Further on WDH's

iana · Guru

Further on WDH's

rockylizard · Guru

Gday...

I can agree with your logic, Ian. However, it does not always apply in practice.

Many (most?) of the utes and 4x4's on the market today will have improved (and safer) towing with a WDH fitted. It is further complicated (muddied?) with manufacturers making statements that they will not support using a WDH "because we haven't tested our vehicle with one". The truth of the matter is that they haven't really designed OR tested their vehicle AS a tow vehicle.

Despite the marketing for these utes and 4x4's stating their wonderful carrying and towing capacities, it is a bit hit and miss in many cases.

This is probably further so with the so-called SUV's.

A WDH is the only thing that will literally spread the weight across the axles of the rig - front and rear axle of the vehicle and some to the axle/s of the van.

If the rear of the tow vehicle 'sags' when the van is connected there will be a corresponding rise in the vehicle's front - removing some weight off the steering and braking wheels. If the vehicle is a Front Wheel Drive it is affected more so.

This is particularly so when the van is a 'modern' big van - I would suggest anything over 2,000Kg ATM - and with ball weights upwards of 180Kg or greater. I truly believe that there is not a ute on the market that can genuinely (and safely) tow a modern van that has an ATM of (or is loaded to) 3,000Kg or greater.

This is mainly because despite the 'marketing' claims of the carrying capacity of modern utes and 4x4's they have very little 'spare' capacity (called payload) to cope with that ball weight.

This site can give some idea of the limitations of the "3.500Kg" towing units these days.

https://practicalmotoring.com.au/car-advice/why-a-3500kg-tow-rating-may-not-really-be-a-3500kg-tow-rating/

Apart from Holdens and Falcons, back in the 1970s and 80s I towed with Landcruiser 60 and 80 series ... they were hopeless without a WDH to control/cope with a large van (2,000Kg plus) or the rally car on a tandem trailer.

I towed with a 100 Series with a 1,900Kg van in the early 2000's and it too was not at all safe without the WDH - steering was quite light without the assistance.

Again, I do understand your logic and I am very aware that there are those who tow with their ute/4x4 without a WDH - but it is something that needs to be carefully assessed before the decision is taken to discard one.

Cheers - John

Peter_n_Margaret · Guru

The load carrying capacity of a ute is designed to be over or in front of the rear axle, not behind it. Some of that load is carried by the front wheels.
A 5th wheeler places the load over or just in front of the axle where some of the load increases the total load on the front wheels. It does not need a WDH and is inherently more stable than a vehicle with a hitch behind the axle.
This is basic physics. There is no debate from those who understand it.

Cheers,
Peter

Haji-Baba · Senior Member

Another consideration is the fact that most small utes, now very popular with the caravan set have most of the on board load behind the rear axel.

This in turn reduces the load on the front wheels even before the trailer load is applied.

Further to that, most utes have a greater distance behind the rear axel to the tow ball adding more leverage and down load to the rear of the vehicle.

I don't have a big van but do tow with a Colorado with a short space cab and a long aluminium tray . This allows us to load all the heavy gear towards the front of the tray in an attempt to keep as much as possible off the towbar and out of the van.

As for a W.D.H. we use one all the time and have done so for close on 30 odd years or more and in my opinion it helps to keep the rig stable.

One other thing, it is almost impossible to detach a van with the Hitch in place.

Have fun Haji-Baba

Steve11 · Senior Member

Hi All, I find these discussions so interesting and also confusing. It seems there is nowhere to go for correct, legal and unbiased advice either. Anyway, I have just bought a hayman reese WDH and have yet to use it on a 2014 Pathfinder and 16ft Jayco Journey. I was watching the video produced by hayman reese and they say not to use when reversing. So what do you do when you check into a campsite? Do you stop and unhitch before reversing? What is the reason for saying this? When I trialed the WDH the rod ends were only about 150mm off the ground, how does this compare with your van? Not happy with the Pathfinder so considering Colorado or MUX 7 seaters....could consider a dual cab as well though.

thanks

Confused Steve...lol

PS 19 days till retiring hooray!

Haji-Baba · Senior Member

I am with you Steve, no instructions, fly by the proverbial seat of your pants. There may be some directions for tension on chains and settings but I have never seen them.

The heavy suspension on most utes doesn't negate the use of a W.D.H.

