Interesting development regarding PDI - U-bolts

[cargary2]

Just wondering...where did the figure of 60 ft/lbs come from as the required torque? I reviewed the dexter manual and it says for the torque to be between 45 ft/lbs at min. and 70 ft/lbs at max.
Is this a figure that Dexter recommended? I just checked mine and none are at this 60 ft/lbs figure.
Thanks.
Cargary

[NCFischers]

The diameter of the u-bolt dictates the torque.

[Tom S.]

quote:Originally posted by Art-n-Marge

Tom S, your response keywords are "never should". That's mostly true, but I still check torque for the tires before starting a new trip and during the trip too, (at least every morning right before getting on the road). I do recheck the torque and while I agree they should be tight and correct, one must check in order to confirm. At the very best you should find the torque is fine and that the click is quick (for the clicker type of wrench - I have two) without the feeling of reseating the nut. I don't feel the need to mess with loctite or jam nuts. That would just make it harder to check the torque when the time comes. I also don't find a need to check every single nut and bolt on my TV or RV. I'll stick with the ones that could be problematic (ubolts and wheel lugs).

Oops, and there are 16 nuts to check, not 8. It's 8 per axle.

Art, sorry for not seeing this earlier. U-bolts aren't the same as wheels when it comes to torque. With a U-bolt, once it's properly torqued, you should never have to mess with it again. Has anyone ever had to re-torque the U-bolts on their car or truck? The problem is they are coming from the factory under torqued.

[cargary2]

You're right about the dia. of the bolt dictating the torque. As I said earlier, I reviewed the specs. from the dexter manual and for the 1/2 u-bolts they give you a range from the min. of 45 ft/lbs to the max. of 70 ft/lbs. I was wondering where someone came up with the 60 ft/lb figure...was this recommended by someone from dexter or is this someones middle of the range figure. I know in dealing with the torque on lug nuts for my tires, I usually use the middle of the range that the manufacture recommends for that purpose. So, I guess if you figure it out, the difference between 70 ft/lbs and 45 ft/lbs is 25 ft/lbs. and if you divide that by 2 you get 12 1/2 ft/lbs. Then if you add 45 and 12 1/2 you get 57 1/2 ft/lbs., which is close to 60 ft/lbs. This is probably how someone arrived at the 60 ft/lbs figure.
At any rate, it sounds good to me and I will set mine accordingly.
That's for the replies. Sorry to be so lengthy.
Cargary

[Art-n-Marge]

Tom, in most applications, I understand once the torque is set, it shouldn't change, however a tire/wheel is constantly under changing stresses especially a trailer axle that is straight up and down and the trailer's tires/wheels are tweakied in all kinds of directions on turns, etc. I agree that a U-bolt shouldn't change which kinda demonstrates that it properly wasn't don't right at the factory. I've noticed NO CHANGE with the U-bolt since I retorqued them and that even proves it more.

[bncinwv]

Ask and ye shall receive! Sorry guys, couldn't resist.

Bolt Torque Specs

Or another reference:

U-bolt torque specs

Now all we have to consider is what hardness is Lippert using for the u-bolts? That oughta extend the thread (definite pun intended!!) for a while!


Bingo

[h2ojocky]

I have never checked my u-bolts or lugs. I bought my trailer used and assumed Camping World would make sure it was safe before selling it to me. I will check them both before my next trip on Tuesday. Thanks for all the helpful advice. I will let you know what I find.

[mach111]

We purchased our '09 2980RL Nov '12. While installing the "wet bolt" I thought , "Check those U-bolts torque." All the bolts had to be tighten ALOT. The original owner had been towing for 3 years with worn and loose suspension parts and Marathon tires. My point is ALL owners need to check those bolts. The previous owner depended on service techs. Our unit had been well cared for from an eye view but these maintenance issues were not.

With new wet bolt kit, new Michelins XPS ribs, TST 507 system, wheel bearing service. and proper torque on ALL bolts the suspension system is ready for the road. Now things can and will break so I must inspect on occasion. After twenty years of driving eighteen wheels I do know the importance of proper inspections of suspensions befor hitting the road. These inspections are a safety issue for you and others on the road.

