Towing stabillity

[Andy_374312439]

Hi, all I'm new to the forum so be gentle with me!

Just replaced my caravan with a 2007 abbey vogue 620 and am using a Jeep grand cherokee to tow with.

My problem is the set up appears to 'tail wagging the dog' even went towing empty when pickup from the dealers. Can only get to about 45mph before it is noticeable but become uncomfortable over 55mph. Is this usual or am I expecting more from my caravan than I should. Measured nose weight and is about 100kg which is max wieght for caravan but under for the car.

Also tow ball is about 2 inches below hitch when caravan is level will this have an effect and can I do anything with it?

Regards

Andy

 

[mcghee]

I use a Grand Cherokee Andy, and its probably one of the most stable towcars around.

I use mine to tow many things, one of which being a 2tonne Hobby, and have never had any issues at any speed.

I would recommend you get your car checked over, failing that I would say in full confidence that the 'van is to blame.

 

[WatsonJohnG]

I am wondering if you have yet towed with the van laden

The suspension will give when loaded and settle with use so you may be almost level soon !

An empty van is not the most stable as nose weight depends on loading and stability will be better with the loaded suspension.

Have you checked the noseweight?

I would aim for the max allowed by car/van specs

 

[Lutz]

If, after having followed the advice of the others, you are still experiencing the problem, try raising the tyre pressures on the car.

 

[Del_374232870]

We tow a Lunar Delta 640EW with a Grand Cherokee and like mcgee I find it the most stable outfit to date. That said I pay particular attention when loading the van by keeping heavy items to the floor over the axle or just ahead and keeping the nose weight as close to 100kg as possible. Last week we went away for a weekend and I forgot to move the cadac BBQ from the rear of the van and have to admit that whilst the van wasnt unsteady I could feel the tail wagging slightly, a quick stop and moving heavy items forward rectified the problem. I would check the noseweight and loading of the van. Also check the vans tyre pressure and the cars.

 

[Dave E]

Andy, I have an Abbey Vogue 600 which the same size, weight distribution etc as yours. I tow it with a Toyota Previa which is lighter if lower than your Jeep.

Mine is very stable at 60 under windy, motorway, and rough road surface conditions.

On a recent trip a biker cut across us on a dual carriageway, crashed into a sign at the entrance to a petrol station and ended up in the road in front of us. I did an emergency lane change and was pleased that the caravan followed along beautifully, enabling us all to escape and sparing my children the horrors of running someone over.

There is certainly nothing wrong with this particular caravan which does imply that there is a specific problem with your setup and once solved it will tow well.

 

[Andy_374312439]

Hi all,

Many thanks for your comments ,it is heartening to know that it is a situation that can be resolved.

it was towed with awning placed over the axles so should have been ok.

Will check tyre pressures again try towing again , and will let you know how it goes.

Many thanks

Andy

 

[Roy2]

I tow a spectrum 535 with the latest grand cherokee,no problem at all.Nose weight about 110 kg.Ref to increase tyre pressure,JeeP do not advise this,and the on board pressure monitor isnt happy either.The older grand had a live rear axle,not so stable,also perhaps the rear suspension should be checked by a dealer for wear depending on age,as they take a fare amount of stick.

 

[RogerP]

Spooky , I was going to post a similar query today.

I picked up my new van from Exeter a couple of weeks ago and had a 160 mile journey home. I have a Lunar Solaris 1 and tow with a Merc ML270 (auto).

Whilst I didn't feel the wagging i could see it in the mirror.

The van was empty apart from the awning. I checked the tyre pressures the following day and noted they were 45 PSI instead of 54. Also my cars handbook states I should run at 39 PSI instead of 32 when towing.

All that said I've sort of assumed that correcting the tyre pressures and adding our junk into the van will make a difference.

We're going out for the 1st time in a couple of weeks so will find out then.

 

[Stephen_5122599]

Hi Andy,

I tow a Superstorm with a 3.2 Shogun LWB it's not as stable when the van is empty, put some weight in it and it tows a dream.

I'm sure you will find the same with yours.

regards

Steve

 

[RayS]

Spooky , I was going to post a similar query today.

