Caravan Clinic

Negative instead of positive

Reader Geoff Nicholls wrote to comment about an item on tyre wear in CW May. I had mentioned a tyre that leans in at the top and has positive camber. Geoff pointed out, quite correctly, that this should have said negative camber.

From experience in wheel alignment, Geoff said that with radial tyres the negative camber has to be at least two degrees to be the culprit.

He adds that if a tyre shows excessive wear on the inside edge it generally indicates a ‘toe-out’ problem as the wheels are not running parallel.

Geoff suggests that if suspension bushes are worn, they need to be replaced. Final tightening of the locating pins should not be done until the wheel alignment has been completed at normal load condition.

In his opinion, this sort of repair would be a simple job for a reputable wheel alignment business but few are interested, preferring to do only cars. Thanks for being observant, Geoff, and for the tips on repairs.

Timely warning

Simon Hunt from Dashlite sent us a copy of a report about Anti-lock Braking Systems (ABS), that appeared on the RACV website and is based on a study carried out by the Monash University Accident Research Centre.

It mentioned that under certain circumstances there could be a greater chance of a crash if the vehicle is fitted with ABS. As this seems to defy logic, the report poses the following question – why should an inherently safer vehicle be over-involved in certain types of crashes? The answer probably lies in the way they are used, or misused, by the driver.

The ABS system, which is a worthwhile safety feature, is designed to stop the brakes locking up under severe braking conditions. Once the brakes lock and the tyres skid along the road surface, braking distances are increased.

Ensuring stopping distances are as short as possible is critical, particularly if there is a chance of hitting an object.

A few experienced drivers may be able to adjust the brake pressure to prevent lock up but most motorists, particularly in an emergency, would apply as much force as possible to the brake pedal, hence the benefit of ABS.

It would be true to say that most drivers have not had experience with an ABS system coming into operation. In one way that is good because it means they have not been faced with an emergency stop.

The problem is that there’s a likelihood the driver will reduce force on the brake pedal when he or she feels the pedal pulsating or senses a shuddering throughout the car. These two conditions are normal when ABS comes into operation.

The answer lies in knowing how the ABS behaves. Every driver of an ABS-equipped car should simulate an emergency stop. This can be easily done by finding a section of deserted straight road and trying to stop as quickly as possible.

Ignore any vibrations, shuddering or pedal pulsations and keep applying maximum pressure. When the ABS control system detects that a brake is about to lock up, it momentarily reduces hydraulic pressure to that wheel. This can happen many times a second and creates the sensation that the pedal is pushed back towards the foot.

There is no doubt that ABS is a great safety feature. But, like driving in general, there is no substitute for experience. So find that quiet piece of road and make out that you suddenly have a kangaroo running across the road and there is a collision imminent. It is a good idea to try it at slow and fast speeds. The know-how may well help you prevent a crash.

Sad loss

Our van was a distinctive custom-made unit that would not be easy to disguise.

After reporting to the police and insurance company we have had no feedback other than when they would pay out on the car (10 days) and caravan (21 days) if not found. How do second-hand caravan buyers check that their purchase is not stolen?

Mike Saint

Parkville, Vic

Anyone buying a second-hand caravan, particularly from a private individual, should establish ownership.

Generally, the registration papers are a good start. However, being shown the rego papers doesn’t automatically guarantee that the person actually owns the vehicle.

Also ask for their driver’s licence. If the name on the licence is the same as the name on the registration papers there is a good chance they are the owners.

Considering the value of a caravan and tow vehicle, security should be a high priority. While most late model vehicles have in-built security systems and immobilisers, there is often room for improvement.

A check of the Yellow Pages under ‘car alarms’ will show a range of equipment that is available. State motoring organisations should also be able to recommend ways of improving vehicle security. I believe that there are systems that can ring your telephone when someone tampers with the car.

CW is currently evaluating a caravan security device that will ring a pre-programmed number when it detects an intruder. More details in a future issue.

