Caravan Stability

[Rob_374420349]

Hi All

Hope someone can help me with my problem

We have had a caravan for the past five years (Elddis Odyssey 505 mtplm of 1500 kg) single axel but not a light van by any means and have towed it with various cars(Nissan x Trail,Mitsubishi Grandis and Mitsubishi outlander 2) and have always found it was a joy to tow and we have travelled lots of miles in this country and in France and have never had any problems with Stability.We decided to swap our van for an Elddis Odyssey 525 which is the same model as our old one but with a different layout ( L shape front seating ,seperate shower,microwave fitted etc)still single axel but it weighs in at 1570 mtplm so 70kg heavier than my old van.We got it late last year and were towing it with the Outlander 2 2.0 ltr diesel and the match was 90% we have used the van a couple times and have had instability problems (snaking) and when you have the wife and three children it is a very scary thing to happen,I checked all the obvious things,(tyre pressure,nose weight,the way I load it etc,always put most things in the boot of the car or in a top box) and put it down to the van being to heavy for the car and in the end we have swapped our tow car to a Hyundai Santa Fe 2.2 diesel new shape and the match is now 83% .The last time we used the van with our new tow car which should be fantastic when we got anywhere near 60 mph or slightly over (when overtaking only) we have the same problem and we had to pull into the hard shoulder after trying to overtake a horse box and the snaking again was terrible.I have taken my van back to my dealer and he has checked everything he can think of and put new pads in my Winterhoff stabaliser and it is ready to collect,my fear is that this could happen again and I am at the point where I dont want to tow it and am ready to swap to a lighter van.

What I cannot understand is my old van was only 7o kg lighter I have loaded no more stuff into my new van than was in my old van and I am now towing with a heavier more powerfull towcar ?so what can be causing the major instability I am now suffering from ??? Could it be down to the stabaliser which should now be ok ? as I have said I realy need some help so please dont tell me to tow at 50 mph as there is always ocasions when you need to go a little faster and with Children involved a holiday should be enjoyable and I used to enjoy the towing as part of my holiday but now it is something to dread

ps wish I kept my old van now

looking forward to some helpfull answers

ok thanks Rob

 

[ProfJohnL]

Hello Rob,

I am sorry to read that you are having difficulties with your new caravan outfit. But at the outset and based on your posting two facts are very clear.

Firstly there is never a legitimate reason to exceed the speed limit - not even for overtaking.

Secondly it is the drivers responsibility to manage the outfit so it remains in full control. Consequently if you are experiencing instability you must take action to bring it back under full control. If that means running at less than the allowed speed limit so be it.

There is nothing in the road regulations that says a caravan outfit must be capable of being towed under full control at 60mph, for some outfits that is simply not possible and so they have to run a lower speeds.

However something fairly significant must be different between your old outfit and new. Clearly the internal layout is different, and that must be affecting the load distribution. This may be affecting the nose load.

The nose load should be heavy enough to maintain stability but must not exceed either the caravans or the cars load limits. Measuring the nose load is the only practical way to check if it is within limits.

Other things that may be different. The compliance of the suspension units, and did your old caravan have shock absorbers fitted? Perhaps fit shocks to your new van as this often helps quite significantly.

It is important to get your outfit to have a stable tow without the stabiliser engaged. Stabilisers are should not be relied on to provide a safe tow under normal conditions. They are there to increase the safety margin in extreme conditions.

 

[xtrailman]

Rob

I have read your post twice over.

It appears that you have gone to great measures already to sort your problem.

Have you tried increasing your nose weight to 100kg?

Also are you sure the tyre pressures on the van are high enough, do you have the data for the correct pressure.

Are the tyre/wheels to the original spec?

My gut feeling is that the different van layout, needs careful consideration, loading heavy items low down, and try balancing the weight evenly ACROSS the van, not just front to rear.

I agree with your comments regarding the towing speed, a van should be stable, at least up to 70mph, in still air conditions.

I do believe that Bailey design there vans for speeds up to 80mph.

 

[ProfJohnL]

Hello Ray,

I am would not be surprised if Bailey do consider their caravans and try to design for speeds up to 80mph, but what Bailey have no control over is the tow car, the owners loading regime, and driver handling skills. So I doubt that Bailey or any other manufacturer would stand up and say their caravans are always stable up to 80mph without adding a number of riders to the claims.

It is known that different combinations of car and caravan can have very different combined handling characteristics, and in some cases a particular design of caravan always has difficulties with a particular model of tow car. Perhaps Rob has stumbled upon one of those combinations that for a variety of reasons just don't tow well.

