Thread: Disco II Weight Distribution Tow Bar Package RAA527

And I was about to post, No You Shouldn't Fitt One

Well done on the reserch, we have all learned the book is wrong

Thanks for that

All the discussion about not using them in a D2 with SLS never made any sense to me so I have used a heavy duty hayman reece unit for years with no obvious problem. My main reason was to prevent compressor burn out after my first one went west.

not to beat a dead horse,,

I had a long talk with a caravan rep at the last show,,

and as you would no doubt expect,() I quizzed him about ball weights,,
(we were sitting in a 23' footer having a cold one, I must have been dressed better that day) and he says they basically just build the thing and weld on the wheels wherever to achieve 10% ball weight.

Does it strike anyone else that that's just a cop out?

I still think the whole ten percent thing is an urban myth/grandfathers axe/my dad said

Has there actually been any real testing done anywhere in the world to support this?

I have already read the one done in England and the conclusion was NOT what you'd expect,,


oh, and this is not a go at people putting WDH's on vehicles,,
its about an industry that has flick-passed its engineering responsibilities onto car manufacturers.

Pedro, and others,
There is a test in Handy Caravan Tips and Techniques no 8, which came with Caravan & Motorhome On Tour, no 143.
The article uses a D3 with SLS and compares hitching a caravan using just SLS and also with a WDH.
Basically, the end result is that with just SLS; provided the vehicle sits at its correct height, you can expect to only see a 5% reduction in the weight of the front wheels as measured by a weighbridge.
It was also indicated that this 5%, made no discernable difference to its steering.

They also noted that this result would likely not work as well with suspension that is only air-bag assisted.

Hope this info helps.
Brian

This is a hot issue on all the caravan threads, precisely because there appears to have been no comprehensive testing on Australian caravans and tow vehicles. Our vans are very heavy by comparison with European ones, due primarily to the places we take ours. My van weighs about 2.7 tonnes loaded, and I tow it with a V8 D2.

I have been a firm believer in the value of WDH for a long time, but on a trip to Melbourne last week I thought I would try slackening off the WDH chains to virtually no tension to see what difference there was.

At the end of my street I gently applied the brakes for the T intersection and found that the ABS was working hard to stop the front wheels skidding (below zero morning). OK, I thought, with ice on the road it might have been the same with the WDH working.

I made it to Nimitabel (less than two hours away) before I had had enough, and refitted the WDH to normal tension. The difference was amazing even to me as a WDH believer. The rig was quite tender without the WDH, but quite stable with it.

I can't speak for the D3 and 4, but a WDH makes a huge difference to a D2 with a heavy van on the back.

A couple of months ago I approached Land Rover direct about this issue with the D4, which I was seriously considering buying. They advised that the vehicle is not designed for the forces imposed by a WDH, and that a WDH should not be used. I asked about weight distribution and how the D4 would cope without a WDH, but they did not answer the question. I raised it also with the local dealer, but I have not yet heard back from them either, although they are considering how we might be able to do a test tow with a D4.

If anyone wants to understand how important ball weight is, a couple of minutes drive with a big van loaded so as to get less than say 5% ball weight should be enough to satisfy anyone about the handling benefits of the "10% rule". Tip: don't use your own tug and van. As I understand it, the Europeans recommend 7 to 14% as the optimum. The ball weight becomes more critical the heavier the van is. The location of the weight in the van is also quite important.

I know from my own experience with various loadings of the water tanks how critical loading is to handling of my rig, but I also accept Pedro's assertion that proper testing needs to be done to prove it one way or the other. I will take it up with the ATSB and DITRD&LG and see if they are interested in sponsoring some appropriate research.

Originally Posted by Grumndriva

At the end of my street I gently applied the brakes for the T intersection and found that the ABS was working hard to stop the front wheels skidding (below zero morning). OK, I thought, with ice on the road it might have been the same with the WDH working.

I'll confirm the same result towing a 2.2T loaded dual axle car float with the D2a with SLS ... slight downhill slope, slightly wet road (misty rain), roundabout at bottom of slope, trailer had overide brakes (in good working order) ... gently apply brakes (at about 40kmhr), only to have the ABS for the front wheels negate my braking effort ... the harder I braked, the more the ABS defeated my attempts to stop, which caused the trailer to shunt ... and we sailed straight out across the roundabout ... scary stuff!

Luckily it was late at night and there was no traffic ... there was no room on the car float to move the car aft a bit to reduce the hitch weight ... maybe next time I'll reverse the car onto the float (fwd car btw).

Otherwise, on the open road it handled superbly ... stopping on a level road didn't produce the same result.

Kev..

Have just started fitting the new tow bar and WDH setup. When I open the carton (57kg worth), I found that it was all Hayman Reese equipment (that has been branded with LR part nos. and badges). Towbar looks the same as the Disco 2 diagram on the HR website.

This is good stuff. Thanks. We are taking delivery of a 23ft Retreat Daydream in 12 months. Will be towing with my '04 TD5 classic manual. I was thinking of a hayman reece 550lbs WDH. Any advise welcome.
Regards
Robbo.