Abstract
KEYWORDS - Low friction, Isolation, NVH, Brake Noise, Brake shim, Brake insulator, PTFE
ABSTRACT
Traditionally, the Western World and Japanese markets have adopted different approaches in solving brake related noise. In Europe and North America, the traditional shim design has been of the multilayer bonded type (‘bonded’), whilst in Japan the main focus has been on clip-on and floating type (‘floating’) shim design (comprising two clip-on shims with grease in between, with the outer layer shim often consisting of stainless steel).
This paper investigates the effectiveness in reducing brake noise by comparing two different shim designs (bonded versus floating). Whilst demonstrating that both have merits and are effective in reducing noise, the paper concludes that floating style shims generally have a better effect on low frequency noise (1 ~ 4 kHz) (1). There is also anecdotal evidence that a floating shim is a more effective solution in reducing noise induced by in-plane rotor vibrational modes. This paper further explores the use of a more durable floating style shims using PTFE coating (vis a vis grease).
Noise reduction performance comparing three different shim designs (bonded vs. floating vs. floating with PTFE) on four different brakes is evaluated by the use of brake dynamometer tests and results are presented.
This paper also addresses the correlation between rotor in-plane and out-of-plane vibrational modes and measured brake noise. Finally, the surface friction level on several typical shim surfaces has been studied.