GM Service Manual Online
For 1990-2009 cars only

Component Specifications Drum Diameters

Rear Brake Drum Diameters

Series

Original

Maximum Refinish

Discard Thickness

1500

283.21 mm (11.15 in)

330.20 mm (13.00 in)

285.49 mm (11.24 in)

2500 and 3500

330.20 mm (13.00 in)

331.72 mm (13.06 in)

332.48 mm (13.09 in)

Component Specifications Brake Systems

Brake Systems

Series

System

Front Brakes

Rear Brakes

Brake Assist

1500 (6100/7100 GVW) 2500 (7300 GVW)

JB6

Disc 11.57 x 1.25

Drum 11.15 x 2.75

Vacuum

2500 (8600 GVW)

JD7

Disc 12.50 x 1.26

Drum 13.00 x 2.50 (Diesel 13.00 x 3.50)

Hydraulic

3500 Single Wheel

JB8

Disc 12.50 x 1.26

Drum 13.00 x 3.50

Hydraulic

3500 Dual Wheel

JB8

Disc 12.50 x 1.50

Drum 13.00 x 3.50

Hydraulic