Tow ball weight limit with WDH

Submitted: Wednesday, Jan 12, 2011 at 22:13
ThreadID: 83621 Views:11929 Replies:7 FollowUps:22
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Hi, I have a question about how the maximum ball weight is affected by the use of a weight distribution hitch:
If my maximum ball weight is 170kg, and I fit a WDH that itself weighs about 35kg (in total), does that reduce the maximum weight my van can put on the towball to 135kg?

I have spent quite some time looking for a definitive answer via the internet and in magazines, but haven't found much regarding the actual weight of the WDH device itself. Most info I have come across discusses how the WDH distributes the load more evenly between the front and rear axles, but does not increase the maximum permissible ball weight.
When people check the ball weight of their van, do they include the weight of the WDH?

Appreciate any help you can give...
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Reply By: Member Boroma 604 - Wednesday, Jan 12, 2011 at 22:35

Wednesday, Jan 12, 2011 at 22:35
Gooday,
The short answer is NO, what it does is transfer some of the weight from the rear suspension to the front of the vehicle to improve the distribution of the extra load.
I am sure you will get a lot more informative answers but that is the reality.
Cheers,
Boroma 604.
AnswerID: 441630

Reply By: Member - Graham H (QLD) - Wednesday, Jan 12, 2011 at 22:46

Wednesday, Jan 12, 2011 at 22:46
The hitch part becomes part of your cars weight as does the ball weight

EG if your car has a payload of 600kg and your actual ball weight is 170kg


You can load the car up with the balance of 430kg INCLUDING fuel and anything else hanging on the car , spare tyres, roofrack WDH, anything in the back and you and mum.

As long as you dont exceed the cars GVM which includes the ball weight.

Then after you hitch your van on the total may not exceed your whole rigs GCVM

The hitch does NOT as mentioned above change the ball weight OR your cars capacity.
It does as described above and this from HR when I enquired the same

Quote
Thank you for your enquiry regarding the weight distribution hitch. Although we have no factual evidence, the explanation that the pressure/force between the ball and the coupling may be increased but the ball weight is not increased or decreased is the same way I describe the action of the weight distribution system. The weight distribution hitch may be assisting to carry the ball weight but it does not vary it.
Unquote

In other words it straightens the joint to balance the rig but doesnt and cant alter the weight in any appreciable way and certainly doesnt allow you to exceed any legal limits.
You can have a lower ball weight but the weight of the hitch is as described above.

Is that understandable











AnswerID: 441633

Reply By: Glennco - Thursday, Jan 13, 2011 at 10:59

Thursday, Jan 13, 2011 at 10:59
Thanks for the replys. I feel more confident about getting the WDH.

Does anyone know what factors a manufacture takes into account when determining the max tow ball weight?
I notice that most cars have a max ball weight about 10% of the max horizontal load, but my car has maximums of 2300 and 170kgs. It's not too much of a problem since I don't intend towing more than 1700kgs, so I can keep the ball load at the recommended 8 - 10% mark, but I'm just curious as to what influences these limits.

Cheers.
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Follow Up By: Member - Graham H (QLD) - Thursday, Jan 13, 2011 at 11:36

Thursday, Jan 13, 2011 at 11:36
10-15 % is better under 10% is not advisable.
The usual way to determine your towball weight is look at your compliance plate It has ATM and GTM

Deduct GTM from ATM to get the approximate ball weight.

HOWEVER it depends on how you load the van and itis best to load everything up and go to a weigh bridge to get an accurate reading.

Then go home and chuck out all what you dont really need to get it legal LOL

I think you are over complicating things really
I would worry if you had a 2200kg van and only 170kg on the ball as it could be seriously unstable at any decent speed.

What vehicle are you towing with and what model van as giving advice on unknowns is like trying to do brain surgery over the phone with a blindfold on. If you get what I mean.

The more info the better answers you will get.

You will be far better with a WDH under any circumstance than without one,
However it will not help if you van is unstable due to to little ball weight


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Follow Up By: Nomadic Navara - Friday, Jan 14, 2011 at 15:46

Friday, Jan 14, 2011 at 15:46
Ball weight = ATM - GTM is not a reliable way to think. The ball weight of a van varies considerably and depends upon how your van is loaded. You may achieve a ball weight as calculated above if you can manage to load a van to its ATM and GTM.

