The shims on the back of the pads should be in place, not all W210 rear pads come with them, so you will need to reuse them along with antisieze.

Also from experience 3 times - pagid brand brake pads will take a while to seat and burnish into the rotor - and they will squeal all the time until they do.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)