Thread: Weight Question

So, if you're in the upper reaches of your weight limit, every time you encounter undulations on a road/track with the van hitched up, it could be very likely that you would be exceeding the defined tow weights when on the downward compression of the rear suspension, therefore, towing illegally.

In my opinion...Stormcup.jpg

Well I've never really thought much about towing a van because I don't have one, but I do get to hear a lot of 'scientific' discussion from a couple of blokes who do.

One of these blokes has a 200 series LC and a big mofo van and is obsessive about the 10% ball weight thing. (he also cleans the stones out of the van tyre treads after a trip)

We only discuss such matters because he didn't believe that a RRC could legally tow 3500 kg or more, till I showed him a pic of the plate on my towbar. Cost him a slab.

He does admit that the 10% thing is only a recommendation, and that he had to get a GVM increase for the 200 when it was still legal to do so to maintain a reasonable payload in the tug, buckling under 300 + kg on the towbar.

A bit of a look around the net reveals the Oz 10% mantra is based on a US study. In the US they can and do go much faster than here.

In Europe the same weight vans are towed with way less ball weight.

Seems like a black art to me.

DL

The dynamics of this are very interesting, and a bit of a mystery to me, so I'm learning from this thread.
The point about semi-trailer and other trucks towing multiple times the prime mover weight certainly shows that a vehicle can tow much more than its own weight if it is set up right.
On trailers, an interesting example is that our camper trailer has, according to the manufacturer, a weight of about 1600kg and a towball of 140kg. However, they offer a extra 100 litre water tank which can be attached to the rear behind the spare tyres. They say adding that 100 litre tank reduces the towball from 140kg to 110kg. So it's interesting to see the effect of where the weight is placed.

Originally Posted by Saitch

So, if you're in the upper reaches of your weight limit, every time you encounter undulations on a road/track with the van hitched up, it could be very likely that you would be exceeding the defined tow weights when on the downward compression of the rear suspension, therefore, towing illegally.

In my opinion...

Not in my opinion as the manufacturer would have taken that into account in setting the static weight limits.

Originally Posted by Graeme

Not in my opinion as the manufacturer would have taken that into account in setting the static weight limits.

Whaaat?

Manufacturers test their vehicles on the Bruce Highway!!!!

Get out of it, Graeme.

Originally Posted by Saitch

Get out of it, Graeme

?

Originally Posted by Saitch

So, if you're in the upper reaches of your weight limit, every time you encounter undulations on a road/track with the van hitched up, it could be very likely that you would be exceeding the defined tow weights when on the downward compression of the rear suspension, therefore, towing illegally.

In my opinion...Stormcup.jpg

Nope the weights are the static limits, the dynamic limits are all worked out from the max static limits.

Originally Posted by Graeme

Not in my opinion as the manufacturer would have taken that into account in setting the static weight limits.

correct.

Some very old vehicles have a normal limit and then special condition limits which allow you to tow a hell of a lot more but under restrictive conditions.

as energy is basically mass x velocity^2 if you cut the speed way down you can push the mass up significantly and retain control.

Originally Posted by Blknight.aus

Some very old vehicles have a normal limit and then special condition limits which allow you to tow a hell of a lot more but under restrictive conditions.

My 1st RRC could tow 8T IIRC (but possibly only 6.5T - another number from long ago) but with a max speed of 40 kph, otherwise 4T.