the black diamond combi disks and preditor pads are now on my vr, but im now getting a scraping sound, in the haynes manual it said that new pads should be 14mm thik including back plate, i have sanded the top layer of the pads of but they remain about 18-20mm thik, so i think there scrapin the pads as im driving, will this cause any problems or will they ware down to the corect width them selvs, sould i file them down to the correct width?