How To Clean Hydraulic Brake Pistons - Tech Tuesday

Prevent "sticky pistons" by cleaning and lubing the pistons every time you change pads. We talk a bit about how the brake functions and walk through the cleaning procedure to help your brakes in the long run.
Questions or comments? Leave them below!
➤ Tools & materials used:
• PP-1.2 Hydraulic Brake Piston Press www.parktool.c...
• DOT fluid or Mineral oil ( use the same hydraulic fluid in your brake)
• Cotton swabs
• Isopropyl alcohol
➤ Fix It:
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• Visit the Repair Help section of Parktool.com: www.parktool.co...
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[@corkhead0]

I always wondered how hydraulic brakes self adjusted. It's beautifully simple. Great explanation!

[@adriansue8955]

I think they're simplifying the explanation here. Also have to remember the oil reservoir on the master cylinder, its open to the cylinder at the resting position, but closed off during motion. This means as the master cylinder returns, just before returning to rest the system becomes open and oil pressure is relieved; so the slave pistons don't get fully sucked back to where they started. At the same time, the flexing seal means there's preferential for the slave pistons to slip more in one direction than the other. Both things need to work together for the pad wear compensation.

[@qisxis]

@@adriansue8955 yes thanks so it is a two sided story.. The pressure side and the relaxing side. Nice to get more understanding

[@cebruthius]

@@adriansue8955 I think the way it works, is that the seal can also flex a bit in the other direction. Only when the master cylinder piston returns past the reservoir timing port, the caliper piston seals can relax to the middle position.

[@oscarbloomer3979]

A 3mm Allen key in the calliper slot where the rotor is positioned will stop the pistons from popping out. (4mm Allen for Sram). This way all the pistons can be cleaned. If disassembling the calliper then this method is great for getting the pistons completely out to check the seals

[@edge24x]

I never knew this!! Amazing and extremely underrated comment.

[@ed0078]

Excellent Park Tool®. We need more of these. Kudos to the graphic artist

[@oot-n-aboot]

This is fantastic! I've been changing my pads and aligning my rotors for years, but never thought to clean and lube the seals. Pesky seals! Thank you,

[@elbobbitosmartito4185]

Another tip. Anti-bleed the breaks if the piston doesn’t quite go all the way in. Unscrew the bleed port on your break handle slightly and push the piston in a little bit. Let a couple drops of fluid out. A little goes a long way so don’t push too hard on the piston.

[@karlbe8414]

Best explanation of a very common and eventual problem for most anyone. Great visuals!

[@user-cx2bk6pm2f]

The illustrations and animated graphics are incredibly well done. Give that man a raise! 😀👍

[@mikecox7574]

Very well done guys. One item of note, if you have a Shimano brake with ceramic pistons do not use any metal tool to cycle the pistons. Also you have to be very careful to push on the center of a ceramic piston as to not get it sideways. With ceramic I will usually leave the old pads in to protect the piston while I cycle them.

[@David_SPN]

I made a mistake, I pressed too hard and the pison came out, I put it back on but it caught air. and after a while I started to lose the mineral oil from the Shimano hydraulic brake. Please help me and explain to me how to proceed to put the piston back so that I do not lose mineral oil again. Thanks!

[@ninjapyro9969]

@@David_SPN put it back and then bleed the brakes

[@HarveyLMiller21]

@@David_SPN You can't put the pistons back without losing the mineral oil or brake fluid. After cleaning the piston and placing it back you'll need to bleed the brake.

[@rodent]

what material is the back of the pad made of? metal. that tool is flat as a pad, so I guess is as safe as a pad to push pistons back.

[@Durwood71]

Towards the end of my ride today, my rear brake started howling like crazy because the pistons weren't fully retracting which kept the pads in contact with the rotor, but thanks to watching this video around a year ago, I actually knew how to fix it. It's a little trickier with four piston brakes, but the general concept is the same, and I used isopropyl alcohol instead of brake fluid as the solvent. End result: my brakes are working perfectly again!

[@jgbarre]

Had a sticky seal on my wife’s recumbent trike. Was able to unstick it with the help of your video. Thanks guys!

[@marky26uk]

Best bicycle maintenance tutorials i've seen, thanks guys :)

[@wtfmimshag]

Great tips. Been working on bikes for how long and never saw an explanation for why one piston might want to move more than the other.

[@adriansue8955]

for me its more like, I've never seen an explanation for why they should want move in synch in the first place. There's no mechanical coupling between them, and fluid's going to take the path of least resistance. So in my mind is a miracle that they'd even be as close as they are.

