check u bolt torque

[JohnDar]

Would there be any reason not to apply some thread-locker/Loctite to the U-bolts the next time one checks the torque? Never having mucked around with the spring hanger system, would it be suicidal to fully loosen one nut at a time, apply the Loctite and torque to spec. Then move to another nut.

 

[wdk450]

Loctite 290 is made to apply to assembled nuts on bolts.

Would there be any reason not to apply some thread-locker/Loctite to the U-bolts the next time one checks the torque? Never having mucked around with the spring hanger system, would it be suicidal to fully loosen one nut at a time, apply the Loctite and torque to spec. Then move to another nut.

 

[westxsrt10]

Loctite 'RED' may work but it will be a bear to remove later. I think the better idea is to "double nut it" using a locking nut on top. I"m still believing a new properly installed and torqued u-bolt will not become loose.

 

[XXLRUNR]

Re: More of the Same

I'm not aware of a method to determine torque wrench calibration. I suggest purchasing a high quality wrench like a Snap-On or Craftsman. I don't advocate spending money unnecessarily but this seems like a tool your life may depend on.

 

[lwmcguir]

Re: More of the Same

I'm not aware of a method to determine torque wrench calibration. I suggest purchasing a high quality wrench like a Snap-On or Craftsman. I don't advocate spending money unnecessarily but this seems like a tool your life may depend on.

We use a device like this in the shop for our Diesel repairs. Have an older mechanical one as well.

http://www.com-ten.com/torque-analysers.html

 

[currituck0209]

Just checked all my u-bolts, three were good to 65 lbs, one was pretty loose. Thanks I appreciate all the data. It sure helps.

 

[wyleyrabbit]

I checked all of our U-bolts last outing, and while most were ~ 65 lbs, several were not!!! In fact, two of them had to be tightened at least a couple of turns before getting to 65 lbs. As I write this, we have less than 1,750 km on our trailer, and having so many loose u-bolts scares me. We're planning a couple of much longer trips and I will do anything to try to prevent disaster.

It seems that the quality of the bolts was low as well. I would have expected the same metal hardness as lug nuts, but these didn't seem that strong. Should these be "upgraded", or would adding a second bolt on top help prevent these things from loosening up?

Any advice from the experts?

Chris

 

[wyleyrabbit]

Re: More of the Same

Is one brand of torque wrench as good as another? How do you know if they are calabrated correctly? I have been pulling trailers for several years and this is first I have heard of this problem. I will be under the trailer tomorrow. Thanks for the heads up !!

When I purchased my torque wrench, it came with a "calibration report" that indicated that it was within 1 ft/lb of spec. Close enough for anything I'd ever be doing.

Chris

 

[2010-mk-2900]

Re: More of the Same

I have a couple of concerns about u-bolts!The first thing i've been taught about them is that if you ever loosen u-bolts they are not to be used again.Reason being is they strech when they are torqed and they are never the same after you loosen them and try to retighten them.So if they are coming loose would it not be safer just to replace them with new ones and torqe those to spec and hopefully that would fix the backing off problem.For what they cost it seems like cheap insurance?I also think lock tite would be fine since you never reuse u-bolts the best tool to take them off is a torch.

Neil

 

[RollingHome]

There is a lot of sage advice here that I believe ALL owners would benefit from in this thread, I hope other owners read this forum as much as I do it's a wealth of knowledge. I also would like to add my knowledge about torque wrench care. Excluding exotic digital and 'other' types there are basically 2 types of torque wrenches. A beam type that utilizes a relaxed spring with a analog needle/scale and a 'clicker' type which utilizes a preloaded spring. The clicker type should not be stored with the spring loaded. After use the vernier scale should be returned to zero to 'unload' the spring as this will help keep it calibrated longer. If you have been storing it loaded or if your wrench has an un-known history (yard sale bought, gift from uncle Lou), you should think about having the calibration checked. A tool repair place should be able to do it or send it away for you, maybe sears too. The cost should be around $25.00 or $50.00 with NIST traceable cert. I have access to a bench mount analog mechanical torque calibrator that I check mine against. These can be acquired from McMaster Carr for about $250.00 Another "just about" way is to compare different wrenches to each other at a rally. The wives will love it, I can hear it now... "There they go again bonding with their torque wrenches, go pull em tiger" Also, wrap your torque wrench in a towel or get a case for it, it'll last longer.

 

[XXLRUNR]

How can we involve Lippert or Heartland regarding this thread? What causes the u-bolts to loosen? Should we be re-tightening the u-bolts ourselves? How do we prevent this from happening?

