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Kawasaki's Kaneyo talks brakes

Kawasaki's Kaneyo talks brakes

Kawasaki's Kaneyo talks brakes

One of the most obvious differences between the bikes that Kawasaki produce for the road and their Ninja ZX-RR racer is that the MotoGP machine dispenses with the metal discs and sintered pads of the road bike's front braking system in favour of a set up that utilises carbon pads and discs.

There are a number of reasons why running a carbon braking system on your MotoGP racer is preferable to the traditional cast iron or steel items found on a road bike. For a start, carbon discs are reputed to be lighter than the iron or steel alternative. But just how much weight do you save by running an expensive carbon set-up on the front end of your bike? According to the Kawasaki Racing Team's technical coordinator, Naoya Kaneko, the weight saving is quite significant.

"A brand new steel disc weighs in at around 1.6kg, while the carbon equivalent tips the scales at around 800g, or half that of the steel item. So, with a twin disc system like the one we run on the Ninja ZX-RR, using carbon discs gives you a weight saving of 1.6kg at the front end of the bike."

"But it's not just the discs. Because they don't need a backing plate, the carbon pads are also marginally lighter than standard metal pads. It might not sound much, but it all adds up."

Lighter weight equals lower inertia, which in turn reduces the gyroscopic effect that counteracts the rider's efforts to get the bike to change direction. And the use of carbon discs definitely gives a noticeable difference.

Carbon discs also offer a slight improvement in both braking performance and consistency compared to metal items. With steel discs the feeling the rider has from the brakes over the course of a race changes, whereas the carbon system is more consistent and feels exactly the same to the rider at the end of the race as it did at the start: A big advantage over a 30-lap MotoGP race.

But carbon brakes also have their disadvantages.

Braking force is virtually nonexistent until the discs and pads reach their optimum operating temperature, which, depending on conditions, can be anywhere between 450 and 670°C. The pads and discs heat up quickly, but extra caution is definitely required during sighting and warm-up laps, as well as the first couple of corners in a race.

On faster tracks, where the brakes aren't used either regularly or heavily, the discs can be cooled considerably by airflow. To combat this loss of heat, some teams run shrouds at the front of the disc to improve the brake response in low ambient temperatures and/or on light braking circuits. The brake covers do not retain the heat in the brake as the carbon cools rapidly; they simply slow the cooling process down by flowing the air around the disc instead of over it.

But possibly the biggest disadvantage of carbon discs is that they don't work at all in the wet, as the discs cool too quickly when exposed to water. When a wet race is imminent the mechanics will replace the carbon fibre brake system with a conventional steel disc set up.

And this requirement to change from carbon to steel in wet conditions is causing teams some concern this season. The introduction of new rules to ensure flag-to-flag races, where riders will have to pit to change tyres and brakes should a dry race be interrupted by rain, means that this change from carbon to steel now needs to be achieved in a matter of seconds, as opposed to the ten or so minutes it took before.

The manufacturing process involved in producing carbon discs and pads is a closely guarded secret. It's a military thing. As well as cars and bikes, carbon-braking systems are used on high-tech, top-secret combat aircraft and, as such, the military are keen not to disclose details about the manufacturing process.

However, what is known about the process is that the blank material for the discs and pads (which are produced together) are manufactured using a carbon vapour deposit process in a special oven. The density of the carbon is fundamental to the performance and is carefully controlled during the manufacturing process.

To produce the densified carbon blank from which the discs and pads are machined takes approximately 12 weeks, which goes someway to explaining why carbon brake systems are so expensive - around €10,000 for the discs and pads alone!.

Tags:
MotoGP, 2005, Kawasaki Racing Team

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