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  1. #1
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    Shimano replacement pistons

    Hi guys

    My names Connor, a student studying 3D design at Plymouth University. I just wanted to gets some feedback on a project I am keen to start.

    Currently running Shimano Saint brakes and unfortunately I discovered that one of the ceramic pistons had broken, to my knowledge Shimano don't supply replacements.

    As an engineer and experienced machinist, after doing some research I am looking into producing my own ceramic replacements. Still very much in it's early stages but before I invest a lot of time and money into this project, I wanted to see how beneficial this would be to other riders, that have experienced the same problem as I have.

    Will be looking into producing a range of pistons, not just for the Saint line but other failer prone calipers like XT's and experimenting with material types.

    After considering material and labor costs, per piston could be sold for around 12-16.

    Please feel free to comment or email me at connor.j.brodie@hotmail.co.uk with any feedback.

  2. #2
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    to me, failure of a piston is a warranty item that should be resolved with shimano and the local bike shop. It's not normal wear and tear.

    Assuming the caliper is out of warranty, when it comes to replacing an actual piston inside a brake, I would prefer to just buy a new brake caliper because the cost of a new piston, installation labor, brake bleed labor, and new brake pads would get close to the cost of a new caliper. Plus, with a new caliper, I get a new warranty.
    "a hundred travel books isn't worth one real trip"

  3. #3
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    Absolutely I agree, failure of the piston does come under warranty. I myself am attempting to claim a new caliper through Shimano's 2 year warranty scheme.

    All things aside this is purely a challenge for myself, as I suppose I consider this more as a project of product development. In this case focusing solely on the pistons, as evidently some have proven to fail. I'm not looking to challenge Shimano's years of experience, merely collaborate with it.

    As an individually sold piston Id like to think that it would be purchased by those much like myself, those that perform their own bike maintenance. This is exactly how I discovered the problem myself and I intend to resolve it. So by all means buy a complete caliper to replace the damaged one, however I see the purpose of this project not only to develop the product but to challenge the lack of resourcefulness in today's society. It is very much common practice now to replace over fix.

    I must argue that although i understand where you're coming from with your statement, I cannot completely justify it. As it is not uncommon for companies, Hope, Formula, FSA, Funn and Hayes being those i found that do manufacture and sell individual pistons and seal kits. So if what you're saying is true, then surely it renders those products useless. However the fact that 'ChainReactionCycles' have chosen to stock these very items, proves otherwise.

  4. #4
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    I have a hunch that Shimano's reluctance to sell repair parts for brakes has as much to do with risk and liability as planned product obsolesce. I've been frustrated by the fact that they don't sell piston seals for levers and I had to retire a set of perfectly good XTR 975 brakes because the lever seals failed. But somewhere in the heart of their corporate legal advisor department, someone probably said that the risk of having someone service a brake improperly is too great and it could result in a life threatening incident, and they decided that replacement parts were too big a risk. They probably cringe at the possibility of having people shortening hoses and bleeding brakes incorrectly.

    On the plus side, Shimano price replacement levers and calipers fairly so it doesn't cost twice as much to buy a brake in replacement parts as it does to buy it assembled. Looking at the price for assembled XT 8000 brakes at Universal Cycles, the assembled brake system is $107 and the lever is $45 and the caliper is $53. The XTR 9020 brake system is $195 assembled and the replacement lever is $75 and the caliper is $99.
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  5. #5
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    This is also about logistics. Stocking all these parts and distribution of them is not cheap nor easy.
    Last edited by thickfog; 11-11-2015 at 01:12 PM.
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  6. #6
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    Any body out there is the same boat as op and me? Got a spare piston for sale?

  7. #7
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    Do saints and zee's use the same pistons? Would be a nice option.

    Metal Piston Hydraulic Brake Caliper Parts For Shimano XT/M785/M8000/SLX675 | eBay

  8. #8
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    Dunno, but I just recently bought some SLX calipers from Jenson for $24.99. They come with new metal brake pads and the caliper bolts and bleed block. Keep in mind the brake pads themselves often go for about the same price, especially at a bike shop. At that price calipers become throw-away. I'm going to pay close attention though and warranty them if they start leaking.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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  9. #9
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    Thanks for the replies! Both those are good options for the dual piston shimanos.

    I ended up getting a replacement directly through shimano by filling out their warranty claim form and sending them in. Luckily they were just shy of the 2 year mark.

  10. #10
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    While we are on replacement pistons for the M8000, mine broke into pieces when I tried to get the out with an air compressor -- psi was only 40. I was rebuilding the calipers due to the leaking pistons.

