Master cylinder - removal, overhaul and refitting
Removal
1 Syphon out as much fluid as possible from the master cylinder reservoir using an old battery hydrometer or a poultry baster. Do not drip the fluid onto the paintwork or it will act as an effective paint stripper.
2 Disconnect the pipelines from the master cylinder by unscrewing the unions.
Master cylinder and hydraulic pipe connections
3 Disconnect the leads from the level warning switch in the reservoir cap. Remove the cap.
4 On models not fitted with a brake servo unit, unclip and remove the trim panel beneath the facia on the driver’s side to give access to the brake pedal. Extract the brake pedal-to-pushrod clevis pin retaining clip and withdraw the pin.
5 Unbolt and remove the master cylinder. On non-servo models, remove the cylinder from the bulkhead whilst, on servo equipped models, the master cylinder is removed from the servo unit.
Overhaul
1.4 litre and XR2 models from early 1986
6 From the beginning of 1986, all XR2 models and 1.4 litre models are fitted with a brake master cylinder of a new design. The new master cylinder is identifiable by its small size and its smooth cylinder body appearance.
Exploded view of master cylinder - XR2 and 1.4 litre models, early 1986 on
A Secondary piston seals
B Secondary piston
C Protecting ring
D Seal support ring
E Return springs
F Retaining ring
G O-ring seal
H Reservoir seals
J Primary piston
K Support ring
L Cap seal
M Primary piston fluid housing
7 The overhaul procedure is as follows:
8 With the master cylinder removed from the car, drain the remaining brake fluid from the reservoir, then remove the reservoir from the cylinder body.
9 Using a screwdriver, lever off the primary piston fluid housing
Levering off the primary piston fluid housing
and withdraw the fluid housing and primary piston assembly from the master cylinder. Be prepared for some fluid spillage during this operation.
10 Separate the primary piston from the fluid housing and remove the fluid housing seal.
11 Tap the master cylinder on a block of wood to eject the secondary piston, then remove the secondary piston assembly from the master cylinder.
12 Prise off the fluid housing retaining ring and remove the O-ring seal from the cylinder body.
13 Extract the two reservoir seals from the master cylinder ports.
14 Carefully remove the two secondary piston return springs, the seal support ring, seal protecting ring and the fluid seals from each end of the piston.
15 Examine the cylinder bore for signs of scoring or wear ridges. If evident renew the master cylinder. If the cylinder appears satisfactory, obtain a repair kit which will contain new secondary piston and cylinder body seals and a complete new primary piston assembly.
16 Lubricate all the seals, the cylinder bore and the pistons with clean brake fluid, then reassemble as follows.
17 Refit the seals, support ring, protecting ring and springs to the secondary piston, then carefully insert the assembled piston into the master cylinder bore.
18 Fit the two new reservoir seals to the cylinder ports.
19 Fit a new seal to the fluid housing and fit the primary piston to the housing.
20 Fit a new O-ring to the end of the cylinder body, followed by the fluid housing retaining ring.
21 Carefully assemble the primary piston and fluid housing to the master cylinder, pushing the piston and housing in until the fluid housing is flush with the cylinder mounting flange.
22 Refit the master cylinder reservoir.
All other models
23 To overhaul the master cylinder fitted to these models, first clean away external dirt and then detach the fluid reservoir by tilting it sideways and gently pulling. Remove the two rubber seals.
24 Secure the master cylinder carefully in a vice fitted with jaw protectors.
25 Pull the dust excluder back from around the pushrod and using circlip pliers, extract the circlip which is now exposed.
26 Remove the pushrod, dust excluder and washer.
27 Withdraw the primary piston assembly, which will already have been partially ejected.
Master cylinder primary (A) and secondary (B) piston assemblies
28 Using a small diameter rod, insert it into the end of the cylinder and push the secondary piston in so that the locking pin can be extracted.
Master cylinder secondary piston stop pin
29 Tap the end of the master cylinder on a block of wood and eject the secondary piston assembly.
30 Examine the pistons and cylinder bore surfaces for scoring or signs of metal-to-metal rubbing. If evident, renew the cylinder complete.
31 The primary piston unit cannot be dismantled and must be renewed as a unit.
32 Prise free and remove the secondary piston seals, noting their orientation. Once removed the seals must be discarded and a repair kit obtained for their renewal.
33 Cleaning of components should be done in brake hydraulic fluid or methylated spirit only - nothing else.
34 Using the new seals from the repair kit, assemble the secondary piston, making sure that the seal lips are the correct way round, as noted during dismantling.
35 Dip the piston assemblies in clean hydraulic fluid and fit them to the cylinder bore.
36 Fit the pushrod complete with new dust excluder and secure with a new circlip.
37 Engage the dust excluder with the master cylinder.
38 Depress the pushrod and locate the secondary piston lockpin.
39 Locate the two rubber seals and push the fluid reservoir into position.
40 It is recommended that a small quantity of fluid is now poured into the reservoir and the pushrod operated several times to prime it.
Refitting
41 Refit the master cylinder by reversing the removal operations.
42 Do not overtighten the hydraulic line unions and take care that they are clean and not crossthreaded when reconnecting. Refer to the specifications for the torque wrench setting.
43 Bleed the complete hydraulic system on completion of the work.