The only way you can determine the ball weight of a van at a particular time is to weigh it then and there. Next time you load the van it will probably have a different ball weight (unless you can load it exactly the same.)

The 10% rule was developed back in the days when the average length of van was around 16' and 18' was considered big. There are people who have worked in the automotive field and studied the dynamics of vehicles in motion that argue that longer vans require a heavier ball weight.

This 10% of course only applies to Australian built vans. Australian builders do not make an effort to concentrate the weight in the centre of the van. They build front and rear kitchens, install heavy bumper bars with all sorts of heavy items on them and the front boots are way larger than the European ones. That is why the ball weight rule for European vans is 5 - 7%. You never see front or rear kitchens, no bumper bars, small or no water tanks and the spare wheel is mounted under the van just behind the axle.

The greater the inertia at the ends of the vans, the greater the ball weight that is necessary to control the van. You can increase the inertia by increasing the end weight or lengthening the van.


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Follow Up By: Member - Graham H (QLD) - Friday, Jan 14, 2011 at 16:31

Friday, Jan 14, 2011 at 16:31
Totally agree Thats why I said load it up and weigh it at a weigh bridge.

Only sensible accurate way.

The ones who add tool boxes on A frame and big boxes on rear bumpers need their heads read.


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Reply By: Member - Phil 'n Jill (WA) - Thursday, Jan 13, 2011 at 11:56

Thursday, Jan 13, 2011 at 11:56
Hi Glennco

My NM Pajero max weight on a standard towball is 135kg - inadequate for the two vans I have had.

After some considerable anguish about legalities, I finally examined the towbar fitted to the vehicle and discovered it is the 'WDH' version and was marked legal to 250kg - problem solved - heartache over (as long as I keep within the max loading rates of vehicle and van).

As stated above - the 'hitch' doesn't figure in you 'towball weight' - it is part of your vehicle gross weight.

The important factor to remember is the weight on the ball is directly affected by the stowage of your van - as long as you don't exceed the maximum allowed, you can vary the weight on the ball by shifting stowage forward or aft.

My first van was 143kg on the ball and before I realised I had the WDH, I spent some time pondering how to overcome the problem. I found that by standing on the rear bar, the weight came within the required 'specs' both for ball weight and gross van weight.

Before I got around to plonking another spare wheel and odd paraphenalia at the rear of the van, I woke up to the WDH already on the vehicle and haven't had any worries since.

G'luck - Phil
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Reply By: Lex M (Brisbane) - Thursday, Jan 13, 2011 at 12:03

Thursday, Jan 13, 2011 at 12:03
I think you've all missed the point of the question.

If the weight of the hitch is 35kg then that will be part of the 170kg max towball weight and will reduce the weight the van can contribute as suggested.

The towball weight specifies the max weight that can be supported by the hitch which will include the weight of the van, wdh and even the weight of the towball.




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Follow Up By: Member - Graham H (QLD) - Thursday, Jan 13, 2011 at 13:34

Thursday, Jan 13, 2011 at 13:34
What you are saying is by putting a heavier tongue in it reduces the allowable downward weight on the towbar.

Have never considered or even seen that mentioned and I am sure that 99.9% of anyone else hasn't either.

I see your point but I wonder if anyone has noted this anomaly in the towing regs.

And if in fact it makes any difference as when I asked the NSW RTA they said they had no rules on towball weights at all.

The only restriction seems to be the capacity of the vehicle as stated by the manufacturer.

An interesting theory.

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Follow Up By: Lex M (Brisbane) - Thursday, Jan 13, 2011 at 13:52

Thursday, Jan 13, 2011 at 13:52
Surely they have regs that say you cannot exceed the vehicle manufacturers limit or the towbar manufacturers limit whichever is lower.


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Follow Up By: Member - Graham H (QLD) - Thursday, Jan 13, 2011 at 14:30

Thursday, Jan 13, 2011 at 14:30
From the reply i got from the NSW RTA regarding another question The last sentence is what I mean


Yes,you can tow the caravan under the following conditions.

1 / You do not exceed the vehicle manufacturers tow capacity of 2500 kg for the vehicle, ( this means that the caravan cannot exceed its GTM, of 2500 kg,even though it has an greater ATM ).

