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Common Brake Performance Questions
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Origin:HUACHI Co.
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Time:2007-10-8 10:08:00
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1. Temperature continuum & brake fade
A brake pad's comfort zone of operation is framed by the temperature range in which the pad is most effective. A great brake pad is a compound of materials, where individual elements of the mix are always effective at delivering friction regardless of the temperature; one material transitions into effectiveness while another material is fading away; all without the driver feeling any difference in the brake lever. When a brake pad starts to operate outside of its ideal temperature range, you can experience 'brake fade'.
There are three types of brake fade:
The first is the conventional burning off of resins as the pads are bedding in. This is known as 'green fade' and occurs when gases from burnt resins are trapped between the pads and discs. When this happens the pedal feels firm but the motorcycle will not stop. Ensure that you do not enter situations that require strong braking when the pads are newly fitted!
The second type of fade is when the pads are forced to work outside their temperature continuum. This can happen more easily when inadequate or inappropriate brake pads are fitted and leads to excessive wear and poor brake performance when you need it.
The third type of fade is 'glazing'. This is when the resins, which soften during active braking, then cool and solidify on the friction face of the pads. This glazed surface is hard and slick, and will not deliver the same level of friction as an unglazed pad.
2. Brake squealing
Don't blame the pads! Brake squeal is caused by vibrations between the pad and disc, usually because the pads cannot move freely back and forth in the calliper. When the vibrations are in an audible range, you hear a squeal-like sound because of the rotation of the system. Providing the calliper and the brake disc are not damaged and properly fitted, unlubricated metal-to-metal surfaces within the calliper or excessive dust /glazing are to blame.
3. A soft handle
You should be able feel clearly the bite point of the brakes when depressing the handle/foot lever. If the feel is soft or spongy, more likely than not it means that air has crept into the hydraulics or worse, the brake fluid has congealed. You should get a qualified mechanic to bleed the system and refill it with new brake fluid.
4. Pad taper
Pads often wear unevenly, usually with the front wearing first. This may be to do with alignment or faulty mounting of the disc and /or calliper, but the most common cause is that the front end of the brake pad tends to heat up more than the rear and as a consequence wears slightly faster. However, if the pads show a strong taper immediately seek the advice of a qualified mechanic.
5. Disc wear
Over time brake pads will carve a channel into the brake disc. This process is accelerated vastly by the use of budget brake pads (e.g. using low cost Sinter pads whose metallic structure is rough and acts like wire wool each time you brake), inappropriate brake pads for the disc type, or excessive grit embedded between the brake disc and pads. When a defined ridge has developed, brake discs must be renewed not least because the next set of brake pads will find it near impossible to bed in. Brake discs are expensive and it is worth insisting on high quality pads at every service and to keep the brakes clean especially during winter.
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