[@akeluify]

@@adriansue8955 the fluid isn't taking any paths of least resistance, as the resistance is the same on both sides of the pistons. Theres the same amount of gap for the fluid behind each piston. So whats happening is even pressure is being applied to each of the calipers, its just up to the seal to bring it back after pressure taken off,

[@hughjanus7354]

@@akeluify "the resistance is the same on both sides of the pistons" ...in lab conditions when both pistons are brand new. And even then there will be differences resulting from how each seal interacts with each piston. Once they start picking up dirt these differences will increase and each side will retract differently.

[@bkxc]

Solid info guys!

[@82lostsoul]

Just done this exact procedure on my PITA SRAM Guide R brakes, best they’ve ever felt the 9 months I’ve had the bike!

[@MTBMOR]

Just did on my 4 pistion SLX brakes...I hope my feel as good on the trail as they do in the garage

[@alanlemap]

(glad it helped but) isn't that against SRAM manufacturers guidance, to NOT use dot fluid around the piston? I am wondering if the fluid would make the seal slide instead of GRIP and pull back, the way it should....? The reason is, I have pistons that don't retract enough after use, so they grip juts enough to stop the wheel spinning freely ...

[@SarcoZQ]

Well done guys. Thanks to this video I was repair a lazy piston yesterday. Felt great knowing what to do and your enthusiasm works really well. Thanks again.

[@wallace8637]

I love this guy talk. Looong and simple at times.

[@RichardE221]

I thought I needed to replace my brake pads and rebleed the system after about 500 miles of mixed riding. I cleaned my pistons and they work like new! Thanks guys. This was the answer.

[@PhoenixT1953]

2:43 *alcohol for our alcoholic friends*

[@nickmihai]

Funny guy! :))

[@Leviathandk]

I came to the comments for this

[@nicolasmasquerade]

Lol wanted, to write same thing ;)

[@1ignis]

..that is ethanol !. Surely a cheaper and better option would be isopropyl alcohol and save the ethanol for a G&T?

[@BPNX]

Could i also use regular brake cleaner or lighter fluid for the cleaning part?

[@MichalSzul]

Before last piston push in I suggest cleaning oil from the piston surface as it will attract dirt and make it sticky again quite quickly.

[@joecanuck3751]

I'm also in the camp of after the cleaning process to remove excess oil with brake cleaner or alcohol so that dust won't collect.

[@hughjanus7354]

Agree, this will prevent unintentional oil transfer and pad/disc contamination.

[@jkamer2168]

Killer video, a huge step I've been neglecting. Sorry wifey...gonna be in the garage tonight!

[@PeterKern63]

Great instructions, explanations (including graphics). Helped us getting hydraulic break pistons cleaned and brake pads replaced! Thank you!!

[@ajlong404]

Terrific job explaining how the pistons work and how to clean them. But, that seal clap and bark is everything! I had to watch the beginning of the video a couple more times. 😆😆

[@MultiGreenGaming]

Woah, this video was uploaded the moment i sat down to clean my brakes, what a coincidence :O. Thank you very much very informative and fun tutorial!

[@matthiasfaler2834]

As usual: great educational video! Keep them coming, please.

[@lytleric]

I have a problem with my brake pistons sticking so I've been researching what to do. It makes sense to me why we need to clean the piston: to prevent debris from working its way back into the seal. However, Singletracks posted an article on cleaning brake pistons that specifically states "brake pistons should not be lubed. They should be cleaned." The article goes on to explain how to clean pistons using isopropyl alcohol. But in this video, you use mineral oil to clean the piston. Isn't that in effect lubing the piston, which is what the Singletracks article says NOT to do?

[@CW-up7xv]

Why not clean the Piston initially with rubbing alcohol, then go to using the mineral oil/ dot fluid when working the piston back and forth? Feel like alcohol does a better job initially removing the dirt...

[@cstrike105]

Thank you for the info. Learned a lot on how to clean my disc brake pistons.

[@bobbyhempel1513]

I just got a new bike, my first set of hydraulic disc breaks so this is going to help allot.

[@MTBMOR]

I just did this and it fixed my brake rub....I have never had to do this in over 5 years of having disc brakes until now...Great Video

[@joemichaelegan8214]

I’ve used some Pad grease as is used with Motor vehicle Brakes and I have improved feeling through the lever as well as the eradication of sticking Pads and noisy metallic scraping from the Cycles Disk Brakes.

