1994-2002 [Subscribe to Daily Digest] |
Hmmm...I'm not certain how they can just make a statement saying "master cylinder is fine". I could be wrong, but I don't think it can be fully tested in the car. Here is the description of the master cylinder operation when the pedal is pushed from the owner's manual. Master cylinder failure will result in long pedal travel.
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Servo pressure:
When the brake pedal is depressed, the primary piston is pressed forward by the pushrod.
The return passage to the brake fluid reservoir closes and the pressure in front of the primary piston increases. The pressure also affects the secondary piston, which is pushed forward and its return passage is also closed by the central valve. The hydraulic pressure in the two brake circuits increases and, since the area of the pistons are the same, the pressure will be the same in both brake circuits. The pressure propagates throughout the brake system and affects the brake piston in each brake caliper. The brake pistons press the brake pads against the brake discs.
When the pedal is released, the pistons in the master cylinder are returned, opening the return passages. The pressure ceases and the piston in each brake cylinder takes up its rest position with the aid of the piston ring.
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Main cylinder, brake applied (one circuit inoperative):
When the brake pedal is depressed and a leak has occurred in the primary circuit, for example, the primary piston is pressed forward by the pushrod until it acts mechanically on the secondary piston. The secondary piston closes the return passage with the central valve and hydraulic pressure builds up in the secondary circuit only.
If their is a leak in the secondary circuit, the secondary piston is pushed forward and will bottom in the master cylinder. In both these cases, a longer pedal travel will be required to obtain the desired braking power.
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I hope that helps!
posted by 167.6.247...
, Mon, 25 Jan 2010 14:01:40, Thu, 28 Jan 2010 14:21:48, Thu, 28 Jan 2010 14:24:23, Fri, 29 Jan 2010 06:46:51
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