Towbar for D2 + Jayco 25ft caravan

[billirwin]

Hi, have just ordered a 25ft Jayco caravan to put behind my 2000 Disco 2, TD5 auto. It has the 47.5mm factory towball so I need to change to 50mm. The local LR dealer has a complete factory 50mm towbar; bad news is they can only sell the complete towbar rather the just the ball itself. Good news is it has been sitting there for ages and instead of list price $1374 they 'only' want $250.

Before I go any further down this path I was wondering if anyone has any experience with this D2/long Jayco combo. I don't have the hitch height of the caravan yet but it seems like the Disco ball height is rather high. If I'm going to have to do the 50mm change I'm wondering if I should look at a 3rd party towbar.

Any thoughts much appreciated
Bill

[BMKal]

You can buy a 50mm towball from any auto accessories place, even most decent garages will carry them.

I've never heard of a "factory 50mm towbar".

If you have the original Landrover towbar (Hayman Reece style), it is simply a matter of replacing the towball with the size that you need.

If towball height is an issue, you can buy various different height towbar "tongues" to suit the Hayman Reece set-up. I have two of them - one is a straight tongue to give me the extra height I need for my camper trailer, the other (original) tongue drops down much lower, and is used for my garden trailer which has a much lower tow height. Both have 50mm balls fitted. I simply change the tongues depending on what I need to tow.

I also have a recovery point (looks like a straight billet with an eye and a "D" shackle on one end) that slides into the same opening on the Hayman Reece towbar that I take with me on camping trips to the beach.

[billirwin]

You can buy a 50mm towball from any auto accessories place, even most decent garages will carry them.

I've never heard of a "factory 50mm towbar".

snipped rest



well this picture shows the towbar fitted from new on my Disco - you can see it is not just a matter of changing the ball. Hence my reqest about how other people had handled the issue.
https://www.aulro.com/afvb/

[StephenF10]

The standard D2 towbar is nothing like a Hayman Reece. You will need a weight distribution hitch for a 25ft van and the LR towbar is not designed for the stresses imposed by a WDH. Get a proper Hayman Reece or equivalent towbar, a Hayman Reece WDH and you will be set. The WDH has adjustable ball height and can cover a fair range of heights.

Stephen.

[billirwin]

The standard D2 towbar is nothing like a Hayman Reece.
snip
Stephen.
many thanks Stephen, you have confirmed what I suspected. I'll check out your suggestions. It's the first time I've had to tow a real load with the Disco so I'm learning the in's & outs.

[LandyAndy]

That is a UK style towbar,was about to say it isnt what is usually fitted here,notice you are in NZ.
I would say the aussie Harman Reece style hitch is stronger.
Andrew

[alien]

Bit of light reading for you...
www.discovery2.co.uk NAS spec Tow Hitch (http://www.discovery2.co.uk/NAS_hitch.html)
(Not sure what Urban Panser hasn't done;))

[BMKal]

well this picture shows the towbar fitted from new on my Disco - you can see it is not just a matter of changing the ball. Hence my reqest about how other people had handled the issue.
http://www.billirwinarts.com/images/IMG_0209.jpg

Sorry mate - I've never even seen a tow hitch like that on a Disco before. :o

What a bloody horrible looking contraption that is.

Every D2 that I've ever seen with a towbar, including my own, has the type of hitch fitted that Urban Panser has installed on his, as shown in the link posted by alien d2.

Maybe there's something that LRA has actually got right. :angel:

[billirwin]

hey thanks all for your info - yes it seems like NZ gets the UK standard option which isn't that flash. I've tracked down a Harman Reese dealer in NZ so am going to go in that direction.

This is a great forum, learnt more in one night than I thought possible!

[scarry]

Every D2 that I've ever seen with a towbar, including my own, has the type of hitch fitted that Urban Panser has installed on his, as shown in the link posted by alien d2.

