice?
 

SYKRAMMAN

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Your 100% positive noise is coming from rear diff? Could it be outer bearings making the noises?
 
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DazSpaz

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That would be nice but they were quiet before the diff job...
 

DodgeDude99

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I know guys on Pirate that say preload should be at 150 not 75.
You’re using the tool that goes in thru the axle tube correct?
 
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DazSpaz

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Made my tool but yes... In through axle tubes. Not trying to do it through the holes near the adjusters with a screwdriver. I don't know how anyone could get any torque nevermind a proper read by doing it that way. I'm pissed with this thing right now so gonna work on the boy and the wife's atv first thing this morning. After that maybe I'll block the truck and retorque to something higher. You think I have wandering or something because I'm only torqued to 75? It's a **** off because there is no pattern to it.
In gonna take an old hose and run it from cab to rear end taped in various spots and see if I can pinpoint the source of the noise a little bit better.
Thanks for the reply mate.
 

DodgeDude99

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Atleast it’s an easy axle to work on.
I rebuilt/regeared the 12 bolt for my Camaro last month, it uses shims to set the preload.
 
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