Weight Distribution Hitch
Submitted: Wednesday, Jun 01, 2011 at 21:33
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Member - Bob G (VIC)
This subject receives a lot of discussion and I am mindful of the many arguments for WDH and also the opposing
views.
I have been influenced that there are compelling reasons to use WDH particularly on medium to large vans to redistribute the loss of weight on front wheels due to Tow Ball Mass.
I thought readers may be interested to learn about the effects on weight transfer I experienced in my latest Van set up.
I am interested to hear any
views as to the merit of the amount of weight I now have on the front wheels and also the adequacy of the tow ball mass.
The weight is [in my opinion] reasonably distributed centrally but produces Tow Ball Mass less than the 10% minimum often bandied around
I took my rig to local weigh station to establish what I really had in the way of weights with new set-up. Here's what I learned...
Vehicle - Landcruiser 200 TTD [with Lovell
suspension mods and air bags].
All up with my 22 footer full van with heavy off road
suspension and 6.5 tonne McHitch Coupling, the Gross Combined Mass [Vehicle and fully laden Van] came in at a not surprising 6.tonnes.
The relevant weights were as follows;
Vehicle inc Tow Ball Mass = 3.540Tonnes
Tow Ball Mass as weighed separately 330kg
Front wheel weight - no Van attached 1,620kg
Front Wheel weight - with Van attached [but no WDH] 1,460kg
Front Wheel weight with WDH operating 1,520kg
That confirmed for me that given the WDH settings I have used [number of chain links employed and positioning etc of the Hitch], I have [only] transferred back approximately 60 kg of the 160 kg that was effectively removed from the front wheels when Tow Ball Mass applied.
Views appreciated.
Bob
Reply By: Member - Bob G (VIC) - Wednesday, Jun 01, 2011 at 21:35
Wednesday, Jun 01, 2011 at 21:35
The GCM should have read 6.58 Tonnes
AnswerID:
456109
Reply By: Member - Rod N (QLD) - Wednesday, Jun 01, 2011 at 21:54
Wednesday, Jun 01, 2011 at 21:54
What are the measurements of the front and rear wheel arch to centre of the wheel with no van, van no WDH and van plus WDH? The WDH should return the measurements to close to no van measurements. This would probably have an influence on the weights.
AnswerID:
456110
Reply By: Dennis Ellery - Wednesday, Jun 01, 2011 at 21:59
Wednesday, Jun 01, 2011 at 21:59
Hi Bob
You need to measure two reference points - one at the front and one at the back of the 4WD with no load.
Connect your van and tension the WDH – measure the two points again and if you have the same level you have distributed the weight equally between the front and rear wheels.
AnswerID:
456111
Reply By: Ozhumvee - Wednesday, Jun 01, 2011 at 22:15
Wednesday, Jun 01, 2011 at 22:15
Isn't the GVM supposed to be 3300 on a 200 series? with a GCM of 6,800.
AnswerID:
456112
Follow Up By: Member - Bob G (VIC) - Thursday, Jun 02, 2011 at 05:06
Thursday, Jun 02, 2011 at 05:06
Peter
They are the maximum allowable weights. The dry Kerb weight of the LC 200 standard may be around 2700kg to which you add passengers fuel etc and the GCM means you should not exceed, similar with GCM.
Bob
FollowupID:
729106
Follow Up By: Ozhumvee - Thursday, Jun 02, 2011 at 07:41
Thursday, Jun 02, 2011 at 07:41
Yes the max GVM is 3300kg so his weight of 3580 hooked up is over GVM.
You have to comply with all the individual weights as
well as the GCM(which is a sum of 3300kg on the vehicle and 3500 towed)
You can't have more on either than allowable.
