One little-known upside of hybrid or electric vehicles—especially those that pile on the miles—is that their brakes last surprisingly long. Thanks to regenerative braking systems, which recapture some of the energy as you decelerate, traditional brake pads have a lot of assistance. It’s not unusual, for instance, for a Toyota Prius to go 100,000 miles on its original set of pads.
That introduces another issue, actually: corrosion. At times, it can change the way traditional friction brakes perform, or the way they “bite” when the driver steps on the pedal. That’s even more important in hybrid and electric vehicles, where systems blend the regenerative braking with the friction brakes—and where the friction brakes might not be used very much but need to be available (and not rusty) so that active-safety systems such as automated emergency braking can perform. To meet those special needs, the supplier Continental has introduced a new wheel concept designed specifically for use in electric vehicles.
In its new design, the disc is aluminum rather than iron, and the braking surface is a larger diameter than commonly used. The most significant difference from traditional brakes, however, is that the brake caliper is fastened to the wheel carrier of the axle while the disc is bolted to the carrier star, stabilized against the wheel hub. That means the braking surface is on the inside of the rotor rather than the outside.
The design saves a lot of weight, of course (although the supplier didn’t release a figure), but one of the real selling points, other than the performance aspect, may be that they’re quieter—an important factor for electric vehicles because, without the thrum of the engine, you hear every little noise as you come to a stop.
Continental notes that the aluminum discs aren’t subject to wear like conventional iron rotors, and that the brake disc lasts a lifetime while brake-pad changes are easier. But given how long brake service intervals already are, easier pad changes may be the least of their advantages.