Here is a link to an article from Outback travel Australia. Note the comments about WDH being used to reduce the tow ball loadings on Subaru vehicles which have very low tow ball weights. Also you may notice that the myth of 10% tow ball weight is also discussed.

https://outbacktravelaustralia.com.au/driving-towing-towing/towball-weight-and-trailer-stability/

Alan

outlaw40 wrote:

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Probably because the second someone comments Yobarr will be on them like a rash on a hookers privates .

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 Steve,there is no need to panic! On the very day that Alan posted this,I sent him a PM saying that I would not dignify his post by responding to it.In my email I explained exactly how a WDH works,and showed that a WDH does not,never has and never will change towball weight.I explained that there were so many holes in the post that it would take me a day to respond.A WDH removes weight from the rear axle  of the car,with around 70% of that weight being returned to the front axle of the car,whilst the other 30% is transferred to the van's axle group.I applauded Alan for acknowledging that GTM is thus increased,and said that all he now had to understand is that ATM also is increased,as towball weight does not change when a WDH is tensioned. With my car,using a WDH to remove 100kg from the rear axle resulted in the front of the car gaining 66kg,whilst the van's axle group gained 34kg.Thus GVM decreased 34kg,ATM increased 34kg,GCM remained constant and towball weight did not change.Simple physics at work! Since I have received neither acknowledgement nor reply,I can only surmise that my detaied explanation has again helped someone understand the workings of a WDH? But I must admit that I know absolutely nothing  about "a rash on a hookers privates!  Cheers

Bobdown wrote:

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I'm no suspension expert by far, but surely a WDH is a legal and worthwhile addition to a van and tug setup.

When I purchased my current van, I measured the height of the rear of the tug, connected the van and measured again.

The back of the tug had dropped 60 mm, the van looked nose down.....tug nose up.

Put the WDH on and the back of tug went up 50 mm, van and tug looked to be sitting nice and level.

To me, the steering was how it should be, it towed really well, not overweight and no swaying.

A lot of toing and froing regards the use of them, but I'm happy with mine..........do you have one Yobarr?

Cheers Bob

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 Hi Bob.....I am happy that your WDH has done what you wanted to achieve,but I do not use one,although there is an HR example in my shed.If the sole reason for using a WDH is to level the car,they may be a good thing,but unfortunately,in the vast majority of cases,the WDH is used in an effort to make a car do things for which it never was designed.The main problem faced by many caravanners is the overloading of the car's rear axle,with the WDH being seen as a "cure all",but it can create as many problems as it solves....think "oversteer". Buying the right car,or indeed,the right van,is the secret.With my car,I run at 6800kg GCM,legal on all axles,and no WDH,because I did my research before buying.There is 1350kg on the front axle,2300kg on the rear axle,and the GTM (weight on van wheels) is 3150kg.The car is thus  around 16% heavier than the car,and very safe.......little chance of the "tail wagging the dog" that often occurs when the van is heavier than the car.If safety is of any concern,the weight on the wheels of the car should be at least 10% greater than the weight  on the van's wheels,with some experts preferring the car to be 20% heavier. Many people have little understanding of weights,and spend thousands of dollars on a GVM upgrade without undestanding what it actually does.One popular model is often given a GVM upgrade from 3350kg to 3800kg,but the rear axle carrying capacity increases by only 50kg.....yes,a miserable 50kg,yet the upgrade costs thousands of dollars.Why would you bother? Cheers

                                     The Neverending Story La dee da da    da

Its all just fun guys.

Peter_n_Margaret wrote:

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ATM, GTM & GCM are RATINGS folks, they NEVER change no matter what you do.
If you don't understand the terminology there is little hope of explaining anything sensibly.
Cheers,
Peter

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 Hi Peter....I absolutely do understand the terminology,but I do always try to simplify things for those who have absolutely NO understanding of  the basic physics involved in the equation.Tomorrow,when I have more time,I will again attempt to help Alan understand that towball weight NEVER changes when a WDH is tensioned.NEVER.All weight transferred is removed from the car's rear axle,(NOT the towball) with a percentage of this,usually about 70%,being transferred to the car's front axle,and  the remaining 30% being transferred to the van's axle group.The reason for using the term "about" is that the weight transferred depends on several things,such as the wheelbase of the car,the TBO (distance from rear axle to hitch point) and the distance from hitchpoint to van's axle group. TOWBALL WEIGHT NEVER CHANGES when a WDH is tensioned.Period.The confusion of people like Alan doesn't really bother me,with my major concern being that the misinformation they post may cause "newbies" etc to make decisions that endanger not only  themselves and other road users,but may cause any insurance claim they need to make to be denied when their insurance company determines that they were overloaded,and unsafe.But ignorance is bliss.Cheers

P.S "Towball listed as zero,but not measured",surely makes a mockery of all submitted figures?

Brenda and Alan wrote:

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Yobbar this quote from your post shows you have not seriously looked at my post, but just rejected it.

