Brake Disc Runout
Runout is the wobble of a brake disc as it rotates.
What is Brake Disc Runout?
It is measured with a dial gauge. It causes vibration. Hub dirt can cause it. Manufacturers specify very small runout limits, measured in hundredths of a millimetre. Even small runout causes the pads to touch the disc unevenly, which over time creates thickness variation that is felt as a pulsing pedal or a shaking steering wheel. Tightening wheel nuts by hand in a star pattern and then to torque helps prevent it.
How it works
Uneven contact creates thickness variation.
Why it matters for your car
Clean hubs before fitting discs. Tighten wheels to torque.
Other terms
- Alternator Pulley (Overrunning Pulley)
- Bonnet (Hood)
- Booster Seat (Child Booster)
- Car Fire Extinguisher
- Crosswind Assist
- Degreaser (Engine Cleaner)
- Diesel Injection Pump (Distributor Or Inline Pump)
- Exhaust Manifold
- Front Grille
- Front-Wheel Drive (FWD)
- Fuel Rail
- Heated Door Mirrors
- Ohm’s Law
- Rear Window (Rear Screen)
- Rocker Arm
- Three-Cylinder Engine
- Valve Cover Gasket (Rocker Cover Gasket)
- Ventilated Seats (Cooled Seats)
- Wireless EV Charging (Inductive Charging)
- Yaw Rate Sensor