Having both the old and the new 82s I replaced the plastic backplate with a alu. one and with a gasket its all good , no rubbing . As has been mentioned make one if you dont want order one in . If youve had the thing in bits maybe the collet that holds the drive hub on hasnt been tightened up and therefore the crank hasnt come forward enough . I would put one in anyway as Im sure the factory does it for a reason. Cheers the pope