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Re-use ring gear bolts?

Root Moose

NAXJA Forum User
Location
ON, Canada
Hey all,

I've been parting some gear to get ready to buy more kit for the XJ. Part of that was some D44 axles.

I've read in a few places that you shouldn't re-use ring gear bolts - always use new ones with a new set up.

What is with that? These aren't torque to yield so there is no plastic deformation...and the torque reading is quite low as well (IIRC, ~60lb-ft).

Anyone know better? Is this just an old wives tale? Excuse for vendors to sell more set up kits?

r@m
 
While ring gear bolts are pretty damn solid, and certainly aren't stressed enough in tension to be "torque to yield" and have trouble with longitudinal plastic deformation, I'd be a bit paranoid about plastic deformation in shear. When you think about the heavy torque loads going thru your ring gear (the most would be in first gear/4LO, which is engine torque times first gear ratio times transfer case ratio...) you're putting a lot of shear on those bolts, and shear strength is typically estimated at 1/3 to 1/2 of tensile strength. There is no direct correlation between tension and shear, and the only effective way to test for shear strength is by destroying a few lots of parts.

That, and I'm paranoid. You've gotten it torn that far apart - why take the chance? Besides, a good setup kit will come with the ring gear bolts anyhow, in addition to the bearings, the shims, and anything else you'll need. If they're doing their job right, you'll have everything you need.

I haven't done the math on the thing, so there's no Earthly reason why Beez shouldn't have had some good luck reusing bolts. Still, I'm paranoid, and usually for good reason...

5-90
 
5-90 said:
While ring gear bolts are pretty damn solid, and certainly aren't stressed enough in tension to be "torque to yield" and have trouble with longitudinal plastic deformation, I'd be a bit paranoid about plastic deformation in shear. When you think about the heavy torque loads going thru your ring gear (the most would be in first gear/4LO, which is engine torque times first gear ratio times transfer case ratio...) you're putting a lot of shear on those bolts, and shear strength is typically estimated at 1/3 to 1/2 of tensile strength. There is no direct correlation between tension and shear, and the only effective way to test for shear strength is by destroying a few lots of parts.

That, and I'm paranoid. You've gotten it torn that far apart - why take the chance? Besides, a good setup kit will come with the ring gear bolts anyhow, in addition to the bearings, the shims, and anything else you'll need. If they're doing their job right, you'll have everything you need.

I haven't done the math on the thing, so there's no Earthly reason why Beez shouldn't have had some good luck reusing bolts. Still, I'm paranoid, and usually for good reason...

5-90

but really.....like you said, considering that MOST R&P kits come with new bolts anyway......"couldn't hurt, might help"
 
I second that.
Same as U-bolts.
You could reuse, but why?
You could drive with your feet if you have to, but that doesn't mean it's the right thing to do.
HTH.
 
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