Weight Distribution Bars

Submitted: Wednesday, Feb 19, 2014 at 22:17
ThreadID: 106328 Views:3540 Replies:9 FollowUps:11
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Can anyone tell of their experience with these, as I've heard some conflicting theories.
I tow a Crusader X Country single axle van with a 100series Landcruiser. The ball weight is around 200kg which makes the steering feel very vague and light.
Hayman Reece have those very heavy systems which I want to avoid to minimise GVM.
My argument is that a lighter WDB system would transfer a certain amount of weight to the front which I'd be happy with. We travel on dirt a lot, but when it gets to real rough stuff I know the bars have to come off.
Any ideas or suggestions much appreciated. Joe
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Reply By: The Bantam - Wednesday, Feb 19, 2014 at 22:53

Wednesday, Feb 19, 2014 at 22:53
the argument of weight distributing hitches aside.

Have you thaught about redistributing some weight within the van to reduce you ball weight.

We have a lot of people with ...interesting...views about ball weight.

Some will say "at least 10%" of the trailer mass as ball weight.

Um yeh that conflicts with the official line and how tow vehicles are rated.

The official line seems to be 5 to 10%..and that is reflected in ball weight in comparison to towing capacity of most vehicles.

So this van with 200KG of ball weight...is it a 2 tonne van?

The problem is that any trailer suspended on a single axle group ( a pig trailer) is fundamentally unstable, and most vehicles used to tow are not specifically designed as tow vehicles....particularly station waggons, which are softly suspended, particularly in the rear as they come from the factory.

Something has to be done to stabalise any long high centre of gravity pig trailer...(most caravans).... towed by a pasenger car.

Spring and scock absordber upgrades have their role..as do weight distributing hitches.

OH BTW..you do realise that every KG of ball weight has to be deducted from the payload of the tow vehicle.

Some of the 6 cylinder and V8 4wd station waggons only have arround 600Kg of payload including pasengers..as they roll from the factory.

Combine that with the fact that the ball weight is applied way out beyond the rear of the wheel base...it is very easy to overoad the rear suspension in these vehicles.

Put 4 average sized addults and their lunch in the vehicle and hitch up with 200Kg of ball weight and you may well be over loaded.

First thing to do is load the rig up as you would to travel and put it over a weigh bridge.

And be prepared for a shock.

cheers
AnswerID: 526838

Follow Up By: WBS - Thursday, Feb 20, 2014 at 07:40

Thursday, Feb 20, 2014 at 07:40
If you are considering redistributing the weight, make sure you don't placed it back too far behind the axle because then you are creating a serious instability problem. Much has been written on forums about the "pendulum effect" of poor weight distribution, (Collyn Rivers comes to mind). Redistributed weight should be put above the axle not at the extremities of the van, front or back.
WBS
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Follow Up By: Member - PJR (NSW) - Thursday, Feb 20, 2014 at 09:03

Thursday, Feb 20, 2014 at 09:03
Yes We had those bars. Only I do not recall them being called WBS. They were a funny shape and a bit like a stretched question mark. And they work. I experimented with a friends pair and it was very noticable at the very first corner so I got some.

That was a few decades back when we towed our Chesney wind up with the family sedan. No big heavy suspension work for towing or anything like that. Just the bars that twisted down on the "A" frame and effectively up on the rear of the car. But note that I had less than around 50 kg on the towbar. I could just lift it. And I moved weight around in the car to keep it around that weight.

And I could easily drive at 80+ MPH. Yeah Fast hey Bloody idiot hey. Hoon and should be off the road. Say or think what yopu wish but please note that it worked. The steering was excellent and very responsive and the whole lot travelled welll.

This is the advice I got from a bloke by the name of Doug Chivas. And it was solid and useful experience not some formula dreamed up by an engineer. But knowledge built on experience.

