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Brake Fade

Kellys Hero

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Oct 21, 2017
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Hi
Been having some braking problems so replaced the pads etc. (no pipes disconnected) however I needed to pump the pedal about 50 times to get pedal back, brakes work fine on the initial use, but fade dramatically on the 2nd 3rd and continual use.
My initial thoughts are the pump, as the steering also seems slightly heavier !
Am I right in saying this pump serves both brake servo and steering?

I have tried the test of engine off, foot hard on the brake pedal and starting the engine, brake pedal moves to floor as vacuum is made.

Any suggestions please?
If it is a pump! are the refurbishment/rebuild kits available ?
 

frank rabbets

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Mar 1, 2010
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Brake fade is when there is no friction between the pad and disc and it feels like you have a brick under the pedal but the car does not slow down. There is no pump, only a vacuum servo, which is probably working if the pedal goes down on starting the engine.
Reading between your lines it sounds like you have a soft pedal which could only mean air in the system or maybe new pads not bedded in yet if the discs are badly scored. First of all is to bleed the brakes and eliminate any air in the system. Reservoir should be as full as possible throughout the procedure as it is possible for the master cylinder piston to suck air through low level as in sink hole.
Could well be a faulty master cylinder on the other hand. This would be confirmed if you keep getting new air in a bled system.
Be interesting to know what you find.
 

Towpack

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AFAIK the steering doesn't use vacuum from the pump. When starting the engine with the brake pedal pressed the pedal should go down slightly and not to the floor, according to the test procedure in the FSM.

1F5F4C43-5556-4F3C-8FF9-4F6C2E05F2A3.png
 

Jake the Peg

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Try a brake pipe clamp on your flexi hoses and see if isolating one caliper makes an improvement, work round all 4 calipers. is it safe to assume you haven’t got a brake fluid leak anywhere or have let the level in the master cylinder reservoir run low? Brake fluid should be a colourless liquid, if it’s black and nasty looking I’d suspect the seals in the master cylinder
 

chapel gate

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my money is on the master cylinder.
 
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Beastrider

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May 31, 2021
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Hi - If the pedal is initially hard, it’s probably bled ok. If it then sinks to the floor, the fluid has to be going somewhere. If there is no external leak, then it could be an internal leak inside the master cylinder. If so, the fluid will be bypassing the pressure seal and going back to the reservoir. When you release the pedal, the master cylinders takes back the ‘lost’ fluid and then the cycle repeats as you press the pedal again.
You might be able to see the reservoir fluid level rise as the pedal creeps to the floor although the level rise might be slight. You could mark the level carefully and see if it rises as the pedal sinks. A level rise would at least confirm an internal m/cyl leak. Good luck.
 
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