Tuesday, Mar 05, 2013 at 23:27
I just had a look at the specifications of the Nullarbor and the BT 50. Unfortunately I could not find any weights for the van on the manufacturer's web site but a review on another site said it is 2343 kg. The Mazda site lists 2112 kg for the heaviest BT50 in the entire range.
I would be looking for a heavier car. The ideal tow car should be at least as heavy as the van and have a long wheel base with the shortest possible distance between the tow ball and the rear axle. All of the utes in the BT 50 class don't shape up all that
well against those dimensions and as a result they don't have a good safety record when towing big vans. There is a discussion currently in progress on one of the major caravan sites as a result of this recent crash
http://video.au.msn.com/watch/video/grandmother-escapes-windblown-caravan/xsaesqu?cpkey=2aa6c7fd-754a-44f1-bfa2-43d122a27419%257c%257c%257c%257c There are countless others on the net.
The van in that accident is most likely within the car's towing capacity but it is physically too big for the car to handle it.
Imagine two BT 50s driving along a highway at around 90 kph. One is towing a 3500 kg van and the other has a 3500 kg four wheel trailer full of bags of cement. Both are hit by a strong cross wind. One will hardly notice it while the other would stand a good chance of making the 6 o'clock news that night. Both cars are within their maximum towing capacity but one is running on a knife edge whenever it encounters a bit of speed combined with wind or anything that causes a sudden change in direction of the car. You can't go solely on the towing capacity of the car when choosing a van.
A BT 50 will certainly tow that van but a much heavier car with a tow ball a lot closer to the axle than the 1.2 metres that most of those utes have would do it with a far higher degree of safety, particularly on the highways.
There is another issue with all utes of this size and that is chassis bending. High tow ball loads combined with too much weight in the back result in huge forces bouncing up and down behind the rear axle. The result is the chassis tries to pivot on the axle and lift the front with disastrous results. This problem is much more likely to occur if the back of the chassis is sitting on after market air bags. Look up bent chassis, particularly on dual cabs, on the net and you wll be amazed at what you see.
I would suggest you read these two articles on car and van dynamics before making any decisions. They would be the best articles of their type that I have found on the net so far.
http://www.caravanandmotorhomebooks.com/pdf/vehicle_dynamics_complete.pdfhttp://rvsupertramp.com.au/Articles/CaravanDynamics.aspx
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