2nd Gen Non-Engine/Transmission spring shackle bolts loose

[farmer1022]

My u-bolts holding the spring and rear axle assembly on my 96 dually were loose and I tightened them to 260 foot pounds less than 500 miles ago. They are loose again! Has anyone ever experienced this? I don't see any evidence of bolt stretching and I can't see where the nuts have backed off.

Wow, does it drive terrible with the rear axle flopping around!

 

[slo-ryde]

I was under my truck a few days ago checking for clunking noises. The u-bolts were tight (38,200 miles on the odo). I did notice there's quite a bit of thread left below the bolts, maybe you could add a jam nut to keep them from coming loose?



260 foot pounds seems like a lot for that sized bolt, did you get that from a service manual?

 

[WestTN]

I don't know if the 2001 spec's are the same as for your 1996, but if they are the problem ismost likely shackle stretch. The 2001 torque value is 110 ft. lbs.

 

[jkalchik]

Uh, wait a sec... ... u-bolts, or shackle bolts? These are *NOT* the same thing.



U-bolts connect the axle tube to the springs. The shackles are at the rear of the leaf pack.



In any event, like Dennis said, you're probably stretching the bolts. If you've over-torqued them by that much, you should be replacing them.