Maybe there's something that LRA has actually got right. :angel:

All D2's that came to Aus had the towbar that takes the Hayman Reece type
tongue set up fitted as standard.Pretty sure it is rated at 3.5 t.
Wth the right attatchment makes a great recovery point

[Grumndriva]

Correct. The standard Aus D2 tow bar has a max towing weight of 3500 kg and a max towball weight of 250 kg.

We tow a 21 foot Jayco Sterling Outback (ATM a bit over 2600 kg) with a Hayman Reece WDH tongue etc in the standard LR receiver. Works well for us.

[Banjo_pluker]

Correct. The standard Aus D2 tow bar has a max towing weight of 3500 kg and a max towball weight of 250 kg.

We tow a 21 foot Jayco Sterling Outback (ATM a bit over 2600 kg) with a Hayman Reece WDH tongue etc in the standard LR receiver. Works well for us.

What is your ball weight just out of interest, I am just about to do the same with the same weights!!

[Grumndriva]

I haven't weighed it yet, but I estimate (based on previous 20 foot Sterling Outback) around 190-200 kg with tanks full.

[chicko]

Hi,
I read with interest your posts regarding towing a caravan. I have a 2002 D2 TD5 and am in the process of upgrading my camper van to a 19' caravan. I would be very interested in any comments you have regarding your experiences towing your van. I have had a chip installed

Thank you
Danny

[Grumndriva]

Chico,

Response e-mailed separately.

[Pedro_The_Swift]

Dont forget,, that 200kg ball weight comes straight off the load amount you can carry onboard,,

[Tombie]

Correct. The standard Aus D2 tow bar has a max towing weight of 3500 kg and a max towball weight of 250 kg.

We tow a 21 foot Jayco Sterling Outback (ATM a bit over 2600 kg) with a Hayman Reece WDH tongue etc in the standard LR receiver. Works well for us.

Just noting..

You do realise that LR towbars arent rated for the 'up' forces of a WDH... And may very well be tearing apart your chassis.

LR state specifically not to use WDH hitches, and if you wish to use one, its recommended to fit the HR style bar, rated for such 'up' forces.

[Grumndriva]

Thanks Tombie. Yes I was aware of that, but the benefits of the WDH outweigh what I am fairly certain are minimal risks with the D2 chassis and the fairly low forces involved in our case. I am currently having a deep and meaningful conversation with LR about the use of WDH with the Disco 4. LR is adamant that WDH should not be used with the D4 both because it is not engineered to take upward forces and because WDH interferes with the SLS. They claim that WDH are unnecessary, and I have sought some sort of verifiable basis for that claim, since it cuts across conventional wisdom both here and in the US.

[Pedro_The_Swift]

I'd be interested to here about the "conventional wisdom" Grumndriva



I have this sneaking suspicion WDH's were invented due to van makers inability to create a vehicle that tows correctly.

[Grumndriva]

Hi Pedro,


Lots of people share your view, but most serious caravaners agree that WDH are necessary for safe towing of today's larger vans. That need appears to be even greater with independent suspensions than with beam axle suspensions.

I am not an automotive engineer and I have not done any controlled experiments to verify the above, because I am neither qualified to do so nor prepared to risk my rig. However I have towed my van both with and without the WDH, and I am personally convinced that the rig travels far better and handles far better with the WDH than without. But I acknowledge that that does not constitute proof. I would also expect severe braking to be better with more weight on the front wheels.

If interested, try Googling "weight distribution hitches" and "weight distributing hitches", and try searching for the same on some of the local caravaners sites such as caravaners forum, caravan world and caravan and motorhome forum, where the subject is regularly discussed.

I have attached a link to the How Stuff Works site which has no commercial interest either for or against WDH, and may therefore be more reliable than some of the sales places which do have a vested interest.

HowStuffWorks "How Towing Weight Distribution Systems Work" (http://auto.howstuffworks.com/auto-parts/towing/equipment/hitches/towing-weight-distribution-systems.htm)

It is interesting to note that some vehicle manufacturers, Toyota amongst them, require the use of WDH in some models and weight combinations. That suggests that the requirement for WDH has some credibility.