I do hope that Rob has simply overlooked some loading issue that has given rise to the handling difficulties, but I would strongly resist going for a 100Kg nose load as this is towards the top end limit of most caravan chassis, and there are some concerns that the high side loads on the overrun brake slide assembly can lead to poor operation of the caravan brakes.

 

[xtrailman]

hello john l

Yes i would not normally advise going to any limit. Including.

100% of the cars kerb weight

100% of the cars tow weight

Or 100% of the van chassis or 100% of the tow bar limit.

However assuming the limit is 100kg for both van chassis, and car towbar/car nose weight limit.

Then what is the problem?

 

[Heethers]

Don't forget the 7% rule which on 100KG would be 93KG.

That keeps you well under the maximum.

NigelH

 

[Lutz]

What 7% rule? It's not a rule, but just a recommendation, and an outdated one at that.

 

[Hamer_5041128]

Rob,

When hitched is your caravan level or slightly nose down? If not this could be your problem .

What exactly is your nose weight when fully loaded?

You say you have a top box, I have known a few years ago one of these causeing stability problems on a friends caravan, but i don't understand why. Did you use the top box with your previous caravan?

Hamer

 

[Heethers]

Lutz, on previous posts l have seen the 7% rule or guideline mentioned as something to look at regarding towing problems.

l as person that towed 20 years ago none of these guidelines were available, l assumed they meant something, are you telling me now we should disregard them.

The one thing l did when l returned to caravanning was to find out the new regulations that are now in place.

I have read everything on this forum since returning to caravanning and you with your knowledge have helped me out considerably.

The problem that new comers have is to much technical information that they have to take in, l for one used to load my van up look at the level of the hitch to the car, if it looked a little nose heavy l was happy, now l find myself with nose weight gauges, working out weight ratios to car and van.

Twenty years ago l towed with a Ford Capri with a Lunar Moonlight and with a full awning stowed just forward of the axle, granted know oven but yes a Electrolux fridge and every conceivable thing your wife and daughter needs, never entered my head l was over weight for the car or van it towed brilliantly.

But things have changed, regulations in abundant, so the 7% guideline went out years ago why mention on this forum and debate it in other posts, all it does in is cause confusion.

Once again l respect your knowledge and always look forward for your comments on technical issues, but sometimes my head is done in with all the guidelines about 85% towing ratio, nose weight, car kerb weight, van kerb weights and now to top it all l have seen on this forum, do you need to be corgi register for gas systems on caravans.

Sorry to go on but do you get my drift.

NigelH

 

[xtrailman]

ngh

The 85% and 7% are guide lines issued by the CC.

I am an experienced caravaner, and would recommend any one new to caravanning to work towards the guides. As i do.

Lutz has his own views, which differ.

 

[ProfJohnL]

hello john l

Yes i would not normally advise going to any limit. Including.

100% of the cars kerb weight

100% of the cars tow weight

Or 100% of the van chassis or 100% of the tow bar limit.

However assuming the limit is 100kg for both van chassis, and car towbar/car nose weight limit.

Then what is the problem?

Hello Ray,

There should not be a problem, but some people have reported difficulties with the free operation of the brakes when high nose loads have been used. Whilst there is no clear evidence for the reasons the suspicion is that the slide mechanism for the overrun brake has stared to bind because of the side load the high nose weight imparts on the slide. The problem would be worse if the lubrication has not been properly carried out.

The actual nose load should be large enough to maintain the controllability of the caravan but not to exceed the manufacturers limits. Loads over an above what is needed compromise the payload capacity of the car.

 

[ProfJohnL]

Lutz, on previous posts l have seen the 7% rule or guideline mentioned as something to look at regarding towing problems.

l as person that towed 20 years ago none of these guidelines were available, l assumed they meant something, are you telling me now we should disregard them.

The one thing l did when l returned to caravanning was to find out the new regulations that are now in place.

I have read everything on this forum since returning to caravanning and you with your knowledge have helped me out considerably.

The problem that new comers have is to much technical information that they have to take in, l for one used to load my van up look at the level of the hitch to the car, if it looked a little nose heavy l was happy, now l find myself with nose weight gauges, working out weight ratios to car and van.

Twenty years ago l towed with a Ford Capri with a Lunar Moonlight and with a full awning stowed just forward of the axle, granted know oven but yes a Electrolux fridge and every conceivable thing your wife and daughter needs, never entered my head l was over weight for the car or van it towed brilliantly.

But things have changed, regulations in abundant, so the 7% guideline went out years ago why mention on this forum and debate it in other posts, all it does in is cause confusion.

Once again l respect your knowledge and always look forward for your comments on technical issues, but sometimes my head is done in with all the guidelines about 85% towing ratio, nose weight, car kerb weight, van kerb weights and now to top it all l have seen on this forum, do you need to be corgi register for gas systems on caravans.

