Hey guys,

I am relatively new to hydraulic disc brakes so hope someone could help me out. I am having an issue with the master piston sticking on my CX bike. I have fixed it twice but it’s just happened again and it’s becoming a bit annoying taking apart the shifter/brake unit every few months. I’ll strip everything down, remove the master piston, clean and regrease and reinstall everything then bleed…but maybe ~4 months of use it’ll be stuck again.

Is this just something I have to live with? A known issue with SRAM? Will upgrade the calipers make any difference?

Thanks!

I’ve got one lever that does this. Strip and regrease didn’t help in my case. I’ve just had a replacement piston delivered but haven’t had a chance to fit it yet. Hopefully that will sort it.

I have thought about replacing the piston, though it doesn’t seem like a part that can really wear much

I wonder if this is the same piston issue that some older guides have where the piston can swell and jam? Is so is it still in warranty – if so I’d go down that route. If it’s not I’m sure there’s another thread on guides and replacement pistons from eBay.

No, unfortunately not in warranty.

I believe you can now get replacement pistons from SRAM though, rather than Ebay? PDW, where did you get your replacement from?

I got mine from ebay. SJS do them, but they’re out of stock:

https://www.sjscycles.co.uk/brake-levers/sram-hrd-hrr-shifter-brake-master-piston-assembly-kit-right/

The eBay one seems to be a genuine Sram part. It’s annoying to have to buy a full kit for £20 when I’m sure the only things that need replacing are the o-ring and seal on the piston.

I think SRAM may have extended the warranty window or they’ve been kind to me at least. Definitely worth getting in touch with your shop.

I just did mine over Christmas… they weren’t sticking, but have benefitted from an overhaul in any case.

This video goes into detail on why they stick, and what SRAM have been doing about it: https://www.youtube.com/watch?v=gqEHA2dRgqs

As someone above has posted, SJS sell replacement pistons.