Home Car modifications A Frame construction

I have been around this island and found having a four wheel drive very useful

in a lot of places especially the NT and WA. The towing posted no problem.

The Rocky a bit heavy for the Mazda. About 1700 KG.

I also used it as a trailer. But to tow a Suzuki on a trailer you probably end up the same weight.

After finishing this trip I have made a few modifications. Hinge the drawbars at the front so the unit can fold up and shorten the drawbars so the Rocky just clears the bus when turning.

As an observation after driving around for two years I have seen a lot of A frames which is good, the only thing is very, few are legal. I have seen A frames with a compliance plate and fixed to the towed vehicle with a few angle brackets to the bumper bar which is definitely not approved. But in most cases the towed vehicle was well above the 750 KG. and no brake system in place. What worries me is what happens if there is an accident. I can not imagine an insurance company paying up when the setup is not approved.


FINALLY DID IT. I have my A frame certified. Because of the uncertainty with the rules and regulations a few years back I decided to buy a dolly when one came up in the local paper. It sat in the garage for a year before I bought a four wheel drive. Daihatsu Rocky diesel. When I put the two of them together it was obvious that the Rocky was to heavy for the dolly. I always wanted to tow with an A frame but when I found out what the rules are. (I live in Queensland and the department of transport has a flyer on rules and regulations on how to tow including an A frame) The rules are the same as set out in your A-Z article on A framing, except the safety attachments have to be chains instead of cables. The rule that the brakes have to be operated from the towing vehicle makes it difficult until I stumbled on a British website. In here they described a system whereby the A frame has an overrider brake installed like on a caravan and a cable attached to the overrider lever and the Rocky brake pedal. The idea is that when I apply the brake the Rocky pushes forward compressing the overrider and applying the brakes on the Rocky.

So far so good. I made the fittings within a couple of days. (Full description and photo's on construction pages) I had to do it quickly as my brother and his wife came over from Holland in a few weeks and we had to show them the delights of far north Queensland. First day on the road worked great. On the level roads you would not even notice the car behind. Different story uphill and headwind. Third day on the road I got stopped by the police and they wanted to see my certification for the A frame which offcourse I did not have. I had to report to Queensland transport in a few weeks time.

When I got there, everyone in the office came out to have a look and a long discussion took place on how to test it. Finally they decided to put the front wheels of the Rocky on the brake testing machine and I had to pull the handbrake lever on the overrider. Without the motor running it was below specification because no vacuum to the vacuum booster. With the motor running it was well within specs. They also did not like the two tow balls sticking out the front. But in the end none wanted to make a decision on what to do. A lot of pictures taken and a letter send to Brisbane which came back saying it was not satisfactory but they would not specify what was not satisfactory and I had to see an engineer. In the meantime I found out that there is a 12Volt vacuum pump on the marker for situations like this $1000 including all valves and hoses.

The department of transport gave me an address of a qualified engineer. He mentioned that he had seen many novel ideas but not this one. He was very positive

Construction cost:

Total cost for materials which include the jockey wheel, electrical modifications is $470

The cost for certification was $35 for Qld transport initial testing and $ 607 for the engineer.

This comes to a grand total $1112. In case you can find an engineer that charges less, for under half a day's work you can make it a lot cheaper.

When you are on the road make sure you have your engineers report with you. Good luck and I hope to see many A frames on the road. The more there are the less we get hassled by the police.

In the meantime I have swapped the Mazda for a Hino RH 160 but the principle is the same

Site created 3.3.2003

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To connect the Rocky to the bus.

Hook up the two tow balls on the Rocky. Wind up the jockey wheel so the front hitch is above the tow ball on the bus and just drive it to the bus. I can do it by myself but it is easier if someone gives directions.

Make a guide on the towbar like a small UHF antenna and the whole thing is a piece of cake.


Before driving off make yourself a checklist like you probably have for the van.

Tow balls locked in position.

Safety chains connected.

Electricity connected and checked.

Overrider brake cable connected and distance set correctly.

Handbrake released.

Key in ignition , one turn to prevent steering lock engaging.

Gears: High neutral. Low 2 wheel drive high . Freewheeling hubs unlocked.

When driving be aware that the towed vehicle wants to take a shortcut around the corners. Don't get caught in a service station.

right from the start and suggested that I might get enoug braking power without the help of a vacuum pump. He made a few suggestions about how to strengthen the whole set-up. When this was done road testing commenced. First the Mazda T3500 had to be weight, 3.8Ton. Brake testing was done by itself first. He had a gadget which measures pedal pressure and deceleration. This fell well within specification. The Rocky was hitched on and the same test done. Not exactly the same result but very close and within specification. It is very important to have the cable tension set correctly.