Know why brake discs are so important.
Brake discs are one of the most important parts in keeping you lot stopping safely, braking later, and consequently going faster. With this in mind, we caught up with Adam from Brembo importers Bike Torque Racing to learn a bit more about the humble brake disc...
FB: What is the purpose of a brake disc?
AJ: To stop you! It is the disc attached to the wheel, which works with the braking system to give you stopping power. They took over from the good old fashioned drum brakes and there’s a wide range of discs offering different levels of performance.
FB: How does a brake disc work?
AJ: In layman’s terms, when you squeeze the brakes, it sends hydraulic force down through the brake lines into the caliper, causing the brake pads to squeeze together. As the disc is connected to the wheel and turns with it, when the pads and disc come into contact, the friction works to slow the disc, slowing the wheel.
FB: What are the advantages of aftermarket discs?
AJ: Brembo make them 5mm thick, rather than 4.5mm like on most OE discs, which gives a better heat range. It also depends on the manufacture, as most OE discs are reasonably good, dependant on the quality of the steel. You have to remember though, no standard disc will be as good as aftermarket ones; after all Brembo discs are designed as an upgrade. As an example, Brembo materials are specifically created to a certain formula for your requirements rather than being the cheapest stuff you can buy, with a high iron and carbon content. This makes the discs more grippy and the friction more effective, which increases braking power, while they are thicker to handle the heat a lot better, staying within a bigger operational range under high stress.
FB: And what’s a floating disc?
AJ: It basically means that the disc is constructed in two parts, with a fixed centre section attached to the wheel and the outer rotor section that engages with the brake pads. Due to the friction a brake disc encounters serious amounts of heat, leading the metal to expand, and by allowing the outer to float separately from the mount, it can then expand and shrink without constraint, meaning the disc won’t be able to warp. For racing, using floating and semi-floating discs will be hugely beneficial, and they will also help out if you’re an incredibly fast road and trackday rider as well. Funnily enough, for the roads Brembo have a disc called the Serie Oro, which has special anti-vibration washers meaning you can use them on the road and track with the floating tendencies, but you don’t get the noise of the rattle like on the top spec racing discs.
FB: How much different are road- based discs to full- on race discs?
AJ: Realistically, with the race product it’s all about performance, whereas the road products are built for quality, performance and also practicality in mind. At the end of the day the discs are serving a different purpose, so on the Brembo HPK race discs the bobbins are rebuildable and vibrate a fair amount, while being slightly thicker to disperse the heat even more. This compares to a quiet, thinner road-going disc that is cheaper, creates less noise but won’t handle the heat as well.
FB: Is it easy to tell the difference between the discs if you were putting them back to back? AJ: Of course, it depends on the level of the rider and the performance of the bike, but yes
you should be able to tell the difference straight away. For starters the quality of the steel will give a much greater fiction co-efficiency and so improve the braking power, while offering better heat dispersion for a wider operating window. Essentially, if you were to put the Serie Oro discs on from standard, you should be able to feel a better bite under heavy braking and be able to use the brakes more intensely, effectively for longer. This is even more obvious if you use a larger disc conversion kit for a bigger diameter disc, which will offer much more braking power thanks to it giving bigger leverage.
FB: What’s the score with wavy discs?
AJ: Although they look nice, heavily-cut wave discs warp at a lower temperature than conventional discs due to the fact that there is less metal and less surface area for heat dissipation. There’s a slight offset in well-designed wavy discs as they create more turbulence and airflow to cool the discs, but Brembo spent a huge amount of money trying to develop a high-performance wavy disc when they came in to fashion. They abandoned the whole project as they just couldn’t make them as effective, and as Brembo are a fiercely technical company, they would not sell a product that’s inferior.
FB: What problems do you get with discs?
AJ: One of the main problems we hear about is having warped discs – although most of the time the disc isn’t actually warped.
There’s so much misinformation surrounding brake issues and discs warp when the operating temperature rises, so much so that the material will distort, and on the road it’s hard to do. A lot of the time it can be something silly like people just leaving their bike over winter somewhere moist, as if you have sintered pads and iron brake discs, the moisture can cause the pad and disc to corrode – creating a pad-like mark on the disc that will create a judder under braking. You also need to take into account that brake discs are fairly fragile, so make sure they’re taken care off in transit.
Easy on the anchors, Marquez. Honda aren’t made of money.
Charlie loves performing the ‘nutt cracker’.