Why Does My Car Shake / Shudder When I Brake?
Brake shudder is noticeable in some cars. It means vibrations felt through the steering wheel or brake pedal when braking – especially when braking hard and from at high speeds.
Fortunately, Disc Thickness Variation (DTV) can be fixed pretty easily.
DTV refers to the thickness of brake discs being irregular. This is what causes car brakes to shudder or vibrate.
Brake discs can become warped over time from heat generated by braking. They can also wear unevenly if the brake pads only come into contact with the discs in certain areas.
Note that in modern cars, brake discs and brake rotors are essentially the same things.
Brake calipers push (or clamp) brake pads onto a spinning brake disc to slow the vehicle down. The brake discs are attached to the axles. It’s this contact between the brake pads and disc that causes friction, which means heat.
(A car’s brake disc, it’s easy to see where the name comes from)
To remedy brake shudder caused by DVT (or warped/damaged discs), the discs need machining or to be replaced completely.
Disc machining is a simple process. It involves removing the disc from a vehicle and spinning it in a lathe. Cutting implements then ‘machine off’ or slice away the minimum amount of material needed to give the disc a clean, smooth surface for the brake pads to clamp onto. Wheel rotation is often performed during a wheel alignment service.
Other causes of brake shudder
If a car’s suspension components are damaged or worn, they can cause vibrations when braking. Suspension is part of the car’s drivetrain so plays an important role in keeping balanced on the road. Commonly, this is the case if a brake shudder occurs when turning and braking at the same time.
Depending on the component (bearings, joints, rods/struts, etc.), readjusting or replacing may be in order. Sometimes dirt, oil or other debris can interfere with a moving part and may only need to be cleaned away and a cover (dust jacket/rubber boot) replaced.
Cars with their wheels out of alignment typically shudder whether braking or not but can be more noticeable when braking. Another sign your wheels are out of alignment maybe your car pulling to one side when it should be travelling straight. A car with aligned wheels will typically save more petrol than a car with its wheels out of alignment.
A wheel alignment is part of routine maintenance. It usually takes about one hour to complete. A mechanic will attach an alignment machine to a car’s wheels to make sure they’re inline with each other and moving in the correct direction.
Typically, they’ll adjust;
- Toe – the angle at which the tires turn when steering. The angle of the wheels when looking down on a car (angled in or out).
- Camber – the vertical angle of the tires when looking at the vehicle straight on.
- Caster – the angle forward or backward from the suspension struts.
- Thrust – makes sure that the front and rear axles are parallel. Compares rear axle with vehicle direction.
Worn brake pads typically result in squeaking when braking. However, worn or warped brake pads can also cause brake shudder.
Fortunately, car brakes are designed to be easily accessed and repaired. Some mechanics can replace brake pads in less than 30 minutes.
Replace the brake pads. This is a simple, necessary and routine part of scheduled car service. Depending on the car, style of driving and pads themselves, brake pads usually last between 15,000 to 70,000 kilometres.
At the end of the day
It’s no secret that car brakes are an important part of a car. Keeping them in proper working order is a no-brainer, especially before going on a road trip.
Luckily, you don’t have to be a mechanic to get an idea of their condition. If you feel brake shudder, hear high-pitched squeaking when braking or notice your brake discs worn and unsmooth, it might be time for a service.
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