FollowupID:
729111
Follow Up By: youngharry52 - Thursday, Jun 02, 2011 at 10:39
Thursday, Jun 02, 2011 at 10:39
As I understand it, Bob's GVM for the cruiser will be 3800kg with the Lovell
suspension upgrade making his GCM 7300kg. (Note: the 200 series does not have a manufacturers stated GCM, so that it is the sum of the car's GVM and the towing capacity, ie 3800 + 3500)
Regards
Chris
FollowupID:
729127
Follow Up By: Ozhumvee - Thursday, Jun 02, 2011 at 10:50
Thursday, Jun 02, 2011 at 10:50
As long as it is an "engineered" and signed off with paperwork for the upgraded GVM then that is ok. Mate of
mine was told that 200 had GVM of 3300kg's as does Toyota's brochure
here
FollowupID:
729131
Follow Up By: youngharry52 - Thursday, Jun 02, 2011 at 12:42
Thursday, Jun 02, 2011 at 12:42
Your mate is correct. The Lovells (3800) and ARB (3580) GVM upgrades are plated and endorsed on your rego.
Regards
Chris
FollowupID:
729141
Reply By: Olsen's 4WD Tours and Training - Thursday, Jun 02, 2011 at 07:26
Thursday, Jun 02, 2011 at 07:26
Hayman Reese provide full instructions on how to set up the WDH. A simple measurement of distance from rim to mudguard at the front wheels and an attempt to restore that once loaded is a pretty good compromise, since it ensure the main objective of restoring steering geometry. hHis is one area covered in a good towing course.
AnswerID:
456121
Follow Up By: Member - onemore - Thursday, Jun 02, 2011 at 08:14
Thursday, Jun 02, 2011 at 08:14
Can anyone on the
forum recomend a "good towin course", as I am getting very confused over all the discussions and endless theories on this.
Thanks in advance.
FollowupID:
729114
Follow Up By: Olsen's 4WD Tours and Training - Thursday, Jun 02, 2011 at 09:17
Thursday, Jun 02, 2011 at 09:17
PM sent
FollowupID:
729121
Follow Up By: Member - Rod N (QLD) - Thursday, Jun 02, 2011 at 09:55
Thursday, Jun 02, 2011 at 09:55
Your vehicle manual should specify the allowable tow weight and maximum towball weight. The towbar should also have it's rating on a data plate. So all you can tow is the lesser of these. The actual towball weight should be about 10% of the van weight. When your van is hitched and WDH used the wheel measurement should be back to near the unloaded measurements.
FollowupID:
729123
Follow Up By: BuggerBoggedAgain - Thursday, Jun 02, 2011 at 11:06
Thursday, Jun 02, 2011 at 11:06
Me too onemore every time I read the posts on this subject, I'm no better off.
Everyones got their own different opinion, some vehicle manufacturers will not warrant their warranties if u use a WDH
Too much info. mind boggling
FollowupID:
729133
Reply By: Member - Clive G (NZ) - Thursday, Jun 02, 2011 at 14:37
Thursday, Jun 02, 2011 at 14:37
Bob.
The effect of a WDH on the front wheels is a ratio thing. The wheelbarrow handle effect if you like.
If you measure the distance from the hitch pivot point the centre of the rear wheel and compare this to the distance between the front and rear wheels you will get a ratio of approx 2.2 to 2.5
This means that that your 60kg weight recovery on the front wheels is about as expected.
WDH hitches do work, but they are just one way of addressing the problem. Air bag assist and
suspension up grades are also equally effective. After towing heavy trailers for some 48 years I firmly believe that the most effective way of maintaining vehicle and trailer stability is keep the whole outfit level, no sag or over lift.
Wouldn’t worry too much about the 10% rule. Remember it’s only Australia and the US that practice this rule. The rest of the world isn’t much concerned about it. I don’t have a clue what my Karavan ball weight is, and don’t care either, just pump up the air bags till it’s all level. Tows and stops just fine.
Regards. Clive.
AnswerID:
456152
Follow Up By: snoopyone - Thursday, Jun 02, 2011 at 17:09
Thursday, Jun 02, 2011 at 17:09
Air bags dont fix it like a WDH does All an air bag does is lift the load above it.
Imagine this as per the wheelbarrow scenario above.
The rear
suspension of your car is the wheelbarrows legs
push down on the wheelbarrows handles. The front goes up
Put two bricks under the legs (similar ot pumping up air bags)
Push down on the handles What happens, front goes up just the same only its all a bit higher.