2 / Your vehicle must have a compliant tow bar fitted and it must be correctly rated,the RTA do not have any requirements on "ball weight".

Regards
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Follow Up By: Glennco - Thursday, Jan 13, 2011 at 14:45

Thursday, Jan 13, 2011 at 14:45
If the weight of the WDH does actually count toward the ball weight limit, that would suggest that the ball weight limit is a factor of the tow bar itself, which seems logical, but the tow bar manufacturers say that installing a bigger and better tow bar (if one is available) won't increase the allowable ball weight limit which is set by the motor vehicle manufacturer and can't be exceeded.

That's why I had the second question about what the ball weight limit is based on. If it's the axle load limit, then I'd say using a WDH would benefit in the way it distributes the load more evenly across the axles.
But I suspect that the ball weight limit might be determined by something like the center of gravity of the vehicle payload (amount other things).
That would explain why my car has a lower than expected ball weight limit because it's a Jeep Wrangler Unlimited (4 door with the long wheel base) and it has a relatively high center of gravity as described by the warning sticker on the sun visor.
The horizontal load limit on the other hand seems to be a factor of the weight of the vehicle and the wheelbase, since the 2 door (short wheel base) version of the wrangler has a much lower horizontal towing load limit, but the ball weight limit is only 10kg's less.

Very interesting, but as Graham says, there is very little official information around about ball load limits apart from "don't exceed it"...

I'm towing a 16' 2005 Jayco expanda pop-top. (plus wife and 3 kids and their accessories...)

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Follow Up By: Member - Graham H (QLD) - Thursday, Jan 13, 2011 at 15:24

Thursday, Jan 13, 2011 at 15:24
The towing weight limit is phrased as follows.

You can tow the vehicle rated weight or the rated weight of the towbar WHICHEVER IS THE LESSER

Buy a real tow vehicle like a Cruiser that has a rated weight of 3500kg and a towball weight of up to 350 kg or a Patrol with up to 3200kg LOL.


The amount of weight shifted by the WDH is not a lot.

Your axle ratings are set by the manufacturer.

Most people who tow vans and check their weights do so with a WDH fitted

and I have never ever heard of anyone, including me, worrying about the

weight of the actual hitch.
Im fussy about legaliies and have never considered that, Perhaps I should, but in my case it doesnt matter as I have about 30kg spare..




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Follow Up By: Member - Phil 'n Jill (WA) - Thursday, Jan 13, 2011 at 18:25

Thursday, Jan 13, 2011 at 18:25
With regard to 'missing the point' - Might I stress that the weight distribution hitch mentioned in my response above, is part of the vehicle - It is not just a tongue attached to the rear chassis - it actuall fits across the rear of the vehicle and extends toward the front of the vehicle on each side.

This is distinctly different from a ' Hayman Reese' style WDH which fits onto the A frame of the van.

Sorry I didn't make this clear in the thread.

I mention it now because it must be really confusing to have two differing types of WDH and I suspect this is not commonly known - I certainly didn't until I read about them on one of the RAC towing guides online (wish I could find it now with the diagram). As stated - this WDH is part of the vehicle - no weight whatever included on the tow ball.

Cheers - Phil
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Follow Up By: Member - Graham H (QLD) - Thursday, Jan 13, 2011 at 18:47

Thursday, Jan 13, 2011 at 18:47
A Hayman Reece WDH Hitch fits into a 50mmsq box section in the towbar.


The only part that is attached to the A frame is the two pieces that you pull the tensioning legs up to and weigh hardly anything.

The towbar extends forward under the chassis with up to four bolts on each leg.

I have never seen anything that would put significant weight on the ball and have never heard of what you are talking about.

A manufacturers name and a link would be good

See These pics and link to show the Hitch fits in tow bar

Image Could Not Be Found

Image Could Not Be Found

[url=http://www.haymanreese.com.au/products.htm]HR Products[/url
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Follow Up By: Member - Phil 'n Jill (WA) - Thursday, Jan 13, 2011 at 19:17

Thursday, Jan 13, 2011 at 19:17
Thanks for the pics Graham - they are said 'to speak a thousand words' and they help in this case.

The top pic has some gear that hangs off the A frame, however slight, and from the coupling back is included on part of the ball weight.

