Brake Judder Repair Hints: Notes

Due to an excessive runout (side-to-side wobble) of the disc plate, the thickness of the 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 the pad contacts the plate unevenly.
• 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 approximately 1,000°C {1,832°F}  . This results in a deformed disc plate.

Due to corrosion, the thickness and friction coefficient of disc plate change. 

• If a vehicle is parked in 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.