The whole idea of the hitch is to try to straighten the line of all the wheels on the combination.

It does work to some extent but to actually straighten out the bends may require too much pressure
on the "A" frame.

As for reversing no idea what they are on about. May be something to do with the mechanical set up of your hitch in conjunction with your "A" frame.

I do know that you should remove bars at least on very uneven ground, creek crossings, deep culverts, or anywhere that causes the outer ends of the vehicles to be higher than the middle.

Excessive strain will be exerted on the "A" frame in these instances.

In this situation you don't need a hitch any way.

Have fun Haji- Baba

greyhoundtom · Senior Member

While there are various instructions on how to set up a weight distribution hitches, I have found them lacking in essential detail.

For instance eventhough the ball weight of the van itself may be within the listed weight handling ability of the WDH, if the rear of the tow vehicle is already sitting down due to it being overloaded in regard to its suspension, it will certainly place additional strain on the hitch trying to then get everything sitting level when the van has been hooked on as well.

The other item that is left out of some of the instructions I have read is how to set the whole thing up so that when the van and the tug are lined up correctly by the the tension of the hitch, that you have a suitable chain length that keeps the ends of the tortion bars the right distance of the ground, and at the same time give you enough chain so that taking fairly tight corners are not affected by a too short a chain length.

In this regard personal experience has taught me that the chain where it hooks on should not be less than 5 links and not be more than 8 links, and that to adjust this you need to adjust the section of the WDH that the ball is fitted to so that it either tips forward or backward which lifts or lowers the ends of the tortion bars. Again not a lot of the instructions I have seen are real clear about this procedure.

rockylizard · Guru

Haji-Baba wrote:
I am with you Steve, no instructions, fly by the proverbial seat of your pants. There may be some directions for tension on chains and settings but I have never seen them. The last vehicle I used a HR WDH was in 2008 - there were instructions provided by HR with my set

The heavy suspension on most utes doesn't negate the use of a W.D.H. Agreed.

The whole idea of the hitch is to try to straighten the line of all the wheels on the combination. Not actually so. The WDH is designed to DISTRIBUTE the weight from the rear axle of the vehicle to the front axle of the vehicle, the rear axle of the vehicle and the axle/s of the van.

It does work to some extent but to actually straighten out the bends may require too much pressure on the "A" frame. Correct. Not just the van's A-frame but also the towbar and/or vehicle chassis.

As for reversing no idea what they are on about. May be something to do with the mechanical set up of your hitch in conjunction with your "A" frame.
Disconnecting the WDH when reversing and/or when traversing gutters etc is to reduce the additional strain/pressure that will inflict on the A-frame and vehicle chassis and tow bar. Many don't disconnect the WDH in those instances. Probably more good luck than good judgement has prevailed.
I do know that you should remove bars at least on very uneven ground, creek crossings, deep culverts, or anywhere that causes the outer ends of the vehicles to be higher than the middle. As above.

Excessive strain will be exerted on the "A" frame in these instances. Correct.

In this situation you don't need a hitch any way.

Have fun Haji- Baba

Gday...

Others may shoot me down ... but my responses are from my use of WDHs over decades.

[edit: I should add, rather than assume it is understood, that it is ALWAYS critical that the loading of the van is done to ENSURE the weight WITHIN the van and at its extremities is balanced/arranged to have the van as CORRECTLY balanced as possible so that it does not have an unnecessarily too heavy (or too light) tow ball weight. A WDH will NOT correct a badly balanced rig (vehicle and van) it will only distribute weight applied to the tow ball to the front and rear axles of the vehicle and to the axle/s of the van]

Cheers - John

-- Edited by rockylizard on Sunday 7th of February 2016 10:49:30 PM

iana · Guru

To throw a cat amongst the pigeon's, I have been told by two tow bar installers that the compliance plate weight and figures for the tow bar only relate to that assembly using the supplied tongue, if any other tongue is used then the figures have to be re-calculated. To do with the moments applied to the tow bar.
The WDH when fitted to the tow bar it moves the ball out 75-100mm further, and also weighs over 30kg.

Gus1949 · Senior Member

The next time I take my van out I will take it to a weight bridge and get the weights checked. As part of the process I will get the vehicles weight at the front wheels measured with and without the WDH and see how much weight is transferred to the van. This will show exactly how much weight is being transferred to the front wheels and the potential effect on steering and breaking. Given the potential for serious damage being caused to a vehicle, tow bar and caravan by WDH's it seems foolish to use them if they are not really needed.

rockylizard · Guru

Gday...

