The following are the main possible causes of brake judder:
Due to an excessive runout (side-to-side wobble) of disc plate, the thickness of disc plate is uneven.
If the runout is
more than 0.05 mm {0.002 in}
at the position
10 mm {0.39 in}
from the disc plate edge,
uneven wear occurs on the disc plate because of uneven pad/plate contact.
If the runout is
less than 0.05 mm {0.002 in},
uneven wear does not occur.
The disc plate is deformed by heat.
Repeated panic braking may raise the temperature in some portions of disc plate by
approx. 1,000 °C {1,832 °
F}.
This results in deformed disc plate.
Due to corrosion, the thickness and friction coefficient of disc plate change.
If a vehicle is parked under damp conditions for a long time, corrosion occurs on the friction surface of disc
plate.
The thickness of corrosion is uneven and sometimes appears like a wave pattern, which changes the friction
coefficient and causes a reaction force.
Inspection and repair procedure
2008 Mazda CX-9 Grand Touring
2008 BRAKES Conventional Brake System - Mazda CX-9
Microsoft
Sunday, November 15, 2009 9:48:49 AM
Page 17
© 2005 Mitchell Repair Information Company, LLC.
