Instability

[IanofMeon]

Hi all

We've just been away for the 1st time with our new van and am a bit worried about instability with just cars passing us on motorway.

Car is Skoda Octavia 1.9Tdi, kerbweight 1500kgs, max tow 1400kgs, noseweight 75kgs. Caravan is Bailey Ranger 460/4 mtplm 1208kgs.

We loaded pretty much as we did with our previous van, Bailey Discovery mtplm 1156kgs, take spare wheel out from locker, place over axle to enable measured noseweight of 80kgs (as close as I can get to 75kgs). Rear fixed bed has chairs/table underneath, clothes in lockers (nothing heavy), bedding under front seats. TV, trolley jack, wheelclamp, hitchlock in boot of car.

Did 35 miles, A roads at 50mph lovely, motorway at 60mph every car that overtook us swayed the van, there was no wind, I'm just glad there weren't a lot of coaches about over the weekend.

Now I'm torn between there being too much weight in the boot of the car making the steering too light, not enough noseweight (which I can't do anything about short of changing the car), or it's the weight of what's under the rear bed (incidentally the chairs/table were carried at the rear of my previous van as well and that outfit was rock solid).

Any ideas/thoughts greatfully received.

Ian

 

[MikeMc]

Check van tyre pressures - and dont trust dealer. Ours was unstable and when I checked after a service they had set our tyre pressures to 32 psi when the handbook said 44psi.

Also check pads on stabiliser dont need cleaning. Again I watch ed our dealer move vans around with a mini tractor and it occured to me that a van that uses a blade type stabiliser will have a greasy towball wereas a hitch base one will not but the same tractor was moving the vans around leading to contamination. I cleaned my towball and pads with white spirit.

 

[Lutz]

Don't only check the caravan tyres, but also those of the car. When towing the tyre pressures should be set for maximum load. Even 2 to 3 psi over the recommended pressure for max. load in the rear tyres won't do any harm as a temporary measure while you are towing.

 

[ProfJohnL]

I concur with the responses above, but also I note that you say you are running with a nose load of 80Kg, but you car is rated to only 75.

You are actually illegal, and your insurance may invalidated. You MUST get you nose weight down to 75Kg or less.

If your outfit feels unstable you should experiment with loading both the car and caravan to see if you can improve matters. Check that you do not have too much load on the back of the car as this may make the steering feel lighter.

 

[Dustydog]

Ian

Are you sure you have an Al-ko stabiliser? I think Mike may be wrong as to the best of my knowledge the Ranger wasn't fitted with one.

I agree with all the previous comments.

Have you tried measuring the noseweight with nothing in the Ranger and car? Try towing unladen and see if that makes any difference to the "feel".

Daft question but exactly how are you measuring the nose weight?

Cheers

Dustydog

 

[IanofMeon]

Hi all

Thanks for the responses so far. Tyre pressures on car are adjusted for full load and van pressures checked before every trip so I know they are okay. I don't have alko stabiliser, I have blade type which I've always found okay.

I check noseweight with a unit that fits on car towball, you then lower van hitch onto it, probably not 100% accurate I agree, but I always seem to be the only one on site doing this. I know that at 80kgs I am illegal but with the stability problems I was having I didn't want to risk lightening the front any more.

When I collected the van from the dealers, it was empty apart from spare wheel and 2 gas bottles in front locker, boot of car was also empty and I never adjusted the car tyre pressures. It towed beautifully but then it was a 20 mile 'A' road trip limited to 50mph max.

I tend to think that maybe the front of the car was too light so next trip I'm going to leave boot empty and put those items over axle in van.

What about wheel carrier behind axle, I know that the wheel weighs 17kg, how much of that and the weight of the carrier will affect the noseweight, then of course there may be too much weight at rear of van. Are these carriers easy to extract at the side of the road with a flat tyre on the van?

