There are a few reasons your brake pedal may vibrate. You must first differentiate between an ABS (anti-lock brake system) activation and a vibration or pulsation that poses a legitimate safety concern. Most drivers have felt the ABS activate while stopping in slippery conditions. ABS produces hundreds of quick pulsations. That’s absolutely normal provided the road conditions are wet or icey. ABS systems are dormant until you need them in situations were your tires can’t get traction and begin to skid. On the other hand, if you experience a similar pulsation during normal braking on dry pavement, that would suggest a problem that requires a brake diagnosis.
Most non-ABS vibrations you feel are due to rotor or drum surface irregularities. Rotors and drums continue to turn while the brakes are applied. The rotor and drum surface where the brake pads meet must be straight and what we call parallel. The majority of vibration problems felt in the pedal while stopping are due from the brake rotors not being “straight” any more. The disc has become warped or uneven somehow.
There are several factors that can cause this to happen and it’s sometimes difficult to pin point the root cause. A common problem we see is when the brake caliper doesn’t fully release or is dragging. It’s the equivalent to riding the brakes all the time. If your caliper is dragging, it will create excessive heat and cause damage. Heat is a major contributor to rotor and drum warp. Personal driving habits such as towing or stop and go traffic can also contribute to excessive heat and rotor/drum warp.
Another consideration is the thickness of the rotor or drum lining. Typically the thinner the rotor, the easier it is to warp. From my experience I’m certain that car manufacturers are making brake rotors and drums “disposal” these days. In an effort to conserve weight, they make them thinner and to save money, they use a lower grade of metal.
And finally, let’s not forget about rust. I have seen cars only 3 or 4 years old requiring brake rotors due to severe surface rust. Of course, this is more prevalent in the snowbelt states but it’s occurring more frequently. Obviously due to the lower grade of metal used in today’s brake systems.
As you see, vibrations and pulsations don’t necessarily mean the brakes are unsafe and require repair but it is a condition that should be inspected by a professional technician. With a simple call, Wise Auto Clinic can inspect your brake system and provide you with an estimate on repairs to remedy any brake issues you may have.
