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Rear axle "tow" rating not GAWR

2667 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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like mentioned, their is no such rating, unless you were looking to hang the tailer off a cliff and held up by the axle (in which case its load rating would come into effect!)

Just because you have a 20,000lb trailer, doesnt mean the "horizontal load" is 20,000lbs. their is no such measurement as this cannot be accurately measured and would vary greatly depending on conditions

The load rating of the axle (vertical) is the rated load that the spindles/wheel bearings and housing can support. this could of course also be used as your "horizontal" load as the stresses on the components are similar.

The tow rating used by dodge (GCVWR) is more of a reflection on the trucks construction than the axle itself. You have to take into consideration the stresses transferred through the driveline, the springs, frame and ultimately the hitch system. Dodge of course always sways on the light side of things to reduce wear and tear as well as saving their azz when someone crashes pulling a huge load.

You could call AAM, as with Dana, they can tell you the axle's (and the axle only) design limits. they should be able to tell you the load rating as well as input torque and an estimated max GCVWR. Of course this in no way means that if they say that axle is good for 50k gcvw, that you wont tear the rest of the truck to pieces LOL

Like mentioned, input torque and heat are the biggest things to watch. you could pull a 5 billion pound trailer with it, if the load on the axle didnt exceed its rating and you didnt exceed its torque rating (granted the torque was enough to move the trailer!)
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