I have a Shimano 105 BR-R7070 hydraulic disc brake and just discovered that the front caliper is leaking oil from one side of the pistons. I'm wondering if this is fixable? If not, what replacement shall I get? I can't seem to find 105 disc brake calipers anywhere. Is it compatible with other calipers and what would you recommend?
Usually, with leaking Shimano brakes, the piston has cracked. Have you changed the brake pads or otherwise messed with the pistons lately?
Aftermarket pistons and seals are available, but that would be a non-authorized hack job that Shimano does not authorize. Don't expect to keep your warranty if you do so, and your safety is no longer guaranteed. Up to you if you think it's worth it.
Every Shimano caliper is interchangeable in terms of functionality.
Concur - given its the front brake, the most important one, I'd buy a new caliper and have confidence in my ability to brake when required.– Criggie ♦Nov 28, 2021 at 23:57
Thanks for the answer. I was bleeding the brake and did hear some squeaking sound while trying to push the piston back after an accidental press. So I guess you are right that the piston is done. Only issue is that getting a brake caliper seems very hard at this time. Can't find an available R7070 anywhere and I'm trying to broaden my choice. Nov 29, 2021 at 1:54
@NingWang Yeah, it's unfortunate that the Shimano ceramic pistons are that fragile. If you're okay with the risk, you could buy those aftermarket pistons OR harvest one from a cheap MTB caliper. Or you can buy any caliper that works with your brake mount setup (flat mount?) Anything from Tiagra to Dura-Ace will work, and even the latest MTB flat mount calipers too. Nov 29, 2021 at 2:48