Traditionally abutment clips used in disc brakes are made from uncoated stainless steel. In later years, due to an increasingly demand on lower brake noise, some brake manufacturers have introduced a new generation of abutment clips made from rubber coated stainless steel materials. It is generally accepted that the use of rubberized abutment clips have a positive impact on squeal noise and clunk noise caused from pad sliding in the caliper when changing from forward to reverse or opposite. Recently PTFE coated stainless steel abutment clips and PTFE coated stainless steel abutment clips with rubber are becoming more and more popular. Among benefits of the PTFE coating is lower surface friction resulting in an improved sliding of the pad in the caliper.
This paper elaborates on the effectiveness in reducing brake noise and sliding force from pads comparing four different abutment clip designs. Noise damping performance and pad sliding force comparing four designs are evaluated through brake dynamometer tests and force measurement rig and results are presented.
In this paper we also evaluate whether the main contribution on brake noise is caused by inplane or out of plane vibrations of the disc. Modal analysis using accelerometers is used to investigate vibrations in the brake and the result is compared to noise measurements. By this comparison we can estimate whether rubberized abutment clips are most effective on reducing in-plane noise or out of plane or both.
Finally, the surface friction level on the various abutment clip surfaces has been studied.
Stjärndahl Johan, Trelleborg Sealing Solutions, Sweden; Jarnestrom, P-A, Trelleborg Sealing Solutions, Australia.