Thanks again

Ian

 

[Lutz]

If, as you say, you are measuring the noseweight with a unit that fits on the the towball, then the nose end of the caravan will be higher than normal while you are taking the measurement. This will result in an increased noseweight once it is brought down and hitched up to the car. Therefore, if you read 80kg, then the actual noseweight may be more like 90kg, depending on the height of the unit and this could be more than the car will handle comfortably (quite apart from it being more than the actual specified limit).

 

[Dustydog]

Ian

Can we assume the Skoda is in a good state of repair, no broken springs or worn our suspension bushes?

In this months Caravan Club Magazine John Wickersham has written an article on stabilisers and stability that will be of interest to you.

Is your current stabiliser correctly adjusted? Strictly speaking you shouldn't need one.

Cheers

Dustydog

 

[IanofMeon]

Another update, just been out with piece of wood cut to height of towbar and measured noseweight on bathroom scales, shows 80kgs loaded for trip with spare wheel in front, on the noseweight gauge I have loaded like that it goes off scale ie over 100kgs so it looks like I was towing with too low a nose weight because I reduced it by 20kgs+ to show 80 on the gauge.

Lutz I understand what you're saying, the bit of wood I've just used was at height on towbar when loaded but then there's an extra inch (height of bathroom scales) so caravan when measured looks slightly higher than when it's hitched to car.

Car by the way is all okay re springs, suspension etc, just been serviced.

Now it seems I need to lose 5kgs from noseweight, I'd like to leave sparewheel where it is so do you think it feasible for me to load say wheelclamp and ramps circa 7-8kgs just behind the axle which seems to reduce it by 5kgs.

Cheers

Ian

 

[ProfJohnL]

Hello again Ian,

I think you fail to understand how the height of the tow hitch affects nose weight. Raise the tow hitch and the nose load reduces, conversely lower the tow hitch and the nose load increases.

To show you how important hitch height is, measure the nose load with the hitch resting directly on the bathroom scales, and then re check but using your piece of wood, you will find the nose load is apparently reduced when it is higher.

For this reason and especially because you are working close to your legal limit you must measure the nose load on level ground with the hitch at exactly the same height as it rests when connected to the car with all loads and passengers in place.

You should also check that the height of the hitch falls between 350 and 420mm (from ground to the centre of the ball). These again are legal limits.

If your outfit does not comply with these you are either over loaded or something has broken.

 

[Ianofwilts]

Just a thought, I'm new to this just a couple of years but many trips under my belt, is it better to even the weight out across the unit to ensure an even down weight from front to back. My van tows very level although its a twin axle and seems very stable when i spread the load with heaviest items over the axle. can the problem with overtaking vehicles worsen if the van sits nose down to the tow car ?

 

[xtrailman]

Ian

Up to your last post, assuming you had a single axle, i would have said you need to lose nose weight, say down to 60/65kg.

But i have no experience of a twin axle.

I used to use my spare tyre in the van to adjust nose weight, so thats ok, i also carry my water bottles in the rear wash room for the same reason.

While you are sorting your problem, try the old trick of moving over to the lhs of the lane when traffic passes, and try a speed reduction.

 

[Lutz]

If I understand the problem correctly, the outfit handles worse with the new caravan than the old, all other conditions remaining unchanged (same car, same noseweight, more or less the same MTPLM of the caravan, etc.). If that is the case, then there is still one issue which can have a significant impact on stability and that is weight distribution from side to side. It has been found that caravans which have a significant difference between left and right can handle badly. Differences of up to about 70kg have been measured on some models and this can have a marked effect.

 

[ProfJohnL]

Hello again Ian,

There are many factors that affect stability, and no one on this forum is going to be able to give you a copper bottomed explanation or cure to your problem. All we can do is offer suggestions, and point out any glaring errors.

The attitude of the caravan is set by the height of towball, so my previous replies may be relevant on this point. There is no general right or wrong to the attitude of the caravan, as the manufactures are all fully aware of the EU towball height limits, (350 to 420mm) and will design their caravans to work with tow balls to that specification. The resulting attitude will be within the design specifications for the caravan.

