Montana Owners Club - Keystone Montana 5th Wheel Forum - View Single Post

Irlpguy · 06-06-2013, 06:37 AM

I do not recall any suggestion that there have been actual failures of the U bolts themselves. Insufficient torque values seem to have been the problem identified, therefore the suggestion that we check the torque on our U bolts was made in the past and is valid.

Early on in this thread the statement was made that in order for the torque value to be correct you must lift the wheels off the ground before torquing them, also if you checked them when the unit was sitting on it's wheels the value would differ. Up to this point there has been "no" qualification of that statement from Dexter and had I or someone else not questioned that idea, then my feeling is that this idea would have been deemed the proper way to torque your U bolts, because 3 people at Dexter said so.

I am no engineer, but I have put a wrench to everything from chain saws to road building machinery and common sense tells me this was a statement made that was not substantiated in any way.

Axles with the springs mounted on top do "not" put the load on the U bolts, they are subjected to considerable lateral forces I am sure, but vertical load bearing is not one of those forces. The greatest amount of load bearing would be when the frame was lifted off the ground and the U bolts would then be carrying the weight of the axles and wheels and nothing else.

My conclusion on this topic is that the Dexter Manual may have been read incorrectly, prompting the question in the first place, and the "people in the know" perpetuated that misconception by also misreading a part of the Manual. They offered no substantive explanation nor could they put a value to the difference one would see in doing it one way as opposed to the other.

Here is my test performed this morning:

1) loosened the nuts on two U bolts on the same axle side with my level up supporting the weight of the trailer on that side.
2) I torqued those 4 nuts to a value of 60# and lowered the unit back onto it's wheels.
3) I rechecked the torque starting at 50# and worked my way up using the smallest increments on my torque wrench.
4) Since you cannot get the nut to actually move using only a pound or two increase it was not until 63 - 65# that I was able to move the nut.

Does that mean there is a difference in value by torquing one way as opposed to the other, perhaps, but it is so insignificant 99% of those checking the torque would not even notice it. Or could it simply be as I believe that it takes several additional pounds increase to actually tighten the nut.

I will perform this same test when my new axles are installed in the next couple of weeks, I expect to see the same result. I still have not heard back from Dexter.

06-06-2013, 06:37 AM	#51
Irlpguy Montana Master Join Date: Oct 2012 Location: Chilliwack Posts: 1,520 M.O.C. #12935	I do not recall any suggestion that there have been actual failures of the U bolts themselves. Insufficient torque values seem to have been the problem identified, therefore the suggestion that we check the torque on our U bolts was made in the past and is valid. Early on in this thread the statement was made that in order for the torque value to be correct you must lift the wheels off the ground before torquing them, also if you checked them when the unit was sitting on it's wheels the value would differ. Up to this point there has been "no" qualification of that statement from Dexter and had I or someone else not questioned that idea, then my feeling is that this idea would have been deemed the proper way to torque your U bolts, because 3 people at Dexter said so. I am no engineer, but I have put a wrench to everything from chain saws to road building machinery and common sense tells me this was a statement made that was not substantiated in any way. Axles with the springs mounted on top do "not" put the load on the U bolts, they are subjected to considerable lateral forces I am sure, but vertical load bearing is not one of those forces. The greatest amount of load bearing would be when the frame was lifted off the ground and the U bolts would then be carrying the weight of the axles and wheels and nothing else. My conclusion on this topic is that the Dexter Manual may have been read incorrectly, prompting the question in the first place, and the "people in the know" perpetuated that misconception by also misreading a part of the Manual. They offered no substantive explanation nor could they put a value to the difference one would see in doing it one way as opposed to the other. Here is my test performed this morning: 1) loosened the nuts on two U bolts on the same axle side with my level up supporting the weight of the trailer on that side. 2) I torqued those 4 nuts to a value of 60# and lowered the unit back onto it's wheels. 3) I rechecked the torque starting at 50# and worked my way up using the smallest increments on my torque wrench. 4) Since you cannot get the nut to actually move using only a pound or two increase it was not until 63 - 65# that I was able to move the nut. Does that mean there is a difference in value by torquing one way as opposed to the other, perhaps, but it is so insignificant 99% of those checking the torque would not even notice it. Or could it simply be as I believe that it takes several additional pounds increase to actually tighten the nut. I will perform this same test when my new axles are installed in the next couple of weeks, I expect to see the same result. I still have not heard back from Dexter.