You will need a key "on 10".
The pressure regulator prevents the rear wheels from locking before the front wheels lock. This allows you to make the most of the braking capabilities of the car and prevent it from skidding.
Repair or replace the failed pressure regulator assembly.
1. From the pressure regulator, unscrew the tip of the brake pipe going to the rear left wheel.
2. Unscrew the tips of the other three tubes from the regulator.
3. Disconnect the tubes from the pressure regulator. Plug the holes in the pipes.
4. Loosen the two nuts securing the regulator.
5. Please note: spring washers are installed under the nuts.
6. Remove the regulator from the studs. Install the regulator in the reverse order of removal. Bleed the hydraulic brakes.