[cargary2]

Thanks Bingo for the spec's. on various u-bolts. That was my first thought - (what is the material that the Lippert bolts are made of) after I viewed the spec's.
However, referring back to the dexter manual regarding the U-bolts, it does give the minimum and the maximum torgue's recommended, and as I have done on other various torque recommendation, I stay in the mid-range of what is recommended.
Great job on the pun's.
Thanks.
Cargary

[rohrmann]

Just was thinking about all the threads on this site about ubolt torque, and the discussion that indicates Dexter torques the nuts at their factory. If that is the only time the nuts are torqued prior to delivery, and Dexter does not torque the nuts in a loaded configuration, on the trailer with wheels on the ground. Dexter is torquing the nuts with the springs unloaded and curved quite a bit compared to loaded by a trailer, then when installed on the finished product, the springs have been straightened out some which could relax the load on the ubolts, maybe causing the nuts to be looser than specs. I'm not sure about this, just wondering.

[Art-n-Marge]

And therein lies the problem, rohrmann. The big deal about torque is that it should be applied under the PROPER application. It had been documented in the past that the torque should be done with the wheels off the ground but connected to its load (the trailer). Therefore if Lippert puts these together and uses the torque not in a real load environment it is not possible to achieve this and the final torque should be done by a final assembly person at the factory when the axle is under load and we're not so sure this is being done since when we do our own check, the torque is all over the place and certainly not consistent. Then we get our rigs, don't raise the rig, and torque our bolts. I don't torque to the max but I am closer to the max than the mid. IIRC, the torque range is something like 40 to 75. Wow! That's quite a range since I've read certain size bolts only have about a 15 to 20 range at the most. I use 65 and I'm happy with it. It's within range but not the max and subsequent rechecks have showed they are holding fine.

[Samiterry]

OK, now this is scary!! After reading the forum on torque wrenches, and never having owned on, I went out and bought a Sears mid line torque wrench. THEN, after reading this post on Ubolts, decided to go check mine. NOT A ONE was even close to spec torque!!! However, on the good side, all lug nuts were.

[Irlpguy]

quote:Originally posted by rohrmann

Just was thinking about all the threads on this site about ubolt torque, and the discussion that indicates Dexter torques the nuts at their factory. If that is the only time the nuts are torqued prior to delivery, and Dexter does not torque the nuts in a loaded configuration, on the trailer with wheels on the ground. Dexter is torquing the nuts with the springs unloaded and curved quite a bit compared to loaded by a trailer, then when installed on the finished product, the springs have been straightened out some which could relax the load on the ubolts, maybe causing the nuts to be looser than specs. I'm not sure about this, just wondering.

rohrmann here are the contents of two emails I received back in June from a Product Engineer at Dexter, these were responses to my questions regarding the concerns in your post.

Email #1:

Ed,
At this point in time Dexter doesn't have an approved published procedure.
Because of your inquiry Engineering will write a procedure and get it
approved for distribution. Not sure of the timing for completion.

Thank You

Email #2

Ed,
Unofficially I would recommend that over slung axles be torqued loaded and
under slung axles be torqued unloaded. The reason the under slug is torqued
unloaded is that the vehicle weight is directly working on the tie plates.

I hope this answers your question
End Emails:

I have no idea whether Dexter have as promised published an approved procedure or not. What I do know is we are all dealing with over slung axles and unofficially he recommends they be torqued "loaded", meaning with the weight on the axles. That is exactly what we have when we crawl under there to check them and torque them.

If this were to be the Official Dexter procedure, then the responsibility would be upon Keystone to properly torque them when the unit is completely assembled and the axle is "loaded". Dexter simply cannot torque the U-bolts in a loaded configuration.
Remember we have yet to get an "OFFICIAL" procedure from Dexter, unless it is now in their owners manual.

I do not know personally anyone who has experienced a problem with U-bolts loosening up to the extent something failed and it certainly has not happened to me.

Give each nut a squirt of oil and torque them to 60 lbs and forget them.

