SRAM G2 RS – stuck pistons

Pistons in my G2 RS brake on one side are stuck, completely. Managed to sort the rear brake with a bit of fettling but the front is completely stuck.

Any tips for removing that won’t fubar the caliper? I’ve taken it apart and tried a bit of persuasion but they don’t want to budge…

Alternatively, where’s the best place to by a new caliper these days now wiggle are gone?

From what I can make out the R and RS are the same caliper and the only place I can see with stock are the german sites or bike inn.

R, RS and RSC all use the same piston, even the original Guides, although i think the bleed port has been updated to Bleeding edge on G2, I ordered from the German sites a year ago.

Wasteful, but look for a set of G2 R’s or even Guide RE’s with the older style code caliper and then chop and change bits to suit.

Any tips for removing that won’t fubar the caliper? I’ve taken it apart and tried a bit of persuasion but they don’t want to budge…

Have you tried something like the R3Pro piston release tool to exercise each piston individually? Failing that compressed air may do the job (with appropriate precautions against flying pistons!).

If they are the ceramic pistons you may also be able to crack them with a punch or similar which may make them easier to remove.

As it turns out, the slot in the calliper will take a 3mm alan key. This is what I do to keep the pistons on my brakes balanced.

1. remove the pads

2. undo the bolts and remove the calliper from the frame. Or remove the wheels

3. Put the 3mm alan key into the slot push it all the way in.

4. Use a cable tie to around the calliper to prevent accidental loos of the alan key.

5. Use the leaver to advance the pistons until they stop at the alan key.

6. clean the pistons with a q tip and isopropyl cleaner

7. push the pistons back in, use a plastic tyre lever to push them back so far. Then put an old set of pads in and use a screw driver between the pads to push the piston all the way in.

8. refit the calliper or wheels & align the calliper (using the slots) with the disc.

9. Put new pads back in & the pump leaver to advance the pistons.

From there you’ll need to balance the pistons.

I do this procedure every couple of months and every time I put in new pads in workshop.

R, RS and RSC all use the same piston,

Helpful – Thanks

Have you tried something like the R3Pro piston release tool to exercise each piston individually?

The bike has been sat for long time. A combination of a shimano bleed block half in and a bit of fettling didn’t budge it – I’m going to buy one of those blocks though – looks useful for more regular maintenance.

Wasteful, but look for a set of G2 R’s

Found new RS on bike-inn for £5 more than just the caliper so bought that. I’ll no doubt have an off and smash a lever at some point so be good for the spares box…

Can go full crazy on the old calipers now and see if I can free them up.

I have the same brakes and they do have a propensity for sticking pistons.

I made my own version of that R3Pro piston release tool using an old Shimano yellow bleed block and a hacksaw (but then later bought the R3Pro tool as its much nicer :-D) and give the pistons a good preventative clean with isopropyl alcohol every time I change the pads.

There’s also some great guides on Youtube about how to fix SRAM sticking pistons without a tool, as well as advancing the pads evenly and centering them properly  e.g. https://www.youtube.com/watch?v=AY80Zt47M3A

The jury’s also out on whether to lube the pistons with DOT fluid (SRAM say absolutely not, but I’ve tried it and haven’t died yet).

or bike inn

That’s were I went to in the end.  I could’ve bought a brand new set of Deore for the price of them, but less landfill changing just the callipers and I’d still need to bleed them (internal routing) o no extra work this way.

Reading with interest as I have these brakes on one bike, just wandered over to it to squeeze the brakes a bit.

Regarding bikeinn I’ve learned to trust them on quality and price, but I’ve also learned to not hold my breath on delivery timescales. Relax, they’ll appear in about two weeks.