Discovery Needs

Our question is do we need a weight distribution hitch and anti-sway system? What do we look for when buying these?

Evan Klatt

A weight distribution hitch is definitely needed to ensure that you maintain the desired contact between the front tyres and the road. Self-levelling suspension does not achieve this.

If your car is fitted with a Land Rover towbar or, more correctly a hitch receiver, it may be necessary to change to one that is compatible with a weight distributing hitch as it is possible that the Rover receiver is not designed to accept a hitch. Check with the dealer.

If the caravan is loaded so that about 10 per cent of the total load is sitting on the ball and the weight distributing hitch is adjusted so that the correct tow car attitude is achieved, a sway control device should not be necessary.

In regard to buying a hitch I suggest that you see a towing equipment specialist who will be able to determine your needs and fit and adjust the equipment.

Changing Needs

While the European use a relatively lightweight chassis, Australian vans seem to be built on heavy steel chassis with offroad vans being even heavier in construction. Although this might seem reasonable, I began to wonder why.

A motor car is supported by its wheels at four points. It needs enough suspension travel as well as torsional body strength, to allow for road surface variations.

A caravan, on the other hand, is supported only at three points, that is, the left and right wheels and the coupling. Even a tandem van with load-sharing suspension is basically supported at three points.

At walking speed a van doesn’t need any suspension to keep the wheels in contact with the ground whereas a car with no suspension would constantly have one wheel off the ground unless the road was dead flat, a bit like a four-legged table rocking on an uneven floor, where one with three legs is always steady.

So, I’m left wondering why Australian manufacturers use the heavy steel chassis design. Are we pulling around a couple of hundred kilograms more than we need to?

Ken Hammond

Email

Of course, you are right about the difference in construction. But it is not quite as simple as only looking at the chassis. European manufacturers look at the total strength of the chassis as well as the body.

It is a little like some of the 4WDs that have gone away from the separate chassis and adopted a monocoque (all in one) approach. When these ‘chassis-less’ vehicles first started to appear some experts said that they didn’t have the strength to handle tough offroad conditions.

Since then they have been proved wrong. In fact a vehicle that is designed to incorporate the chassis within the body structure is generally lighter and stronger than one with a separate chassis and body.

There is no doubt that many caravans use materials in their chassis that are heavier than they need to be. Some manufacturers have applied  engineering techniques and cut back on material where it isn’t needed, hence you’ll see chassis members with holes in the vertical sides.

While I agree wholeheartedly with your thoughts on a trailer being supported at only three points and thereby minimising any twisting forces, it is necessary to consider other factors.

One of these relates to the tendency of caravanners to overload, particularly when embarking on long journeys.

I have seen quite a few chassis that have bent because they didn’t have enough strength where it counted.

On the other hand it shouldn’t be too difficult to lose a few kilograms and retain the required strength.

My crystal ball suggests that in the future those manufacturers which build lighter vans, without sacrificing strength and creature comforts, are going to be on a winner.

With ever-increasing running costs we have to be seriously thinking about lighter and more economical tow vehicles, and this means lighter vans.

I believe this is one reason why European vans will gain a foot-hold in the Australian market. The ones that I have seen may not be all-terrain vans but equally they are not going to fall to pieces on the first bump or pothole.

Easing the load

I saw it on a TV show. It consists of a handle, a couple of arms and two rollers that allow the wheel to be raised and rotated to line up the stud holes. I have tried 4WD and caravan suppliers but can’t find one.

Ian Combridge

Geelong, Vic

It certainly takes the strain out of wheel changing and is called a Wheel Caddy.

The website is www.thewheelcaddy.com. I don’t know of a supplier in your region but the website should be a good starting point.

The path ahead

The Pathfinder is rated to tow 3000kg with a maximum of 300kg on the ball. However, to enable 250kg to be carried on the ball, you cannot have much in the vehicle – mum, dad, two kids, a boat, fuel and an empty boot.

