Nose weights and A-frame length
I'm not a novice to towing by any means but I changed the van last year to a continental van, a Knaus Sudwind. The new van has a much longer A-frame than my previous UK built van and I struggle to get a decent nose weight.
Based on the 5-7% rule the nose weight should be in the region of 65 - 90KG for it's MTPLM (1300KG). If I load the van appropriately I can get the nose weight up in the 70-75KG region which I always used as a benchmark on my previous van. However, the ride in the car is a little choppy, shall we say.
I imagine that's because the longer a-frame has greater leverage on the rear of the car, so the greater the weight on the towball the more effect it's going to have on the ride over uneven road surfaces.
The manufacturer, Knaus, has the recommended nose weight of 40KG. This seems a bit on the light side to me and I worry that it might be unstable, especially on motorways passing, or being passed by, large vehicles.
I've never had a stability issue with any van I've towed, and I attribute that to being conscious of how the payload is distributed and by trying to get a good nose weight, erring on the side of slightly heavier (within the car's limit) is better than too light.
However, I accept that I probably haven't got something quite right in this instance in the trade off between the longer A-frame of the van and the effect that has on the nose weight required for a stable outfit while at the same time retaining a decent ride in the car.
Could anyone offer me the benefit of their knowledge and experience please?
I don't doubt Knaus know what they're doing and 40KG might be ok but I'm also aware that Germany might have slightly different guidelines and limits on what a nose weight should be and what any given car's towball limit should be.
Thanks in advance.
Comments
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40Kg does seem light, I tend to aim for 50 - 75 Kg personally. Of course the longer A frame should help with stability in it's own right.
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The longer A frame should help stability but basically the longer the distance from the hitch to the axle the greater the vertical force at the hitch. If this distance is greater than on the previous caravan then there will be a tendency to bounce more, and if it is a problem you could try adjusting the nose weight to see if it helps, but 40 kg does seem very low. If all else fails then modifying the suspension may be the answer, but if you do that tell your insurer and advise them why.
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Indoors does have a point as a longer A-frame should, in theory, improve stability, although it is perhaps debatable whether an extra 50cm or maybe less in A-frame length makes a really appreciable difference. For reasons already given, the OP's arguments are flawed.
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I am a user of very long "A" frame caravans, but both have been run at just under the 100kg limit of the chassis, and both have been impeccable towing.
The quoted 40 kgs for a 1300 MTPLM caravan jarr very much with both my ideas on "sensible" values and I though way under a German Standard.
Lutz is our man to answer this latter point but reading the documents of my German van there appears a rule that the noseweight must not be less than 4% of the MTPLM, but never less than 25 kgs.
Four % of 1300 kgs gives a figure of 52 kgs which is 30% higher than the discussed 40 kgs, giving me cause to question the authenticity of the value quoted.
Even 52 kgs is lower than I would entertain as I am very much in the school of using as high a noseweight as the kit in use allows, to optimise stability.
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Regulations governing towbar design require that they must be capable of carrying 4% of the maximum permissible towable weight as noseweight. This does not mean that the actual noseweight must be that high (although, in practice, it is always advisable to make full use the permitted noseweight limit), just that the manufacturer must document a limit at least as high as what the regulations specify.
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Don't know how that works, ask the experts ( Generally German caravan manufacturers ). After owning eight Hymer brand caravans since 2001, we on returning to the Uk purchased a Coachman VIP 560/4, it was without doubt the worst caravan I have ever towed ( it lasted 3 months ). Distance between axle and rear end was IMO far too long compared with the distance between axle and hitch.
The OP doesn't mention what tow vehicle is being used, which is also critical to a safe, comfortable tow.
Regards a longer A frame taking up more road space, hows that work ?
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