[cargary2]

Tripguy:
Thanks for sharing your communication (emails) from Dexter. This is what I have been looking for, that is, someone who had communicated to those who set the requirements so that we are all beginning on the same page. Sometime in the future, if it is your intent to follow up with Dexter on what they told you would happen, I for one, would appreciate it very much if you would share what they are going to do in the future.
Thanks to you and all of the others for sharing their knowledge with the rest of us.
Cargary

[Carl n Susan]

quote:Originally posted by Irlpguy

....I do not know personally anyone who has experienced a problem with U-bolts loosening up to the extent something failed and it certainly has not happened to me...

Calling richfaa, calling richfaa, message for richfaa

http://www.montanaowners.com/forums/showthread.php?t=35136&SearchTerms=spring,bolt

[Irlpguy]

quote:Originally posted by Carl n Susan

Calling richfaa, calling richfaa, message for richfaa

http://www.montanaowners.com/forums/showthread.php?t=35136&SearchTerms=spring,bolt

Actually that was a centering bolt which holds the spring stack together. I don't think it was ever determined that it had anything to do with the U-bolts themselves.

Regardless, it pays to at least check the torque on the U-bolts now that we have all been made aware of a possible issue.
Once they are torqued to the proper spec we should not have to worry about them again. Same goes for our lug nuts. I had all new tires put on and although they were torqued to 120 lbs by the dealer when the tires were installed, and I was told to bring the unit back and have them rechecked after I had 100 miles or so on them, I will check them after about 100 miles and I won't likely concern myself with them again unless I have to remove a wheel.

I am not recommending anyone do as I do, just saying.

[Irlpguy]

quote:Originally posted by cargary2

Tripguy:
Thanks for sharing your communication (emails) from Dexter. This is what I have been looking for, that is, someone who had communicated to those who set the requirements so that we are all beginning on the same page. Sometime in the future, if it is your intent to follow up with Dexter on what they told you would happen, I for one, would appreciate it very much if you would share what they are going to do in the future.
Thanks to you and all of the others for sharing their knowledge with the rest of us.
Cargary

After digging out those emails today I went to the Dexter website and looked at their online edition of their Operation Maintenance Service manual and nothing has changed from back in June with respect to what was promised by the Engineer at Dexter. Now that my memory has been jogged I will follow up with that after the Remembrance Day holiday.

I will indeed post any additional information on the MOC forum.

Here is a link to that publication: Specifically page 66 and forward a few pages.

http://www.dexteraxle.com/i/u/614960...anual_3-13.pdf

[cargary2]

Tripguy...
I look forward for the update from Dexter and thanks for the link to Dexter's maintenance manual.
Cargary

[jcurtis934]

Wellll...thanks to this thread I, too, went out today and checked my ubolts. The good news was that 2 of the 16 were close to 60. The others were nowhere near this with all of them taking at least a full turn of the torque wrench. At least I now know they are correct and don't have to worry about them. Thanks folks for this wonderful thread. john

[richfaa]

[quote]quote:Originally posted by Irlpguy

quote:Originally posted by Carl n Susan

Calling richfaa, calling richfaa, message for richfaa


http://www.montanaowners.com/forums/showthread.php?t=35136&SearchTerms=spring,bolt

Actually that was a centering bolt which holds the spring stack together. I don't think it was ever determined that it had anything to do with the U-bolts themselves.

Regardless, it pays to at least check the torque on the U-bolts now that we have all been made aware of a possible issue.
Once they are torqued to the proper spec we should not have to worry about them again. Same goes for our lug nuts. I had all new tires put on and although they were torqued to 120 lbs by the dealer when the tires were installed, and I was told to bring the unit back and have them rechecked after I had 100 miles or so on them, I will check them after about 100 miles and I won't likely concern myself with them again unless I have to remove a wheel.

I am not recommending anyone do as I do, just saying.

It is true that it could not be determined without a doubt what caused the center pin to shear. The best was "outside forces" The other U bolts were loose.

There as a consensus among those who looked at it that the most probable cause was the U bolts. We had never checked the torque on any U bolts so we took the hit on probable blame.

the IS suspension solved the problem.