"A WDH removes weight from the rear axle  of the car,with around 70% of that weight being returned to the front axle of the car,whilst the other 30% is transferred to the van's axle group.I applauded Alan for acknowledging that GTM is thus increased,and said that all he now had to understand is that ATM also is increased,as towball weight does not change when a WDH is tensioned. With my car,using a WDH to remove 100kg from the rear axle resulted in the front of the car gaining 66kg,whilst the van's axle group gained 34kg.Thus GVM decreased 34kg,ATM increased 34kg,GCM remained constant and towball weight did not change." 

You have forgotton that the 34 Kgs returned to the vans wheels is only a part of the towball weight, the rest is now on the tugs axles.So if you claim that the ATM of the van has increased by 34Kgs the GCM of your rig would have increased by this amount also. Obviously this can't be. So the ATM of the van can't have increased.

 Check my post again. All the weights I have used in the example come from a demo weighing by Haymen Reece themselves and is attached to the original post. I can assure you the arithmetic is correct. The weight on the tugs axles transmitted there by the weight on the towbar is 160Kgs, the increase in GTM of the van 60Kgs. the sum of these two weights is the original towball weight.

Don't bother sending me another PM unless you can discuss this issue rationaly unlike your last.

Alan

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 Alan....this post again illustrates that you are well and truly lost in the WDH wilderness.There are so many holes in your "logic" that it will take me hours to explain,but in the 7th line of this post you again say "..the 34kg returned to the van's wheels is only a part of the towball weight...". It seems that you still do not understand that that 34kg was NEVER part of the  towball weight.The 34kg was transferred from the car's rear axle along with the 66kg that was returned to the car"s front axle.Later today I will try to find a couple of hours to PM you a detailed analysis of your post,pointing out the mistakes/misunderstandings,but in the meantime you may like to ponder why your original,post states that  towball weight is "...listed as zero. (but not measured)".This certainly is convenient for your arguement,but is a nonsense.Cheers.

This is a list of the more common towing misconceptions.Of particular relevance to this thread is the explanation,in the third topic,that a WDH does NOT change towball weight.Simple physics at work.Some members might also like to take particular note of the sad truth revealed in the first topic? Cheers..

yobarr wrote:

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This is a list of the more common towing misconceptions.Of particular relevance to this thread is the explanation,in the third topic,that a WDH does NOT change towball weight.Simple physics at work.Some members might also like to take particular note of the sad truth revealed in the first topic? Cheers..

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 I am have no credentials in this field but as a novice and for the sake of towing safety some "facts" on this subject do interest me. 

So, as only a well credentialled Googler and after a quick search, I have discovered that yobarr's list of 4 items is simply part of a list 8 items contained in an article entitled "Top eight towing myths busted" and published on the reputable Australian Cars Guide website at this address:  https://www.carsguide.com.au/tradies/advice/top-eight-towing-myths-busted-73044 . Yes I know that this may be just one person's opinion, but that person is Mark Oastler, who is a long time, reputable, Australian motor sports commentator.  I would not think he would publish such an article without some technical advice to back him up, whatever/whoever that might be, nor would Cars Guide's duty of care/safety allow its publication without any such basis?

Again, a specialist WDH website of Alko, regarded as a "holy grail" of caravan engineering and accessories very clearly says on this link,  http://www.withoutahitch.com.au/caravan/set-weight-distribution-hitch/# , that:

"When a weight distribution hitch is tensioned, the back of the vehicle and the front of the caravan are raised, with a portion of the load shifting to the front of the vehicle. It might then seem logical to assume that the ball weight has been reduced, but this is not the case.  Without a weight distribution hitch fitted, the towbar assembly would just have a simple downward force imposed on it by the caravans coupling. But when a weight distribution hitch is fitted, it requires for that same towbar assembly to twist forward. The towbar is therefore not dealing with less weight when a weight distribution hitch has been attached and tensioned." 

And finally, this link to the specialist caravan website, GoRv, https://www.gorv.com.au/weight-distribution-hitch/ , written by a well known guru and author in the caravan towing field, Collyn Rivers, seems to also debunk the so called myth about WDH and towball weight when among other things Collyn mentions:

"Called a weight distributing hitch, it levered up the rear of that tow vehicle, and levered down the front of that vehicle, in effect lessening some of that tow ball weight on the tow vehicles rear tyres to restore that on its front tyres. A smaller amount was also transferred to the caravans tyres."  There are other websites that make a similar comment. Perhaps such comments support the Cars Guide myth buster as well as yobarr's contention that it is the tow ball's weight on the rear axle that is being transferred, not the weight bearing down onto the tow ball itself?  This is just my layman's conclusion from after reading the above two references.

So before we all "shoot the messenger" (yobarr?), argue ourselves to death and as well as make suggestions about banning a member who refuses to roll over on a subject that he is clearly passionate about, perhaps all posters can provide their own link(s) to any reputable source which backs up any data and comments they make on this technical subject. Then we can all read the links and make our own  objective conclusions?

