Snaking on a light weight caravan

[AlanWoodley]

We have a lightweight Freedom Jetstream 1ST class caravan which snakes at about 50mph, I have read forums and internet articles about snaking but so far what ever we do the caravan still snakes. The only way we can get the manufactuers stated nose weight is by putting everything inside the caravan as far forward as possible, and fitting heavy weight Calor gas bottles. The caravan also has an AL-KO stabiliser fitted. All water tanks are empty when towing and tyre pressures on car and caravan are checked and still it snakes. When empty the caravan is very rear heavy so much so that when unhitched from the car it tips rearward untill the back of caravan hits the ground.
HELP! ! ! any one got any ideas, I don't like towing with the outfit unstable and we are using the caravan less and less.

 

[NigelHutson]

You say that you're trying to get to the Manufacturer's noseweight limit? What weight is that please? What sort of attitude does the car/caravan sit at? And what is the tow car?
Nigel

 

[AlanWoodley]

Hi Nigel.
stated manufacturers noseweight is 50kgs. If I load things just in front of the caravan axle I get nowhere near this weight. My thinking is this figure is not the maximum but the safe towing weight. When attached to car the caravan looks level. Towcar is a Hyundai i10, 1200cc year 2012

 

[ProfJohnL]

Hello Alan,

The nose weight the manufacturer gives is the maximum it should not exceed it.

You in fact only need as much nose weight as keeps the outfit stable, which I know you seem to be having trouble with.

Now providing the weight limits are observed there is sadly nothing that guarantees every caravan will work or tow well with any car.

Getting the car and caravan to look level is not the measure to use, what you must do is to check that the loaded tow ball sits between 350 and 420 mm (centre of tow ball to the ground), and the nose weight does not exceed the lower of either the car or the caravans maximum limits.

Unfortunately I cant tell you if the Freedom is a poor match with the Hyundi, but Can I suggest if you are still having problems ask someone who you may know who also tows a caravan to have look at what you are doing, they may spot something you may not appreciate affects the stability.

If a caravan becomes unstable at a particular speed you must slow down, until the reason for the instability has been fixed.

 

[otherclive]

You haven't said anything about what the caravans loaded weight is, the kerbweight or manufactures towing limit for the car, or max train weight. It's a very light car are you sure all of the essentials are within recommended guidelines or car makers specification?

 

[Gafferbill]

Your caravan at 750kgs MAM is just legal for your car .......but only if it has a manual gearbox.
The tow ball weight limit for your car is 32kgs.......not 50kgs.
50kgs is the limit of your caravan's hitch......but you must not exceed the limit for your car, which according to Hyundi is 32kgs.
I would make sure that I towed with weight in the rear of the car especially if you tow with no rear passengers.
Full tank of fuel and luggage in the back for example!

 

[otherclive]

Your caravan at 750kgs MAM is just legal for your car .......but only if it has a manual gearbox.
The tow ball weight limit for your car is 32kgs.......not 50kgs.
50kgs is the limit of your caravan's hitch......but you must not exceed the limit for your car, which according to Hyundi is 32kgs.
I would make sure that I towed with weight in the rear of the car especially if you tow with no rear passengers.
Full tank of fuel and luggage in the back for example!

Without knowing the Max/Gross Train Weight it is not necessary that the outfit is legal just because the caravan comes just under the max braked trailer weight doesnt automatically make it a legal combination. Agree that adding weight at the rear is a good idea and making sure tyre pressures are at the recomended pressure for twoing too.

 

[AlanWoodley]

Thanks everyone for your help. lots of helpful info. Have been on a towcar info website before iI bought the caravan which stated the weight ratio for my car and caravan to be 76% and a perfect match. I will try less nose weight as did not realise this figure was the maximum. only 2 people in the car and it is fitted with spring assistors.
Thanks to you all once again.
Alan

 

[Sproket]

Your car is approx 5' high & slopes backwards to the rear....
Your caravan height is approx 8' high with a slab front...
Have you thought about using one of these to help with the air flow ???
I use one when we don't put the top boxes on....
The front of the van is a lot cleaner from flies when towing so it must be helping direct the air over the van...

But i would be more concerned as to what you have stored in the van to make it tip up backwards........

