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Ford 8.8 vs. U-Bolts

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Old 02-13-2015, 07:58 AM
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Default Ford 8.8 vs. U-Bolts

Through searching online, I've come across a myriad of opinions on what the torque specs are of the rear leafsping-to-axle u-bolts. I've heard as low as 55ft-lbs to 102ft-lbs. I cranked mine down to 100 even and now I have a popping sound under torque and tight turns. Can't remember what I cranked them down to when the axle first went in.

How tight can I crank those things down? It looks like its starting to distort the retention plate. I seriously doubt I would crush or bend the axle tubes but what do you think the max torque is there?
Old 02-13-2015, 12:26 PM
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I keep mine damn snug. tighten, alternate, tighten, repeat. check it again in a week

bending the ubolt plate? why didn't you buy ruffstuff
Old 02-13-2015, 01:02 PM
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Originally Posted by Atmos
bending the ubolt plate? why didn't you buy ruffstuff


Nah, 3/8" thick from CreepyFabrication, operated by another CF Member, Hammered.


Found this, but they may be pulling that torque spec out of their _______
http://www.4x4proyect.com/product/ru...ing_u-bolts/fr
Old 02-13-2015, 01:07 PM
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That may be it though- RuffStuff's plates (also 3/8") have a lateral bend that would prevent the perpendicular distortion I'm experiencing. I may just weld a couple of bridges on for rigity...
Old 02-13-2015, 10:56 PM
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Torque them to 80 ft lbs, and recheck in a week or a few hundred miles.
Over tightening the U-Bolts makes a ride harsh.,
Old 02-15-2015, 10:19 AM
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Originally Posted by Caish
Torque them to 80 ft lbs, and recheck in a week or a few hundred miles.
Over tightening the U-Bolts makes a ride harsh.,

I already said each nut on the bolts is torqued down to 100ft-lbs, and its still popping them. How tight can I get them before they break?
Old 02-15-2015, 05:04 PM
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How do you know they are what's making the noise?
Check shock bushings and spring eye bushings for good measure. I don't know if I would be cranking them too far past 100.
Like atoms said, ruff stuff is the way to go if you only like buying things once
Old 02-15-2015, 09:29 PM
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Grease the inside of the U. And tap 'em with a hammer a few times and check tork again. One reason they might loosen is if they fetch up a bit cockeyed when you tighten them, and then get knocked straight after a while. Greasing and tapping helps ensure they seat properly and you git all the slack out. I think....

Last edited by goatherder; 02-15-2015 at 09:35 PM.
Old 02-18-2015, 03:36 PM
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Originally Posted by goatherder
Grease the inside of the U. And tap 'em with a hammer a few times and check tork again. One reason they might loosen is if they fetch up a bit cockeyed when you tighten them, and then get knocked straight after a while. Greasing and tapping helps ensure they seat properly and you git all the slack out. I think....


That's pretty much what the problem was- I put a bottle jack on the base of the differential closest to the pinon and tilted the axle up and heard a loud pop from one side. Staring at the clean u-bolts on the shiny axle tubes made me realize what might be going on... When we removed the old bolts, we cleaned up the axle tubes with a rag that already had grease and RTV on it, and I think that made the surface slick enough that the axle could twist a little. All of the welds where the tubes meet the pumpkin are still solid so I'm glad I didn't spin any of them. I removed the u-bolts, sprayed everything down with brake cleaner and wiped it with a clean cloth and then laid down some new black spray paint. I tightened the bolts while it was still tacky and went to 110ft.lbs. and haven't heard a pop since. Thanks for everyone's help.
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