As you report the problems arise when you are travelling faster (stability is affected by speed.) it may be related to the aerodynamics of the combination. Aircraft have to make small changes to their trim to maximise safety and efficiency, so a change of caravan behind a car is quite likely to affect the way air gets past the combination, and it may be more easily disturbed by other vehicles as they pass. This would certainly be more pronounced at higher speeds.

There are no simple curealls for this, perhaps changes to your load distribution may help or possibly the use of a wind deflector but it is largely down to trial and error.

Ultimately if you find you are unhappy with the stability at 60mph, reduce your speed, after all you are obliged to keep you outfit under proper control.

 

[Dustydog]

Ian

As the others say , it's very hard to solve your problem at a distance.

Just a thought.

When you collected your new caravan had it been correctly PDI'd by the dealer? Have you told the dealer about the difficuty you are experiencing? I assume all the wheels and wheel bearings are ok?

Is you caravan fitted with shock absorbers? They are an easy retro fit and do make a difference to handling. That said none of my earlier caravans had them and they always behaved themselves.

Cheers

Dustydog

 

[Royston]

Hi Ian, I have the same van as youself,460/4 I tow with a vectra estate 2.2 dti. This is how I load up our van prior to towing hopefully this may help.

First thing Take out the chairs ect from under your bed, any weight behind the axle will cause the sytems you mention.

Loading starting with the external front locker, inside I have qty 1 7.5kg gas bottle, positioned within the first well on your left as you face the the locker, along side I have qty 2 green empty water barrells, along with their handle.

Inside the caravan, place two chairs and small external table between the front seats on the floor.

Over the axle we have the heavy stuff ie food containers/wheel clamp /all saucepans in basket/elect cable/dogs food container/waste master.

To keep these items from moving forward, i purchased a wooden broom handle,now this is placed just behind the fridge door

across the floor to the door opening, (cut to suit) remainder of the broom handle cut to suit the distance between the wood and the front seat frame support alongside the door entrance, cover both the cut offs with the plastic foam you can buy to lag water pipes.Nothing has moved in all my travels within the last two years

The wardrobe is filled with clothes.

The cuboard under the wash basin along side the bed is filled with all the bathroom requirements, nothing inside the toilet shower area.

The spare wheel is under the van via the alko carrier.

Nose weights, make sure that the van is on level ground when you are measuring the nose weghts, My van is parked at home along side our drive which is on a slope.When I first brought the van home I too had some weird nose weight guage readings, taking the van to a level ground I found that loading the van as above my nose weight reading is just below 75kg, which is the max for my towball.

The only lorries that I have found can cause the caravan to become slightly unstable, are the car transporters, never get to close behind them.

Royston

 

[IanofMeon]

Hi all

I think I've cracked it today. Hooked up car on level ground, loaded car and van as I would, cut the broom handle to right length then measured noseweight via bathroom scales. Showed 80kgs, this is with spare wheel and 2 gas bottles in front locker, chairs etc still under rear bed, water containers in shower room. Now if I place clamp, hitchlock, tool box and elec lead securely over axle with trolley jack just behind it shows 75kgs. Eureka!! So next tow we will see again how it performs, if it misbehaves again with the n/w perfect I will have to look again at the chairs under the bed (they're not very heavy by the way, the canvas types that fit in their own bags).

Royston thanks for you listing there, by the way do you know what sort of weight fitting your spare wheel on the carrier made to the noseweight because I am considering one and are they easy to extract should you need to, do they collect a load of road dirt and grime.

Thanks again all

Ian

PS there's a lot of Ian's on here, mine's not a T/A by the way!

 

[Royston]

Hi Ian,

In answer to your question, the caravan came complete with the spare wheel fitted,so cannot comment with regards to the additional effect it has with regards to the noseweight.

The sliding rods have been greased to enable the wheel to be withdrawn should the need ever arise,never checked to see if it gets dirty, I am in the green flag breakdown which as part of there service will change the wheel for me.

Royston

 

[Robert_374373903]

Another update, just been out with piece of wood cut to height of towbar and measured noseweight on bathroom scales, shows 80kgs loaded for trip with spare wheel in front, on the noseweight gauge I have loaded like that it goes off scale ie over 100kgs so it looks like I was towing with too low a nose weight because I reduced it by 20kgs+ to show 80 on the gauge.

