The master cylinder is designed for a brake system with low drag calipers. In addition to the standard master cylinder functions, systems with a vacuum booster include a quick take-up feature. The quick take-up feature provides a large volume of low pressure brake fluid to the wheels upon the initial brake application. The large volume of brake fluid overcomes the clearance created by the retracted brake caliper pistons.
Reservoir And Cover
The reservoir and cover are made of plastic. The cover snaps onto the top of the reservoir. A seal, located between the cover and reservoir, keeps contaminants out of the brake fluid.
Keep the master cylinder reservoir properly filled with brake fluid. This ensures adequate reserve brake fluid and prevents air from entering the hydraulic system. Do not over fill the reservoir. The brake fluid absorbs heat from the brakes, and expands. An over-filled reservoir cannot allow fluid expansion.
Master Cylinder Identification
Identifying information is stamped into the master cylinder.
A Delphi master cylinder has the following information stamped into the front surface:
| • | The first two digits are the build code. |
| • | The third digit indicates the year the master cylinder was built (Example: 5 means 1995). |
| • | The last digits indicate the day the master cylinder was built (Example: 271 means the 271st day of the production year). |
