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New Grinding Disc Brakes

TheJackalTheJackal Posts: 169
edited October 2010 in MTB workshop & tech
My LBS just replaced my existing Hope Mini rotors and brake calipers with some Magura Martas.

The guy said the rotors were catching a tiny bit in the calipers at the front which I accepted but when I got on it this morning for my daily commute, the back brake caliper had a very noticeable grind coming from it. So much so that the whole frame was vibrating and I returned home within a few hundred metres.

I've taken it back and tried it myself but the grinding is still only there when you sit on the bike and ride, not when the wheel is turned in the work stand!

I've checked for cracks in the frame and the wheel alignment but all seems fine.

Any ideas?
2012 Santa Cruz Highball Carbon 19 lbs
2009 Ibis Tranny __ lbs


  • Chunkers1980Chunkers1980 Posts: 8,035
    Perhaps you should get rotors that match the caliper as I take they weren't changed too?
  • TheJackalTheJackal Posts: 169
    Yes, the calipers and the rotors match. They're both Magura Martas. They're both brand new off my new Stumpy.

    2012 Santa Cruz Highball Carbon 19 lbs
    2009 Ibis Tranny __ lbs
  • bennett_346bennett_346 Posts: 5,029
    Bolts done up to correct torque?
  • TheJackalTheJackal Posts: 169

    It turned out that the axles in the hubs had come loose and separated.

    How? I don't know but when they were undone they just fell out of the hubs! The guy at the LBS thought I'd snapped them until he realised that they were threaded and they had just come undone!

    All OK now, mind. Anyone fancy some old but perfectly working Hope Minis?
    2012 Santa Cruz Highball Carbon 19 lbs
    2009 Ibis Tranny __ lbs
  • njee20njee20 Posts: 9,613
    So your LBS fitted some brakes, without noticing your axles were in 2 pieces? And didn't think to investigate the 'grinding'?

    Find a new LBS before they kill you.
  • TheJackalTheJackal Posts: 169
    Apparently the axles are held in by a hex bolt and it was only when he went to undo them to check if there was anything wrong with them after checking everything else, that the one end fell out!

    Quite how it and the other one had got like that, I've no idea. I suppose the fact is that I may have be riding like that for the past 4 months. Or that it had got slowly worse.

    Of course the only reason he hadn't detected any grinding was that he hadn't ridden on the bike.

    In the work stand the rotors and the callipers were OK. It was only by me putting weight on it this morning, that there was sufficient movement for the rotors to grind against the calliper.

    Thanks goodness I didn't persevere in trying to get to work!!!
    2012 Santa Cruz Highball Carbon 19 lbs
    2009 Ibis Tranny __ lbs
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