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Differential builder in Oklahoma City? I need help
#1680090
09/29/14 11:35 PM
09/29/14 11:35 PM
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Joined: Oct 2011
Posts: 460 Oklahoma
VoodooCLD
OP
mopar
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OP
mopar
Joined: Oct 2011
Posts: 460
Oklahoma
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I recently did my first rear end rebuild. It was a 742 cased aftermarket geared 3.55 clutch type sure grip. I put in new bearings, clutch pack, gears and seals. I bought books and read all about it for months. I put it in and had no issues for about 100 miles. I drove it to the track planning to take the car down the 1/4 mile, but started hearing some noise from the rear end. Mainly when i was turning at slow speed and sometimes some clunking. I thought at first that it was just the new tight clutches slipping, but after a while it had me concerned. The car also was acting a little weird going through sweeping corners on the highway like a little vibration in the steering wheel. I pulled the driveshaft and checked the u-joints (both are new) and they seem to be ok. Then i pulled the axles, but couldn't really look at them as i don't have a press to pull them off. I figured i was that far so i went ahead and pulled the pumpkin as well. I'd like to find someone in the OKC area who is familiar with these 8 3/4 rear ends to verify the specs of my build while dismantling (backlash and pinion depth) and make sure there is no damage, and then reassemble.
I'll pay extra if they let me hang around and see if/where i screwed up. To this point i don't know what the problem was. I don't see any catastrophic failure and the wear on the gears look good (to my untrained eye)
Know of anybody that can help?
Last edited by VoodooCLD; 09/29/14 11:36 PM.
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Re: Differential builder in Oklahoma City? I need help
[Re: Supercuda]
#1680095
09/30/14 01:37 AM
09/30/14 01:37 AM
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Joined: Oct 2011
Posts: 460 Oklahoma
VoodooCLD
OP
mopar
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OP
mopar
Joined: Oct 2011
Posts: 460
Oklahoma
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That was the bearing preload on the pinon bearings. I torqued the nut to 200-300 ft-lbs + with red lock tite. Now when i'm measuring it its only measuring 5 - 7.5 inch pounds of preload indicating the nut loosened up a bit.
Last edited by VoodooCLD; 09/30/14 01:37 AM.
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Re: Differential builder in Oklahoma City? I need help
[Re: DoctorDiff]
#1680102
10/01/14 11:12 AM
10/01/14 11:12 AM
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Joined: Oct 2011
Posts: 460 Oklahoma
VoodooCLD
OP
mopar
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OP
mopar
Joined: Oct 2011
Posts: 460
Oklahoma
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Thanks again Cass. After further diagnosis. My pinion nut was most definitely NOT backed off. It took an elephant sitting on a 4 foot cheater bar to break it. I guess i was measuring bearing preload improperly before. I pulled a shim out and torque the nut again. It seemed REALLY tight. I then rotated the pinion about 50 revolutions in each direction and it seems to loosen up a bit. Final reading after that was about 23 in-lbs.
I'm gonna install tonight and see if that helps.
Would a bearing preload of 5 - 7.5 in-lbs cause a clunk in the rear end, and possibly a little steering wheel vibration on sweeping corners?
Last edited by VoodooCLD; 10/01/14 11:16 AM.
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