I helped a chum change the front pads and discs (albeit slightly used ones)on my 04tf as I have no clue. And ever since I've got this knocking that started in the R/HS, seems to have moved to L/HS across the front of the car now. It's speed related but but after my lock related. Its not uniform, sometimes it's loud immediately, others it's quiet for half a mile. A quick touch of brake and it stops, brakes off, back again. Only really audible up to 30mph. There's no pattern and it sounds like something bumping against something else in a random yet uniform way if that makes sense. Nothing loose under the bonnet...I'm mystified but I got to find it, it's my only car for work and everything, it's two weeks to pay day, so any ideas at all. I am a complete dunce at mechanics (I'm electronics bod) but I can follow instructions well. Please help!