As your googling will show, the use of WDH also appears to be embraced by the horse and boating fraternities.

I have asked Land Rover if their decision not to engineer their vehicles for WDH is based on any science or engineering studies.

Hope this helps.

[Grumndriva]

The following link may also be useful in explaining the use of WDH.

Caravaners Forum • View topic - Caravan Stability- by Collyn Rivers (http://caravanersforum.com/viewtopic.php?f=23&t=950)

[Pedro_The_Swift]

Thats a nicely written article,,

but just a couple of things spring to mind after reading it,,,

Pitching just doesnt happen with top of the line shockies on the tow car,,

If "there can be up to 500kg of up and down force when pitching"
and you've just added a WDH,, havent you just added extra upwards force??

wont a "bullett of sideways wind" hit both the front AND the back of the van?



I'm happy that you have a "nice" van to tow,,

I'm going for a quick search,, there was a vid posted not so long back that demonstated just what we are talking about,, now,, where was it,,,

[Pedro_The_Swift]

YouTube- Land Rover's "Trailer Stability Assist" for Range Rover, Range Rover Sport and Discovery 4/ LR4

and this tech does exactly what the article says,,

it absorbs the motion.

not only that ,, it does it on both axis,,

[Grumndriva]

Thats a nicely written article,,

but just a couple of things spring to mind after reading it,,,

Pitching just doesnt happen with top of the line shockies on the tow car,,

If "there can be up to 500kg of up and down force when pitching"
and you've just added a WDH,, havent you just added extra upwards force??

wont a "bullett of sideways wind" hit both the front AND the back of the van?

I'm happy that you have a "nice" van to tow,,

I'm going for a quick search,, there was a vid posted not so long back that demonstated just what we are talking about,, now,, where was it,,,

Pedro,

Thanks. I am not an engineer so I can't argue for or against WDH except from personal experience, but a couple of quick reactions to your points:

Pitching just doesn't happen???? Sure it does, regardless of whether there is a trailer attached or not, unless you have incompressible tyres and a completely rigid suspension, and even then it will happen after hitting a bump when the wheels leave the ground. (Pitching being any movement about the lateral axis). All that shockers do is damp that pitching so it doesn't continue too long after the initial upset. Perhaps that is what you meant, but it only takes one quick pitch down on the towbar, and that is what you get when the van brakes come on, to reduce the weight on the front wheels and therefore the efficiency of your brakes when you need them most. Mine are Bilsteins, which are not top of the line, but are at least reasonable quality.

The WDH will indeed increase the upward force, but it will also substantially reduce any downward force, such as with heavy braking, which generates the upward reaction.

A natural cross wind which is not blowing through obstacles and is therefore a steady wind, will indeed affect the entire side of the van, and therefore it will always tend to yaw the van UNLESS the effective keel area forward of the pivot point is identical to the effective keel area aft of it. However that rarely occurs because of trees, buildings etc on the side of the road, so in practice the cross wind is usually acting first on the front and then on the rear. In addition, one of the unnatural wind effects which is particularly common and potentially dangerous is the bow wave from a heavy transport which, when overtaking, affects the rear first, tending to move the nose of the tug one way, then affects the forward section, tending to move the nose the other way. The end result is a drift towards the overtaking vehicle. And I can tell you that it is quite "interesting" when a heavy transport overtakes when you have not noticed its approach! This is one situation where I have no doubt that trailer stability assist would be very very helpful.

I am all for getting rid of the weight and complexity of the WDH IF trailer stability assist can fully replace it, but so far that does not seem to be the case. Trailer stability assist can't do anything to affect the fundamental problem which is weight distribution. "All" it can do is help to detect and then try to counter incipient sway before it gets too much (and that is a great help if the vehicle can stop the sway before it gets out of hand). But it is only one of the issues that WDH appear to help solve. In my one personal experience of dangerous sway, its onset was so sudden that I seriously doubt the ability of trailer stability assist to help before the forces exceeded the ability of the tyres to retain grip. We were probably a microsecond away from jack knifing or worse after probably one to three seconds since the upset was intiated. A quick hit of the van brakes alone solved the problem instantly. Any way I have invited LR to give their views on their decision, and as a back up I have foreshadowed my desire to include the van on the D4 test drive if I decide to go further with replacing the D2.

