Proper Torque For Axle U-bolts

As a follow up to my axle tube cracking thread. I've finally been able to remove the axle and will start repairs soon. As I looked into the TSM for the '74 CJ I see a few different torque values that are all dependent on size of u-bolt. Since this is an aftermarket spring set I wonder if the same torque values apply? The bolts are 1/2". I can't find the instructions that came with the springs but I believe they said torque to 85 ft/lbs and that may have been my problem since it seems too high according to the TSM.

What have you all used for u-bolt torque on the rear Dana 44 on a CJ5?

TSM says:
Torque 9/16" to 85-105 ft/lbs
Torque 1/2" to 45-65 ft/lbs
Torque 7/16" to 36-42 ft/lbs

 

65 ft lbs initially, 70 when i recheck em.

 

I would follow the TSM. The rear axle on a '74 has 1/2" bolts from the factory. I kinda doubt the difference between 65 and 85 ft-lb will matter here.

 

Yeah, I'm thinking TSM also.

 

After seeing this thread and your axle crack thread, I think I'll check the torque on mine.

 

I replaced the center pin on a Dump truck left front spring pack in the middle of a state fair parking lot when it broke and the axle moved backwards until the tire hit the fender. The torque it called for on the U- Bolts was 600 ft lbs. I borrowed a huge 1" drive torque wrench from the maintenance guy at the Fair Grounds and with an extension pipe on the handle I was only able to get them to 300 ftlbs and that was with both feet on the frame and my *** 6" off the ground pulling as hard as I could.

Boss ignored me when I told him it had to go to the shop to be retorqued. About 6 months later the thing did the same thing in some womans driveway during a delivery while the boss was driving it. WHAT A DUMBASS

 

At the same time, I believe it is discouraged to "re-torque" after reaching the proper spec.

As I understand it, the U-bolts are engineered to have some elastic stretch in service and retorquing or overtorquing will over-stretch them. That's also why they should not be re-used.

Some one with expert knowledge can correct me if I heard it wrong..

 

For future search purposes, the BDS instructions for the lift I'm just now installing state to torque the U-bolts between 75-85 ft. lbs. for their 1/2" U-bolts, and then to re-check torque after 500 miles.

 

I believe the instructions from my Rancho kit, installed eons ago, gave similar instruction. 75 lb/ft is what I recall and retorque after so many miles.

 

Axle u-bolts when manufactured have the basic shape but are not form fitted. Once installed and vehicle drive they form to the axle and the nuts loosen up because of this. That’s why they should always be re-torqued.