Tommytank

HI THERE I HAVE BEEN GIVEN A FABULOUS XS250 '78 WITH A 400 LUMP IN IT. IT RUNS WELL BUT WHEN MOT'D IT FAILED ON THE REAR DRUM BRAKE. THE CHAP SAID THE LINING MAY HAVE GONE SLIGHTLY OVAL AS IT HAS NOT BEEN USED FOR SOME YEARS. I WASN'T SURE ABOUT THIS SO TESTED IT AND SURE ENOUGH THE BRAKE PEDAL HAS AN INCH OF MOVEMENT UP AND DOWN DURING BRAKING. ON INSPECTION THE DRUM DOESN'T LOOK THAT BAD JUST A LITTLE RUST AND A VERY SMALL CRACK. WOULD IT BE SENSIBLE TO HAVE IT SKIMMED OR IS IT POSSIBLE TO RELINE AN ALLY WHEEL OR AM I MISSING SOMETHING ELSE?