A grinding sound usually suggests metal to metal contact but, as you say, you have changed the pads and disks.
What springs to mind is that that the brake backing plate - the metal disk on the inboard side - are being touched by the spinning disk, or the noise is being caused by a driveshaft or bearing.
However, there are other possibilities. Are there any shims in your braking system? Shims hold the pads in place and stop squeal/rattle.
It also could be that the pads are not being fully released from the disk when the brake pedal is pressed. Depending on your calliper set up it may be something as simple as a slide that is sticking and needs cleaning.
Brake pads are released from the disk by what is nothing more than the spinning of the disk 'knocking' things back. Assisted by rubber sleeves on 'slide pins'. Something may be sticking and need cleaning and a smear of copper grease added.
It would be too easy to say that you have a vacuum leak (or internal seal) problem in the brake servo. A servo problem usually results in a 'hard' brake pedal at all speeds. You don't have this problem.
It may well be that your brakes feel 'spongy' at low speeds because the pads are not being shoved back from the disk because of sticking slides (depending on your system).
It also may be that the pistons in your calliper are sticking.
You obviously can work on cars and use tools - consider overhauling your brake callipers (look on Ebay for overhaul kits) but bear in mind that doing this also means you have to bleed the brakes.
Answers & Comments
A grinding sound usually suggests metal to metal contact but, as you say, you have changed the pads and disks.
What springs to mind is that that the brake backing plate - the metal disk on the inboard side - are being touched by the spinning disk, or the noise is being caused by a driveshaft or bearing.
However, there are other possibilities. Are there any shims in your braking system? Shims hold the pads in place and stop squeal/rattle.
It also could be that the pads are not being fully released from the disk when the brake pedal is pressed. Depending on your calliper set up it may be something as simple as a slide that is sticking and needs cleaning.
Brake pads are released from the disk by what is nothing more than the spinning of the disk 'knocking' things back. Assisted by rubber sleeves on 'slide pins'. Something may be sticking and need cleaning and a smear of copper grease added.
It would be too easy to say that you have a vacuum leak (or internal seal) problem in the brake servo. A servo problem usually results in a 'hard' brake pedal at all speeds. You don't have this problem.
It may well be that your brakes feel 'spongy' at low speeds because the pads are not being shoved back from the disk because of sticking slides (depending on your system).
It also may be that the pistons in your calliper are sticking.
You obviously can work on cars and use tools - consider overhauling your brake callipers (look on Ebay for overhaul kits) but bear in mind that doing this also means you have to bleed the brakes.