Tech Talk: Caravan Clinic

Jacks again
We normally try to avoid leading CW readers astray. One way is to make sure that we always have written information to back up whatever advice we give.

But every so often Lionel lets Murphy interfere and what we get is confusion, to say the least. Back in November 2004 we did a piece on jacks.

As a result, reader John Nicholson told us about his Toyota LandCruiser jacking experiences. He had been informed that an optional jack was available for offroad use. When we couldn’t locate a part number for the jack at a local dealer, we contacted Toyota Australia, which responded by saying that the information supplied to John was wrong. This news was published in the April issue.

Then we received another letter from John, who stated that as a result of our item, ‘The Right Jack’, he had been informed by a Toyota service manager that in fact there is an optional jack and adaptor available and that the information both John and I had received from Toyota Australia about non-availability was incorrect. John was able to also supply part numbers and prices.

Not wanting to be caught out again, CW telephoned Toyota’s regional office and a local Toyota dealer to double-check that anyone in need of a jack that would work in offroad conditions could actually purchase one.

We were informed that the jack is available from the Sydney warehouse but that the adaptor has to come from Japan.

Hopefully we can conclude this saga by telling readers that the part number for the jack is 0911160081 and the cost $110.75. The special adaptor costs $35.50 and the part number is 0912760010.

Jacking solution
Further to the above scenario where John originally had difficulty fitting his standard jack under the car when a tyre was flat, Mal Cameron offers an interesting solution.

His uses his spare wheel as a lifting device. By placing it in front of the flat tyre and driving the car forward Mal is able to raise the car enough to easily place the jack under the spring hanger.

He says it is important to only use the edge of the tyre so that the spare tyre doesn’t obstruct the place where the jack needs to sit. Mal feels that by using this method you don’t have to carry extra bits of wood or other lifting aids to put under the flat tyre.

It’s great to see people thinking outside the square, but personally I’d like to file this one away in the ‘If-all-else-fails’ category. Driving onto the edge of a tyre, particularly as these days most use radial construction, could potentially damage the tyre casing.

Most of us carry a piece of timber or wedge to put under the caravan tyre if the site is uneven. Some also carry pieces to place under the corner stabilisers. It would be preferable to use these to raise the wheel with the flat tyre. But if the spare wheel is the only thing about, go for it.

More on Drawbar Woes
Joe Campbell, who has some experience in metal fabrication, read with interest the item ‘Drawbar Woes’ (April 2005). Joe noted that the break seemed to occur at a point where the underside reinforcing commenced and at the junction of the short cross member.

He suggests that it is possible that the cause of the break was excessive flexing at this combined junction. Joe adds that any welds across a flexing member like a drawbar are fraught with danger, particularly if ‘undercut’ was present in the weld.

Thanks for the comments, Joe. Others have made similar remarks, with one structural engineer suggesting that the way this drawbar was manufactured was poor engineering standards, even more so when the size and weight of the van is taken into account.

While the fridge worked well on 240V he found it unsatisfactory on 12V. Also the 12V interior lights were a little dim. Geoff discovered that the caravan plug, which he had tried to protect from the elements with a plastic bag cover, had corroded inside as a result of sweating in the bag.

Replacing the plug made the lights brighter and slightly improved fridge operation. However, there was still a noticeable voltage drop between the battery and the 12V terminal block at the fridge. Further tests showed that the earth wire going to the car’s seven-pin plug was inadequate as was the power or ‘hot’ wire from the battery.

Both cables were replaced by two 50 amp cables all the way from the battery to the plug. This provided 14.2V to the fridge element when the car’s alternator was charging. According to Geoff, the fridge now works great on 12V while on the road.

He also tells about a fellow caravanner who, like Fred, had to fit another top vent, as the original one was too low. He concludes that three-way fridges do work, provided they are installed to the maker’s specifications and have adequate electricity and gas supply. 
Thanks for sharing your findings, Geoff. When it is necessary to operate the fridge on 12V the best option is to fit two large conductors, as you did, all the way from the car battery to the fridge element.

I would go one step further and use a two-pin Anderson plug to connect the supply from the car to the van. The number ‘2’ pin in the seven-pin connector can then be used to take care of the 12V lights, which draw much less current.

When I moved the tyre there was a large brown stain in the vinyl where the tyre had been resting. I have tried to remove it with all types of cleaning agents including detergent, turpentine, alcohol, 111TriChloroEthane and some abrasive cleaners, all in vain.