Sorry to go on but do you get my drift.

NigelH

Hi NGH,

The technical jargon may baffle some people, but it is more confusing is to quote the 7% (or 85%) figure and call it a rule. This gives the impression that satisfactory results will be guaranteed if it is followed.

Neither of these figures have any basis in law, and the organisation that suggested them has not provided any technical evidence to support them. Vehicle technology has moved on since they were first suggested, and it is telling that no other EU country gives similar advice to there caravanner's.

The optimum weight ratio and nose load is different for each combination, and the weight ratio is only one of several factors that can radically affect towing. In my view the most significant factor is speed and the drivers ability to read the road conditions ahead.

The principal of keeping trailer weights as low as possible compared to the tow vehicle is sensible, but an arbitrary figure plucked out of the air is neither accurate or informative, and has given some people a false sense of safety when towing. the emphasis should be placed on keeping weight to a minimum rather than a fixed figure.

 

[Dave_374330759]

Why do people keep chucking in the "7% rule" - its not a rule but a guideline which may well have been relevant when vans were less than 1000kg and you were towing with a Ford Cortina, but nowadays most cars have a limit of 75-85kg on the towball and most vans are a lot more than 1000kg so 7% is irrelevant and just confuses the hell out of people

In Rob's example above 7% of 1570kg = 110kg, which may well exceed the capacity of the van's tow hitch or the tow bar. The caravan makers, car makers and towball manufacturers all specify what the maximum allowable static load should be and its not hard to sort out which is the lowest out of them and that's the one that should be used, not some strange number conjured out of the air by using the "7% rule".

In my case the van's limit is 100kg on the hitch, the car has a limit of 75kg on the ball and the van weighs 1420kg, so using the mythical 7% makes 99.4kg which is far to heavy for the car. I don;t think I'd get away with quoting the 7% rule if the we had an accident and itwas attributed to the noseweight.

Rant over, lets get back to the topic.

Has Rob tried redistributing the stuff in the van?. A look at the Bailey website has a little game which allows you to change the distribution of stuff around the van and to see what it does to the stability and its is very instructive to see how fairly small shifts in the weight distribtion both side to side as well as fore and aft can affect the speed at which the van starts to snake and how quickly it recovers.

 

[Zafiral]

Rob

Like you we have recently bought a larger van (Pageant S7 Bretagne) and larger car (Zafira CDTi) and we now have a circa 90% match.

Previously we had a 4 birth caravan(Ranger 470/4)with a MTPLM upgrade (1250kg) towed by a Honda Civic (again a 90% match) so we were able to fit the awning in the caravan directly over the axle. However our newer van has less payload and a different layout so the awning cannot be placed directly across the axle.

What I am trying to say is that our previous van was more stable after the weight upgrade (ie better at 90% than 84%) because we were able to put extra weight across the axle.

Our new van is still stable all the way to 60 mph (true mph from Sat nav), but you do notice (more awareness than an issue)the extra 4' in length when it is windy.

So layouts and length (I guess a 525 is about 8" longer than a 505) can make a difference to how we are able to load the same items and std equipment into a van.

 

[xtrailman]

Dave

I suggest you have your rant at the CC, if you feel the 7% guide is a nonsense?

Its logical to me, that an increase in the van should bring about an increase in the nose weight?

Obviously if you use an alko chassis, you may be limited to 100kg, regardless of a higher tow car allowance.

It is argued on this site, that towing with as much nose weight as possible, can help stability.

While we are discussing minor points, Rob and myself are interested in useful and creative ideas, to sort his problem.

 

[Dave_374330759]

Dave

I suggest you have your rant at the CC, if you feel the 7% guide is a nonsense?

Its logical to me, that an increase in the van should bring about an increase in the nose weight?

Obviously if you use an alko chassis, you may be limited to 100kg, regardless of a higher tow car allowance.

It is argued on this site, that towing with as much nose weight as possible, can help stability.

While we are discussing minor points, Rob and myself are interested in useful and creative ideas, to sort his problem.

I was hoping that you'd feel that a look at the Bailey site and experimenting with the loading and understanding how it affects stability would be a creative solution. If Rob has tried shifting stuff around, loading over the axle and getting the weight nearer the centre of gravity/effort of the van then he'll reduce the yaw inertia of the van. It may require the shifting of some of the heavy stuff into the car etc. Is the tow hitch at the right height, if the van is nose up then that would help reduce it's stability. Perhaps he's got too much heavy stuff in the car and the car is unbalanced reducing the weight over the front wheels - that wouldn't improve the stability either. The fact that the van is heavier than the old one shouldn't affect the stability of the outfit - it sounds like its a loading/balance problem and the weight is concentrated at the two ends of the van and not over the axle in the middle. How does it tow when its empty?