Rowan (Gus1949). Another forum I am a member of conducted a "weigh-in" for our vehicles and vans at no charge to us.

The "weigh-in" was conducted by personnel from the VicRoads personnel who's job it is to weigh trucks and other vehicles to confirm compliance and the "weigh-in" was conducted on an official VicRoads weigh station.

Part of the reason for the "weigh-in" was so we, as members, could see the actual weight of our vehicles and vans and their compliance with their 'stated' manufacturer's ratings - ie whether our vehicles were overweight ... and also to see if our vans exceeded their ATM.

The attached PDF file shows the results of the "weigh-in".

It clearly shows the affect of weight distribution afforded by a WDH - an interesting exercise. You can clearly see the weight 'transference' between rear, front axles and the van.

The Discovery 3 and Golden Eagle van in the spreadsheet is mine. I don't use a WDH.

Cheers - John

Footprints · Senior Member

In my humble opinion, based upon several years operating a tow bar fitting and modification and towing accessories fitment business I have come to the conclusion that WDH fitment is purely to mask the problem of incompatible and unsuitable tow vehicles being used for the task. Compared with earlier Holden and Ford vehicles the more modern vehicle is constructed of much lighter materials and use very thin high tensile steel all in an attempt to gain performance and economy. While the modern vehicle is very capable power wise to pull a substantial load the body / chassis is not capable of the same level of performance and durability. WDH exert extreme loads to the chassis of the tow vehicle which can cause cracking and chassis failure, this is exacerbated with the modern twin cab utes by two factors. The point of greatest strain will be at the mid way point between the front axle and rear axle of the tow vehicle, although a higher tensile steel will be stronger it is also more brittle so any flexion caused at this point will "work harden" the steel chassis causing it to fracture. The second point to note is that in the older types of utes such as Holden and Ford the body style was "Style side" which had the effect of stiffening the body / chassis. The most popular Twin cabs etc. do not have that. There are of course exceptions being latter Fords, Holden and Toyota, built to suit the task. I have seen Sedans that have been hauling heavy loads that have had the roof and floor pan stretched approx. 5mm creating an issue with trying to keep the rear doors closed effectively.

One must ask the question of why WDH are necessary when vehicle towing caravans seem to be the only vehicles on the road using them. semis and fifth wheelers obviously don't need them, trucks towing dog trailers or pig trailers don't need them, cars towing horse floats don't need them, cars towing car trailers don't need them. My conclusion is, The tow vehicle is not ideal for the task being demanded of it or the caravan laden incorrectly and the WDH is only masking all of the potential problems that a miss match can potentially create.

Cheers Allen.

iana · Guru

Footprints, well said, and exactly what I am thinking, was going to mention the trailer towing, but elected not to. I brought an extra cab BT50, with the original idea of getting a 5th wheeler, if or any other reason but to get away from all this stuff. I cannot understand why we are still making caravans which would appear to be unstable on the road, when with all these utes available now, that 5th wheelers have not become more popular, while they are in a high price bracket, the only difference between then and a std. caravan is the joggle that makes up the goose neck, and I fail to see why there is this high price. But they are, depending on the trailer wheel position, self stabilising.
Because of this cost impasse, we have brought a caravan, and all the problems that go with it. As one can see from Rockylizards PDF file most of the van/tug combo's are at 100% loading. My direction is to put all 80% of cargo in a canopy on the back of the ute, keeping the weight well forward. As it looks now I have to have a GVM up-grade on the vehicle just to stay legal, and still have a little weight left to carry up my sleeve.
I do not like the way the WDH extends the tow ball farther back than it already is, as well as adding another 30.5 to 35Kgs at the extreme moment of the tug. As you have said I have yet to see a WDH on a trailer including those tradies whose rigs are usually grossly over loaded.

-- Edited by iana on Tuesday 9th of February 2016 12:43:14 AM

-- Edited by iana on Tuesday 9th of February 2016 12:43:47 AM

Cupie · Guru

rockylizard wrote:
Haji-Baba wrote:

As for reversing no idea what they are on about. May be something to do with the mechanical set up of your hitch in conjunction with your "A" frame.
Disconnecting the WDH when reversing and/or when traversing gutters etc is to reduce the additional strain/pressure that will inflict on the A-frame and vehicle chassis and tow bar. Many don't disconnect the WDH in those instances. Probably more good luck than good judgement has prevailed.

