Bit o' differential play

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Rjonesy
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Bit o' differential play

Postby Rjonesy » Thu Mar 08, 2018 6:35 am

My pinion shaft has a bit of play and some resonance in deceleration. My question:

Can a re-torquing of the flange nut take this play up or is a re-build needed. I did replace lubricant when I purchased it last summer. This truck had been meticulously maintained in its previous life and has 150,000 on the odometer so I wouldn't think bearings would be bad but then I'm still learning about my P'up. I understand that the torque on the nut is critical and can compromise the crush spacer.

oldestisuzuist
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Re: Bit o' differential play

Postby oldestisuzuist » Thu Mar 08, 2018 9:40 am

Maybe.
Making noise on coast, not on power is a symptom of a loosened pinion nut. Sometimes re-tightening will cure the problem, if it doesn't or you get the nut too tight then the only fix is a rebuild. Try tightening the nut a bit at a time followed by a test drive to see if the noise lessens. Use a torque wrench, start low, gradually increase until the noise quits, then stop, or at least don't increase much for a final setting, then stake the nut to the shaft to keep it from loosening again. FYI the last two I had success with using this method the noise disappeared at about 100 ft-lbs. This may not be the same with your differential, so sneak up on the final tightening torque, record it to give you a starting point should the problem ever return. You can always tighten a loose nut a bit more, loosening one too tight does no good.
By all means report back the results should you decide to try this method.
'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, body ROUGH, bought new 12/4/78. A pre-P'up?
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch.

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Rjonesy
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Re: Bit o' differential play

Postby Rjonesy » Thu Mar 08, 2018 11:07 am

Thanks. Will do.

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Rjonesy
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Re: Bit o' differential play

Postby Rjonesy » Sun Mar 11, 2018 5:16 pm

Wow - my nut was very loose. Had never been staked. I put the torque wrench on it (I've got the handle dial kind) and set it at 80 lb thinking from your experience that would be low. Just by feel it must have been 40 or less. "little pinky" tight. I hope I didn't over do it as it felt so very loose. I set it at 60. And my word. What I thought had been road vibration and diesel vibration all this time was the dang drive line. I also replaced the rear u-joint, had done the others earlier. The cars in the rear view don't shake any more. I still need to go back and stake the nut. Hopefully didn't over crush the spacer. It sure does drive much nicer though.

oldestisuzuist
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Re: Bit o' differential play

Postby oldestisuzuist » Sun Mar 11, 2018 7:39 pm

I doubt you overtightened. Getting it tight enough to quieten the noise on coast is the main thing, but I would re-torque to the last reading just before staking the nut, as you drive it without a staked nut it can gradually loosen. In fact it may loosen & start making noise on coast again even after staking, if so just tighten until it quits again, but the final torque may be different since you have to overcome the added resistance of the staking. If it doesn't loosen then the staking mark gives a good physical indicator for tightening the nut back to exactly the same place should you ever need to replace a pinion seal.
An overtightened bearing tends to make noise on power as well as coast, so if the rear stays quiet you probably got it right.
BTW I find these rears tend to produce a lot of heat, so make sure the vent if functioning.
'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, body ROUGH, bought new 12/4/78. A pre-P'up?
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch.

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Rjonesy
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Re: Bit o' differential play

Postby Rjonesy » Sun Mar 11, 2018 10:25 pm

Thanks. I was planning to re-check the torque. Just didn't wanna crawl back under there this evening.

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Re: Bit o' differential play

Postby gearbox » Mon Mar 12, 2018 8:56 am

When I did mine I used blue LOC TITE .
81 sport 4x4 diesel [parts]
81 micado 4x4diesel
97 ford 250 7.3 4x4
9600 ford [135 hp tractor]
84 MPG rust over rust 2x4 [parts]
91 space cab soon to be married to above MPG

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Rjonesy
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Re: Bit o' differential play

Postby Rjonesy » Wed Mar 14, 2018 10:52 am

Good idea.