So I always chuckle when I hear figures like 200 kg. I wouldn't dare do that. Even with the 100 series. I can feel the steering get light just thinking about it. Simple physics and no computer to work that out. I don't care what the so called specialists say about it. It felt good and safe.

Take it as you wish but I believe those bars do help. They wont solve fully light steering, or the rear being low and or headlights blinding people even on low beam (dont you just hate that). Nor will it solve bad steering. But it will transfer some weight. Not a lot but some. They will help.

Phil
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Follow Up By: Ross M - Thursday, Feb 20, 2014 at 11:16

Thursday, Feb 20, 2014 at 11:16
Phil
WBS is his name!!!!!!!!!!!!! Not the bars.

I like the mental imagery though, of a pendulum effect being" Collyn Rivers" swinging back and forward.


Driving on the road at 80mph I reckon deserves you being renamed,
"Lucky Phil"

The situation of it being good and feeling safe is just a feeling and doesn't indicate a level of safety. Collyn Rivers spoke of the possibility of all being well until it suddenly isn't. Then it gets interesting.

The Concorde felt good at take off too, however the situation did change.
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Follow Up By: Member - PJR (NSW) - Thursday, Feb 20, 2014 at 11:23

Thursday, Feb 20, 2014 at 11:23
Good on you picking something to have a go at me.

Now to my real point. Why so much weight these days?

Phil
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Follow Up By: Member - PJR (NSW) - Thursday, Feb 20, 2014 at 15:05

Thursday, Feb 20, 2014 at 15:05
Hey ROSS. I missed that bit about his name.

I meant WDS.

Phil
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Follow Up By: Nomadic Navara - Thursday, Feb 20, 2014 at 16:56

Thursday, Feb 20, 2014 at 16:56
Phil, you ask " Why so much weight these days?"

From what I have noticed the tow ball weights are getting lighter, not heavier. Way back when a large van was one with a body length of 18' (5.5 m) it was established that vans with a ball weight of 10% were more stable than ones with a lighter tow ball percentage weight. Back then there were no vans with front or rear kitchens to speak of. When you construct longer vans the yaw inertia increases and you need heavier ball weights to achieve the same stability.

The yanks with their large vans work on ball weights of well over 10%. Some over there recommend 15 - 25% ball weights.

The European vans can get away with 5 - 7% ball weights. That is achieved by employing better dynamically designed vans. You will note that their van designs concentrate the weight to the middle. They don't have rear bumper bars, their spare tyres are mounted under the middle, the front boots are smaller and the list goes on.

While our manufacturers continue to design and build vans with poor dynamic weight distribution we should be loading our vans to have a ball weight of over 10%. Mine is 250kg on a all up weight of 2,000 kg. I am quite happy to have that amount of ball weight.

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Follow Up By: Member - PJR (NSW) - Thursday, Feb 20, 2014 at 17:26

Thursday, Feb 20, 2014 at 17:26
Thanks Peter.

Luckily we don't have any intentions of towing.

Phil
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Follow Up By: The Bantam - Friday, Feb 21, 2014 at 20:09

Friday, Feb 21, 2014 at 20:09
The pendulum effect is exacty what I was talking about when I say fundametally unstable.
This is why the pig trailer is all but extinct in heavy transport, replaced by much more stable dog or fifth wheel trailers.

Yeh what the yanks do is another thing all together.....over there they allow all sorts of things on the road that would not even be considered here...and they do some realy strange things with trucks too....heavy rigids with trainer wheels out the back and semi trailers with an axle in the middle... go figure.

The yanks also in generaly drive bigger vehicles and tow with bigger vehicles....even their very close equavalent of our Hilux...the Tacoma.....is longer, wider and heavier..not by a lot but by some.

The reason remans why people put sooo much weight on their balls....( hmmm...:)..there is a parelell there).....this is an attempt to compensate for a van that is either badly designed or badly loaded.
I remain gob smacked at how far caravan design has not come in the last 30 years.

