Focusing on silent operation: MEYLE brake expert Stefan Bachmann on brake noise, squealing and new product developments

The automotive industry is constantly on the move. What trends and developments does MEYLE observe?

Stefan Bachmann: We note a clear trend towards sensitive perception of sounds. This development is easy to understand, especially with regard to the electromobility: By eliminating engine noises, the driver becomes more sensitive to noise in the vehicle, so that previously unnoticed brake noises can now be perceived as disturbing. Last but not least, the increasing demand for emission reduction should also be mentioned: Brake dust development plays a key role here, so that we will focus our research and development activities on this in the coming years. These requirements, combined with better or constant performance of the brake pads and discs, represent a particular challenge for the industry in the coming years.

The myth of “squealing brakes” – are noises during braking per se bad? Which factors and components can be influenced in product development to minimize brake noise?

Stefan Bachmann: No. A squealing brake does not always mean a broken brake pad or disc. First and foremost, it must be said that there are actually brake systems with mechanical wear contacts. Instead of a message in the cockpit about the wear, a squealing noise is heard when braking. As a rule, the sportier the brake pads are, the more they tend to squeal. In the case of ‘sporty’ drivers, higher loads can result in stronger vibrations between the brake pads and the brake disc, which can be perceived by the driver as disturbing or squealing in certain frequency ranges. In addition, ‘neighbouring’ components such as control arm bushings are worn out and vibration is transmitted in the direction of the last component of the overall suspension – the brake. Nevertheless, a squealing brake can of course also mean that there is a fault in the brake system or that incorrect brake components have been installed. In the case of an unusual process, it should therefore always be inspected by an expert in the workshop!

Generally speaking: brake pads are not always the same. Which factors and driver types can be distinguished when it comes to brake pads?

Stefan Bachmann: When it comes to brake pads, we distinguish between the ‘classic’ and the ‘sportier’ driver: The classic driver places a lot of emphasis on comfort, whereas the sporty ambitious driver attaches greater importance to performance. We have developed the MEYLE-ORIGINAL and MEYLE-PD product lines so that we can offer a suitable product for both driver types: While the MEYLE-ORIGINAL brake pads focus on the lowest possible background noise for the ‘comfortable’ driver, the MEYLE-PD brake pads clearly focus on performance for sporty driving and tight response. With the new “next generation” MEYLE-PD brake pads, we have succeeded in combining the best of both worlds and developing performance-oriented and low-noise brake pads at the same time. This not only helps the environment, but also makes rims look cleaner for a longer time.

What exactly is so special about the new MEYLE-PD brake pads?

Stefan Bachmann: For the MEYLE-PD brake pads, we have adapted the friction material and further developed it technically. The design of the brake pads has also been adapted: Chamfer and slots of the friction pad are optimally and individually aligned to the different vehicles – in addition, the new MEYLE-PD brake pads have individual so-called shims, between three and five layers depending on the application, which decouple vibrations in the best possible way and thus further minimize noise development. The braking time factor also plays a major role in braking performance: for optimum braking performance, the brake pads and brake disc must be in tune with each other. In order to shorten the bedding-in time, two processes are used in production, depending on the friction mixture: scoring (final heat treatment of brake pads) or a special coating of the brake pad surface that shortens the bedding-in time and ensures the usual MEYLE-PD performance from the very first braking.

About Stefan Bachman:

Stefan Bachmann is product team lead of MEYLE’s product team Brake, Drive and NVH. The 38-year-old state-certified technician has been working for the Hamburg-based spare parts manufacturer for almost 10 years. First as product manager and for 5 years in leading function. Together with his team, he is responsible for portfolio design, development and specification as well as production of the brake and drive product areas.