Shortening Spring U Bolts?

I'm in the process of replacing the springs and shocks on my '56 CJ5. I'm finding that the new U-Bolts are a bit longer than the ones I'm replacing. I don't go off road in a radical sense but I don't like these bolts extending so far past the nuts...

Would it harm anything if after I drive around a bit and re-torque everything to specs, I then run a standard nut up to the bottom of the high-nuts, cut the bolts to desired length and back the second (added) nut off to preserve the threads?

See pic of what I'm looking at right now with a 7 leave front spring pack.

I don't think I'll have as much of an issue with the 9 leaf spring packs on the rear (I'll also be using NOS U bolts on the rear).

 

they usually need to be cut, using the 2nd nut is a good idea to keep the threads in shape. although technically I think most places tell you not to re-use the u-bolts.

 

Cutting them is fine. A cutting wheel on an angle grinder makes short work of it. 2nd nut isn't necessary since the 1st nut will do the same function but it will give you a nice level cut and consistency of cut length.

Wear safety goggles and shield.

 

Thanks guys. I've read the same thing about not re-using the bolts so I don't guess preserving the threads is that important. I may add the second nut for symmetry, though, as noted above.

 

reusing u bolts is a common practice.
I would cut the bolts off flush with the nut. This prevents any protruding bolt from being damaged/bent and causing removal issues.

 

Although I’ve been guilty of it too, I would highly not recommend this, especially on a spring-under vehicle like these Jeeps. All the weight and impacts are pulling against those bolts on a SUA setup. Not a place you want a fatigued bolt.

 

I worked in a 4X4 shop for years. We did tons of spring related work and never replaced a U bolt unless it was damaged, specifically requested, or needed. I have never seen a U bolt failure due to reuse, not have I ever heard of one. I have never heard of an issue from other shops as well.

Not saying I'm the last word on this, only I feel this is more of a liability disclaimer than an actual issue.

I'm getting close to installing a 4" lift on the CJ and, if they fit the new packs, will be reusing my U bolts without a backwards glance.

 

Doesn’t make it right or recommendable.
And yes, I’ve had a re-used one fail on me in a race. Front axle on a SOA setup. Snapped where the threads end.

 

Just out of curiosity, how did the bolt fail?

A 6" long, grade 2 7/16" bolt has a proof load of 5,850 LBS. Given there are four of these in a standard spring system, that gives a total weight carrying ability of 23,400 per axle. Given the shear value of the same bolt is 4007 LBS (16,028 for 4 bolts), I would much more concerned with the bushing bolt failure than the U bolts.

Barring overtorqueing, damaged threads or shank, or manufacturing errors, I'm hard pressed to believe one will fail under anything but the most extreme conditions, regardless of how many times they have been assembled/disassembled.

I'm sure there are specific circumstances where replacement may be prudent, however, for the other 99.9% of the rest of the world reusing spring u bolts creates no more serious issues than reusing bushing bolts, U joint bolts, crank bolts, and a plethora of other fasteners that see much higher stresses than a couple of 7/16" or 1/2" U bolts.

If folks don't feel comfortable reusing theirs, replace them. I'll be reusing mine, which have been removed at least four other times over their forty year life and will drive and wheel with confidence.

 

U-bolts aren’t like regular bolts. They're a torque-yield bolt. They’re designed to stretch and hold a spring-load over a long distance. Repeating that spring load fatigues the bolt. Sure, those torque ratings listed are great, but they’re rated for the initial tightening.

I can’t count how many times I’ve heard, “I’ve never had one fail.” Then in the next breath they’ll complain about wallowed out center holes in their spring pads, or fanned leaf springs, or sheared center pins, or lift blocks that won’t stay put. The u-bolt nuts might be set at proper torque, but the re-used bolt is fatigued and is stretching like taffy allowing the spring to move in its mount.

New u-bolts are a small price to pay for a crucial part that’s keeping an axle under our rig in a panic stop. You can obviously do what you want, but it’s disinformation at best to say it’s an advisable practice on this public forum.

 

Those are supposed to get replaced too. In the heavy truck world, it's standard practice to replace the hardware every time a driveshaft is removed.

 

Bought a couple U-Bolts at NAPA this summer in Colorado. Outrageously expensive like $45 each.

I’m rebuilding my suspension as my winter project and U-bolts online (Summit/ Quadratec) are less than $10 each.

Not supper cheap when doing 8bolts but I’ll feel better on the trail next summer.

Broken U-bolt at 11,000’

 

I used to always reuse them, because I was ignorant of how they worked. I still on occasion reuse one, but now I just buy new ones.

One of the multitude of facts and information I get from this site that corrects what I have been doing for years…wrong.

 

Yep. me too.