Yes and then there is the tendancy for people to add significant weight at both ends of the van after manufacture.....just about every aftermarket add on is heavy and either fitted on the drawbar or one an aftermarket rear bumper.

No wonder people have problems.

Now an interesting thing.
If you look at the towing capacities of most modern vehicles..and in particular the permissable ball weights compared to the towing capacity.

There are a lot of people will find themselves, illegal and overloaded on their rear axle even though thay are as much as 2/3 of the towing capacity.

Actually a couple of the high towing capacity utes have very low permissable ball weights...down arround 5%.

It may have a 3.5 tonne towing capacity but unless it is towing a dog trailer ( 4 wleel self streering trailer) the practical towing capacity will be under 2 tonnes.

cheers
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Reply By: Jim* - Thursday, Feb 20, 2014 at 01:39

Thursday, Feb 20, 2014 at 01:39
Joe..
You’ve answered your own question..
‘The steering feels vague and light’ - means braking and steering are less effective than they should be - putting you and others in danger on the road.

Drop 200 kg on the towball and you’ve loaded the rear axle by about 250 kg - the other 50 kg has been removed from the front axle.

You need a WDH that effectively transfers that weight back to the front axle to regain stability and effective steering and braking.
Your argument doesn’t hold up about using a lighter WDH.. You need to use a correctly rated WDH - matched to the actual load on the towball for it to be effective.

The lighter units are good for up to about 130 kg towball download - from 130 to 275 kg you need a Hayman Reece 600lb kit or equivalent. Anything smaller is a waste of money and not effective.

Jim
AnswerID: 526842

Reply By: Member - Beatit (QLD) - Thursday, Feb 20, 2014 at 09:16

Thursday, Feb 20, 2014 at 09:16
G'day Joe,

I noticed that you are already convinced of the value of a WD device and I would also agree with that. I have towed my van with and without WD bars and also with and without suspension modification on the tow vehicle and can only reiterate their value in helping the combination drive better. Your problem of weight is a more difficult story which for me resulted in a vehicle mod as it was just so hard to stay within the load parameters and take all the goodies for a fulfilling trip.

The WD bars are a safety issue and primarily the weight can be managed to a point of frustration as to what you leave behind. I'd have to agree that the basic vehicle does not have a reasonable load carrying capacity for this application and is flat out after a few mods being able to be packed for camping let alone towing.

I hope you work it out.

Kind regards
AnswerID: 526851

Reply By: Nutta - Thursday, Feb 20, 2014 at 09:36

Thursday, Feb 20, 2014 at 09:36
My ball weight was a lot more than that on my GU and it always felt great, unusual for similar rigs.
AnswerID: 526854

Reply By: Ross M - Thursday, Feb 20, 2014 at 09:51

Thursday, Feb 20, 2014 at 09:51
Reetta & Joe
As you probably know the distance from the ball itself to the back axle is a lever, to which when weight is applied it lift the front up to balance the forces that are there.

Many, most, nearly all tow bar tongues are mounted too far back. Often there is quite an amount of shank of the square section protruding from the receiver.

If yours is a stock purchased item it probably is also like that.

Often some modification has to be done the the square section. Because the receiver often has a blind hole the tongue unit cannot be pushed in further, so appropriate shortening may be required before the redrilling of the hole in the tongue square section.

The idea of this is to get the ball as close as humanly and mechanically/physically possible so the lifting of the front is minimized. That combined with the wise advice of appropriate re allocation of weight in the van will surely improve things.

The added advantage of the "close as possible ball position" is the van cannot therefore exert as much pitch momentum or sideways slew control over the vehicle (in windy conditions or emergency steering situations) and the poor bugger steering it.
Much safer all round.

I cannot ever understand how many vehicles are deemed to be professionally fitted and legal with such long distances unnecessarily created but protruding tow tongues.
All checked an OK'd by the fitters though.

