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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22894
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Occasional knocking sound from rear of car (wheels?) when taking

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Occasional knocking sound from rear of car (wheels?) when taking away slowly. Car is a 2005 Aston Martin DB9.

the DB9 uses a AP racing caliper - which is rebranded for Aston

its an excellent part but sometimes the pads can not be the greatest fit so can clonk and rattle about as the disc slightly drags on the pads so pulls them forward and produces the noise

there are 2 fixes available
either source some better fitting pads (ferodo DS300 tend to be very good)

or you remove the current pads - apply a smear of silicone sealent onto the brake piston, then re-fit the pads and press hard on the brake pedal to seat the pad and leave overnight

the silicone sticks the pad to the piston so it no longer rattles - its a bit heath robinson but usually works well
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