Newbee needs help - How High should my towball be off the gro...

[David_374359815]

Hi, I am new to caravanning and just wondered what the suitable height for my towball should be when towing? I have had a few trips and noticed that my jockey wheel when raised is still quite close to the ground - is this normal? I have measured the distance between the ground and the middle of the ALKO hitch at roughly 37cms when hitched to the car but this isn't fully laden.

For info I have a Honda CRV sport 03 and towing a bailey pageant vendee.

If it is too low how do i raise it? A friend has mentioned using a drop plate to raise it but I have read that this must never be done - is this right? Any advice would be greatly appreciated.

Regards

Dave

 

[Alan Partridge]

The centre of the ball should be at 38.5cm +/- 3.5cm from the ground - i.e. somewhere between 35cm and 42cm, which yours is. This is when measured with a loaded car and the trailer/caravan hitched up IIRC.

I believe the pre-2005MY CRV II (I had one) has a max noseweight of 60kg - are you at or within that?

 

[Parksy]

Apologies if I'm wrong but it's not uncommon for new caravanners to wind up the jockey wheel without checking the position of the wheel in relation to the slots in the outer sleeve so that when it's unclamped and raised the wheel is still close to the ground. I did this myself when I first started.

 

[David_374359815]

Hi Alan,

I haven't checked my noseweight but this could be the problem if it is too much - does this mean i have to load my van better?

 

[Alan Partridge]

I would certainly want to have some idea what the noseweight is - regardless of the jockey wheel clearance, too little and you increase the risk of stability problems and too much will potentially overload the towbar or the hitch. I use a

 

[David_374359815]

Hi alan,

My jockey wheel hasn't grounded yet it just looks low - it could be me being paranoid! Thanks for the advice - i will recheck the jockey wheel is in its corredt position and will also check my noseweight so that i am ok on that front.

Thanks

 

[David_374359815]

Hi alan,

My jockey wheel hasn't grounded yet it just looks low - it could be me being paranoid! Thanks for the advice - i will recheck the jockey wheel is in its corredt position and will also check my noseweight so that i am ok on that front.

Thanks

 

[xtrailman]

David

Bailey have gone for the pretty but useless option with the jocky wheel positon in the middle of the A frame fairing. My previous van had the jockey wheel on the outside of the A frame.

This allowed the wheel to raise higher of the groud.

With my bailey i tried removing the jockey wheel, however this took too long. I ended up taking the jockey up as far as possible inside the fairing and even cut a 10mm slot in the wheel support so as not to rub against the brake mechanism.

With you tow car i would expect to see no visable lowering of the back of the car when you load the van on the back.

The jockey wheel still looks low (and is) but take care over speed humps etc and uneven Cl fields and you should have no problems.I havent in 4 years.

Note the van should ride level when hitched to the car. or slighty nose down.

 

[xtrailman]

Sorry i forgot to mention it is now illegal to use a plate to lower or raise a tow ball. (raising has always been illegal)

A level or slightly nosedown ride high is your mission. While keeping inside you maxium nose weight allowance, excessive nose weight will make the tow car unstable. you will feel the steering get light in extreme cases.

When i towed with normal road cars with a nose weight of 75kg i usually tried to get the nose weight to between 60 & 65kg.

 

[ProfJohnL]

Hello David,

I have monitored the last few responses, and no seems to have addressed you question regarding nose weight.

You must check the specification of both the car and the caravan for their respective maximum nose weight limits. If they are different then you have to accept the lower of the two limits.

It is illegal to exceed the limit, so if you are currently to high them you must reload your caravan so as to reduce the nose load.

I take issue with Rays comment regarding the attitude of the caravan. It frankly does not matter whether the caravan is nose up or down, provided the tow hitch is within the specified height range.

If the tow ball is outside the permitted range, then you must recheck the loading of the caravan and the car. If this does not help then there is something more serious adrift, and you should refer the car to the garage or the tow-ball fitter for professional advice.

 

[xtrailman]

Hello David,

I have monitored the last few responses, and no seems to have addressed you question regarding nose weight.