    Anyone tried these metal ones from eBay? Metal Piston Hydraulic Brake Caliper Parts For Shimano XT M785/M8000/SLX M675 | eBay

  11. #11
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    Quote Originally Posted by DerrickT View Post
    While we are on replacement pistons for the M8000, mine broke into pieces when I tried to get the out with an air compressor -- psi was only 40. I was rebuilding the calipers due to the leaking pistons.

    Anyone tried these metal ones from eBay? Metal Piston Hydraulic Brake Caliper Parts For Shimano XT M785/M8000/SLX M675 | eBay
    Hi there,

    I bought one of those from Ebay to replace a chipped piston in a Shimano M675 caliper. It was a real pain to fit and unfortunately I nicked the seal when pushing it in, which I only found out during bleeding. So, I scrapped it.

    Whilst the caliper was apart I measured the piston and seal and found them to be the same size as Hope X2 ones, 22mm diameter (part numbers, for the pistons HBSP235, for the seals HBSP236). I ordered a set of pistons and seals, which came to around 12.

    I fitted the new pistons and seals in the Shimano caliper easily (way more easily that the metal one I messed up). One error I did make was that I didn't measure the height of the piston! The Hope one is about 1mm extra in height, so when fitted they stick out ever so slightly. I also put new pads in, and when fitted back onto the rotor there was just enough room, literally 1/2mm or less, between the pads and rotor, but it was a good fit (no rubbing). I bled the brake and have been using it for a week now on my daily commute. They are really good.

    I did weigh up the cost of getting a new caliper but I only paid 10 for the whole brake to begin with, so even with grease (2.50), fluid (7) and the X2 parts (12) it was still less than a new caliper.

    I hope this helps anyone that finds themselves in a similar dilemma.

  12. #12
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    Nice find thanks!

  13. #13
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    Quote Originally Posted by smirnofred View Post
    Hi there,

    I bought one of those from Ebay to replace a chipped piston in a Shimano M675 caliper. It was a real pain to fit and unfortunately I nicked the seal when pushing it in, which I only found out during bleeding. So, I scrapped it.

    Whilst the caliper was apart I measured the piston and seal and found them to be the same size as Hope X2 ones, 22mm diameter (part numbers, for the pistons HBSP235, for the seals HBSP236). I ordered a set of pistons and seals, which came to around 12.

    I fitted the new pistons and seals in the Shimano caliper easily (way more easily that the metal one I messed up). One error I did make was that I didn't measure the height of the piston! The Hope one is about 1mm extra in height, so when fitted they stick out ever so slightly. I also put new pads in, and when fitted back onto the rotor there was just enough room, literally 1/2mm or less, between the pads and rotor, but it was a good fit (no rubbing). I bled the brake and have been using it for a week now on my daily commute. They are really good.

    I did weigh up the cost of getting a new caliper but I only paid 10 for the whole brake to begin with, so even with grease (2.50), fluid (7) and the X2 parts (12) it was still less than a new caliper.

    I hope this helps anyone that finds themselves in a similar dilemma.
    Hey smirnofred,

    Just to confirm, you said the seals from the Hope caliper matches the ones in the Shimano caliper? It would be nice to have a replacement seal to use with the stock pistons if they are still in god shape.

    Thanks!

  14. #14
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    Quote Originally Posted by smirnofred View Post
    Hi there,

    I bought one of those from Ebay to replace a chipped piston in a Shimano M675 caliper. It was a real pain to fit and unfortunately I nicked the seal when pushing it in, which I only found out during bleeding. So, I scrapped it.

    Whilst the caliper was apart I measured the piston and seal and found them to be the same size as Hope X2 ones, 22mm diameter (part numbers, for the pistons HBSP235, for the seals HBSP236). I ordered a set of pistons and seals, which came to around 12.

    I fitted the new pistons and seals in the Shimano caliper easily (way more easily that the metal one I messed up). One error I did make was that I didn't measure the height of the piston! The Hope one is about 1mm extra in height, so when fitted they stick out ever so slightly. I also put new pads in, and when fitted back onto the rotor there was just enough room, literally 1/2mm or less, between the pads and rotor, but it was a good fit (no rubbing). I bled the brake and have been using it for a week now on my daily commute. They are really good.

    I did weigh up the cost of getting a new caliper but I only paid 10 for the whole brake to begin with, so even with grease (2.50), fluid (7) and the X2 parts (12) it was still less than a new caliper.

    I hope this helps anyone that finds themselves in a similar dilemma.
    Great information. One thing to think about if doing this though, is that Hope brakes use DOT fluid and Shimano uses mineral oil. I would love to know now, since a year has passed, whether this still works or whether the seals swelled and the caliper stuck.

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