Why do I feel vibration when braking?
The harder you brake, the more fluid pressure builds in the calipers, and the more pressure is applied to the brake pads and rotors. If the caliper or caliper pistons become stuck, it is unable to properly squeeze the brake pads against the rotors, which may cause you to feel some vibrations when you hit the brakes.
Why does my car stutter when I brake?
This refers to the uneven wear of brake discs and is the result of rotor run out. If your brake discs are unevenly worn the brake pads come in contact with the flat spots present in the rotor’s surface which causes the vibration that we call brake shudder.
What is a brake shudder?
Brake shudder (also known as brake judder) is the vibration felt through the steering wheel and suspension when the brakes are applied at certain speeds and pressures. It can vary from a barely noticeable vibration to a violent judder – experienced through either the brake pedal or steering wheel.
What is the most common cause of brake judder?
The brake disc developing disc thickness variation (DTV) over time, is the most common cause of judder. Disc thickness variation is when the disc has worn unevenly, causing the two friction surfaces of the disc to no longer be parallel with each other. This is often confused with disc warping.
How do you prevent brake judder?
Best practice advice to prevent brake judder
- Before refitting a disc, first check the discs thickness.
- Ensure that both the hub and disc mounting faces are scrupulously clean and free from rust or any other form of dirt or grease.
- Once fitted, use a dial indicator to check the discs lateral runout.
What causes DTV?
DTV is caused by an excessive lateral runout. Lateral runout is the amount of side to side movement of the rotor as it rotates. Today’s vehicles have extremely tight lateral runout specifications. Most vehicles have a specification of two-thousandths of an inch or less.
What is parallelism on a rotor?
Parallelism is when the rotor thickness varies from one point to another. Brake rotor parallelism causes the piston, with pressure applied, to move in and out of the caliper housing.
What is thickness variation?
Disc Thickness Variation (DTV) is where the rotor or disc varies in thickness as indicated in the diagram. DTV causes torque variation with symptoms such as (i) Pedal pulsation as the rotor passes through the caliper/pads with lower pedal efforts very noticeable and higher pedal efforts less noticeable.
How is brake parallelism measured?
Inspect the rotor for parallelism. Using a brake rotor micrometer, measure rotor thickness, one inch from the outer edge, at six to eight clock position points. Compare your findings to the specification. Generally speaking, maximum allowable parallelism should be about 0.0005 inch.
What is runout on brake rotors?
Explained in this article, Lateral Run-out (or simply run-out) is a measure of how much off-centre a brake rotor is as it spins around the hub. A vibration, or pulsing, in your brake pedal or steering wheel when your apply your brakes may indicate that your run-out is off tolerance.
What is the minimum thickness for brake discs?
Most car mechanics also agree that the bare minimum brake pad thickness is 3.2 mm (⅛ inches). Any thinner than this, and you’ll need an immediate brake pad replacement to avoid brake failure.