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Double Brake Failure

Hi all,

Bit of a story, so please bear with me!

The front brake lever for my XT M8000 started to get a bit squishy. I hadn't beld the brakes for a couple of years so thought, now's the time to do my first.

I was recommended epicbleedsolutions.com as they come with really clear instructions and good kit.

So the kit arrives and I proceed with sticking in the brake block in (wrong way around but i'm assured that it wouldn't make any difference by EpicBleed).

The steps i took were;

1) Attach funnel to lever
2) fill syringe with fluid and attach to calliper
3) Loosen calliper nut and slowly push fluid through until no bubbles are coming into the funnel
4) close calliper nut and operate brake lever

So at this point the bottom calliper has been tightened up, as it was before, with the brake block in. The funnel is still attached to the lever with liquid in it.

At the moment I operated the brake a couple of times to get any air out of the master cylinder... fluid started gushing out from the pistons in the calliper.

I thought, maybe i did something wrong or the calliper had failed. So i read the instructions again, really thoroughly and... same thing happened with the rear.

After speaking with EpicBleed and Evans cycles (LBS), the only thing they can think of is that i've had a double brake failure... surly not?!

New callipers are now in the post but I just wanted to find out what went wrong.

Can anyone give me any tips / advice for my next home bleed?

Cheers, Alex

Posts

  • dcwhite1984dcwhite1984 Posts: 85
    edited 24 July
    One question - did you still have the bleed block in when the brake was being operated? If not it is possible you that you have pushed the caliper out too far.

    When you say caliper nut i'm assuming you mean the bleed nipple? the one that takes a 7mm spanner?

    Is it possible you overtightened / undertightened the caliper bleed nipple so that when pressure was applied to the system it leaked out of the bleed nipple and appeared to be coming from the piston?

    Other than that it sounds like you did everything correctly, i have recently done a bleed on the exact same brakes using the epic bleed kit and its fairly foolproof.
    The only difference being that i have bled brakes before.
  • Thanks DCwhite.

    Yeah, the break block was in the whole time.

    Thanks for the correction, calliper nut = bleed nipple. I didn't use a torque wrench but didn't go drastically tight. Around the level it was before i messed with it.
  • reaperactualreaperactual Posts: 572
    edited 24 July
    Nothing is impossible but really don't think a double brakes failure occurred at the same time as you were bleeding them.

    As said you did do everything right and is a fairly simple thing to do. The other bleed nipple possibility has already been mentioned too.

    Try re inserting the bleed block with a paper towel wrapped around it and keep the lever squeezed with an elastic band or similar to see if you can locate where a leak could be coming from, check all connections, the hoses for any signs of oil.

    Maybe worth leaving overnight and check paper towel in the morning to look for signs of oil from the pistons leaving a ring shape.

    Accurately locating the leak will give you an idea of what may have happened to confirm one way or another a failure or small mistake in the bleed process.
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