Professional_Tool_And_Equipment_News_December_2019 - 31

rotor met the run-out and size specifications, but the offset of the hub flange was
incorrect, which would cause the caliper
to rub on the rotor.
At our shop, the easy fix for these
issues was to switch to purchasing only
high quality rotors. Even then, we make
sure to spend a few extra moments during the installation process to measure
tolerances. Although it takes a few minutes, the likelihood of having a comeback, which will take significantly longer
to correct, is greatly reduced.
It is important to remember that
with many of today's vehicles, brake
vibrations are not only a nuisance, but
may also cause other issues. Vibrations
caused by brake rotors, wheel hubs, or
tires can cause both stability control and
ABS issues and, in some cases, cause false
misfire codes. Yes, a misfire code. The
strategy some vehicle manufacturers use
is to monitor wheel speed sensors for
variations (skipping) when the torque
converter is locked. Unless the vehicle is
on a rough road, these variations could
be signs of the engine misfiring.
Other common errors that can cause
brake vibration but are easily remedied

p Using a brake fluid tester such
as the Cal-Van Tools Brake Fluid
Tester, No. 66, allows the technician
to verify there are no contaminants
in the fluid.

by spending a few minutes with the right
tools, are:
Wheels not torqued properly -
Use vehicle information to obtain the
correct torque specification, then use a
torque wrench or torque stick, such as
the Ken-Tool 30180, to tighten correctly.
You should also tighten wheels in a cross
pattern rather than a circular pattern.
Hub and/or rotor surfaces not
cleaned - Use a hub polishing kit such
as the Steelman 99905 polisher to clean
both surfaces, allowing the rotor to sit
flush to the hub face.

COMMON ISSUE 3:
BRAKES ARE NOISY
AFTER BRAKE SERVICE

This is another somewhat common
issue that can occur after replacing
brake pads, and again there are quite
a few causes of this problem that could
be avoided.
A poor-quality brake pad is one of the
more common causes of a noise complaint, but technicians can also inadvertently contribute to noise complaints
with incorrect installation procedures.
Reusing worn or bent pad shims is one

p The OTC Brake Pressure Test Kit,
No. 7488A, allows the technician to
test the pressure at individual wheels.

www.VehicleServicePros.com

DECEMBER 2019

way this happens, but the most common
source of this type of noise occurs when
the technician does not clean and lubricate components like brake rotors, caliper slides, mounting pins, pad mounting
surfaces, and retaining bolts. The best
method to clean rotors is with hot soapy
water, and other components with a soft
bristle brush and brake cleaner. Be sure
to use appropriate hand and eye protection when cleaning.

COMMON ISSUE 4:
LOW OR SOFT BRAKE PEDAL

Potential causes of either a low or soft
brake pedal are also a little trickier to
determine. For one, pads may need to
be "burnished" or broken in with a few
heat cycles for the pad material to work
properly. If the technician completes this
process during a road test after a brake
repair, the pedal should feel normal to
the customer.
You might also check whether rear
brakes are out of adjustment, if there's air
in the lines, and one of the most common
errors I have found - whether a technician inadvertently "bruised" the brake
hoses. Damaged brake hoses can

p The Ken-Tool Torque Starter
Kit, No. 30180, is designed to help
technicians easily tighten wheels to
the correct torque.

PROFESSIONAL TOOL & EQUIPMENT NEWS

http://www.VehicleServicePros.com

Professional_Tool_And_Equipment_News_December_2019

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