Bicycle hydraulic brake caliper piston oil leakage repair parts maintenance upgrade kit for Shimano SLX M675 M7000 M7100 XT RS805 M785 M8000 M8100 XTRM9020 R9170 M9000 M9100 calipers, Black

The first piece of information I wanted to share is that I used these Pistons on a Shimano XTR 9020 . There was a previous review that said it wouldn’t fit, I had no issues with mine. Putting them on the XDR 9020 was a little bit different than the video shown on this ad page because the 9020 has a uni-body construction. But with that said, using the air pressure hose to blow out the Pistons worked like a charm. Getting the O-rings in was a little bit of a struggle, but with a litte patience it can be done.

The pistons fit perfectly inside the R9170 existing seals. I did not try to replace the original seals with the included ones so I can’t vouch for the fitment but overall I am super happy with the product and ease of installation!

The seals fit fine. O-rings not so much.

I needed to replace the pistons in my GRX disc caliper as one cracked after pushing my brakes past their limit on a very tough (read dumb) ride. The caliper disassembly and rebuild was straightforward with the pistons and piston seals. I did not use the kit’s smaller o-rings. After a couple of fluid bleeds, the brakes pumped up nicely and my original lever feel has been restored. I do not see any leaks or reason to believe they will start leaking.Although my measurements show the EXNAVI pistons as 0.01mm larger than the OEM version, be mindful that 0.01 is within the error of this type of measurement tool and technique. I run a machine shop and have done a ton of mechanical repairs in all sorts of machines over the years and had no qualms about dropping these replacement pistons in. Although I can’t specifically pinpoint the exact material these are made of, it does appear to be a ceramic. I would even say that the surface finish appears to be smoother than the OEM pistons - perhaps that’s a good thing?Overall, If I ever need to repair another caliper, I would have no hesitation to buy this kit again.

Purchased a while back, didn't use them and thought I'd try them on a new caliper. Just wanted to post for anyone looking for a set for BR-RX400 grx. They are to big for the housing of the piston and piston seals.