Hacky Races – Braking

The Hacky Racer rules require that every racer has a mechanical braking system. Brakes which rub on the tyres or the ground do not qualify, nor do electro-braking and regen.

Here are two ways to create a manual brake.

Convert Automatic Brake to Manual

Many Hacky Racers are based on mobility scooters and these vehicles generally already have two separate brake systems: a manual brake which acts directly on one pair of wheels; and an automatic anti-runaway brake which generally acts on the motor shaft. If the manual brake is in good condition, then it can be re-used unmodified. If not, then the anti-runaway brake can be converted to manual use.

It’s tempting, when converting a mobility scooter motor for use in a racer, to unbolt the seemingly complex automatic brake and bin it. However, with a couple of simple mods, it can be converted into a superb manual brake.

Begin by unbolting the brake from the back of the motor, knock out its magnetic coil (which normally releases the brake) and removing the heavy-duty spring (which normally applies the brake) then reassemble just as before – with those two parts missing – and refit to the motor.

Then, fit/bodge a lever onto the brake or motor body so that the lever presses onto the central spindle of the brake and gives about 2:1 or 3:1 leverage. This will apply the brake when the lever is pulled towards the motor.

Finally, fit a bike brake cable and brake handle, and the job is done.

This brake is easily strong enough to stall our motor even when it’s at its full 30A torque – which can be handy for getting a quick start off the line because we can max the throttle, let the soft-start build up to full current, and then release the brake at the ‘go’.

Fit Bike-Type Calipers and Brake-Pads to the Driven Sprocket

If your Hacky is chain-driven, you’ll have a large sprocket on the rear axle (or the diff – if any). Provided that you’re happy to remove the chain every time you want to oil it, this sprocket can be used as a brake disk.

Standard rubber brake blocks work fine but the leverage required is considerably higher than a standard bike caliper can provide – around 3:1 or 4:1 is needed. The braking action is dramatically improved if the ‘disk’ is cleaned occasionally with acetone or similar powerful solvent.

Dual-purposing the sprocket is not ideal – lack of proper oiling on the chain becomes a problem after each rain shower – but it’s a cheap, quick way to get a first brake fitted and with the correct leverage it will be powerful enough to lock the rear wheels.