Watch this Video about how it works

 

[Mel]

I am on this forum for moral support not technical support so I'm not going to comment on the weights and measures discussion.
However I do have a Hyundai i10. I have never towed with it; but even solo it is by far the most skittish car I have even owned. Stiff breeze; skittish. Damp road; skittish. Bit of luggage; skittish. Even if my very big lad shifts position in the passenger seat I have to compensate with the steering. Honestly, I am not kidding.
It may not be the noseweight, it may be the cr~p stability of the i10.
mel

 

[Mel]

p.s. Sprocket, if you stuck one of them fin things on an i10 it would probably tip over.

mel

 

[Sproket]

p.s. Sprocket, if you stuck one of them fin things on an i10 it would probably tip over.

mel

 

[Mel]

Love it Sprocket. Thats exactly how it drives!!
mel

 

[TonyH1]

I've never heard of an unloaded caravan tipping up backwards when unhitched. There's got to be something loading the caravan to the rear. What about spare wheel or motor mover? If these are present and mounted behind the axle they could be the problem.

Regards

 

[ProfJohnL]

I've never heard of an unloaded caravan tipping up backwards when unhitched.

Hello Tony.
I have moved several different models of caravans in their ex works state and some Singe axle caravans do have enough mass at rear to keep them tipped up if lifted, yet they still have some nose weight if the hitch is lowered to the ground

The reason is the position of the caravans centre of gravity. To produce a nose weight the CofG has to be forward of the caravans main wheels. So imagine looking at the side of a caravan when its set level using the jockywheel the CofG will be located approximately 1/3 of the height of the caravan and just forward of the main axle line make an imaginary mark to you can see its motion when the caravan is tipped. If you lift the hitch, the caravan effectively rotates about the axle, the position of the CofG describes a partial arc around the axle. As it approaches the vertical above the axle the nose weight reduces to zero, and if the CofG can pass behind the axle, then the nose weight becomes negative, and the the caravan will remain tipped up.

Conversely, if the nose is lowered, the the CofG advances further forward which increases the nose weight, and this is the reason that it is very important to measure nose weight at the actual towing height of the car being used. The shorter a caravan is the greater tip angle can be achieved so the effect is more likely to occur in shorter caravans (and trailers) like the Freedom.

The weight distribution in Twin axles is far more complex due to the interaction of twin axles and the effect of suspension systems. A matter of 2 or 3cm difference in a TA hitch height can make 10 to 15kg difference in nose weights under some circumstances, which is why it is even more important to measure TA's nose weights at the EXACT towing height.

 

[TonyH1]

Hi there Prof,

Quite agree with your comments and have also experienced caravans that would tip up if lifted but Alan's experience seems much more extreme. He says he has to lower the rear legs before unhitching to stop it just tipping up! This cannot be right.

Regards

 

[ProfJohnL]

Hi there Prof,

..............He says he has to lower the rear legs before unhitching to stop it just tipping up! This cannot be right.

Regards

I did not recall any reference to using the rear steadies in the OPs contributions, and having re-read the entire thread, he doesn't and nor does he state the caravan tips up of its own accord, so perhaps you know something I don't on this one.

However if as you suggest the caravan spontaneously tips up from the towing height without any external force, then there is a negative nose weight in that condition. That is not a satisfactory towing condition, and is probably illegal, as the mechanics of the systems are designed for a positive nose load when towing.

I'm not convinced that is the case here, perhaps something has been lost in translation.

But it is possible to have some positive nose weight at the correct towing height, and for a short trailer to be tipped up and for it to sit tail down for the reasons I explained previously, but it does depend on where the CofG sits in relation to the main axle, and the extent of rotation the design allows when the hitch is lifted.

Having looked at the web site for the Freedom jet stream details, I do note the kitchen and wash-room are both mounted at the extreme rear of the caravan, and only the twin seats are forward of the axle, The fridge and heater are over the axle. This could lead to a nose light caravan, and that might be enough to allow it to sit back on its tail.

But with the addition of gas bottles and the under bed storage of clothes and nic naks, and any awnings and poles on the floor my guess is the nose weight should be enough to generate the 35 to 45kg of nose weight this caravan is likely to need.

 

[TonyH1]

My apologies Prof, you're quite right the op doesn't mention lowering the legs. Don't know where I was getting that from but he does say
" that when unhitched from the car it tips rearward untill the back of caravan hits the ground."
I took this to be inferring it was tipping up unaided. I do agree that a reasonable nose weight should be achievable which is why I say something must be loading the rear of the caravan. The op says he's already putting his loading as far forward as possible and refers to gas bottles in the plural.