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  1. #1
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    Juicy 7 and piston taking out to clean

    If you take the pistons out to clean because one is stuck do you have to rebleed the brakes afterward?

  2. #2
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    Yes.
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    On a side note, how far can the pistons come out before they pop out or leak fluid?

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    It differs from brake to brake, but you can get an idea of the depth of the piston by looking at the inboard half/side of the caliper. Bear in mind that the piston seal will be situated around 1 to 1.5 in from the pad end of the piston bore.

    If you can find a washer which is thick enough to slide neatly into the caliper's rotor aperture, that should do fine for letting you extend the pistons far enough to get the maximum amount of the piston cleaned without having to remove it completely. Once the pistons are extended, you can use silicone spray and a cotton bud to wipe them clean. Giving them a spray then pushing them back in, then extending them again for another spray/wipe, will help clear any crap out from in front of the piston seal. Silicone spray works better than brake fluid as it is much thinner and will pick up - and carry away - more dirt from the piston bore/seals.
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    Will WD-40 work for silicon spray or no?

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    "Will WD-40 work for silicon spray or no?"

    No, keep that stuff far, far away from your brakes. I don't know what effect WD40 would have on the seals themselves - though I can't imagine it to be good - but the oil left behind after the solvent has evaporated would ceratinly end up on your pads and/or rotor, leading to irreparable contamination.

    You can buy a silicone spray (link) from 3-in-1 (same company as WD40). Very good on brake seals and very good as as water diplacement aid on bicycles as it drives water out without attacking grease and without leaving any oily residue. Excess fluid after cleaning the pistons should always be wiped away, though.
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  7. #7
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    If you've had the brakes for a while you may want to consider a rebuild. Putting in a new set of piston seals works wonders. The seals in my J7's were 1.5 years old and have had a sticky piston the entire time. When I rebuilt them, one of the seals in each caliper was coming apart. There were small bits of shavings in the back of the piston. They were easy to rebuild and a fresh bleed of course always helps.

    Good luck

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    Two other side notes....

    Should it take a good amount of force to push the pistons back in after you squeeze them out, meaning about 3/4 of your own full strength with a screwdriver to push them back in?

    Also is there a way to make the gap after releasing the brakes any bigger w/o it self adjusting so there is a bigger gap so the rotor doesn't rub as much and just have to pull the brakes in furthur to stop the bike?

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    "Should it take a good amount of force to push the pistons back in after you squeeze them out, meaning about 3/4 of your own full strength with a screwdriver to push them back in?"

    It shouldn't do. Sounds like you've got the piston on the piss, or snagged on the seal or seal recess. Use a plastic tyre lever instead of a screwdriver. You can get too much leverage with a driver and end up causing some damage of you persist. It can also damage the piston, or slip off and damage the caliper.

    "Also is there a way to make the gap after releasing the brakes any bigger w/o it self adjusting so there is a bigger gap so the rotor doesn't rub as much and just have to pull the brakes in furthur to stop the bike?"

    No.

    It seems as though you're trying to paper over a crack. You need to fix the seal so that you have properly moving pistons. If cleaning doesn't work, then you'll have to replace the seal(s) and bleed.
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    Anyone know a good place online to get seals then for the caliper? Cheapest preferably....

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    Try a search. Jenson USA should carry them. You'll need a bleed kit, too.
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    I have the bleed kit but feel hesitant to do as the brakes work well but just rub sometimes. Not sure if it is worth it till they are really bad...

    Side not, what is purpose of the lever going forward as it can in the Juicy 7's?

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    Quote Originally Posted by gigabyte772
    I have the bleed kit but feel hesitant to do as the brakes work well but just rub sometimes. Not sure if it is worth it till they are really bad...

    Side not, what is purpose of the lever going forward as it can in the Juicy 7's?
    Buy the seals and wait. The rebuild was a piece of cake. It took about an hour or so to do both and it's pretty straight forward. There is a seal kit and a complete caliper rebuild kit. The complete one is more expensive as it has the pistons and bolts as well. The seals would have done well for me but the shop that ordered them got the big kit by mistake.

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    If only one is sticking can I just buy the kit and hold the one piston that is fine in why pumping lever to push bad one out and then clean it up and reseal it and add some 5.1 inside prior to replacing then bleed the system? Will This work.

    also second question....What is purpose of the lever going forward as it can in the Juicy 7's?

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    Also after putting pistons back in do I mount to rotor prior to bleeding and if not when I pump the levers to release air wont the piston start coming out?

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    Quote Originally Posted by gigabyte772
    If only one is sticking can I just buy the kit and hold the one piston that is fine in why pumping lever to push bad one out and then clean it up and reseal it and add some 5.1 inside prior to replacing then bleed the system? Will This work.

    also second question....What is purpose of the lever going forward as it can in the Juicy 7's?
    You have to take it completely apart in order to get the seals out so you might as well do both while it's open. Go to the Sram/Avid website and look up the Juicy tech manual and they have a step by step for rebuilding the caliper.

    I have no idea about the lever moving out and clicking.

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    Quote Originally Posted by gigabyte772
    Also after putting pistons back in do I mount to rotor prior to bleeding and if not when I pump the levers to release air wont the piston start coming out?
    There is a little red brake pad spacer that comes with a set of brakes when you buy them. I doubt that you get them when you buy a bike but any shop that sells Avid brakes should have a pile of them. The spacers are needed to keep the pistons from coming out during the bleeding process. The video on youtube shows the spacer being inserted.

  18. #18
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    Quote Originally Posted by gigabyte772
    also second question....What is purpose of the lever going forward as it can in the Juicy 7's?
    --> The purpose of the lever going forward and "clicking" into place is so when you have the tire off your bike it's a safety feature. This way you don't accidently pull your brake lever and cause the brake pads to get stuck together. This is great when do repairs but even better if you have a friend that you ride with and they have a roof rack and if your an idiot like myself and can never get the bike on the rack by myself - your friend won't accidently pull your brake handle in by mistake b/c then you will have to pry apart your brake pads. Just remember to "unclick" them before you ride down a really steep section b/c the first pull only disengages the safety feature, it will not engage your brake

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