Everyone regards those situations to be normal and therefore no problem, BUT they ARE the cause of many problems. Your is one such problem.

I have shortened a few because they were just plain dangerous.
When fitting the towbar on my vehicle I also made sure the ball position was as close as is possible before ever towing anything.
No good finding out by "accident" it was to far out.

Cheers
Ross M
AnswerID: 526856

Reply By: Racey - Thursday, Feb 20, 2014 at 10:09

Thursday, Feb 20, 2014 at 10:09
The "heavy Hayman Reeces types" won't effect your GVM enough to worry about. The real answer to your problem is to fit a WD system, such as the HR type, which is correctly rated to suit your set-up. A lighter system will be a waste of money. When the HR type systems are set up correctly, the tow vehicle and the caravan will sit level. You will be surprised at the difference. The steering will be restored and see sawing minimised. The whole set-up will have a more stable feel. You will need a 600 lb kit which covers ball weights 135 - 270kg. Well worth the money.
AnswerID: 526859

Follow Up By: Nomadic Navara - Thursday, Feb 20, 2014 at 17:59

Thursday, Feb 20, 2014 at 17:59
Quote "The "heavy Hayman Reeces types" won't effect your GVM enough to worry about."

Adding any weight does not affect your GVM. GVM is a technical term defined in the motor traffic regulations. It is defined in the ADRs as:

"GROSS VEHICLE MASS (GVM) - the maximum laden mass of a motor vehicle as specified by the Manufacturer‘."

Adding any weight on the tow bar will ad to the total weight of of your tow vehicle. However it will not add much weight to the rear axle as the van will if you don't use WDH. The chart below is an actual demonstration recorded by Caravan World technical editor Tom Olthoff at a Melbourne caravan show..

You will note that the 220 kg ball weight added 360 kg to the loading on the rear axle. The extra 130 kg comes from the weight removed from the front wheels when the van is coupled without WDH.

If you are not using WDH with your van then you should allow for that increased axle loading. Nissan calculates this for their vehicles. If you have any other vehicle you have to work it out yourself if you don't employ WDH.




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Reply By: pop2jocem - Thursday, Feb 20, 2014 at 11:20

Thursday, Feb 20, 2014 at 11:20
Reetta & Joe,

Do a Google search for Collyn Rivers. This guy contributes a lot to other forums on the very subject you are chasing.
I believe his advice is sound and based on years of research and experience. He has written books but also gives free advice on his web site.
Lots of "armchair" experts like my self but I think you will find this guy knows what he is talking about.

Cheers
Pop
AnswerID: 526866

Follow Up By: 671 - Thursday, Feb 20, 2014 at 14:36

Thursday, Feb 20, 2014 at 14:36
I have to agree with you Pop, he has been keeping up to date on suspension design since his GM research engineer days in the 1950s and has paid a lot of attention to caravan dynamics for the last twenty years.

This is an extract from a post he wrote on another forum yesterday.
-----------------------------------------------------------------------------------
Any trailer towed via an overhung hitch has an inherent tendency to yaw. It is an unstable device that can, within limits, be rendered less unstable to an acceptable level.

There are two main approaches.

Australia
To have such substantial tow ball mass that a very large disturbing force is required to introduce yaw. This is effective - until one needs to swerve very strongly (to say avoid a head-on accident). Or subject to a sudden strong gust of wind.

This (in my opinion) the more potentially dangerous form as the huge front end mass commonly causes the rig to feel ultra-stable until a high disturbing force occurs whilst travelling at speed.

USA
This is much as above but changes in 2015 when long-delayed legislation includes obligatory and rigid stability testing. The allowable trailer mass is also specific to the tow vehicle and takes into account hitch overhang. (Technically it is the radius of gyration divided by the hitch overhang.) The standard requires the tow vehicle to maintain understeer up to 0.4 G.

Much of the above standard is based on the sources that I have quoted in other related threads.

