Magazine for the auto service professional
Issue link: http://asp.epubxp.com/i/684411
26 | ASP June 2016 Technical Brake system NVH woes Addressing and avoiding noise, vibration and harshness issues By Jef Taylor T he usual complaint after performing a brake service is typically going to involve noises — squeaks, squeals, squawks or vibrations. You name it, brake noise under moderate to light applications is a common complaint, but what causes it? And why don't they make noise under a hard application? In a nutshell, the cause is vibration, where the rotor or drum act as the speakers. Te actual brake material is vibrating; most commonly it's the pad assembly, but shoes can do it, too. Tis noise is most commonly made during light application because there isn't enough force keeping everything tight in the abutment bracket assembly as it would be held under a hard stop. Brake part replacement and services are something that we all do regularly, and most of us do it routinely without issues. But we have all had to deal with the fact that brake jobs can often lead to comebacks from noise and vibration that may or may not have been created by us, the techs who performed the job. We usually are quick to blame the brake component manufacturer, the pad mate- rial type or the customer's driving habits, but in many situations it was something we overlooked and let go. It takes more than just slapping in a new set of pads to prevent these noise issues, but with attention to detail and doing a complete and thorough job the frst time, we can prevent a number of self-induced comebacks. Starting the brake job: disassembly Almost all light-duty vehicles today are using a foating caliper design, so the issues We've all seen the television commercial where the guy applies his brakes and they squeal, causing everyone to look at him. Then, the announcer goes through the sales pitch, including a low price and everyone is happy. Happy, that is, until the brakes begin to pulsate, squeal, shimmy, pull or worse a month or so later. The fact is brake comebacks are not fun for anyone. The customer isn't happy, and you shouldn't be either. Here we ofer you some great tips to eliminate brake NVH problems. Paying attention to detail can go a long way to avoid brake noise, vibration and harshness issues.