Same thing in the car and if you weighed the front before and after pumping up your bags you would get the same result.
If airbags fixed it why would we spend $700 on a WDH when a couple of hundred on airbags would do the job NOT.
The reason Aussie use the 10-15% rule is that our vans are often built with rear set axles and dont put all the weight in the center like Geist and Adria do and they therefore get away with a lighter weight.
FollowupID:
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Follow Up By: Nutta - Thursday, Jun 02, 2011 at 18:38
Thursday, Jun 02, 2011 at 18:38
Even though if you put bricks under the legs of the barrow it should still be harder to to tip back because the nose and everything in it are pointing even further down
hill.
FollowupID:
729170
Follow Up By: snoopyone - Thursday, Jun 02, 2011 at 19:12
Thursday, Jun 02, 2011 at 19:12
Im lazy and was using an empty one LOl
It was to emphasise a point Not a literal wheelbarrow
FollowupID:
729174
Follow Up By: Member - Clive G (NZ) - Thursday, Jun 02, 2011 at 19:44
Thursday, Jun 02, 2011 at 19:44
Right on Nutta.
It gets back to that level rig that I went on about. If the car has its tail dragging then the front is up, the opposite to snoopyone’s example. Pump up the air bags until the rig is level and the front is then at the same height. Normal service is resumed.
Clive.
FollowupID:
729179
Reply By: Member - Clive G (NZ) - Thursday, Jun 02, 2011 at 19:46
Thursday, Jun 02, 2011 at 19:46
Snoopyone.
With respect, it’s not just about the dead weight on the front wheels when stationary, it’s about the balance of the car whilst in motion. When the brakes are applied the load must transfer forward onto the front wheels (nose drops). If it doesn’t there is no control and the car skids. If the car has its tail down and nose up that weight transfer under braking is severely compromised. So pumping up air bags to achieve a level rig does the same job as a WDH. If it didn’t there would be no point in upgrading ones rear springs etc to carry a heavier load. A level rig is where it all begins, how it’s made level is less important.
Why do travellers in Aussie spend $700 on a WDH?? Good question. I suspect it has more to do with good marketing than good engineering. Plus WDH’s don’t require permanent modifications to the car, which suits a lot of people.
WDH’s are very rare here in NZ, I really can’t remember when I last saw one. It’s all air bags, heavier springs or adjust the load. Having said that we have our fair share of idiots, just like you guys have. Sad really.
Regards. Clive.
AnswerID:
456176
Follow Up By: snoopyone - Thursday, Jun 02, 2011 at 20:42
Thursday, Jun 02, 2011 at 20:42
Well why as I have airbags does my car not come back level when I pump them up and hook the van on.
As you say airbags are to carry a heavier load IN THE CAR not hanging a metre behind the axle
Probably something to do with a 300kg ballweight.
A bit different with just a camper on the back.
I know about weight distribution thats why I have a WDH.
The original poster put the weights up which must account for something
Of course if you have only a light load on the towball it may appear to be level but a run over a weighbridge may decide the weight is not returned on the front.
This has been an endless discussion on here and other forums and the consensus has been at odds with your theory.
Incidentally is that a D shackle attaching the chain to the A frame.
Illegal here.
Nice picture of
Mount Cook though.
Was better when the Old Pukaki Inn was there
FollowupID:
729189
Reply By: Member - Clive G (NZ) - Thursday, Jun 02, 2011 at 21:34
Thursday, Jun 02, 2011 at 21:34
Yes Bob did put up the weights and it shows about 60kg recovery on the front with a WDH. I did say that they work, but also said that a WDH isn’t the only way to fix the problem.
I don’t know what my ball weight is but other owners in OZ say it’s in excess of 200kg. Takes about 25 PSI to bring the rig level when loaded (including the dog).
Yes it’s a D shackle that you see(2 of), legal here. I’ve fitted an extension to the drawbar and the original chains are welded to the A frame, then galvanised, so I extended them. If you look closely you’ll see that the chains are bolted to the drawbar extension as
well, as welded on chains are not allowed here.
Different rules!! Don’t you just love them??
