What Does a Weight-Distributing Hitch Do?

[Per Walthinsen]

When I installed the dedicated Honda hitch on my '99 I noted that it had "Max Load 3500 lbs" and "Tongue weight 350lbs" stamped on it.

[Gary Lynch]

My 2006 Toyota Pre-Runner owners manual does state it is best to always use a WDH when towing. It goes into a lot of detail but concludes that even with the WDH the owner should never exceed the GVWR or GAWR. There are no separate figures/calculations for using a WDH.

[Brian B-P]

...I interpret the disclaimer to use the Towing Vehicle's Manufacturer"s Rating if it is lower in my case to mean that I should use the Weight Carrying numbers as if they were the Weight Distributing numbers.

Mixing the Weight Carrying and Weight Distributing this way is confusing to me. Frederick, you're using a WD system, so wouldn't your limit (along with all of the axle limits, etc) be simply the lower of Honda's WD limit and Reese's WD limit?

I have friends who are confused, and tell me that if the label on the hitch says I can tow a 5,000 pound trailer, then I should be able to tow a 5,000 pound trailer!

Scary, but unfortunately not surprising!

[Frederick L. Simson]

Mixing the Weight Carrying and Weight Distributing this way is confusing to me.

Frederick, you're using a WD system, so wouldn't your limit (along with all of the axle limits, etc) be simply the lower of Honda's WD limit and Reese's WD limit?

I expressed it the way I did because Honda's WD limit equals Reese's Carying limit, and Reese's WD limit is too high for my Odyssey. I was having an <strike>arguement</strike> ...er discussion with my confused friend, who compromised his thinking on the subject with me due to the 3,500 / 350 limits being actually displayed... and not hidden in a manual that he did not have time to read and comprehend...

[Roger H]

Attachment 6572


I interpret the disclaimer to use the Towing Vehicle's Manufacturer"s Rating if it is lower in my case to mean that I should use the Weight Carrying numbers as if they were the Weight Distributing numbers. I have friends who are confused, and tell me that if the label on the hitch says I can tow a 5,000 pound trailer, then I should be able to tow a 5,000 pound trailer!

This is an aftermarket Reese hitch. The hitch itself is capable of towing 3500 lbs with a 350 lb dead hitch weight. It can pull 5,000 lbs with a 500 lb max weight if a WDH is used in conjunction with this receiver.

The catch is that the hitch may be more competent than the tow vehicle. I put exactly the same hitch on my '94 Toyota compact truck with a 3500 lb tow limit. Merely that I installed a hitch capable of towing 5000 lbs didn't increase the ability of the truck to tow more than 3500 lbs though.

Roger

[Gina D.]

on my Element, I had a class 1, 200/2000 limit FOR THE HITCH. I sometimes wish I had put a larger one on, but in reality, I didn't need it at all for my Burro 13, and because I kept with the limit for the car, which was less than the hitch.

Other E owners were putting on C3s, which could carry over 3 times the towing limit of the car.

Some had the same misguided thought "I have a hitch that can tow 5k lbs, I am gonna do it".

With the C1, I could not use a WDH, and that was the main reason for wanting a 3.

[Gary Lynch]

Owners manuals should go into more detail about towing.

[Brian B-P]

While there may be manuals which don't say enough about towing, I found with my Toyota that the manual says lots - it should be more concise, and have summary table of limits, but it's all there over several pages. I think the bigger problems are:

• many owners don't read the manual; and
• the information is not readily available before purchase, to aid appropriate vehicle choice.

In addition, the various bit of add-on towing equipment (such as WD systems and friction devices) are not part of the vehicle, so it would be difficult for the vehicle manufacturer to describe their function or proper use. The tug, trailer, and hitch are all designed and sold separately, by different companies, but they need to work as an integrated system. That's a challenge.

[Gary Lynch]

When I priced a Class III hitch at the Toyota dealer, they wanted $300. I thought that was a rip off. So I looked at after market hitches and most were around $125. But then I took a lot at how each was built. I was amazed at the difference. The Toyota hitch was a bit thicker steel and is attached with seven 1/2" bolts per side. The after market had three bolts per side. I went with the Toyota product and they did the labor for buying the truck from them. Now I wonder how many after market products are weaker designs compared to original factory parts?