You must check the specification of both the car and the caravan for their respective maximum nose weight limits. If they are different then you have to accept the lower of the two limits.

It is illegal to exceed the limit, so if you are currently to high them you must reload your caravan so as to reduce the nose load.

I take issue with Rays comment regarding the attitude of the caravan. It frankly does not matter whether the caravan is nose up or down, provided the tow hitch is within the specified height range.

If the tow ball is outside the permitted range, then you must recheck the loading of the caravan and the car. If this does not help then there is something more serious adrift, and you should refer the car to the garage or the tow-ball fitter for professional advice.

John l

post 2 has already establish the ball height is correct.

All the recomendations i have ever seen over 30 years of towing have recommended a level ride hight, or slightly nose down.

To suggest that towing nose up or down providing the ball height is within range, is clearly nonsense. and for a newbie dangarous advice.

I believe the bailey hanbook has imformation on this also'

 

[xtrailman]

John l

post 2 has already establish the ball height is correct.

All the recomendations i have ever seen over 30 years of towing have recommended a level ride hight, or slightly nose down.

To suggest that towing nose up or down providing the ball height is within range, is clearly nonsense. and for a newbie dangarous advice.

I believe the bailey hanbook has imformation on this also'

 

[ProfJohnL]

Hello Ray,

On what technical factors do you base your statement the caravan must be level or nose down?

 

[Lutz]

I suspect that a nose up attitude is generally criticised because it "looks wrong" and suggests that the noseweight is too low, whether this is true or not. However, if the noseweight is adequate, even in the nose up case, I have yet to see any proof that this could any way be to the detriment of stability. The only disadvantage is that you loose ground clearance at the back of the caravan.

 

[ProfJohnL]

Hello Val,

I agree with your point. It would allow customers to 'customise' their vans, however I cannot see much chance of this happening with the current manufacturing processes commonly used.

Caravans are generally produced in batches, and it is difficult to incorporate special one off's in to a production and purchasing schedules.

The only way this might be achieved is if the finishing touches such as fitting ovens etc is carried out by the supplying dealer, however the costs are likely to increase along with the added complexity of the supply chain for parts.

If caravan manufacturers were to adopt the 'Quality Circle' production method demonstrated by Volvo, then specials are easier to accommodate into a production line system.

 

[ProfJohnL]

Hello Val,

I agree with your point. It would allow customers to 'customise' their vans, however I cannot see much chance of this happening with the current manufacturing processes commonly used.

Caravans are generally produced in batches, and it is difficult to incorporate special one off's in to a production and purchasing schedules.

The only way this might be achieved is if the finishing touches such as fitting ovens etc is carried out by the supplying dealer, however the costs are likely to increase along with the added complexity of the supply chain for parts.

If caravan manufacturers were to adopt the 'Quality Circle' production method demonstrated by Volvo, then specials are easier to accommodate into a production line system.

Sorry wrong posting here see below

 

[ProfJohnL]

Thank you Lutz,

My point exactly. I can't think of a technical reason for a caravan to be constrained to level or nose down attitudes. I discount aerodynamics, as these will be affected more by the tow vehicle than the flight angle of the caravan.

All the caravan manufactures selling into the EU will be aware of the tow ball height restrictions, and they will be designing their caravans to accommodate this criteria across the range of the tow ball heights. They will be able to predict quite accurately the range of attitude the caravan will assume.

If a manufacture determines that the attitude must be constrained on a particular model, they should design the caravan to keep within that limit when used within the standard tow ball height range.

If an outfit cannot be arranged to maintain the required tow ball height, given the necessary nose loading, then either the outfit is incompatible, or there is some fault with either the car or the caravan.

 

[xtrailman]

http://www.autotrader.co.uk/CARAVANS/buying/safe_on_the_road.jsp
Brought this up via goggle.

look under "suspension"

Can't remember sources from 30 years ago. No doubt you will rubbish this article also.

