2007 Wrangler JK Factory Service Manual 5 - BRAKES

MASTER CYLINDER

DESCRIPTION

The master cylinder has a removable plastic reservoir. The cylinder body is made of aluminum and contains a primary and secondary piston assembly. The cylinder body including the piston assemblies are not serviceable. If diagnosis indicates an internal problem with the cylinder body, it must be replaced as an assembly. The reservoir and grommets are the only replaceable parts on the master cylinder.

OPERATION

The master cylinder bore contains a primary and secondary piston. The primary piston supplies hydraulic pressure to the front brakes. The secondary piston supplies hydraulic pressure to the rear brakes. The master cylinder reservoir stores reserve brake fluid for the hydraulic brake circuits.

REMOVAL




1. Siphon and drain the fluid from the reservoir (2).
2. Disconnect the fluid level electrical connector (3) from the reservoir (2).
3. Remove the brake lines (4) at the master cylinder.
4. Remove mounting nuts (5) from the master cylinder.



5. Remove master cylinder.
6. Remove cylinder cover and drain the rest of the fluid.
7. If master cylinder reservoir requires service,
(Refer to 5 - BRAKES/HYDRAULIC/MECHANICAL/FLUID RESERVOIR - REMOVAL).

INSTALLATION



NOTE: If master cylinder is replaced, bleed cylinder before installation.




1. Clean cylinder mounting surface of brake booster (3).

NOTE: Insure the O-ring is on the master cylinder at the booster interface.


2. Install master cylinder onto brake booster studs (4).



3. Install mounting nuts (5) and tighten to 17 N·m (151 in. lbs.).
4. Connect the brake lines (4) to the master cylinder and tighten to 19 N·m (168 in. lbs.).
5. Connect fluid level electrical connector (3) to the reservoir (2).
6. Fill and bleed base brake system,
(Refer to 5 - BRAKES - STANDARD PROCEDURE).