- Cracked Shimano piston… Any hope of spares?
There are so many threads on this topic it’s depressing 🙁 I’m tempted to have a go at 3d printing some. The issue is heat insulation and I’m not expert enough to figure out what material would be best.
The thing to bear in mind is those eBay ones are £8 each while you can often get a complete new XT caliper for £30 in sales (including pads and other spares that can be pillaged)
If taking apart the caliper I’d also be wanting to replace seals (or at least have spares handy) and the other piston unless the brakes are < 2 years old. Thus suddenly you’re looking at >£16 + your time vs £30 – £6 (pads) = £24 for a new caliper with warranty.Posted 3 months ago
1) possibly stupid question- it is a ~22mm piston so has anyone tried a Hope 22mm phenolic jobbie (possibly machined down)? X2 is 22mm and quite cheap
2) The minimum conceivable (to me) cost for a custom piston in solid high quality thermally insulating ceramic would be £6 in small runs.
If using a ceramic insert into an alloy cup I think £4 is feasible.Posted 3 months ago
Mtbr thread where someone claims an X2 piston works despite the extra depth:
I also found a discussion in French where someone mentioned machining around 1mm off.
I might have a bash at some alloy + ceramic pistons too for fun.
It’s possible those eBay ones are ok but they seem expensive for what they are.Posted 3 months agotomparkinMember
I also had cause to ask this question previously — eventually sourced a second hand replacement caliper.
I spent a while toying with the idea of rebuilding the broken one with an eBay piston, but in the end the risk of something going wrong with it didn’t seem worth the candle 😐Posted 3 months agodamascusMember
I can’t see why you would risk messing with brakes when a new caliper and pads are £35.
Shimano unfortunately are throw away at those prices. If you want sustainably, replaceable etc then buy hope.
I always put my old shimano brake parts on ebay as spares or repairs. Someone always buys them as you can’t get new parts.Posted 3 months agomunkiemagikMember
I found myself in the exact same position before.
I went ahead and ordered the Hope X2 piston HBSP235.
It is fractionally taller but identical diameter to the SLX M675 piston it replaced and there was enough space between the pistons to fit new pads without rubbing. You just wont be able to get two Hope X2 replacement pistons in, one on each side without sanding some pad material off maybe.
Just obviously don’t try and use the Hope piston seals!!! Because Hope are dot fluid they use a different rubber for their seals and it will expand like crazy in the mineral oil shimano brakes use.
Sizes for the seals are identical though but no industrial supplier anywhere that I came across sold the correct size square seal made in NBR rubber that you need for shimano back when I was searching.Posted 3 months ago
Just as an aside, I was able to pop out the good piston (literally) by using the tubeless compressor on my pump and blowing air into the caliper so at least I have a good spare.
Tempted to try and get a cheapo caliper to cannibalise on eBay and see if I can rebuild it though…Posted 3 months agojohnjn2000Subscriber
Bloody good job you didn’t take me up on my offer. The boy was changing his rotors yesterday and was having trouble aligning the calliper, turns out the piston was screwed so I had to swap my spare to his bike. He has a race on Sat so that was a stroke of luck.
Hope you get it sortedPosted 3 months ago
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