Mistamist
Member
Registered: 16th Jul 03
Location: Gillingham, Kent
User status: Offline
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What causes this? had a bit of a scary moment earlier on the motorway, brakes faded really badly and pedal almost hit the floor?
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carnuts
Member
Registered: 28th Aug 05
Location: Hertfordshire
User status: Offline
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over heating normally mate
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corsa.v6
Member
Registered: 10th May 06
Location: in my caravan all over
User status: Offline
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i agree to its the standard
brakes
maybe need pads??????
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Mistamist
Member
Registered: 16th Jul 03
Location: Gillingham, Kent
User status: Offline
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anyone be a little more specific as to what causes it, the science behind it. i know its caused by overheating pads and disks just wondered why it happens.
pads are std jobbies at the moment, been on about 3 months.
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DarkBahamut
Member
Registered: 4th Jun 06
Location: Cambridge, Cambridgeshire
User status: Offline
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You say it happened on the motorway? Had you done alot of heavy high speed ish braking before this happened? If not and it happened out of the blue after motorway driving then it would be weird for your brakes to be overheating.
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CorsAsh
Member
Registered: 19th Apr 02
Location: Munich
User status: Offline
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quote:
What is brake fade and why does it occur?
Pad fade occurs for several reasons. All friction materials have a coefficient of friction curve over temperature. Friction materials have an optimal working temperature where the coefficient of friction is the highest. Sometimes you can use the brakes so hard that you get the temperature over the point of maximum friction to where the coefficient of friction curve starts to decline.
The mechanics of this decline in the coefficient of friction are varied. At a certain temperature, certain elements of the pad can melt or smear causing a lubrication effect, this is the classic glazed pad. Usually the organic binder resin starts to go first, then even the metallic elements of the friction material can start to melt. At really high temperatures the friction material starts to vaporize and the pad can sort of hydroplane on a boundary layer of vaporized metal and friction material which acts like a lubricant. Pad fade is felt as a car that still has a decent, non mushy feeling brake pedal that won't stop even if you are pushing as hard as you can. Usually it builds somewhat slowly giving you time to compensate for it, but some friction materials have a sudden drop off of friction when the heat is put on them resulting in sudden dangerous fade.
Green fade is a type of fade that manifests itself on brand new brake pads. Brake pads are usually made of different types of heat resistant materials bound together with a phenolic resin binder. These are thermosetting plastic resins with a high heat resistance. On a new brake pad, these resins will out-gas or cure when used hard on their first few heat cycles. The new pad can hydroplane on this layer of excreted gas. Green fade is dangerous because many people assume that new brakes are perfect and can be used hard right off the bat. Green fade typically will occur much earlier than normal fade so it can catch a driver that is used to a certain car's characteristics unaware. Typically the onset of green fade is rather sudden, further increasing the danger factor. Green fade can occur if you change the pads and drive on the street for a few hundred or even thousand miles, never braking hard, then suddenly start using the brakes hard.
[Edited on 10-07-2006 by CorsAsh]
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