EU
The EU approach is to totally accept that the 'van will sway but, by centralised low mass design, to substantially reduce its effects Tow ball mass is typically much lower than in USA and Australia and the inevitable but less dangerous yaw (as forces are far lower) is dissipated as heat via friction mechanisms or restrained by sprung cam mechanisms. The ESC is seen only as a further aid. WDHs are hardly ever required or used.
-------------------------------------------------------------------------------------------
Our huge tow ball weights are a primary reason why it is very common for a driver to say the van felt so stable --- until it suddenly jack knifed.

Note the .4 G understeer requirement for the tow car in the US. The usual way to make a car understeer or oversteer is to transfer more weight to the outside wheel in a corner via stiffer springs or sway bars. Almost all cars are designed to understeer. By stiffening the rear suspension of an overloaded tow car, you are making it more likely to oversteer (i.e swing the rear end out first in a corner). That is the last thing you want with a swinging front heavy caravan on the back.

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Reply By: Member - Bruce C (NSW) - Friday, Feb 21, 2014 at 13:18

Friday, Feb 21, 2014 at 13:18
Hi Reetta & Joe,

I bought my first van in 1973. It came with a set of weight distribution bars and I thought as they were supplied I would use them. I was immediately impressed with their function and the feel of the car and caravan as a unit.

Previously I had towed boats on trailers of varying weights and sizes but never with a WDH.

After that first tow with them I decided I would never tow a heavy load without one again. Ever.

Since then I have done countless miles towing and have never had a problem with respect to the WDH or the vehicles handling.

I have formed the opinion that they ought to be mandatory on any vehicle over 1 tonne.

You will find an even greater benefit due to you having only one axle. These devices take out most of the rocking horse effect you get with a single axle van. Wouldn't tow without one.

When on really a undulating track it is best to remove them, as you are aware.

Cheers, Bruce.

At home and at ease on a track that I know not and
restless and lost on a track that I know. HL.

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AnswerID: 526945

Reply By: Member - Reetta & Joe (NSW) - Friday, Feb 21, 2014 at 22:49

Friday, Feb 21, 2014 at 22:49
Thanks for the huge response to my weight distribution problems.
Lots of good advice there, most of which I do have covered.
Sounds like the Hayman Reece shop here we come!
Many thanks, much appreciated.
Joe
AnswerID: 526992

Follow Up By: awill4x4 - Saturday, Feb 22, 2014 at 15:52

Saturday, Feb 22, 2014 at 15:52
Joe, a little advice if I may as I have gone down this line myself.
I have an onroad single axle van which I have modified with independant coil spring suspension and while not a dedicated "offroad" van like yours it's pretty close in size, weight and ride height.
I've also modified and strengthened my chassis so the drawbar is like yours and 6" deep.
I had an older "classic" trunnion style Hayman Reese WDH and I found that with the deeper van chassis that clearance was an issue as the arms angle downward from the adjustable height towhitch to the caravan drawbar.
I also wanted to incorporate some type of sway control and for me the stand out in active sway control is Hayman Reese's dual cam sway control which is an active type of sway control which resists sway from the onset rather than reacting to it like the friction type sway controls work.
I won't go into electronic sway control except to say it's something I will have fitted later to act basically as a last line of defence.
If as you say you are looking at a WDH I would suggest you buy the "standard" series round bar type ones as these run under the drawbar and are designed to use with 6" deep van chassis as the pic below shows.



This next pic shows just how close the "classic" style series runs to the drawbar and this is on only a 4" deep chassis.



The link to the ebay seller gives an approximate price they sell for.
Hayman Reese 6" drawbar WDH

The benefit of buying this system is that if you wish you can add the dual cam sway control at a later stage if you wish.
If you were to buy the "classic" trunnion style WDH you may find it very difficult to fit the dual cam sway control due to the angle of the arms and their possible interference with a 6" deep van chassis.
I hope this gives you some food for thought.
Regards Andrew.
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