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5-80
Disc Brakes
In order to correct brake pulsation, refinish the rotors
using an on-vehicle brake lathe. Follow the equipment
manufacturer's recommended specifications and
procedure.
Important: Remove any rust and scale from the rotor
and spindle hub mating surfaces. Failure to do so
may introduce excessive lateral runout when the rotor
is mounted on the brake lathe, or when the rotor is
reinstalled on the spindle hub.
The following two procedures are recommended and
achieve adequate results using two different
off-vehicle disc brake lathes. If any other lathe is used,
follow that lathe's instructions and recommendations:
Accu Turn® Brake lathe
1. Locate the deepest score and turn the rotor
micrometer knob until the tool bit bottoms out
at the deepest point of the score.
2. Zero the scale and back out the tool bit.
3. Advance the cutter handwheel until the bits have
cleared the inner edges of the rotor face.
4. Adjust the micrometer knobs for approximately
0.127 mm (0.005 in) more than the first reading.
Use this method in order to resurface the
rotor in one cut.
Front Rotor Finish Cut
Spindle Speed
105 rpm
Depth of Cut
As necessary
Cross Feed (per rev.)
0.08 mm (0.003 in)
Vibration Dampener
Yes
Nondirectional Finishing
Ensure that the rotor surface is nondirectional by
dressing the rotor surfaces. Use a non-directional rotor
finisher such as the 54-433179 Non-Directional
Rotor Refinisher listed in the GM Dealer Equipment
Catalog, or a suitable equivalent.
If the brake lathe is not equipped with an adequate
nondirectional finishing tool, use a sanding block with
150 grit aluminum oxide sandpaper.
With the rotor turning at the equipment manufacturer's
highest recommended cutting speed, sand each
rotor surface for a minimum of 60 seconds using
moderate pressure.
After the rotor has been sanded, clean each surface
with denatured alcohol or a suitable brake cleaner.
Important: Replace any rotor that does not meet the
minimum thickness specification recommended by
the manufacturer. Do not resurface new brake rotors.
New brake rotors are manufactured with the proper
surface finish.
The finished rotor surface should be as close as
possible to that of a new rotor. Failure to obtain the
best possible rotor finish may affect braking
performance.
Brakes
Refinishing Brake Rotors (Rear}
Important: DO NOT refinish brake rotors when
performing routine brake maintenance, such as
replacing worn disc brake pads. Refinish a rotor ONLY
under the following circumstances:
• There is a complaint of brake pulsation.
• There is scoring greater than 1.5 .mm (0.060 in).
All brake rotors have a minimum thickness dimension
cast into the rotor. This dimension is not a minimum
refinishing dimension. The minimum refinishing
dimension is larger than the discard dimension. Do not
use a brake rotor that, after refinishing, will not meet
the minimum thickness shown on the rotor. Always use
a new rotor. Refer to Component Specifications.
Accurate control of the rotor tolerance is necessary for
proper performance of the disc brakes. Machine the
rotor using precise equipment. Service the machining
equipment on a regular basis. Follow the
manufacturer's recommended maintenance procedure.
Ensure that the following tool accessories are in
good condition when refinishing the rotors:
• The attaching adapters
• The tool holders
• The vibration dampeners
• The tool bits
Always use sharp cutting tools and bits. Replace
cutting bits using equipment that is recommended. by
the manufacturer. Dull or worn tools leave a poor
surface finish which will affect braking performance.
Always use anti-chatter silencer attachments when
refinishing braking surfaces. The attachments eliminate
tool chatter and will result in a better surface finish.
Ensure that the adapters are clean and free of nicks.
In order to correct brake pulsation, refinish rotors
using an on-vehicle brake lathe. Follow the equipment
manufacturer's recommended specifications and
procedure.
lmp·ortant: Remove any rust and scale from the rotor
and spindle hub mating surfaces. Failure to do so
may introduce excessive lateral runout when the rotor
is mounted on the brake lathe, or when the rotor is
reinstalled on the spindle hub.
The following two procedures are recommended and
achieve adequate results using two different
off-vehicle disc brake lathes. If any other lathe is used,
follow that lathe's instructions and recommendations:
Accu Turn® Brake lathe
1. Locate the deepest score. Turn the rotor
micrometer knob until the tool bit bottoms out at
the deepest point of the score.
2. Zero the scale and back out the tool bit.
3. Advance the cutter handwheel until the bits have
cleared the inner edges of the rotor face.
4. Adjust the micrometer knobs for approximately
0.127 mm (0.005 in) more than the first reading.
Use this method in order to resurface the
rotor in one cut.
(
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