 

[rvn4fun]

Just ran into San Antonio today, bought torque wrench and checked u-bolts this afternoon. Only one was tighten to 65 pounds. In fairness to Heartland I have had 5, 5th wheelers now, not Heartlands, and this is the first time I have ever checked these. Probably wouldn't have ever caused a problem because they weren't overly loose, but thanks to the forum I did check them and now I know they shouldn't give me a problem. Now if I can just make it home on these springs and tires.

 

[SmokeyBare]

I was told once, when we had springs replaced on our Old (SOB) Five'r. That I was going to need to check and tighten the U-Bolts after I pulled/towed the fifth wheel for a hundred or so miles. They explained that because "new" U-Bolts were used on the install, they would stretch somewhat, and I would need to re-torque the U-bolts. So perhaps this might be what is happening to these as well.

I had springs replaced on our BigHorn after the Rally... THANK YOU LIPPERT!! I have since torqued the U-Bolts. They were tight when I left Trail-Air's shop. I know that for a fact as I watched the installation of them. So I believe they do become lose some after the RV's been on the road a while. That's my thoughts anyway.

 

[DW_Gray]

When I had one of my axles replaced last year for warranty repair, I was told to torque the U-bolt to 70 foot pounds. Yesterday I torque them all and found some were not nearly tight enough. I estimate some were about 40 pounds based on the number times I had to turn the ratchet.

Caution: When you crawl under your rig don't be surprised to find other problems like I did. That's another story and post.

 

[Iver]

Re: More of the Same

Can I assume that the U-Bolts on my size trailer should be torqued to 65 lbs. also?

 

[wdk450]

How can we involve Lippert or Heartland regarding this thread? What causes the u-bolts to loosen? Should we be re-tightening the u-bolts ourselves? How do we prevent this from happening?

Gang:
I suggest that some of us bring a Sharpie marker along when we next do this chore, and mark the threads and nuts so we can tell down the road if the nuts have loosened, or if it is metal strech. The results should be reported to this thread. I personally don't think the nuts are turning on the threads.

 

[DW_Gray]

Re: More of the Same

Can I assume that the U-Bolts on my size trailer should be torqued to 65 lbs. also?

I doubt it matters on any model. If it's a Lippert frame they're all probably the same and should be 65-70 pounds.

As Bill suggested, I think bolt stretch is reason for the need to tighten the nuts periodically. I think the U-bolts are designed to stretch because a hardened bolt would tend to break.

 

[jbeletti]

Hi all,

I passed this thread of information to Lippert to get their input on it. They sent me some Q&A that some may find insightful. See below.

This said, I won't be able to answer any questions for you on all this. Sorry about that. Just not my area.

LIPPERT AXLE ENGINEERING DEPARTMENT

Q. What causes the u-bolts to loosen?
A. U-bolts, tie plate, and u-bolt nuts make-up the clamping mechanism to sandwich together a leaf spring and axle tube. U-bolt tension loss is typically experienced when the “sandwich” changes.
Several factors can affect the “sandwich” and may include gaps in between leaves of the leaf spring so it’s important to check torque when unit weight is on the axles
Springs going flat, check by measuring center of eye to center of eye measurement, should not exceed 26”
U-bolt relaxation, typical phenomena in clamped joints and why periodic checks are required
Tie plate bending due to over tightening, once plate bends it does a poor job of maintaining clamp load
Under tightening, use good torque wrench
Road conditions namely pot holes, and un-level towing.


Q. Should we be re-tightening the u-bolts ourselves?
A. See attached memo, yes periodically (post #40 by cookie on suspension maintenance)



Q. How do we prevent this from happening?
A. Proper torque and periodic checks


Q. Would there be any reason not to apply some thread-locker/Loctite to the U-bolts the next time one checks the torque?
A. Loctite makes it impossible to check torque in the future after it has set-up. Typically ubolts get loose from things mentioned in Q1, not because the nut backs off. So you could loctite the nut so never moves but still loose u-bolt tension. It’s recommended to not apply and check torque periodically. Proper torque and periodic torque checks will keep everything safely, and comfortably together.

 

[superduty08]

I agree that the changes noted can cause the torque change. I am just thankful that this was brought up so that we know to add it to our check list. Things like this exist on any thing that has stress and movement including your TV.

 

[boatdoc]

Thanks Jim B.!!! Bet they wouldn't have explained that to the everyday Joe. They don't seem to think us everyday Joes can understand suspension lingo. Thanks again!!