Mystert Camper 001The Lug_Nut View.  Trailer hitches, we all have them, most of us use them.  Today’s trailer hitches, or Hidden Hitch like assemblies, are found on pretty well all SUV’s, pickups, vans, cross-over’s, trucks and motor coaches.  They are out of sight, reliable and are not the shin bangers of yesterday’s design.   At least as long as you remove the ball shank when not in use.

Fortunately these covert mounted assemblies require little or no maintenance, as they are out of sight, and out of mind.  While they do not require maintenance, adjustments or tweaking, they do require to be used within their specifications and have periodic inspections.  Abuse and environmental conditions can render them unsafe and in some cases, outright dangerous.  Age, rust and decaying welds and metal over time can reduce their original bond and strength.  Abuse, whether by accident or neglect, may eventually lead to a total failure and possible separation from the vehicle.  This in turn can result in not only losing the towed vehicle or trailer, but even the safety chains which are also fastened to the severed assembly.  This, unfortunately, does occur.

Most hitch assembly failures are caused by physical damage.  Damage caused by impact, such as backing into a solid obstruction or over stressing by exceeding the design limitations.    

Today, we will look at one of the most common ways that people overload their hitch capacity, exceeding the tongue weight.  Hitches are rated in pound capacity.  That is, the total loaded weight of the vehicle or trailer.  This can be anywhere from 2,000 to 20,000 lbs.  It is important to realize that all component capacity ratings, like the ball and shank, are equal or higher, otherwise the rating will be that of the lowest.  The next consideration is the bumper point tongue weight (Not applicable to flat four down vehicle towing).  That is, the actual weight at the tongue, ball, or contact point.  As a general rule this will be 10 to 15% of the total weight of the trailer.  Too light at this point can cause vehicle handling issues such as trailer sway or light end at the rear of the tow vehicle.  Too heavy can cause hitch assembly over stress and light front steering axle on the tow vehicle.  The tongue weight is set by the weight and load distribution within, or on. the trailer.  The more the load is moved forward, the heavier the tongue weight will be.   

So, exactly how do people determine the correct loading distribution?   Well, this is where the problem begins.  Many people load their trailer with what they believe is about right, noting the amount the tow vehicle sinks when the tongue is lowered onto the hitch.  This, of course, is not a safe method.  Take a stacker trailer, a unit that can carry two cars, one above the other.  Their gross vehicle weight may be 15,000 lbs.  This would require positioning of the two vehicles and other cargo to apply about 1,500 lbs. on the hitch ball.  This can not be done by just observing the hitch sink.  A large diesel class A may sink only slightly with twice that weight or more.  Definitely not a safe practice.

The only correct way to verify the tongue weight is to weigh it.  Once the correct weight is accomplished, stops and markings can be made inside the trailer for future similar loading.  If one of the carried vehicles are replaced with a new one, a re-weighing is needed to assure the correct weight balance.  Don’t forget also to check the total trailer weight to avoid an over gross weight issue.

Hitch Break

The picture to the left shows an actual hitch failure on a motor home.  Fortunately, the driver of this rig had pulled over for a break and then spotted it.  The hitch assembly would have probably separated from the coach within a short time.  As the safety chains are connected to the assembly’s frame, the trailer would have took off on its own.  Certainly a very dangerous situation was averted. (Note: This failure was reported to be caused by incomplete hitch assembly installation.)  Again, an inspection would have found this issue.     



Regular inspections should be done, and can be carried out by the owner.  This may be particularly important if you believe your hitch could have been overloaded at an earlier date.  Verifying that all bolts are tight and in good condition is relatively easy.  Checking that no cracks are present in the hitch assembly, frame fastenings and related welds may require cleaning first.  This will allow you to see the physical condition of the metal surface better.  If you have never inspected a hitch assembly before, have a mechanic or like expert check it out.  By observing what he does and looks for, may allow you to be able to do it yourself in the future.

