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Anyone had good or bad experiences with replacement ceramic pistons?
First time ever** in shimano I've had one of the pistons crack INSIDE the caliper (I'm scratching my head on how)
Couldn't get pistons to retract so took it apart and little bits of ceramic in the ports... I blew one out and its a big bit missing off the back on that side.. yet to remove the other 3 but I expect at least the same side will be damaged as well
I've cracked one pushing it back ages ago but that was the outside and cracked one blowing it out with an airhose and it hitting a ceramic floor tile but never seen them disintegrate on the inside
I thought it was basically same price to just buy a new caliper?
Sounds like Shimano are just a bit crap tbh. Everything I have read suggests the best route is just to replace the caliper with a new one. If it’s disintegrated inside there maybe shards of it floating about / scratching inside the bore etc.
Ironic that this post should come up just after I'd cracked a piston and bought a new caliper.
Top tip: use the proper bleed block for four piston calipers or they'll crack!
I couldn't decide whether to buy some new pistons off eBay, which were about £30 (and I wasn't sure of quality) or just get a new caliper. So, I ordered a caliper in the end for £68, which comes with finned pads worth around £25.
I thought it was basically same price to just buy a new caliper?
£70 for replacement new...(though with free pads)
vs £4 for dodgy aliexpress (HEPPE Bike Hydraulic Brake Caliper Ceramic Piston MTB Road Bike Disc Brake Piston For M640 M810 M820 M7120 M8120 M9120 4-Piston) to £40 dodgy eBay vs look for someone selling a broken Shimano 4 pot and take those out
Hence why I'm asking for experience
If it’s disintegrated inside there maybe shards of it floating about / scratching inside the bore etc.
Once I find pistons I'll flush and airhose
@stevextc Where did you get to with this? I bought one of the cheapo Heppe kits from Aliexpress as a sort of precaution before stripping down a suspicious Zee caliper, but curious as to whether you tried one of those or just bought a new caliper?
In the end I just put a 6120 on (£50 with a free lever and hose )… had to cut the banjo off so never bothered trying to go back. Still got it so if I end up with another broken 4pot I’ll maybe resurrect it.
Cheers, I'll report back if I end up using the replacement pistons/seals. It's a shame, but utterly predictable, that Shimano doesn't sell a proper, bona fide rebuild kit, but there you go.