Brake pads contaminated?

skaffen
skaffen Posts: 72
edited May 2011 in MTB workshop & tech
Bit of a weird one this, I've got Formula R1s that have been great for the last few months. The last couple of rides, the front brake has been awful for about the first 10 miles of the ride (no power at all). Once it's had enough "warm up" though, suddenly they start behaving as they used to, good feel and all the power comes back.

The only thing that I can think of is that something has got on the brake pads, but would the brakes behave like that? It's not as if something burns off after a bit of use, because it's done this for a few rides now, it's just almost as if when they've had enough heat through them they suddenly start working.

Anyone any ideas?

Comments

  • RupertCommunicator
    RupertCommunicator Posts: 734
    You probably have air in your system. Do you keep your bike upside down? If so, the air in the system will rise to the calliper when resting, only to get pumped into the reservoir when in use, leading to them working after a few pumps.

    Solution - bleed your brakes and keep your bike the right way up!
  • skaffen
    skaffen Posts: 72
    Nope, bike is stored on it's wheels in the understairs cupboard, so I'd be surprised if that was the case. The actual pressure on the pads seems fine, it feels the same in the lever, and the pads are definitely contacting the disc pretty early in the pull. It just feels like they're not biting.

    I can re-bleed them to see if it makes a difference but it felt more pad related, I just couldn't work out what could have happened to make them act like that.

    Thanks.
  • pilsburypie
    pilsburypie Posts: 891
    You can rule your "pads heating up and working" theory in or out quite quickly. Find a bit of a hill and perform 15-20 hard stops in a row without completely stopping. Your pads and rotor will be hot enough to sizzle if you splashed water on them. Are your brakes working now?

    If not then contamination could be a reason. Change your pads. They are fairly cheap from superstar.
  • fielonator
    fielonator Posts: 100
    Maybe try baking them in your oven for a bit. This should get rid of any oil or grease on them.
  • skaffen
    skaffen Posts: 72
    pilsburypie wrote:
    You can rule your "pads heating up and working" theory in or out quite quickly. Find a bit of a hill and perform 15-20 hard stops in a row without completely stopping. Your pads and rotor will be hot enough to sizzle if you splashed water on them. Are your brakes working now?

    I think the thing is that because the brakes just aren't gripping very much, getting heat into them actually takes a while. Even down a long hill at the beginning of the ride, if I hold the front brakes on all the way down, I'll need to use the back brake to actually stop. When I said they're awful, they're REALLY awful :)

    I swapped the pads over today anyway so hopefully that will sort it. I don't know what could have got onto the pads,but I gave the disc and caliper a good wipe down with IPA so fingers crossed if there was something hanging around, that would have got rid of it. The pads almost felt a little grainy when I took them out, but it's hard to be sure if there was something up with them, or if I just thought they felt odd because I knew the brakes had been a bit weird. Should know after a quick ride tomorrow.

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