I picked up my new van from Exeter a couple of weeks ago and had a 160 mile journey home. I have a Lunar Solaris 1 and tow with a Merc ML270 (auto).

Whilst I didn't feel the wagging i could see it in the mirror.

The van was empty apart from the awning. I checked the tyre pressures the following day and noted they were 45 PSI instead of 54. Also my cars handbook states I should run at 39 PSI instead of 32 when towing.

All that said I've sort of assumed that correcting the tyre pressures and adding our junk into the van will make a difference.

We're going out for the 1st time in a couple of weeks so will find out then.

I tow with a MB M270 cdi auto and have had no problems even without a stabiliser. I did notice, however that a new empty van was less stable than an older full one and - guess what - the tyre pressures on the van were way down - about 60% of what they should have been. So much for

 

[Hamer_5041128]

If your tow ball is 2 inches below the hitch when the caravan is level, when hitched up the caravan will be nose down. This results in the front wheels of the caravan taking an excess of the caravan weight, and can in some instances exceed the tyre weight limits. Therefore any twin axle trailer i.e. caravan is designed to be towed level. If the twin axle is 2 inches nose down the rear tyres will be carrying very little load. This causes instability. A twin axle is designed to tow level with even weight distribution on each tyre. Tests have been carried out and it has been proved that towing a twin nose down, or to a slightly lesser extent nose up is dangerous. It is also why twin axles when towed empty and nose down show signs of instability, but when fully loaded if they are level tow perfectly.

Hamer

 

[ProfJohnL]

Hello Hamer,

i am not disputing your posting, but you say that test have been done that confirm your position, can you tel me where i can find these tests and the results please.

 

[Hamer_5041128]

Hello Hamer,

i am not disputing your posting, but you say that test have been done that confirm your position, can you tel me where i can find these tests and the results please.

Hi,

All I can tell you is that firms/ councils towing twin axle trailers with heavy vehicles like small diggers or mini jcb type vehicles, were having tyre failures. When gone into by a

"government body" the reason came to light. Further tests were done to prove the point. I am related to the person who looked into it and did the report, a highly respected engineer.It was found that the vehicles on the trailers were set too far forward.

Hamer

 

[Hamer_5041128]

John L,

Further to my "comment" it was found that many of these trailers were being towed by vehicles which did not have really firm rear suspentions. As a result if the vehicle being carried was set to far forward the hitch would dip and therefore most of the weight was being carried by the trailers front two tyres which were not designed to carry so much weight. A twin axle caravan travelling nose down can produces the same problem.

Hope this helps.

Hamer

 

[Lutz]

One has to allow for design tolerances somewhere. It will therefore be pure coincidence if the caravan is standing level.

The standard height of the towball when the car is fully laden should be between 350 and 420mm. However, the standard height of the coupling on the caravan when it is standing level should be between 395 and 465mm. Therefore, assuming a fully laden car, the caravan will almost always be nose-down. Of course, if the car is well nigh unladen and its suspension relatively soft, the caravan could actually be slightly nose-up.

 

[Hamer_5041128]

Lutz,

In our case we must have had 8 coincidences on the run, as all have towed level, or very slightly nose down when hitched to the car. It does not alter the fact that to tow a twin axle 2 inches nose down is asking for trouble. From the patio on the rear of our bungalow on a Friday and Saturday I can see cars towing caravans going to the local caravan parks. Most tow level or very slightly nose down. You do get the odd one very much nose down or nose up. I accept your guide figures but surely manufacturers must work to much finer tolerances to enable the vast majority of caravans to tow level or slightly nose down.Could it be that many tow bars now come with built in drop plates?

My last 2 came with 2 positions for the tow ball and the previous one with 3 positions.

Hamer

 

[Lutz]

The figures that I quoted for towball and coupling height are industry standard and therefore the caravan manufacturers will be fully aware of them. They will take all permissible tolerances into account in their design specifications.

Drop plates are only intended for use on 4x4's which are exempt from the standard and may have higher towbars in order to ensure greater ground clearance. However, there is therefore absolutely no need for drop plates on other cars.

