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here is a paper discussing towing stability.
Quote:
The study showed that the most important factors that affect the lateral stability
of caravans are; speed, caravan mass, caravan yaw inertia, tow ball load, axle
position, wheel track and tyre stiffness.
Of secondary importance were caravan suspension damping, caravan roll inertia and the height of the centre of gravity, all
of which make the caravan more prone to roll over
As the O.P. I think we have gone a little off track, I am not using a WDH at present, and according to the experts (Commercial operators that I have called on here in Sydney) they believe I have a rear end problem (don't we all ).
Will post the results after it has had some work done on it, goes in tomorrow but will be the end of the week before we get the van back on it.
My van tows perfectly behind other vehicles, we have owned it since new and it now has around 150k on it. Suspension done up fully about 15K ago, I will be disappointed if the Disco can't handle a normal van ?
Some of you seem to be saying that the van needs to be "different",
I have not weighed it this trip but is normally around the 2800kgs mark and approx 300 on the ball. The tyres in the van now have 80K on them have been rotated once have no cupping or strange wear patterns, but are getting past their use by date, so I suspect there is nothing wrong in that department, out of interest they have a maximum pressure allowance of 36psi which they are at.
DD
DD/Glynhouse,
The issue of stability is not solely down to the van or the vehicle, it is the combination of the two that determines the speed at which you will not be able to recover from an instability event/snaking. If your tow vehicle is heavy enough and has a stiff enough rear end it will not go unstable. One of the things that you require for the system to start snaking is lateral movement of the tow ball. Therefore too much flex in the tyre walls could be enough to cause that lateral movement.
There are things that can be done to the van to make up for too light or to soft a tow vehicle, a simple one in design is to make the A frame longer, not much help to an existing van I know.
According to the youtube promotional video [ame="http://www.youtube.com/watch?v=5gyc4Dmgbew"]linked here[/ame] if you have trailer stability assist which is available in the later Discos, D4 yes, don't know about D3, you should be able to make up for some instability that others would not.
Has anyone seen this caravan fitted stability control system from Al-ko that can now be ordered on new Jayco's or retro fitted to older vans?
About AL-KO Electronic Stability Control (ESC)
It seams to work pretty good from the video.
I'm not saying just fit it and don't worry about how your tug handles when towing, rather it looks like a great safety over ride system that keeps everything sorted when the kaka really hits the fan.
Terry a belated thanks for the weekend accommodation !
Met a few vans with it fitted when we were in the U.K. those that had it fitted thought it was great, but when asked why they felt that way and was it obvious the answer was alway. " No but it will be if I need it ! "
Can't help you any more than that.
DD
I tow at the extreme end of the D4 capability my van is 3500kg in travel trim I have a 320kg ball. I have a Kaymar Rear bar and a long ranger tank all up I am at 6580kg.
I have had no issues even when I had worn rear shocks (replaced under warranty) I had no issues.
This problem with sway must come down to rig setup or driver issues. There was someone a while back with sway issues with a D4 it turns out he was over correcting when he felt motion from the van.
My van is defiantly more stable on its Control Rider (coil shock independent) than it was on Simplicity Suspension. I know many people are happy with Simplicity but until you have towed the same van with both you simply wont understand how average Simplicity is.
The van towed ok on Simplicity it however was more prone to moving around and being affected by cross winds and trucks passing.
If you have a sway issue look at the van configuration first. Then think about how you actually drive because the problem may really be between the seat and the steering wheel.