Have fun Haji- Baba

-- Edited by rockylizard on Sunday 7th of February 2016 10:49:30 PM

Snip ...

Looks like I've had 16 years of 'good luck'.

I have never removed the spring bars while reversing.

Jaahn · Guru

Hi smile

There is a lot of loose discussion here but real discussion at least.

WDH have been around since the 1950s at least. Nothing new here. However the rise in popularity of Grey Nomads who have the money to buy buy buy stuff to drag around the country has provided a market for BIG CARAVANS and that means people now tow much bigger vans than ever before. Not only that they expect to drive fast too and cover large distances. Then along come the mid sized utes and a marketing opportunity is seen. So plenty of adds showing unreal applications.People believe it all confuse

In the old days when you had a big caravan you got a big tow vehicle and put up with the limitations or you had a car and limited the van size to what it could tow. Seems like that common wisdom has been lost. Bigger is a marketing opportunity and the real facts are a bit hazy from the sales people. The average punters will believe anything really hmm

I have towed some big trailers over the years, car trailers and building trailers, behind cars and vans mostly. A couple of caravans too. I have always used WDHs if the load was big and the distance demanded it. They always made towing better and the rig more stable. Towing race cars with a small vehicle 500Ks for a weekend was a piece of cake with a WDH compared to a straight trailer. I would always use one if I had a caravan now. However they are not an answer to a badly loaded rig just another tool for safe driving or perhaps comfortable driving. aww

This statement "As it looks now I have to have a GVM up-grade on the vehicle just to stay legal" shows the trap most people fall into.

Jaahn

-- Edited by Jaahn on Tuesday 9th of February 2016 07:18:40 AM

iana · Guru

Jaahn wrote:
This statement "As it looks now I have to have a GVM up-grade on the vehicle just to stay legal" shows the trap most people fall into.

Just curious as to what you mean by that statement Jaahn?

Jaahn · Guru

iana wrote:
Jaahn wrote:
This statement "As it looks now I have to have a GVM up-grade on the vehicle just to stay legal" shows the trap most people fall into.
Just curious as to what you mean by that statement Jaahn?

Hi iana,

That statement and this one " most of the van/tug combo's are at 100% loading" indicates to me that the tug vehicles are not up to the task that people need. Starting at 100 % loading and then getting an "upgrade", what ever that means, to enable some more stuff to be carried in my humble opinion is crazy. confuse

In my working life in practical engineering, I would never design a project that was at 100% of its capabilities. Let alone then load it more ! I always allowed a bit of a margin for error or extra or something. If i was starting out with my whole life relying on the rig I would be allowing a bit more even. cry

Being legal and common sense are not the same !! If I had a big caravan I would have a big tug. I note Footprints has a truck. Good choice perhaps but I find the ride and the cab access is not to my liking. I have chosen a converted small bus MH and reduced the amount of stuff to well below the maximum weight, however we are not full time. But it drives nicely and good fuel consumption aww

Cheers jaahn

indicates

-- Edited by Jaahn on Wednesday 10th of February 2016 08:13:49 AM

Footprints · Senior Member

One slight correction. The later model small trucks ride quite smoothly and the entry is only approximately 200mm (8 inches from ground level in fact it is easier to enter and exit the Isuzu with its 90 degree opening doors than it is to enter and alight from my Commodore. Being a short wheelbase it is parked easily in any city street car parking space and the turning circle is so small that it is able to "U" turn in most streets, remembering that these light trucks are designed mainly for inner city delivery runs where ease off entry and good manoeuvrability is essential. I give it a 10 out of ten. Cheers Allen

Gus1949 · Senior Member

The post by Rockylizard of 9 Feb and the data sheet attached to it indicates that using WDH bars increases the weight over the front wheels when a caravan is attached by a significate margin and correspondingly reduces the weight over the rear axle.

This suggests the WDH is over compensating and placing too much weight to the front of the vehicle. Given that the WDH is placing strain on the A frame of the van and the vehicle tow bar it indicates that the bars should be loosened off or taken off altogether. Or have I missed something?

Rowan

rockylizard · Guru

Gday...

