Home Car modifications A Frame construction


Heavy to carry easy to roll.

The A frame is constructed from 50 X 50 X 5 box section and 10 mm mild steel plate. The Overrider brake is rated 2000Kg and so are the other tow ball connections. All the steel was ordered to size so it was just a matter of drilling all the holes, bolt the hitches to the steel and weld it up. The easiest way to get everything lined up is to attach everything to the towed vehicle, spotweld everything in place. (Disconnect the car battery) It is very important that the hitches line up otherwise it is difficult to connect. All bolts to be high tensile.

The safety chains have to be welded on. (For Queensland) For other states consult your engineer about cables and hooks.

The handbrake lever has to be modified otherwise the leverage will not be sufficient. I extended the lever by 100 mm. I also drilled a few holes in it so I could experiment with different ratio's.

Total length of A frame is 1600mm. Some people suggested that the longer it is the more stable but I found no problem with the length and the whole unit is already heavy enough as it is. You could use 3mm box section and reinforce the ends where the bolts go through.

I also fitted a jockey wheel which makes for easy maneuvering when you want to attach the car to the towing vehicle and also when you want to get it out of the way.


Standard mechanical overrider. Turnbuckle for adjusting free play.

Setting up:

It is very important to set the correct distance. In my case when the handbrake is tightened up there is a 20mm distance between the pushrod and the handbrake lever. The distance can be varied because I put a turnbuckle in the line. To set this quickly I made a gauge to that size. I can check it easily half way during the day in case something has stretched. When braking hard the overrider brake just misses full compression.

The whole setup works beautifully.


Overrider with extension bar fitted.                             Gauge for adjusting free play

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