Mazda MX-5 Miata / Grand Touring. Manual — part 35

Fig. 37: Exploded View Of Caliper (Front) (With Torque Specifications)
Courtesy of MAZDA MOTORS CORP.

2. Assemble in the reverse order of disassembly.

PISTON DISASSEMBLY NOTE

1. Insert a piece of wood in the caliper as shown in Fig. 38 , and then blow compressed air through the

bleeder screw hole to remove the piston from the caliper body.

Fig. 38: Removing Piston From Caliper Body By Blowing Compressed Air Through Bleeder Screw
Hole
Courtesy of MAZDA MOTORS CORP.

REAR BRAKE (DISC) INSPECTION

BRAKE JUDDER REPAIR HINTS

Description

CAUTION:



The piston could be damaged if blown out with great force. Blow the
compressed air slowly to prevent the piston from suddenly popping
out.

2008 Mazda MX-5 Miata Grand Touring

2008 BRAKES Conventional Brake System - MX-5 Miata

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

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

Fig. 39: Rear Brake Inspection & Repair Flow Procedure
Courtesy of MAZDA MOTORS CORP.

Lateral Runout Inspection

1. To secure the disc plate and the hub, insert the washer (thickness 10 mm {0.39 in} , inner diameter more

than 12 mm {0.47 in} ) between each hub bolt and the hub nut, then tighten all the hub nuts.

2. After tightening all the hub nuts to the same torque, put the dial gauge on the friction surface of disc plate

10 mm {0.39 in} from the disc plate edge.

3. Rotate the disc plate one time and measure the runout.

Rear disc plate runout limit

0.05 mm {0.002 in}

NOTE:



The component parts of the SST (49 B017 001 or 49 G019 003) can be
used as a suitable washer.

2008 Mazda MX-5 Miata Grand Touring

2008 BRAKES Conventional Brake System - MX-5 Miata

Fig. 40: Measuring Rear Disc Plate Runout
Courtesy of MAZDA MOTORS CORP.

Thickness Variation Inspection

1. Clean the disc plate-to-pad friction surface using a brake cleaner.

2. Measure the points indicated in Fig. 41 using a caliper (micrometer).

3. Subtract the minimum value from the maximum, and if the result is not within specification, machine the

disc plate using a lathe.

Thickness variation limit

0.015 mm {0.00059 in}

WARNING:



Do not exceed minimum disc plate thickness.

2008 Mazda MX-5 Miata Grand Touring

2008 BRAKES Conventional Brake System - MX-5 Miata