The Rich Hitch - A safer way to haul your scooter!  By  bigguy (Read 1,156 times)

I was planning on doing the same however you do have to do the math and calculate weight transferance based on the distance of the load being carried from the center of the rear wheels to determine how much extending the carrier and load away from the hitch will have toward unloading the front wheels causing steering stability issues.

Motor homes usually do not have the hitch mounted to the chassis of the OEM vehicle its based on but an extension made of lighter gauge and strength steel. Motor home manufacturers may put a receiver that of iteself may have a very high tongue weight rating for a load placed within 12 inches of it however the sub frame its mounted on when talking motor homes is usually rated at less than 400 lbs unless your talking a HaulMark or similar SuperC based on an Interstate box truck cab and chassis. Air bags make no difference either. I have inspected a number of Class A and Class C Motor Homes where folks have beefed up hitches and after a few rides over rough roads end up with the rear frame over the axle cracked and a hump in the floor where the entire back of the motor home has dropped 1 to several inches. Trussing that back up and repairing the damage is very difficult since you have to evenly lift everthing back into its original location which may not be possible without removing the sidewalls, basement parts, etc. Been there helping others and its not pretty.

Blue OX used to have a calculation sheet that you could fill out with the length, front and rear axle locations along with the total weight and axle weights to see how much a load so many inches from the center of the rear axle would unload the front wheels. It was amazingly accurate at predicting the effects of the proposed load on steering but still did not overrride the Motor Home Builders rear frame limits. Unfortunately on many Motor Homes that info was on a sticky lable somewhere on the receiver, rear of the vehicle or possible on the wall in the back of a closet or some other obscure location.

Bottom line is that you can not rely on whats stamped on the receiver or what third party software indicates about the receiver itself especially when its mounted on a Class A or Class C motorhome and more so if its a gasoline powered front engine chassis.

I like the effort and would like even more to make the math work however its not going to for many and possibly most.

I find most out there narrow sighted in this reguard and do not take a 4 corner weight of the vehicle on a scale first in order to do correct calculations nor do they calculate impact loads based on the spring and shock absorber ratings nor do they consider tire ratings and inflation tables.

You have to survey the entire vehicle front to back. A 400 lb load placed 4 or so feet from the receiver and 20 some feet from the rear axle centers has a lot leverage and can really lighten the weight on the front axles even if the frameset can withstand the forces involved. The unknowing simply reading this may try to do the same without understanding all thats involved which is what gets very many folks into trouble. I have seen a lot of damaged motor homes at dealers that people were trying to get rid of after overloading the rear frames. The damage to the main cross frame over the rear axle can be very severe however most won't see it since its many times buried out of sight. Some even had the entire rear frame with the spare tire subframe or generator set come down dragging on the roadway since the guy who modified the hitch did not consult the RV Builders engineers. Remember that 500 lb tongue is within a foot of the receiver not a few feet back and its a tongue weight not a dead weight with its higher shock loads.

It's actually SOP to add two additional receivers to balance the load instead of just a locking collar on the main hitch when putting a motor bike carrier on a motor home. Some will go the extra and put a caster style wheel with a highway tire on it underneath the bike carrier after monting it to a hinge type coupling. A bike on the back of a motorhome can be like elderly Archamidies moving the world because he was handed a long enough lever to do so.

I have most of the stock set aside to do the two receiver setup on mine and just have not been up to it. Confirmed with the Coach Builders that while the hitch is rated for 1,000 lbs tongue weight that the rear frames which are already supporting a few tons of coach plus a large propane tank and 5 KW Generator set are only capable of supporting a tongue weight of 400 lbs in addition to what they are already carrying as is the same with the rear axle and tires.

Most times this is what we are talking about:


With whats underneath several feet shorter and added onto with much lighter duty materials:

Thanks Kat!

I think the point he was making is, someone is going to overload their motorhome unknowingly, just because someone else did it. Most RVers don't even know what a 4 corner weight is. Some know how to balance with a truck scale, but most just hit the road, overweight and unbalanced and wonder why they can't handle the drive!

He brought out some good points and a disclaimer is indeed in order!

-Rich

Back at ya Leo! oldchopperguy


One of these days I have to get over there and crack a few cold ones with you!


-Rich