 

[ProfJohnL]

Hello Ray,

Please feel free to continue to tow with a level or nose down outfit, provided you are not breaking the EU regulations of nose load and towball height there is nothing wrong with this configuration.

I fully agree that level and nose down gives the impression of a well sorted outfit, but there is no technical evidence that excludes a nose up configuration as also being technically acceptable.

This issue of preferred or allowed ride angle is in the hands of the caravan designers, as they base their designs on the limits of towball height set out in the regulations.

If it is not possible to achieve both an acceptable nose load and tow ball height with a particular outfit, then there is either a mismatch between car and caravan, or there is something wrong with either of both vehicles.

I do not intend to add further to this aspect of this thread.

 

[Lutz]

I can only reiterate what John L has written that there is no evidence that a slightly nose up attitude is unsafe if all other criteria (noseweight, correct load distribution, etc.) are fulfilled. Why should it be?

 

[JTQ]

A nose up attitude must impart an element of aerodynamic "incidence" to a caravan; well to a long parallel height one it would, and all importantly feature a flat underside.

As the lift point ought to be within the first third, i.e. before the axle then it should follow that this reduces the "dynamic" [as opposed to the static]nose weight.

Further as this is happening so close to the road then the "ground effect" of the air being wedged between the van floor and the road ought to multiply the lift.

Clearly the van is "flying" in disturbed air which will vary depending on tow vehicle and separation, but that potentially can both mitigate and amplify the lift.

Overall I judge it an unwise attitude, at best tolerable but potentially destabilising rather than stabilising.

 

[Lutz]

At the sort of speeds encountered when towing, aerodynamics (other than drag) play a negligible role. One cannot compare aerodynamic performance of a Formula 1 racing car with that of a caravan. The enormous aerodynamic drag of a caravan outweighs any other aerodynamic effect. Even when the world speed record for caravans was set up at 144mph, the caravan made do without any aerodynamic modifications.

 

[JTQ]

And the drag certainly adds to the dynamic reduction of the nose weight, as it acts above the van's axle height.

Based on seeing the "lift" on a fence panel carried on a cars roof rack break it, I feel its unwise to dismiss something with at least four to five times the lift area. Where static nose weights are of the order of 70 odd kg then a contribution of a few tens of kilos from speeds even as low as 55 mph can not be insignificant?

 

[Lutz]

Yes, but due to aerodynamic drag, the noseweight decreases with increasing speed whether the caravan is level, up or down. The attitude of the caravan has practically no effect on dynamic changes to noseweight. The drag is determined only by frontal area and the boxy shape of the caravan. It is so high that aerodynamic measures such as spoilers, etc. are going to have next to no effect at the sort of speeds that the caravan travels.

 

[xtrailman]

I have monitored the last few responses.

First I would ask Lutz.

Why would you assume that a nose up attitude suggests a too low nose weight?

I would assume that the tow ball height is set too high.

John l

In my experience with the X-trail. The attitude is not affected by a nose weight of 100kg.

That is to say there is no visible change in attitude when a 80kg or 100kg is obtained.

The X-trail has a max nose weight of 100kg so why should it?

David

If you refer to the bailey owners manual page 2-3 section 2.2.3

I quote "It is important to ensure that the caravan is towed either LEVEL or slightly nose down.

If it is not, then the car's towbar may be at the wrong height"

page 2-5 shows a correct loading giving a level ride height or attitude .

Referring to the Alko manual page 2

Illustrates a level ride height obtained by correct loading.

However a nose up ="high skid risk together with poor braking" Load too far back.

Nose down="Steering and braking ability reduced, increased loading on the rear axle and chassis of the tow vehicle"Load too far forward.

Finally John l

To my knowledge the max nose weight is not set by the EU.

For the X-trail Nissan set the max nose weight limit.

For my witter tow bar Witter set the max nose weight for that bar.

For my Alko chassis the nose weight limit is set by Alko.

In all cases the limit is 100kg.

I will no longer refer back to this topic.

I leave it to the readers to decide who is giving sound, safe advice to a newbie , and who is just having a laugh.