The photo was taken from the car park of the new Lake Pukaki
visitor centre. Nice place but hang onto your wallet. Camped about 2ks East from there, down by the water, man it was cold. Nov 2009
Clive.
AnswerID:
456187
Follow Up By: Member - Bob G (VIC) - Thursday, Jun 02, 2011 at 23:26
Thursday, Jun 02, 2011 at 23:26
Some good
feedback as
well as some healthy debate. Thanks to all for your input, some advice has encouraged more work.
My van effectively has a GVM upgrade but it is not certified, I am indeed aware of the technical non compliant situation and potential ramifications of same. I have investigated getting Lovell's to issue compliance plate and may do that in the future just to minimise needing to satisfy somebody sometime that I have a safe and stable rig. My primary objective is to satisfy myself that weight and handling of the rig is as reasonably safe and stable, as it can be [hence 6.5 Tonne hitch and other improvements to be sure to be sure].
I have previously measured the height set up with two prior Vans using reference points as suggested by contributors and will do so for good order again with current set up.
My objective in this trial was to learn exactly what happened with front wheel weight with and without the WDH as opposed to just relying on the position of the reference points. I purposely have not cranked the chains up past what I considered was an appropriate amount of tension. My reasoning was that I wanted to maintain as many links in the chain so as to increase the fulcrum - [distance or is it the radius] the WDH bars can travel, before reaching maximum travel and causing stress/damage. The vehicle did return close to pre load position but no measurements taken this time.
Also I am sure if I crank the chain up a notch, I can achieve original front wheel weight.
I did not clarify my request as
well as I may have and probably should have simply said something like - given the size and weight of the tow vehicle and the van, is the front wheel weight loss of the 100kg [1520kg with Tow Ball Mass applied as opposed to 1620kg without any TBM] do any readers have an informed view as to any ramifications of that weight loss.
Bob
FollowupID:
729217
Follow Up By: Graham & Ann - Sunday, Jun 05, 2011 at 13:41
Sunday, Jun 05, 2011 at 13:41
On our rig with tension applied to WDH around 90kgs goes back on front wheels of the tow tug and around 45kgs goes back on van wheels. I can vouch that when travelling loose gravel roads with no WDH tension used anything other than light braking can cause front wheel lock up. Same goes for damp bitumen roads.
FollowupID:
729511
Follow Up By: Member - Bob G (VIC) - Sunday, Jun 05, 2011 at 18:42
Sunday, Jun 05, 2011 at 18:42
Graham
I am interested to learn the net effect of the weight transfer to front/rear wheels.
What was the [original] weight on front and rear wheels prior to attaching the WDH? also, did the position of the Vehicle return to where it was prior to putting the van/tow ball mass onto the vehicle? [assuming you had reference point measurements]
This information will assist me in better understanding how much weight is transferred back if the vehicle returns to pre load position and as it relates to vehicle position [obviously every vehicle will differ]
Bob
FollowupID:
729548
Follow Up By: Graham & Ann - Monday, Jun 06, 2011 at 14:42
Monday, Jun 06, 2011 at 14:42
I should clarify when I said 'our rig' it was with this same van but tow tug then was R50 Pathfinder, much shorter wheel base than current Navara D40 so weight transfer would be different now. As for actual weights on front, rear & van axles I no long have these figures, and the with the van hooked up the front of the tow tug did not return to same height as it was without van hooked up, but only by about 10-15mm. With this set up van/tug were pretty darn level. Without van on tug was sloping fwd, ie rear of tug slightly higher than front. As it is with current tug.
FollowupID:
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Follow Up By: Graham & Ann - Monday, Jun 06, 2011 at 14:48
Monday, Jun 06, 2011 at 14:48
Forgot to mention so as to make it clear that the 135kg odd that was transfered to front of tug & van wheels, came off the rear wheels, NOT off the ball weight as some folk mistakenly think.
Also keep in mind that while a wdh reduces weight from tugs rear wheels it increased the pressure between the ball and the ball coupling, ball wears more, so we use 'dry lube' on the ball & wdh cams, have no problem in dusty conditions.
FollowupID:
729639