Does the same apply to other vehicles or can you load them to the limit and, in the case of a Prado and Pajero, still maintain a ball load of 250kg?

It seems that in the diesel market the only family tow vehicles left are the Prado and Pajero.

The Patrol and the LandCruiser are too big for our needs. Any suggestions?

Rob Munro

Email

In the case of the Pathfinder with a petrol engine it is necessary to reduce the gross vehicle mass (GVM) by 170kg for a ball load of 300kg. In the case of the diesel the GVM must be reduced 350kg to allow 300kg on the ball.

This doesn’t make much sense as the GVM for both is the same, 2800kg, and the kerb or unladen mass within 45kg, depending on model variant. The gross rear axle load for the two engine types varies by 180kg.

I haven’t been able to find out why it is possible to place an additional 180kg inside over the rear axle when there is a petrol engine, yet the GVM is the same for both.

The carrying capacity for the diesel and petrol is between 667kg and 715kg, again depending on model. This amount includes fuel, occupants and anything that you may put in the vehicle.

If you opted for a diesel version your load would be limited to 330kg for a maximum ball load of 300kg.

Even with a maximum ball load of 250kg the GVM has to be reduced by 270kg, giving you a carrying capacity of 410kg. As you said, mum, dad, two kids, a tank full of fuel and the picnic set and that’s all.

So where does that leave you? With an 1800kg van and a ball load of say 200kg, there aren’t too many problems if you go for a petrol version (only available as an auto) as you then have to reduce the GVM by only 40kg. With a diesel this reduction is 200kg. Realistically you need to consider the Pathfinder as a 2500kg towing vehicle.

A couple of months ago I wrote to Nissan asking for some clarification. I asked why the different figures for the diesel and petrol, why there are four towball download figures stated for the petrol model and six for the diesel model, why does Nissan not recommend the use of a weight distribution hitch, and why were certain confusing statements made in the owner’s manual? After six weeks I received a half page reply which was mainly a copy of the towing specs from the brochure.

Anyone looking at a Pathfinder as a towing vehicle should get something in writing from the dealer that it is permissible to use a weight distribution hitch to ensure safe and stable towing.

Otherwise, as you suggested, a Prado or Pajero may be a better option. At least you don’t have to worry about how much you put in the car if you want to have a ball load of 250kg.

I agree that the Pathfinder has a lot going for it, but if they could get the towing specs sorted out, it would be great. We are still looking forward to trying one out.

Tow vehicle and RV selection

Although we haven’t done a lot of homework, we are already confused as to the type to vehicle and caravan most suitable. We discovered Caravan World a couple of months ago. Can you help?

H. Emery

Wagga Wagga, NSW

A lot depends on the size of the budget. If you haven’t had any previous towing experience it is a good idea to opt for a van that is no heavier than the towing vehicle. A sedan is just as suitable as a 4WD.

One advantage of a 4WD is that it usually has a higher towing capacity. This is generally due to the greater weight of the vehicle. Remember that the bigger and heavier the car is, the less economical it becomes. On the other hand, it can be frustrating and even unsafe to use an under-powered tow vehicle.

Some people travel full time with a Commodore and 16ft 6in (5m) van while other believe that it is necessary to have a 4WD and a 26ft (8m) unit with all the mod cons. When the overall length becomes greater, parking or finding a suitable campsite can be a problem.

As a starting point you might want to consider a Falcon or Commodore and a compact – maybe an 18ft (5.5m) external body – tandem. If a 4WD is your preferred mode of transport, I would recommend that you still keep the length to a reasonable figure.

Most of the time you are towing it or sleeping in it rather than spending hours on end simply living inside. It isn’t necessary to have a shower and toilet to enjoy caravanning as most parks have excellent facilities.

Another option is to visit a tourist park and chat to caravanners who look as if they have been at it for a while. These people can often provide lots of dos and don’ts.

Once you have shortened the list, write to us again with your preferences and we may be able to offer some more advice.