Section No. EEE.1


For all other service and repair procedures see Section E.

Section EEE. 1



The master cylinder consists of an alloy body with a polished bore to which are connected the fluid inlet and outlet ports. The fluid reservoir is connected to the inlet port at the end of the cylinder by a length of steel pipe. Connected to the outlet port in the top of the cylinder body is the pressure pipe to the clutch slave cylinder. The inner assembly is made up of the push rod, dished washer, circlip, plunger, plunger seal, end seal, spring thimble, plunger return spring, valve spacer, spring washer, valve stem and valve seal. The open end of the cylinder is protected by a rubber dust cover.

Dismantling the Clutch Master Cylinder

  1. Release the master cylinder push rod from the clutch pedal as described in Section E.4.
  2. Disconnect the inlet and pressure pipe unions from the cylinder and remove the securing bolts, then withdraw the master cylinder.
  3. Drain the fluid from the cylinder. Pull back the rubber dust cover and remove the circlip with a pair of long nosed pliers. The push rod and dished washer can then be removed.
  4. When the push rod has been removed the plunger with seal attached will be exposed; remove the plunger assembly complete. The assembly can be separated by lifting the thimble leaf over the shouldered end of the plunger (Fig. E.1).
  5. Depress the plunger return spring and allow the valve stem to slide through the elongated hole of the thimble thus releasing the tension on the spring.
  6. Remove the thimble, spring and valve complete.
  7. Detach the valve spacer taking care not to lose the spacer spring washer located under the valve head. Remove the seal.
  8. Examine all parts, especially the seals, for wear or distortion and replace with new parts where necessary.

Assembling the Clutch Master Cylinder

  1. Replace the valve seal so that the flat side is correctly seated on the valve head.
  2. Locate the spring washer with the domed side against the underside of the valve head, and hold it in position with the valve spacer, the legs of which should face towards the valve seal. (Fig. E.5).

Fig EEE.1 Components of the master cylinder
Fig EEE.1 Components of the master cylinder

  1. Replace the plunger return spring centrally in the spacer, insert the thimble into the spring and depress until the valve stem engages through the elongated hole of the thimble, making sure the stem is correctly located in the centre of the thimble. Check that the spring is still central on the spacer.
  2. Refit a new plunger seal with the flat of the seal seated against the face of the plunger. Insert the reduced end of the plunger into the thimble until the thimble leaf engages under the shoulder of the plunger. Press home the thimble leaf.
  3. Smear the assembly with Girling red rubber grease or with the recommended hydraulic fluid. Insert the assembly into the bore of the cylinder, valve end first, easing the plunger seal lips into the bore.
  4. Replace the push rod in the cylinder with the dished side of the washer under the spherical head, followed by the circlip which engages in the groove machined in the cylinder body.
  5. Replace the rubber dust cover and refit the whole unit into its aperture in the scuttle, not forgetting to fit the packing washer first. Secure the unit by means of the two bolts on the flange and refit the pressure pipe and inlet pipe unions to the cylinder.
  6. Reconnect the push rod fork with its corresponding hole in the brake pedal lever, securing it with the clevis pin.
  7. Bleed the hydraulic system.