Any suggestions as to how I can get rid of the stain?
Don Ferguson
Moe, Vic

A Your comment about chemicals from the tyre interacting with the vinyl is probably right. New car dealers are well aware of this problem and generally place an additional vinyl tile under the tyres of cars parked in showrooms with vinyl flooring.

Considering all the cleaning agents you have tried, it is quite likely that the stain has ‘set’, making removal almost impossible. I spoke to a couple of contacts in the tyre and flooring industries who said that to their knowledge there was nothing that could remove these stains as they penetrate into the vinyl rather than being on the surface.

But you never know – one of our resourceful readers may have a solution. If all else fails, you may need to talk to the insurance company. Good luck.

Excessive pressure
Q Tom, I wrote to you before regarding tyre pressures for my van tyres with four-wheel independent suspension.

Recently I changed the suspension to beam axles and leaf springs and fitted LT 265/75R16 112/109S tyres to match the tow vehicle. In your previous reply you mentioned that the recommendation would be different if the suspension was load sharing.

Does this mean that I can lower the tyre pressures below the 220kPa suggested? Objects are moving around a lot in the cupboards. Alternatively, is it possible to remove a leaf from the springs? The loaded weight of the van is 2400kg.
Brian Lyne
Mt. Tamborine, Qld

A Everything else being equal, it is possible to run lower inflation pressures with load sharing suspension, if four-wheel independent suspension, without uneven weight-distribution, is fitted.

However, the type of suspension used also plays a part. While two leaf springs interconnected by a ‘rocker’ do share some of the trailer’s load between each other when travelling over undulations, this system does not provide full load sharing as, for example, a Simplicity tandem suspension does.

According to my data a LT265/75R16 is rated to carry 1120kg@350kPa. The experts tell me that the minimum pressure for this tyre should be no less than 250kPa, providing for a load of 890kg.

Calculating the load carried by your van’s tyres and allowing for a 25 per cent safety margin, a tyre with a carrying capacity of 750kg would do the job. This means dropping the tyre pressures to about 200kg. It is worth keeping in mind that most available tyre data, particularly for the type of tyres you are using, relates to motor vehicle fitment,
not caravan.

Probably the 220kPa that was suggested is the best compromise. If ride quality is a problem it may be worth consulting a spring specialist.

By measuring the length, width and thickness of the spring leaves and counting the number of leaves in each spring, a spring manufacturer should be able to calculate the load carrying capacity. This will then tell you if the springs are suitable or too stiff.

Medium size tow vehicles
Q Wanting to replace my 3.0 litre turbodiesel Nissan Patrol with something that is more suited to city as well as country work, I have been doing some research on mid-size tow vehicles.

As the loaded weight of my van is 2350kg, cars like the Falcon, Commodore, Hilux, Bravo, etc, are unsuitable. This leaves the LandCruiser, Patrol, Pajero, Prado and the SsangYong Musso Sports Ute.

The latter has a five-cylinder diesel engine. Although on paper it has slightly less power and torque, I wonder about its towing ability. It has many good features including a
car-like feel. Would CW consider this for a tow test?
Morris Joyce
Annandale, Qld

A Having a van that weighs close to 2.5 tonnes certainly limits the selection of tow vehicle. The vehicles you mentioned, apart from the Musso, should be suitable based on our experiences.

As far as the SsangYong Musso Sports is concerned, watch out for a tow test in a future issue of CW.

At this stage the jury is still out. Like you, I’m of the opinion that it will be a good performer although possibly not in the same league as the more powerful competition. But as they say, engine capacity isn’t everything. And if economy around the city is important, the Musso could rate high.

The problem is that re-assembly requires the front half to be sleeved into the rear half, which is quite difficult.

Can you suggest a method whereby I can have a roll-on/roll-off platform on the back of our 4.8 metre Millard Micro caravan? I could then remove the seat and batteries to reduce the weight at the rear. The Millard seems to have a fairly robust chassis, but may need some reinforcing at the rear.

Apart from ball weight considerations, the Jackaroo should be able to handle the extra weight as the van is around 820kg. I can also mount a spare wheel on the A-frame to balance the scooter at the rear.
Jim Butler
Parkes, NSW

A My suggestion is to go back to the drawing board. Your idea of the extra weight at the rear is not appealing: even if the total weight was 50kg, including the frame, the potential of flexing at the rear as well as wagging the van’s tail is too great.

I’d suggest getting someone to strengthen/extend the drawbar so that you can carry the scooter at the front. A weight-distribution hitch will take care of the additional ball load. A visit to a weighbridge before you start may also be a good exercise as your 4.8 metre van is likely to be more than 820kg.