[Pete Dumbleton]

Many newbie towing folks have been fooled into thinking that what it says on the step bumper or on the receiver hitch or even on top of the ball is the upper limit on the tow vehicle itself... If I tie-wrapped a 5,000 capacity receiver hitch to a Segway, could I tow a 3,000 lb trailer safely??

The true capacities are in the owner's manual, ***reduced*** by limitations of the towing gear.

[Brian B-P]

I hope you don't mind, Pete, but I'm responding to your interesting analogy from Towing with a Jeep CJ, YJ, TJ, LC FJ-40, LR SIII 80? here in this topic, which is dedicated to WD system operation. Pete, if you intended the questions to be rhetorical, then I suggest people come to the own answers, then compare to mine, and let me know if I've missed something.

No offense is meant in this discussion to short people or those - like me - who are middle aged and have protruding middles...

I've thought up a WDH analogy:

Picture a middle-aged guy on the floor, doing a pushup -- His hands and toes are on the floor, as is his belly -- Hands are front axle, belly is rear axle and toes are trailer axle.

Add a strong midget, standing sideways on the man, one foot on his back (slightly north of belly) and the other foot on his thighs -- One foot is the WDH hitch head and receiver hitch, the other foot is the trailer frame connection to the bar(s).

The midget has a rope looped under the guy's belly -- As the guy gets everything off the floor except his belly, the midget takes an upward strain on the rope, making the belly lighter on the floor (or even lifting it up) --

Interesting, but I don't think the "anatomy" is quite right. To really work like a WD system, both of the midget's feet need to be at that point on the thighs, and he needs to use an implement of some sort to pry the guy's belly up. The obvious attachment method cannot readily be described in a family-friendly forum... so I leave that as an exercise for the reader's imagination.

[Brian B-P]

So let's say we use this rope approach, instead of the prybar... the physics of the combined "vehicle" work out the same, anyway...

Is any of the midget's weight on the guy's toes, or is it all on his hands?

The foot on the thigh is adding load mostly to the toes, but partially to the hands; the other foot is adding mostly to the hands, and less to the toes. The midget can shift his feet trying to change this, but if (for instance) he moves the foot on the thigh higher up to put less on the toes, it just takes more the midget's weight (and his pulling force on the rope), so it doesn't change the overall result.

If the guy is strong enough to do the pushup without the midget's "help", when his belly comes off the floor, does any of its weight appear on his toes? If he's **really** strong, can he lift his toes off the floor??

The relationship between the weight on the toes and and the weight on the hands depends entirely on where the centre of mass (or "centre of gravity") is, relative to the hands and toes. If he moves his hands towards his belly, for instance, they'll get more of the weight. The only way to get his toes off the floor is to put his hands right under the centre of mass.

If the guy had strong hands and a handle on the floor, he could try to take weight off his toes by twisting his grip on the handle. This is what the WD spring bars do to the hitch; the big difference is that a vehicle doesn't have an anchor in the ground to work with.

[Frederick L. Simson]

When I priced a Class III hitch at the Toyota dealer, they wanted $300. [b]I thought that was a rip off. So I looked at after market hitches and most were around $125. But then I took a lot at how each was built. I was amazed at the difference. The Toyota hitch was a bit thicker steel and is attached with seven 1/2" bolts per side. The after market had three bolts per side. I went with the Toyota product and they did the labor for buying the truck from them. Now I wonder how many after market products are weaker designs compared to original factory parts?

In 2003 I had negotiated a below MSRP /no trade /no finance deal. After 4 hours of negotiating, the Honda dealer was in no mood to do me any favors on the "Towing Package", which he claimed [b]did not include the coolers. He quoted me $800 installed for a hitch receiver and 4-pin trailer pigtail, plus $800 installed for the transmission & power steering coolers. Since the Reese equipment was rated higher than Honda's brand, for less than $200, I chose to install the receiver & pigtail myself, and bit the bullet on the factory coolers to maintain valid warrantees. The WDH was included with the Fiber Stream.

[Gina D.]

Fred, for future reference..

your warrantee can not be void for the installation of an aftermarket product if:

It is properly installed, preferably by a qualified technician (Uhaul, mechanic etc)
AND the part is suited for the purpose of which it is intended.

Example: Uhual puts in your tranny cooler. It is the correct cooler for the gig. The cooler is installed to standard and no part of the cooler or installation fails.

Your tranny fails due to a weakness from the Honda factory in the tranny. Honda HAS to honor warrantee.

OR, your shift knob falls off. Honda still has to honor your warrantee.

