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post #1 of (permalink) Old 09-02-2006, 12:07 AM Thread Starter
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torque specs ring gear amc 20

anyone have the factory torque spec for the bolts of the ring gear to the carrier in a amc 20 rear end. In the Jeep CJ Rebuilder's Manual by Moses Ludel on page 283 it say's to torque the bolts evenly in a cross pattern in three steps bring torque to 105 lb-ft the jeep/amc factory spec. But I think this may be a misprint because looking at general torque specs for 7/16 bolts it is 40 to 65. The bolts on the dana 44 are speced at 55-65 and I would assume the bolts are about the same size. does anyone have the sepc for this from jeep.? and If I already torqued them to 105 should i get new bolts and replace them. I don't want these braking off because I have over torqued them. no good inside the diff.
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post #2 of (permalink) Old 09-02-2006, 03:06 AM
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Re: torque specs ring gear amc 20

I have had the same problem. Yukon gears install manual avilable online says 65 ft-lbs. However, other places online say 105 ish. I asked about this a couple of days ago and Jim was kind enough to look up this up in his FSM here is a link to the post. link
Sadly I only torqued to 65 ft-lbs so I need to remove the bolts and clean out the locktight and retorque.

I think the reason that the bolts are tighter then standard torque for 7/16" bolts is because they are one use bolts that are deformed on torqueing, like some head bolts. Most Dana 44's use 10 3/8" bolts. While the AMC20 uses 8 7/16" bolts. Note that the strength of bolts in tension and shear is proportional to the square of diameter so a 7/16" bolt is 1.36 times as strong as a similar grade 3/8" bolt in tension and shear. The torsional strength of a 7/16 bolt is proportional to the 4th power of the diameter. So a 7/16" bolt is 1.85 times as strong as a 3/8" in torsion. So a torque spec of 105 vs. 65 is not unreasonable.

Many things do not scale in a linear fashion, for example a one inch wide by 1/8 inch thick stripe of metal is 8 times as strong as a stripe 1/16" thick by one inch wide when loaded on the wide side. Provided ofcoarse that the metals are of the type and tensile strength.
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