I guess we have hijacked the thread, but caravan handling can be a real safety issue, not just for those towing but also for any unfortunate soul who has a van jack knife in front of them. I have enjoyed the discussion.

[Grumndriva]

This site is also interesting, but doesn't prove anything apart from the effect of weight distribution: Bailey of Bristol - Caravan Stability Studies (http://www.towingstabilitystudies.co.uk/)

Check out the simulator.

[Mundy]

Whilst I agree with Pedro that the article is quite good at explaining the principles, there are two matters that are not quite right, one practical and one pedantic. I also think there are a few practical summary conclusions which would help to be made, too.

Collyn Rivers is right that in the absence of any other influence, a body will rotate around its centre of mass. However this is only a minor effect in terms of the impact of the trailer on the towing vehicle. The major vertical and horizontal influences are the rotation of the trailer around its axle and wheel pairing. There is a lesser horizontal influence relating to the rotation around the hitch point. The discussion of rotational dynamics relating to the distribution of the mass of the trailer and energy absorbion are all valid.

The practical summary points I would make are:
1. the centre of mass of the trailer should be just forward of the trailer axle and as low down as possible.
2. the heaviest parts of the trailer should be as close to and as low down to the trailer axle as possible
3. all other things being equal a longer draw bar will result in lower vertical and horizontal loads on the hitch point.

The pedantic point I would make is that under our SI (metric) system of units, mass is measured in kilograms and weight, which is a force, should be measured in newtons. If you wish to talk of weight in kilograms you should use kilograms force (kgf) for which the unit of mass is the metric slug. For you older types who pine over the imperial system, you either use mass of ‘pounds mass’ (lbm) with force in poundals, or you use force of ‘pounds force’ (lbf) and mass in slugs.

Mundy

[biggin]

Whilst I agree with Pedro that the article is quite good at explaining the principles, there are two matters that are not quite right, one practical and one pedantic. I also think there are a few practical summary conclusions which would help to be made, too.

Collyn Rivers is right that in the absence of any other influence, a body will rotate around its centre of mass. However this is only a minor effect in terms of the impact of the trailer on the towing vehicle. The major vertical and horizontal influences are the rotation of the trailer around its axle and wheel pairing. There is a lesser horizontal influence relating to the rotation around the hitch point. The discussion of rotational dynamics relating to the distribution of the mass of the trailer and energy absorbion are all valid.

The practical summary points I would make are:
1. the centre of mass of the trailer should be just forward of the trailer axle and as low down as possible.
2. the heaviest parts of the trailer should be as close to and as low down to the trailer axle as possible
3. all other things being equal a longer draw bar will result in lower vertical and horizontal loads on the hitch point.

The pedantic point I would make is that under our SI (metric) system of units, mass is measured in kilograms and weight, which is a force, should be measured in newtons. If you wish to talk of weight in kilograms you should use kilograms force (kgf) for which the unit of mass is the metric slug. For you older types who pine over the imperial system, you either use mass of ‘pounds mass’ (lbm) with force in poundals, or you use force of ‘pounds force’ (lbf) and mass in slugs.

Mundy

:eek::eek::eek::eek::eek:

Can't agrue with that!

:D;)

[Pedro_The_Swift]

a few more thoughts,,

10% is an urban myth.
maybe 30-40 years ago this wasnt a bad guesstimate, but times and weights change and so should the advice.
Vans are not designed to be towed, they are designed to be sold first,, then overnighted in. Just because it has wheels doesnt mean Ferrari had a hand in its design,,
(more likely Country Road:p)

I do find it hard to believe EVERY single grey nomads van has had a brush with death,,

maybe the caravan world is full of good salesman:D