Example 2: Uhaul installs a cooler too small for the gig. It is installed properly to standard.

Tranny fails due to overheating. Warrantee voided.

Example 3: Uhaul installs a properly sized cooler, but uses defective hoses. Leak springs after a period of time.

Tranny fails due to overheating. Warrantee voided.

Bottom line, if your failure is not DIRECTLY related to improper equipment or installation, the Void Your warrantee line is against California and federal law.

The "new" Honda is very good at blowing smoke at you on this one. Don't let them get away with it.

Rant over. (I looked this up when I got the same line, the FTC I believe)

Back to your regularly scheduled thread...

[Pete Dumbleton]

Brian, the whole point of the midget using the rope, rather than a pry bar, is that the WDH has no contact with the ground except through the tires. His feet are spanning the belly, which corresponds to the rear axle (one foot is the effect of the hitch head/receiver bolts on the TV frame and the other is where the chains mount to the trailer frame). As he pulls up to get the belly off the ground, his feet push down transferring the weight to the hands and toes.

The strong pushup can't involve a handle because there is no handle in the road, only wheels. No handles, no pry bars, no balloons, just weights, springs/leverage and three sets of tires on the ground.

Maybe this explanation on a different group would help:

WDH

[Brian B-P]

The strong pushup can't involve a handle because there is no handle in the road, only wheels. No handles, no pry bars, no balloons, just weights, springs/leverage and three sets of tires on the ground.

That's exactly the point I was trying to make... just like you can't lift your toes off the ground doing a push-up unless you have a handle, the vehicle combination can't avoid carrying load on the trailer axle, and increasing that load if it reduces the rear axle load.

[Brian B-P]

...His feet are spanning the belly, which corresponds to the rear axle (one foot is the effect of the hitch head/receiver bolts on the TV frame and the other is where the chains mount to the trailer frame). As he pulls up to get the belly off the ground, his feet push down transferring the weight to the hands and toes.

But the WD system is mounted entirely behind the rear axle (south of the guy's belly), while if this midget's feet are spanning the belly he haa a foot on the guy's back... that's cheating. Anyway, same point, the midget (or the WD hardware) doesn't get to touch the ground, and has to apply forces only to the body (or tug and trailer).

[Brian B-P]

Maybe this explanation on a different group would help:

WDH

You have to get to the fourth post in that discussion before the explanations become correct, ignore that last part of the fifth one, and then the sixth is pretty sound... but if you can follow that sixth one, you probably didn't need an explanation!

Frankly, I'm not looking for an explanation for me, but anything which will help others who might not yet have a (wheelbarrow) handle on the situation.

[Pete Dumbleton]

But the WD system is mounted entirely behind the rear axle (south of the guy's belly), while if this midget's feet are spanning the belly he haa a foot on the guy's back... that's cheating. Anyway, same point, the midget (or the WD hardware) doesn't get to touch the ground, and has to apply forces only to the body (or tug and trailer).

You're right, the analogy is flawed -- I put his foot on the other side of the belly because that's where the effect of the WDH is felt because of the leverage on the receiver hitch to the frame...

[Brian B-P]

The lull in posts suggests that everything so far is now making sense, so I'll take a shot at applying the principles to an example, with drawings to illustrate. Since CD Smith generously offered a set of dimensions and weights for his Cadillac Escalade and Casita 17', as well as his weight-distribution intentions, I'll use his rig for the example. I hope that's okay, CD...

First, here are the tug (Escalade) and trailer (Casita 17') separately:
Separate Vehicles




All of the downward force on the two vehicles is their weight, which is shown as a single force acting at each centre of mass - the point at which the whole mass of the vehicle would be concentrated if it could be squeezed down to a single point in space.

The upward force is the road holding up each axle, and a stand located at the coupler of the trailer. The distribution of load between the axles (and stand) is entirely determined by the distances to those supporting points from the centre of mass. Those centres are just calculated, and since we measure the axle loads directly on a scale there's really no need to know them... they're just there for interest.

In this and the drawings to follow, the forces are in pounds, the dimensions in inches, and while the calculations are based on CD's dimensions, the drawing is slightly off in some cases because the background grid didn't quite cooperate... the principles are unchanged.

The size (in pixels) of the drawing is larger than the FiberglassRV guideline (500 pixels wide), but a drawing like this is not clear enough to read in a small size, and the file size is small because it is mostly white space. I hope this is okay...