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Rear axle "tow" rating not GAWR

2666 Views 6 Replies 6 Participants Last post by  ykdave
Do Chrysler engineers use a formula or a value or rating for determining the shear or tensile stress on our rear axle or 5th wheel hitch? I know that there isn't a practical way of users to determine what it is but...Everything that is talked about with specs is just load or vertical load? If I have a 17000# toy hauler fully loaded and have a 1400# plus sandrail behind the 3 axles then my pin weight might be within the 6000# GAWR of the truck (6000#- rear axle truck dry scale weight) because of the location of the sandrail load but what about the pull or tow weight of the load/toy hauler? Or do you assume that my 6000#GAWR vertical load of the truck is the weak factor. In other words, can the internals of the rear axle or be over worked with a horizontal load before you hit the GAWR of 6000#. My father in law fried a bearing in his rear axle pulling a heavy toy hauler recently. Yes, he was over loaded and never had it on the scales but I am curious why horizontal load is never discussed or is it worked into the vertical load specs? Or am I just missing something??
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I don't know of any horizontal load specs.
There is one but I've never seen it published any where. At some point the twisting forces on the axle or pinion or the shear forces on the ring and pinion teeth will become enough to break something. I would guess it is somewhere around 3000ft-lb as according to Dana the Dana80 is good for input torque of 3000 Ft-LB <> and the AAM 11.5 is in the same class.

I would agree with you that heat is the biggest concern though. I would expect tire traction to give up before the torque limit was reached; however, a good shock load like a tire spinning in the air and slamming into the ground while towing a heavy load might exceed the maximum torque.
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