It happens to almost all of us at some point during our time behind the wheel, we step on the brake pedal and there’s this beating, pulsating type feel beneath your foot. Many folks who aren’t familiar with braking systems can become concerned about the safety of the vehicle while others who may be more seasoned in the world of automotive systems quickly assume the brake rotors are warped.
If you’re familiar with how today’s automotive brakes work, it’s easy to understand how at times you might feel warped rotors pulsating the brake pedal. If the rotor surface is uneven, the high spots will push back against the caliper pistons causing brake fluid pressure to increase and decrease rapidly in the brake lines. That pulsation is then easily felt in the pedal, it’s much like the way you at times can feel the pulse in your wrist.
If the suspension system has been poorly maintained and there are worn bushings or links then it’s possible to have the steering wheel shake…sometimes violently
There are a few reasons that brake rotors will warp or develop high spots, one reason is uneven heating or cooling. Those that live in wet and rainy areas are constantly subjected to driving the car through puddles of water that can splash on the rotors and cause some premature warping.
Another common reason for rotors to warp is parking the vehicle after extended heavy usage, for example, let’s say you’ve just towed a heavy trailer through a mountainous terrain, that added weight places a heavy demand on the brake system. In that example, all the heat that has soaked into the brake pads keeps one section of the stationary rotor hot while the rest of it cools.
The number one reason however, is improper tightening or installation of the wheels. Brake rotors on most newer vehicles are made thinner in an effort to reduce the overall vehicle weight and it’s not only thinner at the friction surface, it’s thinner everywhere including the point where it contacts the rim of the tire. If your service center isn’t mindful of setting proper lug nut torque, then it’s possible and even probable that the brake pedal will pulse and warp prematurely.
We’ve talked briefly about the consequences of uncontrollable heat and uneven lug nut torque, lets now look at one last culprit that can cause grief and frustration and that’s contamination and corrosion.
Typically wheels and brake rotors are made of dissimilar materials. Most wheels today are made of aluminum whereas rotors are made of steel or iron, aluminum is softer and thereby can corrode heavily at the rotor contact point. General Motors as well as other manufacturers strongly recommend routine cleaning of those surfaces during routine tire maintenance.
In today’s busy world, it’s easy to postpone automotive maintenance and adopt an “I’ll get to it later” mentality. Here at Horsepower Broadcasting we strongly urge our readers and our Horsepower for an Hour radio show listeners to reject that sort of reasoning. In the long run, proper maintenance is easier on your wallet and a properly maintained vehicle will serve you reliably for many years.