Mazda MX-5 Miata / Grand Touring. Manual — part 32

Fig. 27: Aligning Brake Pipe To Dual Proportioning Valve Marks
Courtesy of MAZDA MOTORS CORP.

DUAL PROPORTIONING VALVE INSPECTION

1. Connect the SSTs to the brake pipes as shown in Fig. 28 .

2. Bleed the air from the brake system and the SSTs . (Bleed the air from the SSTs through air bleeding

valve A.)

2008 Mazda MX-5 Miata Grand Touring

2008 BRAKES Conventional Brake System - MX-5 Miata

Fig. 28: Identifying Special Tools
Courtesy of MAZDA MOTORS CORP.

3. Measure the fluid pressure of the master cylinder and the rear brake.



If not within the specification, replace the dual proportioning valve.

2008 Mazda MX-5 Miata Grand Touring

2008 BRAKES Conventional Brake System - MX-5 Miata

Fig. 29: Dual Proportioning Valve Fluid Pressure Graph
Courtesy of MAZDA MOTORS CORP.

DUAL PROPORTIONING VALVE FLUID PRESSURE SPECIFICATIONS

FRONT BRAKE (DISC) INSPECTION

BRAKE JUDDER REPAIR HINTS

Description

1. Brake judder concern has the following 3 characteristics:

Steering Wheel Vibration

1. Steering wheel vibrates in the rotation direction. This characteristic is most noticeable when applying

brakes at a vehicle speed of 100-140 km/h {62.1-86.8 mph} .

Floor Vibration

MASTER CYLINDER PRESSURE (kPa

{kgf/cm

2

, psi})

REAR BRAKE PRESSURE (kPa {kgf/cm

2

,

psi})

A: 3,430 {34.98, 497.5}

A': 3,130 {31.92, 453.9} - 3,730 {38.04, 540.9}

B: 5,880 {59.96, 852.8}

B': 4,010 {40.9, 581.7} - 4,810 {49.05, 697.6}

2008 Mazda MX-5 Miata Grand Touring

2008 BRAKES Conventional Brake System - MX-5 Miata

1. When applying the brakes, the vehicle body shakes back and forth. The seriousness of the shaking is not

influenced by vehicle speed.

Brake Pedal Vibration

1. When applying brakes, a pulsating force tries to push the brake pad back. The pulsation is transmitted to

the brake pedal.

2. The following are the main possible causes of brake judder:

Due To An Excessive Runout (Side-To-Side Wobble) Of The Disc Plate, The Thickness Of The Disc Plate Is Uneven

1. If the runout is more than 0.05 mm {0.002 in} at the position 10 mm {0.39 in} from the disc plate edge,

uneven wear occurs on the disc plate because the pad contacts the plate unevenly.

2. If the runout is less than 0.05 mm {0.002 in} , uneven wear does not occur.

The Disc Plate Is Deformed By Heat

1. Repeated panic braking may raise the temperature in some portions of disc plate by approx. 1,000°C

{1,832°F} . This results in a deformed disc plate.

Due To Corrosion, The Thickness And Friction Coefficient Of Disc Plate Change

1. If a vehicle is parked in damp conditions for a long time, corrosion occurs on the friction surface of disc

plate.

2. The thickness of corrosion is uneven and sometimes appears like a wave pattern, which changes the

friction coefficient and causes a reaction force.

Inspection and Repair Procedure

2008 Mazda MX-5 Miata Grand Touring

2008 BRAKES Conventional Brake System - MX-5 Miata