Shimano Brake Piston Popped out while cleaning.

[nord]

I had a Shimano brake piston pop out of the caliper while i was cleaning the the sides of the piston. I got the piston back in the caliper just by pushing it back in. Now its sticking/ Slow extending.
Is there any some way to fix this? Do popped out piston normally slide back in the the caliper easily?

[rideit]

Gently apply cash to your piston, (new caliper) pretty sure that’s it with these. I hope I’m wrong…

[TCNROMPER]

I killed a caliper the same way a couple years ago...Mine leaked shortly after and killed the pads as well.

[nord]

Thanks for the feedback. The caliper or piston may be toast.
I probably scuffed or scratched the piston pushing it back in. The outboard side was the free moving side,. After the outboard piston popped out and got pushed back in, its the sticky side. My calipers are the alivio-unbranded deore level with the black plastic pistons. So it won't be that expensive to get a new caliper. If I can find a lightly used caliper, I could take the pistons from that. The effort/reward ratio may not be good when salvaging pistons and then installing into a used caliper.

[rideit]

In general, once a shimano piston has come completely out, there is really no way to get it working properly again. I am sure someone has done it, but a caliper only at that level is so cheap, it’s best to just start from scratch, IMO

[kalisto]

^ Actually not true, but they are _very_ sensitive.

I did some caliper rebuilding with some photos here:
https://www.tetongravity.com/forums/...himano-caliper

If the piston entirely fell out, and looks structurally sound with no cracks/chips, it's probably just the seals. The problem is that you basically can't source them from anywhere, but if you can salvage another broken caliper, then you'd be good to go.

I actually have some seals kicking around courtesy of Falcon3, so if that's what you need and they'll fit. I'd gladly send them your way.

[nord]

^ I actually have some seals kicking around courtesy of Falcon3, so if that's what you need and they'll fit. I'd gladly send them your way.

Thanks for the offer. My Caliper takes the 22mm Black (Plastic?) pistons so I can' t use your parts from your 4X 17.5mm ceramic piston caliper.
If anyone else has a 2 piston Shimano Caliper for parts or in good working shape I could use it.

[rideit]

Ah, I stand corrected. Cool to know.

[kalisto]

Thanks for the offer. My Caliper takes the 22mm Black (Plastic?) pistons so I can' t use your parts from your 4X 17.5mm ceramic piston caliper.
If anyone else has a 2 piston Shimano Caliper for parts or in good working shape I could use it.

I think there was a few in that thread that may have what you need.

[XXX-er]

So my SLX brakes would lose lever completely with the bike sitting in the truck on its side overnight and they would come back/work OK when I pump them a few times, obviously i feel the need to bleed

So I got a free bleed from a local bud with a bleed kit he didnt wana lend it but he would do it, long-story-short after getting the bike home there was too much fluid left in the system probably cuz he didnt use a bleed block so I couldn't get the new padz in the caliper

so text shop bro (a real shop bro), he suggests as opposed to fucking with the caliper rotate the lever flat, crack the screw to takeout some fluid,

spread the pistons enough to get the new padz in, except for what pukes out the top fluid stays in the system the air stays out, they are now awesume and no spongy lever !

Your takeaway is if you end up with too much fluid in the system remove it by cracking the bleeder screw on the lever not the caliper

[Canada1]

clean the seal. Put high silica grease on the seal. Re-insert. Better is to replace the seals. I've had them go back to better than before. I've had them weep. It doesn't cost you anything to try.

[LC]

So my SLX brakes would lose lever completely with the bike sitting in the truck on its side overnight and they would come back/work OK when I pump them a few times, obviously i feel the need to bleed
...
Your takeaway is if you end up with too much fluid in the system remove it by cracking the bleeder screw on the lever not the caliper

Over-filling Shimanos is the way to go for the best feel and consistent bite point. This is a good guide. Really does only take 5 minutes for both levers once you know how to do it. I do it about 4 times in the life of each set of pads whenever it feels like there is a bit too much lever throw, and a full bleed once a year just for the hell of it not because they feel like they need it. Having to put a funnel or open syringe in the lever before resetting pistons for a pad change is the only downside, but then you're ready to fit the pads, fit the wheel, pump the lever, remove the funnel and close off the lever bleed port for a rock solid feel.

I'd recommend replacing the free stroke blanking screws in your SLX with grub screws - same as most pedal pins, I can check the measurements if you want. The freestroke mechanism is inside but the blaking screws don't let you use it easily. The adjustment is subtle but does do something despite what anyone writes online including reviewers on several big sites - if you have a good bleed then compare the lever feel and position when the screw is all the way out and all the way in. Be sure to stop tightening the screw when you feel the slightest bit of resistance of you'll break the mechanism inside the lever. It's not really useful for adjustments, except for if you want to match front/rear lever feel, but is helpful for getting the best possible bleed (full bleed or bubble bleed): bleed with the screw out, close everything up, then tighten the screw.

On cleaning/lubing pistons, I clean with a q-tip and isopropyl every pad change unless I'm in a rush. Never tried flossing them with string or yarn soaked in isopropyl but that's meant to work well. For lubing I used to use Castrol Red Rubber Grease - might be a Euro thing, but a tiny pot was cheap on eBay UK. Switched to a mix of that grease and mineral oil a couple of years ago which seems to keep the pistons lubed for longer.

Side-note: a friend put XT levers on his Magura MT5s a couple of weeks ago and they feel great - firmer lever feel than full Shimano and less throw. I considered buying parts to do the same on my new bike but played it safe with Saints, but will definitely be trying this whenever I need new brakes.

[XXX-er]

It looks like I may have done the right thing entirely by misteak !

The SLX did feel really good being overfilled and then bled out the lever,

I only did a few rides on the Yeti before selling it to who else but a medical proffesional

but thanx for the offer anyhow !