Lutz I understand what you're saying, the bit of wood I've just used was at height on towbar when loaded but then there's an extra inch (height of bathroom scales) so caravan when measured looks slightly higher than when it's hitched to car.

Car by the way is all okay re springs, suspension etc, just been serviced.

Now it seems I need to lose 5kgs from noseweight, I'd like to leave sparewheel where it is so do you think it feasible for me to load say wheelclamp and ramps circa 7-8kgs just behind the axle which seems to reduce it by 5kgs.

Cheers

Ian

Hi Ian, i also take it that you are weighing on level ground, it makes complete differance if it is not.

 

[xtrailman]

Ian.

Have you got the light weight gas bottles?

Do you really need two?

I only carry one 6kg bottle. But do use electric hook up.

I would carry the trolley jack in the car, it can cause a lot of damage to the fittings of the van, if it comes adrift.

As for the alko wheel carrier, i took mine off, the carrier itself must weigh about 10kg+

The wheel is very difficult to remove from the carrier, and yes the wheel does get dirty etc. And access for checking the pressure is not easy.

 

[Iain]

We towed a 2007 Ranger 460/4 with a 2007 Octavia vRS TDi Estate. I always found it a really stable outfit, both before and particulary after the fitting of shock absorbers on the 'van. I always found the 460/4 quite light on the nose compared to our previous Baileys and our current 2008 Pageant. We had a mover in front of the wheels and the spare wheel behind the axle in an Alko carrier, with little under the bed we had to load the front of the 'van to get up to 75Kg.

As for the Octavia it is one of the most stable cars we have towed with, so much so we have swapped it for an 09 model.

 

[Gafferbill]

Ian ... you report your outfit is affected by the bow wave of overtaking vehicles on motorways at around 60mph but is stable at 50mph.

Lutz and John L have pointed out the importance of correct tyre pressures on your tow car, and the fact that you can reduce your speed and move to the left of your lane to reduce the resulting instability.

Bow waves exert pressure on the relatively high sides of your caravan as the overtaking vehicles passes.

This is a positive pressure at the head or the wave, followed by a negative pressure at the tail, as it passes.

This translates to a push / pull lateral movement at the hitch point causing your tow car to slightly rear steer.

This can develop into full-blown snaking .. the main reason we fit stabilisers.

In your case I would increase the weight on the rear axle of the tow car by loading the boot whilst maintaining the correct nose weight on the hitch.

This will result in the rear axle of the tow car being less likely to rear steer, giving you a smoother tow.

Most of the weight of your Octavia is on the front axle, especially if you have an empty fuel tank and no rear passengers!

 

[Royston]

Hi once again Ian,

Not sure why you need to carry a trolley jack with you, bit dodgy if that shifts within your van also a unecessary weight. We have been caravanning for the past 8 years travel a lot , always only ever carried qty 1 7.5 kg gas bottle using gas only for cooking which we do a lot of,on the average the bottle will last us 2 to 3 years .

Always start the tow with a full tank of diesel, and forgot to mention in my last post its important to check your rear tyre pressures, driving solo no towing, my vectra rear tyres 32 psi when towing I increase the rear tyre pressure to 38 psi, fronts remaining at 32 psi.

I travel over the A66 quite a lot towing from Scots corner A1 to the M6 can get quite windy up their but as per my previous post

loading the van never ever had the slightest wobble.

Be going over their again this May heading for Galloway from Essex.

Best of luck towing Royston

 

[IanofMeon]

Hi Royston

 

[IanofMeon]

Try again!!

Hi Royston

I suppose I could leave trolley jack behind, I belong to CC green flag but I've always worked on the basis that if it's safe I'd change my own wheel on the van, maybe I'll leave it to them, doesn't feel right somehow though.

I carry 2 4.5kgs gas bottles, one always full, one not and we don't use a lot of gas admittedly, probably only for cooking so that may be an option if I'm still having problems.

Cheers again

Ian