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brake systems

  • Pautan angkup brek radial menjadi pilihan ramai pada hari ini.
  • Namun, pautan axial yang ‘normal’ masih lagi boleh dijumpai.
  • Apakah kelebihannya memaut angkup secara radial?

(more…)

  • Radial brake caliper mounting is all the rage nowadays.

  • But the “normal” axial-mounting is still present.

  • What are the benefits of mounting the caliper radially?

To rehash, we’ve seen the basic principles of the brake system in Part 1, about how the pressure from your fingers is transferred into fluid pressure, resulting in braking force.

Brake System: How it Works (Part 1)

Next, we took a look at how the ABS system works in Part 2, in order to allow for maximum braking force while avoiding the wheels from locking up.

Brake System: How it Works (Part 2 – ABS)

Continuing the series, we also checked out tips on how to choose the correct brake pads for your bike in Part 3.

Brake Systems (Part 3): Padding Your Brakes

Therefore, let’s now examine the methods of mounting the front brake caliper to the motorcycle, or more specifically, about the radial mounting arrangement that’s all the rage these days. Yes, so popular they are that even lowlife thieves couldn’t resist them.

Axial master cylinder

One, the traditional type is the “axial” master cylinder, found on almost all motorcycles with front hydraulic brakes from small to large.

In this arrangement, the master cylinder’s bore is perpendicular to the lever’s travel, seemingly elongated to the left side viewed from the top. A protrusion on the end of the lever pushes the plunger in cylinder, forcing brake fluid into the calipers.

Radial master pump

The second and more recent type is the radial master cylinder. The master cylinder’s bore is parallel to the brake lever’s movement, looking more directly fore-and-aft when viewed from the top.

What’s the difference between the two? Other than a different type of piston movement, the radial master cylinder provides a better feel at the lever for what the brake is doing. The radial master cylinder is more rigid as there are fewer moving parts.

Axial-mount calipers

With the advent of radially-mounted brake calipers, this format has gone on to be called the “normal mounting.” The caliper is mounted to “bosses” cast into a fork’s bottom tube, with bolts that run parallel to the wheel axle.

There isn’t anything wrong with this type of mounting. However, custom brackets need to be fabricated should one want to install a larger brake disc. Other than that, there may exist a little torsional flex for lateral movement, although it’s hardly perceptible when ridden on the streets.

Radial-mount calipers

In this setup, the caliper is still mounted to bosses cast into the lower fork legs. However, the bosses are cast to allow bolts to be fitted directly from the rear, instead of from the side, and perpendicular to the wheel axle.

Being mounted this way means there is virtually no deflection because the braking forces are on the same plane as the brake disc’s rotational forces.

What are the benefits of radially-mount calipers?

First and foremost, being mounted from the rear means all the rider needs to do is install spacers and longer bolts when switching to a larger disc, instead of having to custom make a mounting bracket.

Picture from MotorMadMan

There is a myth surrounding radially-mounted calipers as having more braking power. Want us to be honest?

As we highlighted in Part 1, “brake power” is defined by the amplification of brake fluid pressure, in relation to the size of the master pump’s piston and caliper pistons’ sizes.

What radial mounting does though, with the lack of deflection, provides for a crisper feel when braking, i.e. better braking feedback, and in turn allowing for better modulation of the front brake.

Where it’s usually more important for the track than the streets.

  • There are different brake pad compounds available in the market.

  • Each provides a different braking feel.

  • Find a type that suits your riding style and use of the motorcycle.

Brake pads are often overlooked for the majority of riders, “Hey as long as it stops, no problem.” Or we just ride replace the pads when the mechanic tells us that it’s time do so. It’s almost like we have no choice in it, except when it comes to paying, “Brape? (How much?)”

Perhaps, it doesn’t have to be so with a little more understanding, then we could dictate on what we actually need, instead of being led by the nose.

Brake Pad Friction Rating

Before we go further, be aware that there are two current friction ratings for brake pads, GH and HH.

Both those letters signify the brake pad’s coefficient of friction (CoF); the first being the CoF at normal working temperature, and the second at an extreme temperature of 650 oF (343 oC). Therefore, the ratings indicate how much friction is there at certain operating temperatures. The G-rating offers between 0.45 and 0.55, while the H-rating’s CoF is from 0.55 and up. These ratings are usually stamped on the outside of the pad’s back plate, although there are manufacturers who don’t do so but specify it on the brake pads’ packing, instead.

Brake Pad Material

Having the right type of pad material determines how it feels when the brakes are applied and how it stops a bike.

Organic

Organic pads may sound like they’re something grown without chemicals, it just means they don’t contain metal. Instead, they’re a blend of rubber, glass, carbon, aramid, Kevlar (the real contents differ among manufacturers), bonded by a resin.

Organic pads are popular among riders due to their progressive braking feel, which doesn’t “bite” aggressively. Additionally, it’s softer and doesn’t score brake discs. However, they typically wear out faster due to being soft.

Sintered

The pad material, usually copper particles, is fused to the backing plate under extreme pressure and temperature (the process is called “sintering”) to form a friction material that’s wear resistant. They can handle a wide range of conditions, hence well-suited for any type of riding including trackdays.

Sintered pads offer a stable CoF whether cold or hot, and they bite instantly. Apart from that, they are resistant to fade, perform well in the rain or mud, and usually last longer.

However, the do wear brake discs quickly. Most, if not all, motorcycles use the harder stainless steel brake discs these days. However, if you encounter deep grooves or “blueing” on your discs, you may have to consider replacing your brake pads for those of less aggressive material.

Semi-Metallic/Semi-Sintered

Manufacturers infuse organic pads with some metal material to increase the bite, durability and fade-resistance, while still maintaining the progressive feel and low disc-wear of the organic brake pads. This may be a good compromise for most riders.

Ceramic Composite

They are made by fusing high-strength ceramic fibres and ductile non-ferrous (non-iron) metal filaments at extreme pressures and heat. The metal filaments provide the initial bite while the ceramic compound provides high temperature resistance to avoid brake fade.

Besides that, the metal filaments carry away heat quickly to reduce rotor wear and deformation (disc warp).

Notes

  1. First and foremost, you should not use any brake pad which or brake lining that contains asbestos. It has been established decades ago that asbestos is carcinogenic and could cause lung cancer should you inhale the asbestos dust. Although the use of asbestos has been banned you may still encounter it in some ultra-cheap drum brake linings.
  2. If you’re replacing your brake pads for daily use, please select “STREET” or “ROAD” varieties. Racing brake pads do bite but they may have to reach a certain operating temperature to provide optimum braking.
  3. Take some time to “bed in” the new pads (usually 300 to 500 km). They need time to conform to the irregularities of your brake discs, and will not grip at their maximum when new. So keep that in mind when riding away with a new set.

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