Magazine for the auto service professional
Issue link: http://asp.epubxp.com/i/684411
28 | ASP June 2016 Technical and problems are fairly similar across the board and across manufacturers. Te frst step is disassembly, which sounds easy enough, but there are a few steps to which we need to pay particular attention. After removing the caliper, don't let it hang by the fex hose, as this can easily stress and damage the fex hose. Tings have never been lighter or smaller than on the modern vehicle and a fex hose can easily be damaged. Now that we have removed the caliper and its bracket from the mountings on the spindle or axle assemble, it's time to formulate a plan of attack for proper service that will give us the absolute best chance of this brake job not coming back with a noise or vibration complaint. A careful visual of the abutment bracket is the next step. Tis is the piece that holds the pads and this bracket needs particular attention. Tese brackets contain major areas of concern that need to be addressed during proper brake service. Tey can be a signifcant cause of noises and issues if not serviced properly. In the area that the abutment pad resides, the guide pins/guide pin boots and guide pins themselves all require attention. Tis bracket is subject to all the heat and forces that are generated during a stop; they gather brake dust, road grime and salt (I'm from the North, and this is a huge issue) and other road-clearing winter chemicals. Removal of the abutment pads will expose rust and debris that needs to be thoroughly cleaned. Tis is critically important. Te area is designed to have just enough space to allow free pad movement but also keep the pad tight enough to absorb the pad noise that can cause vibrations. Te buildup of corrosion and rust often locks the pads in place causing accelerated wear, pad failure, uneven braking, uneven wear and noises. Tere are a number of ways to perform this operation from wire wheels, gentle fling, sand or glass bead blasting, if available, to replace- ment in extreme cases of corrosion or wear. With the rotor frmly secured with all lug nuts at full torque, set up a dial indicator and slowly rotate the rotor to check for runout variations. Brake rotor thickness should always be checked at multiple clock positions on the disc surface with a calibrated micrometer. Disc brake pad separator/ spreader designs vary, from wire spring clips as shown here, to pad abut- ment clips with built-in spring fngers.