i recently purchased a replacement set of front and rear brake pads for my 93 240. i replaced the front ones fine, but the back ones are giving me hell and im wondering if anyone is familiar with my situation. the pistons on the rear calipers are not compressing (pushing in) at all. i am using a 6" c-clamp and they are not budging!!! the front pistons compressed fine just like the ones on my old sentra. is anyone familiar with what's going on?! let me know so my rear brakes stop grinding and skeaking (its pretty embarrasing)! thanks.