Hit the brakes!
Retrofit trailer brakes for towing confidence.
Abraked trailer adds a whole new dimension to towing your boat. It means being able to slow down and stop quickly, without the trailer jack-knifing or shunting your vehicle off the road.
You can retrofit brakes to your existing trailer relatively easily but, as always, there are choices. You need to decide which braking system is best for your trailer and tow vehicle and, of course, your wallet. If you’re not familiar with braking technology, sifting through the options can be confusing.
HERE’S AN OVERVIEW:
Trailers generally use one of three types of braking methods – mechanical, hydraulic or electric. Mechanical and hydraulic systems use either disc or drum brakes – electric systems only use drum brakes.
Because electric brakes contain electro-magnets within the drum, they are unsuitable for trailers dunked regularly in seawater. Similarly, mechanical and hydraulic drum systems tend to seize up when submersed in saltwater. Avoid them. In effect, this means that for your DIY trailer-brake-retrofitting journey you only need to concern yourself with two options –
mechanical disc brakes or hydraulic disc brakes.
Using the diagram overleaf as a reference, note that you can select either a set of mechanical disc brakes with a mechanical override/surge coupling ( the staggered black arrow) or hydraulic disc brakes with a hydraulic override/surge coupling ( staggered red arrow). Each has advantages and disadvantages.
This is a component that’s fitted to the trailer’s drawbar, just behind the ball coupling, and it’s needed to activate the trailer’s new brakes. Both the mechanical and hydraulic coupling mechanism have a spring-dampened, movable coupling head which uses the tow vehicle’s momentum and deceleration (from braking) to operate.
The mechanical override coupling uses an attached lever connected to the trailer’s brakes by cables or solid rods, or a combination of these. The hydraulic override coupling uses a small hydraulic master cylinder, and it’s connected to the brakes with hoses carrying hydraulic fluid. Mechanical override coupling – this is a more basic type of system with a harsher braking ability, and it has a limited amount of sensitivity to the tow vehicle’s actions. Because the connection between coupling and brakes is either cable or rod/cable, both need careful adjustment and
regular attention to ensure that any wear in the calliper brake pads, stretch in the cable, or damage to the rod/cable setup is fixed. If you fail to do this the brakes might wear prematurely or fail to operate correctly when you need them most!
When towing with a cable-only brake set-up, the trailer hubs will be regularly moving up and down as the suspension moves. This movement can cause the cables to slacken and tighten, and if incorrectly set-up, your brakes will activate every time the cable tightens.
As well as being uncomfortable to tow and increasing your fuel use, the brakes may over-heat and the callipers will quickly wear out. For this reason, cable-operated brakes are not suitable for any off-road activity.
Hydraulic override coupling – a step up from the mechanical system, this system offers an improvement in both braking efficiency and control. The hydraulic master cylinder attached to the coupling softens the impact of the coupling motion and gives a slightly more proportional amount of braking control. The system is easy to install and set up, requires less maintenance than mechanical systems, and spare parts are readily available.
Hydraulic override couplings operating disc brakes are probably the most common type of braking systems on trailers up to 2,500kg GVM (GVM is the combined trailer tare – trailer and boat weight).
DISC BRAKE 101
Disc brakes comprise a hub attached to a disc (sometimes called a rotor), with a separate calliper unit. The calliper bolts onto the trailer axle. Within the caliper, brake pads sit either side of the disc/rotor and squeeze the disc by either mechanical or hydraulic power.
The greater the diameter of the discs, the greater (better) the braking torque. As a rough guide, for every one percent increase in disc diameter, the braking efficiency increases by one percent due to the leverage gained as the calliper moves away from the axle. Larger diameter brakes also allow better dissipation of heat generated from heavy or constant braking.
Ideally, the best braking comes from bigger rotors and the appropriate calliper piston to force it against the rotor. Callipers come in many options with single or multiple piston arrangements. They can be made from cast iron, alloy or stainless steel, with differing piston materials
ABOVE Using the diagram, it’s clear that the only options for retrofitting a boat trailer are mechanical disc brakes or, even better, hydraulic disc brakes
BELOW In a panic braking scenario things often end untidily.