The lower pic is they type I was trying to describe - same principle similar build - and is part of the vehicle itself - excluded from the ball weight - which is what we were trying to establish for Glennco .... my slant on it anyway.

Cheers - Phil
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Follow Up By: Member - Phil 'n Jill (WA) - Thursday, Jan 13, 2011 at 19:21

Thursday, Jan 13, 2011 at 19:21
I guess I should add, that because of the design of the lower pic WDH - this increases the capacity of the tow ball - in my vehcile - from 135kg to 250 kg - so there is no need for the chains and lever style operation in the top method WDH. - Phil
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Follow Up By: Member - Graham H (QLD) - Thursday, Jan 13, 2011 at 20:17

Thursday, Jan 13, 2011 at 20:17
You entirely miss the point of how they work.

When you measure the ball weigh of a van you disconnect it from the car and drop the bars of the WDH and weigh the A frame of the van by putting the ball socket on a scale.

The bars to do their work actually pull the A frame UP and thereby straighten the joint between the car and the van. As said in my answer above it does NOT decrease or increase the ball weight

By this action you transfer some (a little) weight forward to the front car wheels and some (even less) back to the van wheels. This equals up the rig and restores some steering weight to the front wheels

Putting one of those Towbars on will only increase your towing capacity IF YOUR CAR ALLOWS IT otherwise it is the lesser figure of the two That is of the car or the towbar.

If you have a 250 kg ball weight you SHOULD use a hitch as in the top pic Once you have you would never tow without one

In my opinion anyone who doesnt use one with that weight should be shot.

What the OP meant I think was did the part that sticks out from the towbar become part of the ball weight because it is not actually part of the bar.
IMHO no However I will ask my contact at HR and post the result when I get an answer.

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Follow Up By: Member - Phil 'n Jill (WA) - Thursday, Jan 13, 2011 at 20:36

Thursday, Jan 13, 2011 at 20:36
Graham - Sorry you seem upset at the legalities of the weight allowance on my rig - but suggest you don't shoot the messenger - take it up with the RAC and Manufacturers.

RAC only confirm what my Owners Manual state.
Phil
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Follow Up By: Member - Graham H (QLD) - Thursday, Jan 13, 2011 at 20:56

Thursday, Jan 13, 2011 at 20:56
Im not upset at all

Just pointing out that because the towbar says it is rated to a certain figure it doesnt mean that by fitting it, the vehicle can tow that amount UNLESS it also is rated to the towbar limit.

If your vehicle is rated to that very good.

EG Pre 1995?? 80 series were rated to tow 2500kg if I remember correctly.

A 3500 kg towbar would fit on the vehicle but it still couldnt tow more than its rated 2500kg. As that is the lesser of the two figures.

Thats what I was meaning. I wasnt meaning you couldnt do it and the lower picture was of a towbar .

The top one is a Weight Distributing Hitch which doesnt figure in the ball weight.. im out of here.

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Follow Up By: cycadcenter - Friday, Jan 14, 2011 at 02:00

Friday, Jan 14, 2011 at 02:00
Graham,

I understand perfectly what you are trying to say. the photo at the top is a proper WDH I would call the bottom one a heavy duty towbar which distributes the weight on the chassis of the car. Can't see how it would alter the allowed tow ball weight, in fact it may lower the towball weight as it is an addition weight placed behind the rear axle
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Reply By: RobAck - Thursday, Jan 13, 2011 at 19:27

Thursday, Jan 13, 2011 at 19:27
The legal issue is simple. Your vehicle has an ADR compliance on ball weight, GVM and GCM. That does not change with a distribution hitch. The only way you change the vehicle characteristics is to have a certified practicing engineer re-certify your vehicle after modifications such as a suspension upgrade that changes your GVM

Regards

RobA
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Follow Up By: Member - Phil 'n Jill (WA) - Thursday, Jan 13, 2011 at 20:03

Thursday, Jan 13, 2011 at 20:03
Have to agree with you Rob on the issue of legal limits of the vehicle being fixed.

Research shows the allowable weight on the ball will differ, depending on the type of 'hitch' you have on the vehicle.

