If you a later Tornado or the aluminium upright conversion sold by Tornado, there may be other issues. Although the manufacturers of the units rate them to carry NO MORE than 750kG, THESE HAVE BEEN SUPPLIED AND FITTED to gt40Ss , which are substantially above that weight. We have seen the steel spindles coming loose in the aluminium casting, which can cause the brake disc to run out in the caliper and make nasty noises you describe.