Water tank relocation. Is it worth it ?

Warren,
If there any particular reason you need to reduce the ball weight by 20Kg?
Ozjohn.

Hi Warren, Certainly moving the tank rearwards would lower the tow ball weight, possibly even more than 20kg. At least, mounted between the axles would mean that the tow ball weight would change little, if at all, between tank full and tank empty. Only you can evaluate if the relocation is worth the trouble.

Have you compared the tow ball weight difference between a full tank and an empty tank? That would give you a fair idea of the effect of relocation.

Giidday Warren - I've been mulling over solutions for the very same issue.

I've not thought about moving the water tank but I have thought of adding a swing away rear wheel carrier. Not too sure of all the pro's & con's of such an idea but I do know that cost is one downside.

Does that idea grab you?

Cheers - Wayne

Warren.

Read through these two links. There may be an advantage in reducing the weight but there is a lot more involved in it. I can't find anything better on the net than this to explain it.

http://www.caravanandmotorhomebooks.com/articles/caravan_dynamics_cw.pdf

http://www.caravanandmotorhomebooks.com/pdf/vehicle_dynamics_complete.pdf

How about filling 5 jerry cans and placing them in the middle of the van . Weigh it to see if the ball weight has changed.

G'day Warren
Just a comment about the ball weight you are trying to reduce.
The most recent Jayco caravan pamphlets show a ball weight less than the 10% everyone seems to blindly follow.

Theirs is about 8% on their newest range and would indicate that 10% is just a figure thought of by someone and so sheep follow.

By trial and error, without risking your life, you should be able to reduce it and still have adequate control.
290 kg is alot of weight especially for a smaller vehicle like the dmax. Most of this size vehicle claim a 3ton tow ability but this is in ideal conditions and IMO really pushing the limits as the van weighs in at a figure significantly above the tug weight.
To try and compensate for 290kg with a WDH on a Mazda/Ford/Navara/Collie/Dmax is just asking too much of the chassis design strength. All ok if flat travel but trouble if you hit the ups and down bits, particularly at speed where the caravan smacks the tug around via the towbar and WDH. Think bend and crack of chassis if overload forces become too much.

To safely reduce the ball weight is a good idea.
Be careful as the 55mm lifted suspension won't be there with a van in tow and the nose up effect with van will cause the camber of the front wheels to alter and the toe in to also change. If used for 1000'skms in this condition abnormal tyre wear WILL happen. Try to make the front suspension ride height as it is without the van for best results. Not so critical for beam axle Lcruiser though.

Ross M

Warren,
i wasn't going to answer this post until you explained why you wanted to cut back on the tow ball weight.

What you want to do is your choice ad I have no problems with that. A properly setup rig should not need one. Just remember that the weight you place on your rear axle will take weight off your front axle.

Moving the tank back will not do very much to your tow ball weight as it is close to the axle already.

My suggestion is get the weight out of the front.

Have a look in your boot and check what you have never used. Ditch it or relocate some of the weight rear wards.
How many plates and cups , pots and pans do you need.Do you have a full annexe in there that has never been used.
Can you move weight rear of the axles.
I won't go into all the things that can be shifted or removed but if you can do it.

Have a good think about it,

RA.

Hi all
Its not the ball weight you have to fix it is the weight on the front suspension
The way to do it is to measure the distant from the ground to the eyebrow ie the wheel arch, that ie back and front

Then add the caravan to the tow vehicle then measure the front and rear eyebrow again if the difference is more that 10 or 15 mm then you have to add the WDH or add more suspension to the rear suspension ie air bags

If you have you caravan sticking the front up in the air of your vehicle you will have less braking on the front and this could be disartrase. The ball weight is to do with the weight on the rear axle if it is too much you may break the diff or the chassis like i saw when i was up the cape completely broke in half.

If by moving things around to make the caravans be able to have no WDH how many other people would have done it.
Caravan manufacture would have done it before now.
Terry

Before you go any further read this article. After you do you will probably consider increasing the ball weight.

It's easy to calculate the change of ball weight by shifting the tank. First measure the distance of the coupling from the centre of the axles. Then measure the distance of the centre of the water tank from the axle group centre. Divide the second distance by the first distance. Multiply the weight of your water by that fraction and that is the weight on the ball caused by the water (add a couple of kilograms to the water to account for the tank.)

When you have done that you will be able to establish the ball weight without a water tank. You then can use similar simple calculations to find out your ball weigh with the tank in various positions. It's just simple 1st year high school physics application of levers.

I think you will have to shift the tank a fair distance to remove 30 kg from the ball weight. After the experience I have had with WDH I will not tow a van without it. Even with a stable van on the back the tug handles much better. In my early days towing with a 1992 model Hilux I towed my van 30 km without the WDH to a service agent, I made sure I took the bars with me for the return trip.

Also I don't think removing 20 - 30 kg from the ball will alter the handling of your rig by much.