Thread: Weight distribution hitch

Mate - given the 5-10% that the RTA appear to be on about you could end up with a 3,000kg tow capacity at 5% towball weight (I have a 95 D1 with a 4000kg tow capacity....in theory...which cannot obviously be achieved even at 5% tow capacity if my 95 is 150kg (I have not checked - when I towed my boat which would have had that or a bit more I didnt worry - HR receiver and hitch I had not a ounce of worry about capacity given the live axle and massive chassis set up).

HOWEVER, for 5% I personally would be getting a bit concerned. I think at 5% I would automatically want to check old suspension bushes, make sure the shocks are stiff and good, make sure that the trailer is well sorted, make sure I had either springs that didnt sag or air bags and go to the expense of WDH and anti-sway bars. You could do it on the sly and go all the above save for the last 2 and then go and see how it behaves but to my mind that would be insane with a 1.8tonn or more load and 5%....cause it can go from sweet to swinging/flip too quickly to do much about it - have seen it and it isnt nice.

Cheers

The only hard and fast rule I know of is that you can't lawfully exceed either of the vehicle and tow bar manufacturers' published limits. The maximum "horizontal" limit is based on the ATM stated on the caravan's compliance plate (which also cannot be exceeded) not on the actual weight). The maximum "vertical" limit is based on the actual download exerted by the A frame without a WDH being used.

However, based on the best available advice from engineers and road transport agencies, as well as my own and others' personal experience, the maximum caravan weight you should be towing with a Disco 1 is that which will still keep around 7% minimum on the tow ball, or around 2100 to 2150 kg with 150 kg on the tow ball. Based on the best available advice, that should give you adequate stability provided that the van is properly loaded to give you that 150 kg on the tow ball and avoiding a major concentration of weight at either end, but particularly at the rear.

If you want to tow something heavier, you should consider a tow vehicle with a higher tow rating. The Disco 2 is rated to 3500 kg horizontal and 250kg on the tow ball. Using the minimum recommended towball weight of 7%, a 3,500 kg van is possible, and that covers most vans available in Australia. I tow a 2,700 kg dirt road van, which tows well behind my D2, but I am not sure that I would want to go an extra 800 kg.

Bear in mind that 7% is the minimum recommended weight on the tow bar for safety.

Many of us who have tried towing with and without a WDH believe that use of a WDH will improve that level of safety further, by restoring the proper weight distribution on the tow vehicle and thereby enhancing braking and handling. But I can't prove that.

There are some who don't believe that tow ball weights need to be as high as 7%. In a recent thread on a caravaning forum, concerning the number and causes of caravan accidents due to dynamic instability, it was stated that in most cases, the driver claimed that the rig had always felt very stable until the accident. Dynamic instability is always lurking, and strikes very, very quickly. I can't argue that 7% is the absolute minimum, but I can urge those towing carvans to take seriously the advice of those who should know, particularly the road transport agencies, in order to maximise their chances of safely completing their travels