I doubt whether an inch or two up or down at the towball is going to make an awful lot of difference in the static front and rear tyre load of a twin axle caravan. Dynamic variations and possible imbalance in tyre pressures are going to make a lot more difference.

 

[stevebrookman]

Hello,

Funnily enough i was about to ask the same thing. I used to tow an Abi Marauder with an Omega estate-very stable. I now tow a Fleetwood Colchester with a 99 Range Rover -with a Bulldog stabiliser. when I first towed at Whitsun I had one slight wobble-didn't think about it. Having just returned from Torquay I had quite a few waggles. I did have more weight on-two bikes and a few other things. The noseweight was around 85kg. If the bikes were slightly more towards the rear would this cause the problem or is it a fault of the towcar. All tyres good-caravans new and to specified pressures.

Many thanks again

Steve B

 

[Lutz]

Hello Hamer,

i am not disputing your posting, but you say that test have been done that confirm your position, can you tel me where i can find these tests and the results please.

Could it be that the twin axle trailers carrying diggers or other heavy equipment and which suffered from tyre failure were either

a) overladen anyway, or

b) their suspension was bottoming out, not necessarily due to overloading but the spring travel was inadequate by design, or

c) were not fitted with any proper suspension but had the axles bolted more or less straight to the chassis frame and therefore relied solely on the tyres to absorb road bumps?

d) trailers carrying earth moving equipment are often driven on building sites without proper surfaced roads and are therefore more likely to have their tyres damaged due to sharp stones, etc. Besides, such trailers, are often notoriously poorly serviced.

Any of the above could result in premature tyre failure. It probably has nothing to do with them having twin axles.

 

[Hamer_5041128]

Could it be that the twin axle trailers carrying diggers or other heavy equipment and which suffered from tyre failure were either

a) overladen anyway, or

b) their suspension was bottoming out, not necessarily due to overloading but the spring travel was inadequate by design, or

c) were not fitted with any proper suspension but had the axles bolted more or less straight to the chassis frame and therefore relied solely on the tyres to absorb road bumps?

d) trailers carrying earth moving equipment are often driven on building sites without proper surfaced roads and are therefore more likely to have their tyres damaged due to sharp stones, etc. Besides, such trailers, are often notoriously poorly serviced.

Any of the above could result in premature tyre failure. It probably has nothing to do with them having twin axles.

Lutz,

I can assure you it was the positioning of the vehicles on the twin axle trailers which caused the problems causing the front pair of tyres to fail. As I said earlier tests were carried out and taken very seriously. I was kept informed of developments. it had nothing to do with the vehicles going of road as some did not go off road. The problem was asked to be looked into due to the situation. It was included in safety letters by the government body.

Hamer

 

[ProfJohnL]

Hello Steve,

You are trying to compare two very different setups, and it is almost certain that you will notice differences in towing characteristics.

Range Rovers and Disco's have quite compliant suspension with long travel struts, and coupled with the comparatively high centre of gravity the body will tend to roll around more than a well sorted road car. These factors along with others will make the towing experience rather different.

Having experienced a large road car, which will probably be quite taught, RR's and discos can feel less tight; these comments can apply to many of the large 4x4's. I must stress that handled properly 4x4s can be great safe towcars.

As with all outfits, it is important to follow the manufactures guidelines on tyre pressures and load with as much of the heavy items near the trailer axel as possible, and to adjust it to br9ing the nose weight up to as close to the maximum (depending on manufactures specifications for both car and trailer) permitted.

Definitely avoid if possible having heavy items at the extreme ends of the caravan as the added mass in these areas will affect the stability of the outfit.

 

[Garfield]

Just towed our new (2004 model ) lunar Lexon 640 fb (21' twin axle) to Norfolk and back with a Ford S-max (92% match) we had to move the spare wheel from the front locker to under the bunks and place the awning and poles in the rear bathroom (amongst other items) to get the noseweight down to 75kg, ie lots of weight at the back and the wife had packed all the tinned food and fruit juices in the upper lockers, the result was...... complete stability, no wiggles, waggles etc even when overtaking hgvs on the dual carriageways at 65 mph or being passed by hgvs on single carriageways