BRAKE PAD WEAR INDICATORS

Mechanical pad wear indicators, which have been around since the early ’70s, are so simple and can head off so much damage that it’s surprising they didn’t show up even before then. All that’s required to warn the driver that he’s almost down to the rivets is the addition of a light steel tab that contacts the rotor when the linings are getting too thin for comfort. This produces a high-pitched squeal that appears suddenly and is unmistakable. The tab is too flimsy to cause any damage to the disc, unlike the rivets, which will grind away at that nice stopping surface, leaving wide, deep grooves. With bonded linings, the steel pad plates will do the same, and have been called “full-mets” by brake guys with a twisted sense of humor. By the time you hear and feel either, considerable rotor damage has already begun. Unfortunately, many of the cars out there still aren’t so equipped, and often replacement pads for cars that had wear indicators as O.E. don’t include this helpful device.

A slightly higher-tech variation on this theme is the electrical pad wear warning system, which first appeared a couple of decades ago on such cars as Toyotas and Mercedes. Here, the pad is drilled for an electrical contact that stands slightly proud of the lining rivets. When wear reaches the point that this touches the rotor, the ground circuit to a Brakes warning light on the dash is completed, and the lamp winks on. Again, unfortunately, some companies that manufacture replacements for these applications don’t bother to include the contact, with the result being that the wire ends up tied off in the suspension somewhere.

A disc brake pad having a visual indicator of brake wear to eliminate the current necessity of dismantling related parts for brake pad inspection by an automobile mechanic. The improved brake pad uses an existing conventional brake pad friction material having a recess cut into a rear surface of the friction material where the friction material is connected to the brake pad backing. This recess is filled with one or more layers of a brightly-colored visual indicator dye or dyes. As the friction material is worn sway by contact with the brake rotor, the thickness of the friction material is reduced until, eventually, the visual indicator becomes exposed at a predetermined depth. The visual indicator dye is pulverized and discharged onto the exterior surface of the wheel rim as colored brake dust. The presence of the colored brake dust alerts the driver of the need for brake pad replacement. (end of abstract)