Usage:
Old Style Master Cylinder
(1) High-pressure cup. (2) Retainer. (3) Primary spring. (4) Cup. (5) Secondary piston. (6) Cup. (7) Filler plug. (8) Gaskets. (9) Relief valve. (10) Gasket. (11) Filler plug. (12) Housing. (13) End plug. (14) Seat. (15) Check valve. (16) Spring. (17) Seal. (18) Gaskets. (19) Primary piston. (20) Secondary spring.
Disassemble Master Cylinder
NOTE: Before starting disassembly, obtain the repair kit for the master cylinder. The part number for the repair kit is located in the Parts Book for the machine.
1. Place the master cylinder in a vise in a horizontal position.
2. Remove filler plugs (7) and (11) from the master cylinder.
3. Discard both gaskets (8). These will be replaced with new parts during assembly.
4. Insert a wide screwdriver into the body of relief valve (9). Remove the relief valve by turning it counter-clockwise. Remove gasket (10) from inside the reservoir.
NOTE: If relief valve (9) seems stuck, position screwdriver on the relief valve and rap sharply with a hammer. This should loosen the relief valve for removal.
5. Discard relief valve (9) and gasket (10). These will be replaced with new parts during assembly.
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End plug (13) is under spring tension. Remove carefully in the following step to prevent injury from flying parts. |
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6. Remove end plug (13) from the master cylinder. Some internal parts should follow the end plug as it is removed.
7. Remove spring (16), check valve (15), and seat (14) from inside the end plug. Discard the spring, check valve, and seat. These will be replaced with new parts during assembly.
8. If primary piston (19) did not come out with the end plug, remove by prying away outside gasket (18) with a screwdriver.
9. Discard two gaskets (18) and one seal (17). These will be replaced with new parts during assembly.
10. Remove secondary spring (20) from inside housing (12).
11. Remove the remaining internal parts by pushing secondary piston (5) with a wooden dowel from the push rod end of the master cylinder.
12. Remove primary spring (3), retainer (2), and high-pressure cup (1) from end of primary piston (19) or from inside secondary piston (5).
13. Discard high-pressure cup (1). This will be replaced with a new part during assembly.
14. Remove cup (4) and cup (6) from secondary piston (5). Discard both cups. These will be replaced with new parts during assembly.
15. Thoroughly wash all parts to be reused in clean alcohol. Do not use petroleum products to clean master cylinder parts.
16. Check the cylinder bore for pitting, scoring, or corrosion. Make sure ports inside housing (12) are open.
17. If necessary, hone the cylinder bore lightly. Use brake fluid as a lubricant while honing. If the bore does not clean up readily, the entire master cylinder must be replaced with a new part.
18. Thoroughly wash housing (12) in alcohol after honing, to remove any contamination. Wipe the cylinder bore with a clean, lint-free cloth.
Assemble Master Cylinder
NOTE: Be sure to replace old parts with the new parts contained in the repair kit.
NOTE: Lubricate all rubber components with clean brake fluid before assembly.
1. Install new cups (4) and (6) onto secondary piston (5).
2. Install secondary piston (5) assembly into housing (12).
3. Install retainer (2) into the small end of primary spring (3). Note the correct direction of the retainer.
4. Insert primary spring (3), large end first, into secondary piston (5).
5. Set a new high-pressure cup (1) into place inside secondary piston (5). Note correct position of the cup.
6. Install secondary spring (20), small end first, over the primary piston assembly inside housing (12).
7. Set a new inside gasket (18) in place inside housing (12).
8. Install a new seat (14), new check valve (15), and new spring (16) inside end plug (13).
9. Push the secondary piston (5) assembly forward about 38 mm (1.5 in.) from the push rod end with a dowel rod. Hold the secondary piston in this position while primary piston (19) is installed, as follows:
a. Install primary piston (19) into housing (12) so that the base of the piston seats against inside gasket (18). The stem end of the piston must fit through high-pressure cup (1), into retainer (2).
b. Slowly release the force of the dowel rod against secondary piston (5). At the same time, apply pressure to the base of primary piston (19). This is necessary to prevent high-pressure cup (1) from moving out of position.
10. Insert a rod or screwdriver through the reservoir into the relief valve opening. Pry the tool sideways against primary piston (19) with enough force to prevent the assembled parts from moving out of position.
11. Install a new outside gasket (18) and a new seal (17) against primary piston (19).
12. Thread end plug (13) assembly into housing (12). Tighten the end plug to 68 to 108 N·m (50 to 80 lb. ft.).
13. Remove the rod or screwdriver from inside the reservoir.
14. Set a new gasket (10) inside the reservoir at the relief valve opening.
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Do not turn the adjusting screw on relief valve (9). This would change the relief setting, and could prevent the master cylinder from operating correctly. |
15. Thread a new relief valve (9) into place inside the reservoir. Use the slots in the relief valve body to tighten the relief valve to 20 to 27 N·m (15 to 20 lb. ft.).
16. Install two new gaskets (8) on top of the reservoir. Thread filler plugs (7) and (11) into place.