How can I fix a problem I have with my Vauxhall Cavalier car?

When I am driving along and press the footbrake to slow down on the approach to a junction there is a distinct grating/knocking sound which seems to be coming from the suspension leg/hub assembly area at the n/s front wheel. The grating/knocking sound can only be heard when the car is moving and the footbrake has been applied. I have replaced the wheel bearing/brake discs/brake pads and coil spring. There is no sign of damage and no wear/play in any of the subframe/suspension joints/bushes. There is nothing wrong with or loose with the brake calipers/hoses. It makes no difference whether the wheels are in a straight position or on either lock when braking, the noise still remains. There are no signs of damage to the driveshaft/alloy wheel or tyre. The car is a 1995 VAUXHALL CAVALIER 1.8 HATCHBACK with power steering/ABS/fuel injection. If you could help I would be very grateful. Regards.