I have a copy of a document from 'Caravan Industry / RACQ Towing Mass Limits' (Copywright) whiich from memory covered all vehicles in Aust - the one page I copied covers 20 Mitsubishi models.

The 'Ball Max Max' is 250 kg - but there is a reference to 'Conditions' which states 'Load Level hitch req. above 135kg'

So I have been remiss in babbling on about WDH allowances (sorry about that).

The technical term which allows my vehicle to handle the max ball weight is the 'Load Level Hitch' which is fitted and stamped to carry 250kg.

From memory I only found about 4 or 5 vehicles in the whole range of vehicles listed, which could handle something like 150kg ball weight or greater, without 'conditions'.

I have just tried to relocate the document in full from the RACQ website, but my search criteria doesn't turn it up. Great guide for all if anyone can locate it.

Another top document I dragged from an earlier computer is 'Towing Guide - A practical guide to safe towing' put out by Mitsubishi and Big 4 Caravan parks'. I have it as an Adobe document but wouln't have a clue how to arrange a link. Can't find it on the web again and when I try to 'Copy & paste' I can get the text, but not the pics.

Frustrating being a 'pre -boomer' I can tell ya.

Cheers - Phil
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Follow Up By: Member - Graham H (QLD) - Friday, Jan 14, 2011 at 15:16

Friday, Jan 14, 2011 at 15:16
Any Cruiser or Patrol can handle more than 150kg without any assistance.

A hitch is normally a Hayman Reece Weight distributing Hitch.

A towbar as in the lower picture I posted is just that A towbar.
It does not distribute weight "along" the chassis. It just hangs from it and pulls tha rear down when loaded

They come in various makes and weigh capabilities.
Eg straight tongue ones like on a Commodore are I think Class 2 and can handle towing up to about 2000kg Above that you need the model pictured.

The "Hitch" is the part that is attached to the towbar and comes in several types and capabilities. This is what distributes weight along the chassis.

There are the Camec 2 and 4 bar equalisers for light vans.

Then there are several weights of Hayman Reece weight Distributing hitches.

These have the same head that slides into the receiver on the "Towbar" Or Receiver if you like

they have different thickness arms to give more weight capacity.

They are part of the car and have nothing to do with ballweight of the van.

This is weighed completely unattached from the tow vehicle and any other bits.

If your vehicle manufacturer recommends a WDH it is to assist the car to handle the weight with regard to the weight distribution through to the front wheels.
The fact that it allows a heavier ball weight than recommended is not to increase the cars capacity but to allow for any vehicle deficiencies above a certain limit.

The cars ballweight amount is set by the manufacturer and as I said putting a heavier towbar that may exceed your cars legal limit does not allow you to load it up past that.

Perhaps a read of this will help you understand the terminology and methods


Safe Towing



http://www.towingguide.com.au/couplings.html


Hayman Reece

Cheers

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Follow Up By: Member - Graham H (QLD) - Friday, Jan 14, 2011 at 15:47

Friday, Jan 14, 2011 at 15:47
And here


towbars etc



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Follow Up By: Member - Graham H (QLD) - Friday, Jan 14, 2011 at 15:51

Friday, Jan 14, 2011 at 15:51
And here is a good explanation


WDH
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Reply By: Glennco - Thursday, Jan 13, 2011 at 21:27

Thursday, Jan 13, 2011 at 21:27
Wow, can of worms eh!
I have just received a response from a Hayman Reese technical support rep who says that while there are some differences of opinion in the towing industry about my original question, they "do not consider adding the weight of the actual weight distribution hitch as ball weight"
They consider it as additional rear axle load.

So adding the WDH to the car does not decrease my allowable ball weight from the van (it would be the same as sticking the WDH in the boot -it would be somewhat less effective there though!)

All weight limits (such as axle weight, GVM, etc) still need to be observed of course...
AnswerID: 441730

Follow Up By: Member - Graham H (QLD) - Thursday, Jan 13, 2011 at 22:22

Thursday, Jan 13, 2011 at 22:22
Hopefully thats what we said.



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Follow Up By: Lex M (Brisbane) - Thursday, Jan 13, 2011 at 22:54

Thursday, Jan 13, 2011 at 22:54
"there are some differences of opinion in the towing industry"

"Hopefully thats what we said. "

Yep. Differences of opinion. That's what we said. :-)



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