"squealing" in disc brakes is caused by the pad vibrating against the caliper. This vibration causes a high pitched sound which to the human ear sounds like a squeal... It is actually really easily fixed by removing the pads and applying a thin layer of grease on the BACK of the pad and reinstalling them. This will eliminate the vibration against the caliper and hence remedy the squeal...

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Current Cars:

2008 X5 4.8i - Blk/Saddle
2001 330Ci - Titanium/Black Sport/Premium

Past Cars:
1993 325is Blk/Blk Sport
1995 M3 Blk/Blk
1997 328iC Blk/Blk Sport/Premium
1998 M3 Silver/Black
2001 M5 /Black/Black/Sport
2005 X5 3.0i - Blk/Blk Sport/Premium