April 4, 2012
By Jim Kerr; photo courtesy Ford Motor Company
In this era of rising fuel costs, manufacturers are using all kinds of techniques to improve fuel economy. Smaller engines, aluminum alloy body parts, higher strength but thinner steels, and more plastic parts are but a few of the features found on today’s vehicles to reduce body weight, and the less a vehicle weighs, the better potential fuel economy it can achieve. The bean counters (accountants, in polite circles) also like smaller and lighter. Less material used to build the vehicle means lower costs for raw materials and, in the end, more profit!
There are some parts of an automobile where bigger is better and nowhere is this more evident than in the braking system. Stopping a car takes a lot of power. A 200-horsepower engine may accelerate a car from zero to 100 km/h in about eight seconds, yet the braking system can stop that same car from 100 km/h to a standstill in less than half that time! It is the friction of the brake pads against the rotors that slow the vehicle that quickly, and when they do that they generate tremendous amounts of heat. The heavier the brake rotors, the more heat they can handle without brake fade or rotor distortion. Brake engineers like stopping power. To do that, the brake system components need to be large and heavy. The Bean Counters, on the other hand, want to reduce brake system weight to improve vehicle fuel economy and reduce the manufacturing costs. Sometimes the brake engineers win. Sometimes the Bean Counters win. Most of the time a compromise is reached but with the new brakes on the 2013 Ford Taurus and 2013 Ford Flex, I think the brake engineers came out on top.
For example, the four wheel disc brakes on the 2013 Ford Taurus SHO have 19 percent more thermal mass on the front rotors and 53 percent more thermal mass on the rear rotors. The heavier rotors can absorb more heat without experiencing brake fade. Brake fade occurs when the brake rotors get so hot that they cause the brake pads to overheat and form gases. The gases are formed between the rotor and brake pad and reduce the friction between the parts. Anyone who has experienced severe brake fade will know that it feels like there are no brakes on the vehicle no matter how hard you step on the brake pedal. It can sometimes feel like the vehicle is actually speeding up slightly rather than decelerating.