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  1. #1
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    Just changed pads for Juicy 3. Sticky wheel

    Hi folks,
    Just managed to change the pads on my rear brakes, Avis juicy 3's. Had a few problems getting the caliper wide enough to slot the pad assembly in, sorted it in the end but only just, so when the wheel went back in it was a snug fit to say the least. Question I need answering is this: Will the calipers now stay pressing the pads against the disc or will it just wear the top surface of the pad off and in time loosen off.
    Because at the moment the wheel does not spin freely enough, comes to a halt after a few seconds.
    Cheers
    Andy

  2. #2
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    The pistons have self-adjusted (extended) as the old pads have worn down. You need to remove the wheel again and use a large, flathead screwdriver to push the pads/pistons apart again. You could also remove the pads and use a plastic tyre lever to push the pistons back into the caliper to get the same result. The pistons should self-adjust to the correct position for the new pads with a couple of pulls of the lever.
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  3. #3
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    Hi Steve, thanks for the fast reply. I have pressed them back, they didn't go back far enough so I had to bleed some fluid out from the bleed screw while pressing them, this helped but they are still rubbing on the disc. The pads were an absolute mare to get in with the spring so I've been opening the calipers with long nose pliers with the bleed screw open by prising them open through the top hole and then the bottom hole where the two prongs poke out from the pad.
    Shall I persevere this way?
    Cheers
    Andy

  4. #4
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    By "opening the calipers with long nose pliers", do you mean pressing back the pistons? If so, I think you may be running the risk of damaging the pistons. As I said, a plastic tyre lever is the ideal tool for this job.

    Allowing fluid to escape when the pistons are retracted is good thinking; however, if the DOT fluid is still good, you really shouldn't need to allow fluid out as it should simply refill the master cylinder when you retract the pistons (assuming that the system wasn't over-filled originally). How old is the system? Any idea when the last bleed was?

    Oh, and if you're letting fluid out, I'd recommend removing the pads. A splash of DOT will ruin them pretty quickly...
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  5. #5
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    The bike is just turning a year old and this is the first pad change, the pads were totally worn out as I did a couple of laps around 'follow the dog' at cannock and it was really wet and muddy so I think it finished them off.
    The pads are now in so I have been trying to open them by using the pliers to open the pads out while in situ, not making contact with the pistons just the lugs that are accessible from the hole in the top and the bottom of the calipers. Sorry, didn't mean to confuse you, was getting my terminology wrong.

  6. #6
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    Ah, I see. I'd suggest that you remove the pads, clean the caliper interior and whatever is showing of the pistons (silicone spray is excellent for this job) and then push the pistons in from there, one at a time. If the pistons simply won't return, then perhaps you do need to flush the fluid*.

    *DOT fluid thickens as it deteriorates from heating and as a result of contact with the small amount of air that passes the caliper and lever seals. This thickening might explain the reluctance of the pistons to return, although I would say it was fairly unlikely after only a year.
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  7. #7
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    That's great, thanks for the help Steve, I'll do that.
    Just one more if I may, I notice that when you look at the pistons it looks like a cup with a rod in the centre that stands proud (the bit that clicks in to the pad and keeps it there). Can I press ether part of the piston back? ie. the edge of the cup or do I press the centre rod or does it not matter.

  8. #8
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    update, I've got it 90% better, I think the calipers were slightly off centre, sorted them by tightening them up while holding the brake hard. I'll have a go at letting a bit more fluid out tomorrow if it's no better after a ride to work.

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    "I notice that when you look at the pistons it looks like a cup with a rod in the centre that stands proud (the bit that clicks in to the pad and keeps it there)."

    I'm not particularly familiar with Avid's caliper design, but I have a feeling that the cup/rod gizmo may be a magnet to retain the pads. Don't hold me to that, though; I'm sure somebody will pipe in to confirm one way or another. Regardless of what it is, I would imagine that the 'reset' position would be one where the rear plate of the pads is flush with the caliper interior. If it looks too risky applying leverage to the cup/rod thingy, then leave the pads in and use a big, fat screwdriver to push them back. A piece of card folded into a 'V' and inserted between the pads first will ensure you don't mark the pads with the tip of the 'driver.

    I should have thought to suggest checking caliper alignment. I know that Avid uses the dubious-to-useless CPS washers for caliper alignment, but I'd recommend removing the pads and getting the caliper lined up first before refitting the pads.
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  10. #10
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    Nice one Steve. Thanks for this. Feeling more positive about the whole shananagans. Will have another go tonight, hopefully just a case of getting the calipers on straight.

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