Pressing back pistons

Two of my four sram Code RS pistons are stuck out and I can’t get them pushed back in again. They’re on the same side. Have tried the normal screwdriver between old pads and a brake pad spreader all to no avail. Anyone got any tips? The brake is brand new so it’s not like it’s seized with mud and muck. Should I loosen the reservoir cap and try again?

Remove the pads.

Add a drop of oil on the piston.

Use something soft/plastic like a tyre lever against the piston. Make sure you’re applying pressure on the centre of the piston.

And yeah, open the reservoir, but you’ll likely have to bleed the brake afterwards.

I have a double ended ring spanner wrapped in masking tape that I use for this kind of thing. Take out the brake pads and carefully work the smaller end in and ease back the pistons, then switch to the larger end. However, I am not a bike mechanic and someone is bound to have a better solution/tool for you… 🙂

If it won’t go in by pressing in the centre of the piston, try working around the edge of the piston (with the brake pad still in, ideally). Sometimes they push in a little crooked, and need a little coaxing to be square again before they’ll push in cleanly.

They’ll be wonky and need squaring up

Pump them out a tidy bit more to get them square. Once you try to push them at an angle they won’t budge again.

Put a spot of appropriate oil on the piston to help them move.

Push the middle, or with something flat to keep them square in the cylinder.

Plastic tyre levers, works a treat if you get them nice and centred as your pushing evenly on the piston then.

Pedros tyre levers are perfect shape for this job.

Cheers guys….will try all those things tomorrow.

small woodworking c-clamps work quite well (with the pads in and some card on the outside of the caliper) Also good for holding one side in while pressing the other.

if they’re straight but still not retracting, crack open the bleed screw on the lever, you can have too much oil in yhe system to get them back fully, allows a little out

Can’t believe nobody had suggested a new bike yet!

Don’t put lube on them. SRAM say not to in their documentation.
As above they’ll be wonky. If you’ve got a pad spacer put it in with the pads out and squeeze the lever to extend them out a bit more. The spacer will stop them popping out completely. Then use a tyre lever to push them back very carefully. Failing that your LBS will likely have the SRAM piston tool to correct exactly this problem. Or you can buy it yourself but it’s £80!

Sram Tool Ultimate Piston Press (Evenly Pushes Pistons Back For Pad Replacement And Bleeding) – Fits Small, Medium, And Large Calipers:

After years of struggling with various prodding tools, I now use one of these: https://www.ebay.co.uk/itm/363055974403?itmmeta=01HXXM92KB0SE53DMCCW4YEXM1&hash=item5487d28803:g:cZAAAOSwVgxgnabZ&itmprp=enc%3AAQAJAAAAwCsMMY6kOA%2BG2r84TdOr9PljZqLHfoOxgfKJYleUgEYWJQh5kl3gRSlkVNEqGzUTNomXGn3Mpt0P%2BwQV8gD0NaQS7zjU2O7j1qOsyGIRcEESy6gbH6spOGpFZbBQ%2BUAB08kcGDZI5GslIHRDYdC102pjzPOjdhTL3mQdiyaKud93xhBoFRps38mcgkWzJsdDwAmbLHtX5Rphm58pt3KwK7iKCdczZy4b%2FndzIW36EDiEdnLhLSCH47k1yhp2EvX8Qw%3D%3D%7Ctkp%3ABk9SR4aqpLTvYw as per Klunk’s response above.

[ETA: may depend on the model of calliper you have.]

I had no idea this was so complex. I’ve just been using the ‘push the high point down with a tyre lever’ technique.

Using lube isn’t the best idea as depending on which one it can expand the seals and cause more problems.

Use either dot fluid or dot friendly grease (usually the red stuff) and wipe down once they are back in.

Smear a bit of grease or dot fluid on the piston, undo the bleed screw and push them back with a Pedros Tyre lever. It’s worth edging the two pistons out that are currently retracted as well and smear them with dot/grease and then push them back. Sometimes you can end up with pistons sticking out because the other two are stuck in.

I know Sram say not to apply even Dot fluid to the pistons, but I have a Code calliper where the pistons kept on getting stuck and triggering unevenly and the cotton bud of Dot carefully applied to the edges of the extended pistons technique, immediately solved it. The brake set was old OEM dead stock I think had been sitting around for years before I bought them cheap and the sticking pistons even had a sort of whitish mineral crust on them when popped out. Once pushed back in after this, I cleaned the inside of the calliper well with brake cleaner and there’s been no downside so far. It was this or give up on them anyway TBH.