GM Service Manual Online
For 1990-2009 cars only

General Specifications

System

RPO Code

Caliper Housing Bore Diameter

Rotor

Diameter (nominal)

Rotor (On-Vehicle) Lateral Runout

Front Hub /Rear Axle Shaft Flange Lateral Runout

Front Wheel

JM3

--

267 mm (10.5 in)

0.08 mm (0.003 in)

--

JC1

--

274 mm (10.8 in)

0.08 mm (0.003 in)

--

Rear Wheel

JC1

48 mm (1.88 in)

295 mm (11.614 in)

0.10 mm (0.004 in)

0.05 mm (0.002 in)

*All brake rotors have a discard dimension cast into them. Replace any rotorthat does nopt meet this specification. After refinishing the rotor, replace any rotor

Rotor Thickness Specifications

System

RPO Code

Original

Thickness Variation

Minimum Thickness After Refinishing

Discard

Front Wheel

JM3

26.2 mm (1.03 in)

0.010 mm (0.0003 in)

24.89 mm (0.980 in)

24.51 mm (0.965 in)

JC1

29 mm (1.14 in)

0.010 mm (0.0003 in)

28.0 mm (1.10 in)

27.5 mm (1.08 in)

Rear Wheel

JC1

20.00 mm (0.787 in)

0.013 mm (0.0005 in)

19.64 mm (0.735 in)

18.50 mm (0.728 in)

* All brake rotors have a discard dimension cast into them. Replace any rotor that does not meet this specification. After refinishing the rotor, replace any rotor the does not meet the minimum thickness specification.