February 2018

40 AFTERMARKET FEBRUARY 2018 BRAKES B raking technology has moved forward along with overall vehicle construction. We have seen this trend over many years, with the move from drum brakes to disc brakes, the development of ABS and beyond. This trend is ongoing, as you would expect, influenced by overall shifts in vehicle design. Hybrid and all-electric power units may make the headlines, but the braking system has to keep pace. Even if you are not seeing the latest braking tech in your workshop today, you know it’s coming tomorrow. Directional brake pads As Graeme Ryder, technical development manager at Apec Braking explains, one of the key advances has been the introduction of directional brake pads: “Their primary purpose isn’t, as you might think, to increase stopping power, but to reduce noise, vibration and harshness (NVH) and improve the driving experience. “There are various types of directional brake pads, but they generally have either chamfers or shims which dictate how they’re fitted. Chamfers overcome the problem of traditional brake pads which can be pulled or grabbed by the disc when the brakes are applied. This can damage the pads, causing uneven wear and increasing NVH. Directional pads with a chamfer of up to 45° offer a transitional edge to the disc, to keep wear even and reduce noise. “Directional pads with shims have a half-moon or crescent cut-out on the shim, which allows the piston to push the pad against the disc at an angle. The angle has been determined to ensure even pad wear and the ideal distribution of force across the brake pad surface. This reduces the chances of the pad moving in the caliper, and so prevents noise.” Correct fitting Correct fitment is vital for any part, and directional brake pads are no different. Luckily, there is often some guidance on the part itself, as Graham explains: “Most directional pads have an arrow on the back, facing in the direction of disc rotation. “If there’s no arrow on the back of a chamfered pad and only one chamfer, fit it so the chamfer is at the leading edge, which contacts the brake disc first. If there are two chamfers of different sizes, the larger chamfer should be at the leading edge. “If a shimmed directional pad has no arrow on the back, the cut-out should be at the leading edge, i.e. where the pad first contacts the disc in the normal direction of travel.” It is vital that the instructions are followed when the pads are fitted says Graham: “If directional pads are fitted the wrong way round, the driver will experience noise and poor braking performance.” Graham adds: “Apec Braking offers a range of directional pads as direct replacements for OE equipment.” Legislation – R90 Technology is one thing, then there’s legislation on top of that. R90 has been a legal requirement for just over a year now, but it is worth being reminded what it is for. European Regulation R90 calls for brake linings to be tested for speed sensitivity and cold performance. Replacement brake pads and brake shoes are permitted to deviate from the frictional characteristics DON’T STOP – THINKING ABOUT TOMORROW Find out how technology and the impact of legislation is changing brakes in your workshop... If directional pads are fitted the wrong way around, the driver will experience noise and poor braking performance ” Below: Coated disc from Brembo Right: Pad with crescent