In addition to the aforementioned, you should always visually check your hitch and trailer any time you stop.  Make sure everything looks good, safety chains in place, wiring harness secure, trailer tires fully inflated, etc. 

So, if you are towing a heavy trailer, or have plans to, don’t forget to use your hitch within its designed specifications and to inspect it regularly.   If you do, your hitch will give you years of safe service.

Pulling For You    –    Lug_Nut     –      Peter Mercer

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  11. Lug_Nut

    John, Glad you found the article of interest. I don’t know of a supplier that has wet bath hubs for the smaller axles, but I’m sure they are out there. Thanks for your participation on this topic.

  12. John

    Hi Lug_nut,
    Great article ! I wonder if any shops offer an metal x-ray service for your hitch or other potential metal fatigue areas of frames and bolts? Shouldn’t be too difficult as it is used to check welds on oil and gas pipelines.
    A lot of provinces and states are now requiring a breakaway switch.
    In the event that the trailer does seperate the trailer brakes will stop it. Here in B.C. it is mandatory.
    I will be having a custom aluminum car hauler trailer made this summer. The building shop n Parksville said they make theirs’ standard with the switch.

    Alll I need to find now is a manufacturer or supplier of oil bath instead of grease lubed wheel bearing assemblies. Have you seen any of these in your travels?


  13. Lug_Nut

    shrpram, Nice catch. I will correct that. Thanks for being so observant.

  14. Lug_Nut

    Fred Brandeberry, SR, Yes, that’s a topic on its own. Flat towing and base plate mount inspection will be a future topic. Thanks for reminding us all about maintaining a secure base plate.

  15. Lug_Nut

    ModMyRV, Great point. Normally what comes from the manufacturer is correct. There are shops, however that may not be as careful in selecting the right grade bolt for the application. Thanks for the great input.

  16. Lug Nut:
    Please discuss the attachment points on our ‘toads” the metal is fracturing from the mounting bolts, and pulling through the chassis metal.
    We do a seminar called”let’s Talk rving” a hear of these issues.
    I need to look under my toad occasionally and look for cracked metal.

    Happy Camping,
    Fred b.

  17. I had an ’05 Gulfstream Endura that had a recall for improper grade bolts that held the hitch to the frame. One of the bragging points Gulfstream was making at the time is that the new Enduras could tow up to 10,000 lbs. If an unsuspecting RVer actually towed that much weight with the improper grade bolts, that could have been a disaster!

    Fortunately, the problem was caught early in production and bolt kits containing grade 8 bolts and extra plates were sent out to those units affected, including me. When I went to install the kit, 2 of the 6 bolts holding the hitch to the frame were loose. And I had been towing a 5000 lbs truck! I was lucky so check your hitch bolts often, especially if you have caster wheels or skids on your hitch.

  18. Lug_Nut

    jerry cooney, That was very fortunate and amazing that the vehicle was not even damaged. Sounds like you have solved your towing issues. Thank you for taking the time and in sharing your experience with us.

  19. Lug_Nut

    Curtis McRee, Glad you found the article of interest. Thank you for your input.

  20. shrpram

    Must have been a short person to have the hitch be a chin banger

  21. jerry cooney

    I had a Jeep Commander come of the back of my Beaver Marquis at interstate speeds, go over a mile down the highway and park itself in the median without hitting anybody. This was because of a weld failure on the receiver which meant that my safety cables and my break buddy break away were still attached to the receiver which was still attached to my towbar. I see hummers and fullsized pickups being towed with those same receivers and know that it is just a matter of time. I now have a 25k hitch with alternate hookups points for my safety cables and break away.

  22. Good story lug-nut. A trailer hitch is only as good as it is tighted to the frame of the vechile. Happy trails to all of you.

  23. Feeline, That could be messy, the first part I mean………………or maybe both. Thanks for your great comment, albeit partly amusing.

  24. Feeline

    Great point,The failure of a hitch or any of it’s components can result in severe injury or even death to one or more people.

    If your are lucky, it may result only in the necessity to change your shorts.