GM Service Manual Online
For 1990-2009 cars only

Component Specifications Dimensional

Application

Millimeters

Inches

Brake Rotor Surface Runout (On Refinishing Machine)

0.13

0.005

Brake Rotor Surface Runout (On Vehicle)

0.38

0.015

Lining to Rotor Maximum Clearance

0.13

0.005

Piston-to-Shoe Maximum Clearance

1.77

0.070

Replacement Lining Thickness

1.60

0.063

Rotor OD Runout

0.76

0.030

Rotor Thickness Variation

0.05

0.002

Component Specifications Brake Systems

System

Master Cylinder Diameter

Front Brakes (Disc)

Rear Brakes (Drum)

Rear Brakes (Disc)

Brake Assist

JB7

31.8 mm

1.25 in

318.8x39.3 mm

12.50×1.54 in

331.5x64 mm

13.00×2.5 in

--

Hydraulic Hydro-Boost

JB8

31.8 mm

1.25 in

318.8x39.3 mm

12.50×1.54 in

331.5x89.3 mm

13.00×3.50 in

--

Hydraulic Hydro-Boost

JF9

40.00 mm

1.57 in

357.0x36.7 mm

14.00×1.44 in

--

936.2x36.7 mm

13.60×1.44 in

Hydraulic Hydro-Boost

Component Specifications Rotor Thickness

Original

Maximum Refinish

Replacement (Discard)

32.51 mm (1.28 in)

31.25 mm (1.23 in)

30.86 mm (1.215 in)

39.11 mm (1.54 in)

37.59 mm (1.48 in)

37.21 mm (1.456 in)