Chevrolet Cobalt Service & Repair Manual: Brake Rotor, Reface

Chevrolet Cobalt Service & Repair Manual / Brakes / General Procedures / Brake Rotor, Reface

Warning: Avoid taking the following actions when you service wheel brake components: Do not grind brake linings. Do not sand brake linings. Do not clean wheel brake components with a dry brush or with compressed air. Some models or aftermarket brake components may contain asbestos fibers which can become airborne in dust. Breathing dust with asbestos fibers may cause serious bodily harm. Use a water dampened cloth in order to remove any dust on brake components. Equipment is available commercially in order to perform this washing function. These wet methods prevent fibers from becoming airborne.

The disc brake rotors do not require refinishing as part of routine brake system service. New disc brake rotors do not require refinishing. Do not refinish disc brake rotors in an attempt to correct the following conditions: Brake system noise, squeal, growl and groan. Uneven and/or premature disc brake pad wear. Superficial or cosmetic corrosion/rust of the disc brake rotor friction surface. Scoring of the disc brake rotor friction surface less than the maximum allowable specification.

Before refinishing a brake rotor, the rotor must first be inspected for adequate thickness to allow the rotor to be refinished, and remain above the minimum allowable thickness after refinish specification. Refer to manufacturers brake rotor thickness measurement. Disc brake rotors should only be refinished if they have adequate thickness to be refinished. Discard if one or more of the following conditions exist: Thickness variation in excess of the maximum allowable specification. Excessive corrosion/rust and/or pitting. Cracks and/or heat spots. Excessive blueing discoloration. Scoring of the disc brake rotor surface in excess of the maximum allowable specification.

Disc brake rotors may need to be refinished as part of the process for correcting brake rotor assembled lateral runout (LRO) that exceeds the maximum allowable specification.

If the vehicle is equipped with cross drilled rotors, use a lathe with positive rake tooling. This setup requires less cutting pressure, which will result in less vibration, and a better surface finish. Also, use a vibration dampener when cutting. Otherwise, refinish according to the following instructions.

Whenever the brake rotor has been separated from the hub/axle flange, clean any rust or contaminants from the hub/axle flange and the brake rotor mating surfaces. Failure to do this may result in increased assembled lateral runout (LRO) of the brake rotor, which could lead to brake pulsation.

Thoroughly cleaning the brake rotor will prevent the possible transfer of finite metal dust left as a by-product of machining to the brake pad material during the burnishing process, thereby reducing the possibility for brake squeal or other brake noises to occur.

1.	Thoroughly clean any rust or corrosion from mating surface of hub/axle flange using Wheel Hub Resurfacing Kit tool No. CH-42450-A, or equivalent.

2.	Thoroughly clean any rust or corrosion from mating surface and mounting surface of brake rotor using Rotor Resurfacing Kit tool No.CH-41013, or equivalent.

3.	Inspect mating surfaces of hub/axle flange and rotor to ensure that there are no foreign particles or debris remaining.

4.	Mount brake rotor to brake lathe according to lathe manufacturers instructions, ensuring that all mounting attachments and adapters are clean and free of debris.

5.	Ensure that any vibration dampening attachments are securely in place.

6.	With brake lathe running, slowly bring in cutting tools until they just contact brake rotor friction surfaces.

7.	Inspect witness mark on brake rotor. If witness mark extends approximately 3/4 or more of way around brake rotor friction surface on each side, brake rotor is properly mounted to lathe.

8.	If witness mark does not extend 3/4 or more of way around brake rotor, mount rotor to lathe.

9.	Refinish brake rotor following brake lathe manufacturers instructions.

10.	After each successive cut, inspect brake rotor thickness. Refer to manufacturers brake rotor thickness measurement.

11.	If at any time brake rotor exceeds minimum allowable thickness after refinish specification, brake rotor must be replaced.

12.	After refinishing brake rotor, obtain desired non-directional finish as follows:

Follow brake lathe manufacturers recommended speed setting for applying a non-directional finish.

If lathe is equipped with a non-directional finishing tool, apply finish with 120 grit aluminum oxide sandpaper, using moderate pressure.

If lathe is not equipped with a non-directional finishing tool, apply finish with a sanding block and 150 grit aluminum oxide sandpaper, using moderate pressure.

After applying a non-directional finish, clean each friction surface of brake rotor with a solution of mild dish washing detergent and water, or a suitable brake cleaner and a clean shop towel, to remove metal particles remaining from machining. Repeat cleaning process, if required, to remove all metal particles.

13.	Remove brake rotor from brake lathe.

14.	Measure assembled LRO of brake rotor to ensure optimum performance of disc brakes. Refer to manufacturers brake rotor assembled lateral runout measurement.

15.	If brake rotor assembled LRO measurement exceeds specification, bring LRO to within specifications. Refer to manufacturers brake rotor assembled lateral runout correction.

Brake Rotor Deglaze

Caution: Whenever the brake rotor has been separated from the wheel bearing flange, clean any rust or foreign material from the mating surface of the rotor and flange with a suitabl ...

Brake System, Inspection

A visual inspection must always be performed to confirm the presence of aftermarket components, potential collision damage, or areas of concern. Always clean all brake syst ...

Chevrolet Cobalt Service & Repair Manual: Brake Rotor, Reface

Brake Rotor Deglaze

Brake System, Inspection

See also:

Chevrolet Cobalt Owners Manual

Chevrolet Cobalt Service Manual