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  1. #1
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    Hope's have stopped working since new seals

    Hi,
    Need somebody to come to my rescue!
    I have the old style Hope Mini brakes. Earlier I did a seal change on the caliper, and installed the 'new' phenolic pistons. All was well I thought.
    When I attempted to refill the system with 5.1 fluid, this was a very slow process - each squeeze of the lever resulted in hardly any fluid being introduced into the system. After 10 goes of this, I believed the system to be full.
    Now, my problem is that the pistons do not move at all. They are installed the correct way up (letter facing towards pads), and were coated with fluid prior to installation.
    Can anyone offer any advice ?

    Thanks
    Brad

  2. #2
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    What happens when you pump the lever? Air lock for a certain time can be common, increased by the positioning. I will assume the caliper was well below the lever?

    Is it possible to explore the possibility of a clogged bleed valve? Same thing when you remove the bleeder valve?

    I am not an expert on the old type of Minis, predating the Mono line, so page Steve UK to this thread. He's quite knowledgeable about Hope products in general and very helpful. He also has a tutorial on the boards with an excellent collection of pictures.

  3. #3
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    Thanks for the quick reply. When I pull the lever, there is hardly any resistance. Whilst looking at the pistons at the same time, a tiny amount of fluid is trying to seep out.
    I have followed Steve's guide & Hope's but am non the wiser! Thinking now that I should have just left it well alone!

  4. #4
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    What's the possibility of the seals not sitting right?

    What's done is done and the intent was to maintain the brake for the better, so don't worry, there will be a solution soon. The good thing about Hope is they are investment parts, rather than throwaway parts. Mess it up, there's always a repair/rebuild solution.

    It's about 7pm UK time, so Steve should be waking up just about now

  5. #5
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    The system should be filled after 4-5 lever cycles. Could you describe how you are performing the bleed? If the lever moves but the pistons don't, then the system isn't full.
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    What luck for rulers, that men do not think - Adolf Hitler

  6. #6
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    Ok Steve, here goes: Remove diaphram cap on lever, top up with fluid to max, undo bleed nipple 1/4 turn, squeeze lever to bar, hold, retighten nipple. repeat.

    The strange occurance with this 'bleed' is that the fluid did not get introduced from the filler cap to the rest of the system very quickly (only taking a few mm at each try). I have not noticed this before when bleeding - it should flush through quickly.

    The question is why is it so slow to let new fluid into the system? I bleed brakes using the 'manual' method. Should I go out and get an air powered system to force the issue?

    Brad

  7. #7
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    "Remove diaphram cap on lever, top up with fluid to max, undo bleed nipple 1/4 turn, squeeze lever to bar, hold, retighten nipple. repeat."

    All good there. Sorry, but I had to check.

    From your description so far, I'm still of the feeling that there's air in the system. If the seals were 'holding' onto the pistons, as new seals often do, then you'd be getting the corresponding resistance at the lever, but you're reporting that that lever is unusually light. This is one of two things; air in the system, or a fluid leak (which would exacerbate the problem by also introducing air to the system). Do you have a block between the pistons when you bleed? Although it's not mandatory, having something inhibiting the pistons during a bleed allows you to check lever feel as you go, so you don't need to get pads and rotor back in to see how the bleed has gone.

    A manual bleed is adequate, so unless you have the bleed kit to hand I wouldn't be worrying about it. If the system is full of fluid and properly sealed, the pistons have to move, it's that simple; there's nowhere else for the fluid to move to. I wouldn't be concerned with the rate that the fluid bleeds from the reservoir, just keep an eye on the fluid leaving the tube at the bleed nipple. When you've had no air for two or three cycles of the lever, you should be air-free.
    Last edited by SteveUK; 01-06-2008 at 12:11 PM.
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  8. #8
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    OK Thanks Steve. No, I don't usually put a block between the pads as you do. I will however try this in future.
    I am now thinking that there may be insufficient fluid in the system, I will try and re-bleed and will report back (when there is daylight!). Any idea how much fluid the 'average' rear brake actually requires? How many full top-ups should it need from empty?

    Brad

  9. #9
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    "Any idea how much fluid the 'average' rear brake actually requires? How many full top-ups should it need from empty?"

    4-5 reservoirs worth should do it.

  10. #10
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    I got the 5.1 fluid all over the body of the lever (black caps and main body). I washed it all down with water but will this actually cause any damage to the finnish. I can't imagine it would as it's the same metal inside that has to hold the fluid. Just wanted to check

  11. #11
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    Well the inside isn't painted, now is it? Left on the surface long enough, it'll damage the paint. Usually a few seconds won't hurt the finish if you wipe it off and rinse it down.

  12. #12
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    The finish is anodized anyhow.

  13. #13
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    UPDATE:
    Must have carried out the 'squeeze & tighten' procedure 50+ times - finally it works.
    Let this be a lesson to anyone filling up a Hope system from scratch. There was obviously lots of air in the system, and trying to force fluid into the caliper using the tiny fluid reservoir meant that it was always going to be a long job. Thanks for the tips on perserverance guys!
    BTW the phenolic pistons I have upgraded to do not as yet feel any different. I am going on a long XC ride at the weekend - maybe notice some difference then?

    Brad

  14. #14
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    Likely difference will be fade resistance.

    Yup, if there's a lot of air in the system, air locking provides a lot of resistance and there is a smaller stroke volume that will necessitate lots of pumping from the reservoir. I have done this in the past:

    Larger volume syringe attacked directly to the bleed port (valve removed) and pumped up from the caliper towards the lever. In the past, I've primed the line from the caliper by removing the master cylinder. i've also gone in reverse, also primed each component, then bled the bubbles out. Works great.

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