Trailer Axle U-bolts

[BigG]

I have had the u-bolts break on my Big Tex trailer. The front axle yesterday and the rear axle back in December. Both have happen where the highway butts up to a bridge. Has anyone else had a problem with the u-bolts? This is getting expensive. Almost $1000 in parts and new tires. And way more then that in lost work.

When we fixed the axle in December my son ran the nuts up tight with a Dewalt impact and stripped the threads. I was watching him and he did not get a chance to pound on them at all before it stripped. The replacements came from Redneck Trailer parts.

Is there a better place to buy u-bolts? Redneck would not tell me a torque value nor any type of spec. I thought that an axle u-bolt should be a higher quality/grade bolt. However these seam to be a low grade bolt.

Any ideas are welcome.

Thanks

 

[bcp]

I would go up a size on the U-bolts (larger diameter) even if custom was needed.

Here's one:
https://www.truckspring.com/suspension-parts/u-bolts.aspx

Bruce

 

[lugbolt]

bigtex among other trailer builders all use the absolute cheapest junk that they can source. Keeps the cost lower than if it were all GOOD stuff; and helps their margin as such.

Torsion axles solve the problem forever but sounds like you're already stuck with conventional axles.

If you're breaking them, there could be other issue. It's not common to break u-bolts, although I broke one a few months ago as well.

 

[GreensvilleJay]

30 years. 30 trailers I built , NO busted ubolts.even when hauling 5K in a 3k5 trailer...
I have never,ever used an impact gun to tighten suspension nuts. The fact your son STRIPPED them, says waay too much torque and shock.
Ubolt makers will know torque, though I just hand tighten 'Snug'. Ubolts don't 'carry' the weight, just keep axle onto springs.

 

[ken erickson]

When I needed 5 inch ubolts for my tractor seat lift I purchased them from uboltsdirect. Great customer service, they called to make sure I was ordering the correct number of nuts after I placed the order online. They are very specific about torque specs and the proper pattern when installing.


https://www.uboltsdirect.com/torque-specs.html

 

[Magicman]

Nice link. It is also interesting to note that 5/8" and above are grade 8. Below are grade 5.

 

[GreensvilleJay]

That link says not to reuse the ubolts as the threads are roll formed, not cut.

OK.... has anyone bought ANY bolts that were CUT, if so where and $$.

The 'don't reuse if rollformed' would also apply to every bolt I've ever come across in the past 50-60 years....

Hate to think what a machinest turning a lathe would charge for a 'cut' bolt....

 

[BigG]

First thank you for the replies.

I looked a torque chart:https://www.dultmeier.com/pdfs/tech-library/C_BoltTorque.pdf and after a second call to Redneck trailer I am thinking these bolts are Grade 5 but they may be of a poor quality. Today they said to torque them to 50-60 ft-lbs. So they look to be Grade 5 on the chart.

I am no engineer but the Grade 5 bolts are not strong enough in use. The testing may say that they are good but in the real world they do not hold up.

The trailer is 2.5 years old with only 170,000 miles on it.

 

[ken erickson]

That link says not to reuse the ubolts as the threads are roll formed, not cut.

OK.... has anyone bought ANY bolts that were CUT, if so where and $$.

The 'don't reuse if rollformed' would also apply to every bolt I've ever come across in the past 50-60 years....

Hate to think what a machinest turning a lathe would charge for a 'cut' bolt....

GreensvilleJay,
Are you referring to the Uboltsdirect link or the truck spring.com link?

I was not able to find uboltsdirect recommending to not reuse due to the threads being roll formed but did find this.

"You can overtighten a U-Bolt. This action can be as detrimental as not tightening the bolts hard enough. We also recommend that you do not re-use your old U-Bolts. If you were to reuse an old U-Bolt, there could be an issue with their retightening abilities. The nut tends to grab the old threads, and these threads have been weakened because of exposure to road conditions such as salt and moisture."

Thanks in advance, just making sure I am not missing something.

 

[Kennyd4110]

The trailer is 2.5 years old with only 170,000 miles on it.

Is that a misprint?

 

[BigG]

Is that a misprint?

It is how I make a living.

 

[GreensvilleJay]

one of them,says 'do not reuse ubolts', so I google that and magically get to another page within one of the sites that said, ubolts are roll formed... well EVERY bolt I've come across IS rollformed. Worked at STELCO decades ago and they spitted them out 1,000s per minute....
As for the 'strength', the bolts only 'bind' or 'mate' the axle to springs ,no real 'strength' is needed, if axle is above springs, most trailer are this way.

Would have to lookup the specs for shear and strength and is a Ubolt considered ONE bolt or TWO ?

It may just be a 'scientificspeak' way to not have you use old, rusty ubolts,but anything less than 5 years that's been painted should be OK. I degrease everything before install, paint with primer,cure, install, then paint with enamel, brushed on. Never had a failure.
If the Op is breaking ubolts due to shock loading, THAT is another problem. If the trailer has 170,000 miles on it, it's seen a LOT of tires and brakes and spring work and wiring and other repairs....

 

[North Idaho Wolfman]

As for the 'strength', the bolts only 'bind' or 'mate' the axle to springs ,no real 'strength' is needed, if axle is above springs, most trailer are this way.

I don't agree, if the axle is above the spring, then the U Bolts are carrying the entire weight load, I would suggest the strongest bolt combination possible.

 

[boz1989]

I don't think I have ever reused a ubolt. I don't think I've ever taken one apart without the fire wrench.

Sent from my LGMP260 using Tapatalk

 

[GreensvilleJay]

well I did say 'most trailers are below style mounts'.....

If you need 'persuassion' of any kind to remove the nuts,it's best to look very carefully at the rest of the trailer, odds are there's a LOT of rusty steel, corroded wires, 'missing' spring bushings......

had a neighbour drop his trailer off, NO bushings AND 2 of 4 spring mount bolts were 1/2 GONE.....

 

[Magicman]

Most trailers can also be adapted to using a "wet bolt" shackle kit. No more worn/missing spring bushings.

 

[GreensvilleJay]

yeah, but anyone who doesn't inspect their trailer regularly and not see 'no bushings', probably won't grease 'wet bolts' either......

$6 vs $2 for normal, good investment for high use trailers.

 

[D2Cat]

GreensvilleJay, I think you stated the axle in both positions. In post #4 you mentioned axle under the spring, then later said "...no real 'strength' is needed, if axle is above springs, most trailer are this way."

The second comment is what North Idaho Wolfman responded to. I also noticed it but didn't respond. Probably your mind thinking one thing and fingers doing something else.

I think North Idaho Wolfman tries to point out those thing so when folks come to the forum down the read they get correct information.

 

[GreensvilleJay]

hmm.. if the axle is below the springs, ubolts don't support the weight. That configuration is the most common. I think that's called 'overslung'. Underslung , where axle is below the springs, drops the trailer bed down about 3" more or less but then ubolts do support the weight.
while googling this, I found one reference that says nuts should be torqued to 45-50' #s, which ain't a lot. My pickup wheel nuts need 100# +-. Same site said using impact gun is bad, will easily overtorque the nuts.
btw I've never seen the wet bolts up here......cept on my '57 Willys 4wd pickup...

 

[Magicman]

An example with wet "greasable" bolts: LINK