Car shakes when braking
Shaking that appears only when the pedal is pressed is almost always brake-disc-related: thickness variation or heat distortion on the discs makes the pads grab and release once per revolution. Vibration felt in the steering wheel points to the front axle; a pulsing felt in the seat or pedal points to the rear. If the shake is present without braking as well, the cause is in the wheels or suspension, not the brakes.
Urgency
Visit a workshop soon
Possible causes, most likely first
- Brake disc thickness variation (DTV)
Pulsing pedal and steering shake that gets worse from higher speeds. Measure disc thickness at 8 points with a micrometer; more than 0.015 mm variation or runout above 0.05 mm on a dial gauge means the disc needs machining or replacement. - Heat-distorted or glazed discs
Appears after hard braking, a long descent or driving through water with hot brakes. Blue or dark patches on the disc face and a hard, shiny pad surface confirm it; the disc usually also shows measurable runout. - Uneven pad material transfer
A thin, uneven layer of pad friction material on the disc causes judder even with mechanically true discs. Visible as dark, cloudy patches on an otherwise shiny disc; a few hard stops from 80 km/h may clean it, otherwise skim or replace. - Sticking caliper or slide pins
One wheel noticeably hotter than its pair after driving and a car that pulls slightly when braking. Check that the piston retracts and the slide pins move freely in their boots with fresh grease. - Worn wheel bearing or hub runout
Brake shake combined with a humming noise that changes on corners. Grab the wheel at 12 and 6 o'clock and rock it; any play or roughness when spinning by hand points to the bearing or a bent hub flange. - Loose or worn suspension components
Worn ball joints, tie rod ends or control arm bushings amplify a small disc runout into a big steering shake. Check for play with the wheel lifted and a pry bar on the joints. - Disc not seated flat on the hub
Rust or dirt between the disc and hub after a recent brake job causes immediate judder. Remove the disc, clean the hub face to bare metal and check runout again.
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What you can check yourself
- Note whether the shake is in the steering wheel (front) or in the seat and pedal (rear).
- Check if the vibration is also present at the same speed without braking - if yes, suspect wheels or tyres.
- After a drive, carefully feel the heat radiating from each wheel; one much hotter wheel means a sticking caliper.
- Look at the disc surface through the wheel for blue patches, deep grooves or a visible lip at the outer edge.