The no wheel arch damage assumes that the rubber components act as designed and maintain conformity. My axle relaxed badly on the offside and reduced loaded clearance to around 12 mm. The rubber had partly “ extruded” from its tube so was clearly not available to resist movement. Given the state of roads I wasn’t prepared to continue to use the caravan and purchased a complete axle assembly.
I sold it in 2021 so the new owner befitted. I also put dampers on it whilst they aren't as effective as car dampers, but at the price anything that would protect it a bit more was worth it. A recent thread described axle failure on a new Swift caravan with an MTPLM of 1300kg, but an axle rated at 1500kg, and initial discussions with the Dealer led straight to "you must have overloaded it"
I'm aware of one occurence, reported on a caravan forum, where the owner identified a faulty suspension because the tyre had worn a hole in the top of the wheel arch - so it certainly wasn't always the case.
When university of bath tested caravan suspension they concluded that the Alko dampers did not give much benefit to the Alko suspension. As I mentioned in an above post I fitted them to my new axle on the basis that at less than £100 “every little helps”. But to be honest I couldn’t feel any difference compared to the old degraded axle with no dampers, and the new axle with dampers.
Our our 2011 Lunar TI it made a massive difference to towing as no more open drawers and things shaking about. No idea if it helped the suspension.
Best you direct that question to the University of Bath who worked icw Bailey. Prof probably has the reference available,. But it has been mentioned a number of time before on the Forum surprised you haven't picked it up before. Perhaps the 30% came from the same source as the 85%....anon! (TIC)
Is that the same institution that came up with the 85% theory sometime in the early 20th century that some take as being legislation?
As the 30% figure is from a German source and the 85% from the UK it’s unlikely that the origins are the same. Besides, the 30% is a legal limit whereas 85% only a recommendation. One would assume that tests were carried out before the 30% limit was set because further percentage differentiations are made depending on technical spec.
And
Makes you winder where the CC got the 85% guideline if it was not from a university?
Despite numerous threads seeking the source of the 85% recommendation no one has ever been able to pinpoint where and when it came from. Lost in the depths of time.
I suspect (but have zero evidence) that it came from "self-appointed expert opinions". All done with the best of intentions no doubt but as you say, the origins now confined to the mysteries of the world.........
You might be interested in this University of Bath 2013 MPhil project thesis concluding that the Alko dampers have significantly less effectiveness than would normally be provided by dampers for example. Laboratory testing combined with theory was followed by a series of tests at the Millbrook proving ground using a Bailey Valencia caravan. Overall the Alko dampers were considered nit to be particularly effective. The caravan failed to complete the tests as it chassis fractured.
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