I think the Santa Fe has a towball limit of 100kg anyway so the "7% rule" is not valid anyway.

 

[Dave_374330759]

I've just checked, the Santa Fe towball max is 88kg for the manual (5.6%) or 80kg for the auto (5.1%) so 7% (109.9kg) is definitely illegal

 

[xtrailman]

Dave

I do apologise, my comments were a knee jerk reaction.

Yes your suggestion re the Bailey site is a good idea, i will be playing on it my self after footy.

I wasn't aware the nose limit was so low, assumed it was 100kg.

 

[Heethers]

Hi NGH,

The technical jargon may baffle some people, but it is more confusing is to quote the 7% (or 85%) figure and call it a rule. This gives the impression that satisfactory results will be guaranteed if it is followed.

Neither of these figures have any basis in law, and the organisation that suggested them has not provided any technical evidence to support them. Vehicle technology has moved on since they were first suggested, and it is telling that no other EU country gives similar advice to there caravanner's.

The optimum weight ratio and nose load is different for each combination, and the weight ratio is only one of several factors that can radically affect towing. In my view the most significant factor is speed and the drivers ability to read the road conditions ahead.

The principal of keeping trailer weights as low as possible compared to the tow vehicle is sensible, but an arbitrary figure plucked out of the air is neither accurate or informative, and has given some people a false sense of safety when towing. the emphasis should be placed on keeping weight to a minimum rather than a fixed figure.

John l totally agree with your comment, what l was trying to say, that new comers would get bogged down with all the jargon on this forum.

I as a person always tow well within the speed limits of the law and road and traffic conditions.

What l cant get me head round is the all the guidelines that come up on this forum. Surely its about common sense, but maybe some of us don't have any, racing down the road at 62mph when 57 mph would get us their 10 min later.

One thing l would recommend is if you have no towing experience enlist on the CC towing course, they will tell you how to load your van before you even start to tow.

NigelH

 

[ProfJohnL]

Hello Dave,

In your comment to Ray's posting, you say that that if the caravan is nose up, that may affect stability. Not so - Provided the height of the towball with the caravan hitched sits between 350 and 420mm from the ground to the centre of the ball, the caravan is sitting within in the design range even if that causes the caravan to be nose up.

The comment that a caravan should be level or nose down is another of those misguided edicts from the day when car manufacturers did not have specific regulations to follow with regard to towing specifications.

 

[Guest]

I'd check wheel balance and nose weight and get weight low down and near to axle if this has not already been done.

If the roof box is not mounted on the car roof centre line move it and it could halp moving it towards the back of the car. Too far forward and the box may cause air turbulance to build between the car and van.

In theory JohnL's advice about ball tow ball heaight may be correct. In Practice a nose high largish trailer or caravan is a recipe for problems. Have always found slightly nose high lends to a skittish towing experience.

As for speed, Rob mentions that he has towed in France. So it is would be wise to have his outfit as stable as possible. If he tows in France again with this outfit he may well find occasions where he is legally above the UK limits.

Re the regular sniping at speed and the following point

"Firstly there is never a legitimate reason to exceed the speed limit - not even for overtaking"

If you drive to that way of thinking your driving standards are somewhat suspect.

 

[Garfield]

It strikes me that the one "vehicle" that is most prone to instability is the caravan yet it is fitted with the most basic suspension system with little or nothing in the way of effective damping, I once swapped my boat from a trailer with indespension units that was unstable above 55mph to one with coil springs and hydraulic dampers- rock solid at 85mph!!

Fit dampers, they should be standard on all caravans

 

[xtrailman]

john l

Where do you get your information re the levelling of the caravan, declare your source, because it is in direct conflict with the information that i have.

1/ the Bailey handbook clearly states the van should be level, or slightly nose down.

Are you saying Bailey is in error?

2/ The ALKO handbook clearly states the van should be level or slightly nose down.

Are you saying ALKO are incorrect also?

 

[Lutz]

There are 2 reasons why it is normal to have the caravan sitting level or slightly nosedown when towing. One is that if the noseweight was measured in the level condition, it will be less if the nose is up, and this is detrimental to stability. Consequently, one would have to make allowances for this change. Secondly, a nose up attitude reduces the ground clearance at the back of the caravan, which could cause problems when negotiating speed humps, for example. Otherwise, there are no further inherent disadvantages in a nose up attitude.

 

[Guest]

There is one other factor that affects stability and that is the distance between the towhitch and the axle relative to the distance from the axle to the rear of the van. Basically the greater the diference between the two the better the stability. A longer A Frame allows for a greater difference and according to our German pals increases stability by a significant measure.