Whilst the WDH will place 'some' strain on the towbar, chassis and A-frame, it is that 'strain' that re-distributes the weight across all axles - rather than having the 'strain' (weight?) unbalancing the rig, overloading the rear axle and reducing the ability to steer, brake and control the rig.

With no WDH fitted the strain on the rear of the vehicle, in itself, is considerable.

The transference/removal of some weight from the rear axle to the front axle of the vehicle and back to the van restores some 'balance' and 'control' to the outfit.

The transference/restoration of some weight back onto the front axle restores steering and braking abilities.

As stated previously, a WDH will NOT correct a badly balanced van (or vehicle). It will only re-distribute the weight across all axles. The first step should ALWAYS be to have the van properly balanced BEFORE towing and/or using a WDH.

See the attached diagram - hopefully it gives some idea.

Cheers - John

-- Edited by rockylizard on Saturday 13th of February 2016 09:45:45 PM

Jaahn · Guru

Gus1949 wrote:
The post by Rockylizard of 9 Feb and the data sheet attached to it indicates that using WDH bars increases the weight over the front wheels when a caravan is attached by a significate margin and correspondingly reduces the weight over the rear axle.
This suggests the WDH is over compensating and placing too much weight to the front of the vehicle. Given that the WDH is placing strain on the A frame of the van and the vehicle tow bar it indicates that the bars should be loosened off or taken off altogether. Or have I missed something?
Rowan

Hi Rowan smile

Yes you have missed something !! WDH is short for weight distribution hitch. It's actual purpose is to take the weight off the rear and distribute it to the front wheels and also has to add some to the van wheels. That is the reason to fit them ?? It does place some extra strain on the towbar and the A frame but no more than they can handle if properly set up.

John has given some more detailed figures in his post and points out "The transference/restoration of some weight back onto the front axle restores steering and braking abilities." That is the point of a WDH.

Possibly they can also have some other benefits depending on the detailed design.

Jaahn

-- Edited by Jaahn on Saturday 13th of February 2016 09:48:53 PM

Radar · Guru

One thing I have found with bars is the way under heavy braking the vehicle responsed better.

I did find with our car towing our braked camper trailer on dirt roads the ABS come on as the vehicle lost braking traction on corrigrated roads at the front wheels then once bars were fitted we never experience this again in normal driving to the conditions

Gus1949 · Senior Member

Rockllizard & Jahaan, I understand and always have what a WDH is and what it does. You have missed the point I was raising. From the data sheet Rockylizard posted the WDH bars appear to be over compensating and placing more weight over the front wheels than exists when a van is not attached to the tug. I am not saying WDH bars should not be used as clearly there are situations where they are very important but before shelling out a grand or so for a WDH it would seem sensible to run the rig over a weigh bridge to ascertain whether or not they are necessary and not just blindly fit them because "that's what everyone does". Are WDH's just a hangover from the times when vans were towed by Holdens and Falcons?

rockylizard · Guru

Gus1949 wrote:
Rocklizard & Jahaan, I understand and always have what a WDH is and what it does. You have missed the point I was raising. From the data sheet Rockylizard posted the WDH bars appear to be over compensating and placing more weight over the front wheels than exists when a van is not attached to the tug.~~~SNIP

Gday...

I guess you may have misread the data included in the table provided as a pic. Those figures were obtained as the result of an ACTUAL weighing of ACTUAL vehicles and ACTUAL vans on a VicRoads weighbridge, conducted by VicRoads Compliance employees in their own time.

Here is a bit of the table/pic showing only the front axle info -

WDH affect A.jpg

You can see that the ACTUAL weights on the front axle show -

weight on the front axle BEFORE the van was attached = 1,500Kg;
weight on the front axle AFTER the van was attached, but without WDH attached = 1,300Kg;
weight on the front axle AFTER the van was attached WITH the WDH attached = 1,440Kg.

Therefore, attaching the van took 200Kg OFF the front axle of the vehicle and fitting the WDH restored 140Kg of those 200Kg to the front wheels. There is still 60Kg LESS on the front axle than before the van was attached.

I find it very hard to understand (believe?) your comment that the WDH places more weight on the front axle of a vehicle than was there BEFORE the van was attached.

If you go back to the complete spreadsheet I provided earlier you will see this is a typical re-distribution of weight across axles when using a WDH - across a variety of vehicles and vans that attended that weigh-in.

Cheers - John