Cheers,

Phillip

PS: When and if there is a 2021 Sydney Caravan Show, I shall ask the Hayman-Reece WDH specialisit conducting the demo there what facts and documentation he can put me nto that might debunk or back-up the so called myth!

-- Edited by Amigo1 on Thursday 14th of May 2020 11:52:22 PM

-- Edited by Amigo1 on Friday 15th of May 2020 10:44:57 AM

I have refaimed from commenting on this thread for hope it would remain amicable.

On another forum as soon as one appears the anti WDH brigade hops on to the thread and makes stupid comments about them as being band aids etc etc, I have even asked some of these people to provide us with their personal experiance in the use of a WDH, none has been forthcoming.

So would like to put the to you the anti WDH posters, your negative comments serve no purpose in assisting those who ask questions about their use or suitability, likewise my responses are about my personal experiance and research I have made, I do not expect every combination to have a WDH, however one will never know if they do or do not need to use one unless their coupling and ball heights are not setup correctly.

Initally you dont need to know ball weights, axle weights or towball overhang to assess, if you require the services of a WDH.

A good starting point is to read your owners manuals towing section and if the manufacture has a towing guide consult it for their recomendations, some demand the use of a WDH others forbid their use with others offer no reccomendation one way or the other, at the end of the day it's up to you if you need one or not.

One responder suggested following the advice of the person he named, I have found when asking that person specific questions about the use and application of weight distibution hitches, his responses were all based on theroitical data, when pressed about praticial experiance he retreated from the conservation, just like he did when he was a supporter of SAE's J2807 document where he and others took a single testing control and extrapoulated that to be a reccomundation applied to all WDH's retrospectivly.

Now going back to the OP whislt I am a supporter of the use of weight distribution hitches, there is a problem with these presentations as they are primarlily designed to sell their products, they mislead punters because they are in a controlled enviroment and are devoid of reality.

Lets go to reality the punter buys a vehicle he perceives to be suitable for towing the van of his choice, generally he has no idea about the weights of his vehicle other than it can tow 3500kg because thats what the advertising and salesman said it could, as for the van he can the little compliance plate which gives him the ATM, GTM and Tare(the tare is a fictious number). The salesman at van dealer if he's any good he will up sell you a few items which you may or may not need, one of them could be a WDH.

You have got your new tow vehicle and van home where you load them up with all sundry of items, then you hook them together, oh! crikey, the arse of the tug is down low and nose of the van is there to. At this point in time you do not know you axle weights nor the GVM or GCM along with your ball weight and actual GTM and ATM, or you may be lucky enough to have it all look pretty good.

If you have the former you may proceed to adjust where things are loaded in both units to make it look pretty good, you may decide to use that WDH you brought, one would hope you follow the instructions as supplied with it. Now everthing look real good we have an approximate idea of our ball weight because that salesman sold us one of the towball scales, now is the time we should go to the weighbridge and weigh everything, does that happen maybe maybe not.

This is where reality and fiction differ to get to the weighbridge if are required to use a WDH you need to set it up using the measurement system and then get to the weighbridge to confirm your weights and make any neccessary adjustments that are needed, unless you have a weighbridge in your backyard.

yobarr wrote:

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 Hi Graham...it is not often that I agree with your representations,but you are to be commended you for this GREAT post.As you suggest,the ONLY way to get your weights right is to visit a weighbridge and conduct a series of tests.This is how I produced the figures I have already posted on this forum, showing that a WDH has NO effect on towball weight. Cheers.

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 Yes you are correct a WDH has no effect on towball weight.

Likewise towball weight becomes irrelevent when tow vehicle and caravan are connected, all that matters thereafter are the GCM, GTM Axle Weights and the towing capacity of the the tow vehicle.

No body has mentioned "Center of Gravity". If we were to take a single axle van with an ATM of 2500kg, and the center of gravity (which I will call C of G) was at a point vertically above the axle, the ball weight would be zero.

With the draw bar (hitch point) set at the horizontal, which I will call zero degrees, a set of scales at the hitch would read O kg. If some of the weight in the van was moved forward, the scales would begin to read, as the C of G moves forward. Now the hitch is sharing some of the load. By moving more of the internal cargo load forward, so that the ball weight now reads 250 kg, the C of G will have moved forward, by how much would depend on the van, and I would have no idea where the C of G point is.

We can now say the Ball weight is 250 kg with the hitch point at 0 degrees to the horizontal.

If you hitch the van up, and the weight of the draw bar causes the back of the vehicle to drop, the draw bar is no longer at 0 degrees, it is now maybe -2 degrees, the van has rotated about its axis (in this case the axles), and the C of G has moved forward. The hitch will now be sharing more of the van load. The ball weight has increased, it is now maybe 260 kg.

If you now use some method to raise the tow ball using heavier rear springs, air bags, or WDH, so that the hitch is now back to zero degrees to the horizontal, the load sharing of the hitch will be back to 250 kg.