[@parsnips800]

Great information in this video. Thanks for taking the time to produce this .

[@bendenisereedy7865]

Great explanation. Most people think the pistons slide in and out of the seals.

[@gcdcg4d]

Best explanation ever. Now we know what's going on!

[@alrocky]

3:36 Recommend you *_do not_* insert Q-tip into container but instead pour small amount of mineral fluid into small (Dixie) cup.

[@David_SPN]

I made a mistake, I pressed too hard and the pison came out, I put it back on but it caught air. and after a while I started to lose the mineral oil from the Shimano hydraulic brake. Please help me and explain to me how to proceed to put the piston back so that I do not lose mineral oil again. Thanks!

[@veejay2901]

​@@David_SPN you will have to bleed it from scratch.

[@pminiger9278]

So working on your bike's brakes is a two person job! Awesome!

[@45graham45]

I've heard it said that you shouldn't use oil (fluid) to clean the pistons. Reason: if you do then the seal won't have as much grip on (it slips) it which makes it more difficult for it to retract the piston. IPA or brake cleaning fluid should be used. Also, whilst preferable to clean the piston, just pushing them back without cleaning them occasionally isn't a problem , normally the seal just pushes the dirt off the piston.

[@ItsABarmcake]

Exactly what my pistons are doing on a used bike I bought. This might have saved me a trip to the bike shop!

[@slashdoink2501]

I have a Shimano 4 pot piston from a mountain bike that’s less than 15 month old, I have explained to the bike shop that the outer bottom piston is not retracting all the way back and is causing intermittent disc rub at certain speeds which is quite annoying, they have had the bike once and said they have done a front brake service on it. I took this bike out and it is now worse than it was before. I have taken this bike back again but I don’t have much confidence of them fixing it.

[@jamesturner9481]

The very last bit might help me out, I have one side that moves a fair bit more than the other so moving the caliper should help. Crossed my mind to try that 👍👌☺️

[@b.s.adventures9421]

Good tips. I’ll be employing those at work soon. Thanks.

[@hardtailshredder]

They cut apart a caliper for people to understand better. I love these guys

[@MaquinasDePalomitas]

You just gotta love these guys.

[@btown8210]

This are superb tutorials/info! Thank you

[@LesssIsMore]

Great video but I'm confused. Were you using the right hand brake lever for the front brake? Isn't it the other way around?

[@JohnnieDorman77]

Guess the bike is set up for a left hander. Ha! Good thinking.

[@alanlemap]

Countries that drive on the right have front brake on the right. Opposite for GB AU NZ SA( and probably HK and JP...,)

[@robertdewar1752]

Nice diagram of how the seals work

[@wlouisharris]

Very informative. Hydraulic disc brakes are a pain though. They stop with amazing precision but there are a number of components to maintain. The part I am having a problem with is reaching the pistons while I have the brakes compressed.

[@mrbarkeater1]

haha, after all that they never show successful endpoint where when you pull lever, both inboard and outboard pistons extend same amount. I would bet 99% of the hydro brakes out there operate with only one piston (for two pot caliper) doing most of the work. still, good video guys. keep up the good work

[@butchgreene]

Don't bet...try it. You'll be 100% right. With 4 piston pucks its even whackier

[@AngelaCastuera]

Great video. This is the problem to my hydraulic brake now. Thanks

[@MTBMOM]

Lazy seals lol great video!

[@that70sschwinn]

Nice demonstration guys...

[@JasonTong]

Thanks guys... this cleared up alot of questions I had.

[@akuma9132]

thank you so much for the tutorial, the inner piston was rubbing the right part of the rotors then when i did this tutorial it actually worked!.

[@robertleslie3396]

Great tips, sorted out my sticky brakes in no time

[@RochX-7]

This was not the video I intended to watch... but I'm glad I watched it. You guys are solid af. lmao :)

[@johnnywalker9067]

brilliantly explained! Chapeau! I do have a question though: In the old days of cantilever rim-brakes, even though designed to have a symmetrical pressure on the rims, I usually found, that one brake-shoe would hardly move and stay close to the rims, whilst the other side would do all the travel. I think, this was due to recoiling springs to wear out unevenly. So why does the same thing happen to the pistons in hydraulic brakes (seen in your video at 3 31 minutes), when the pressure in a liquid is evenly distributed? Should the pistons in a new bike maybe get a coating of some greasy material to keep muck sticking to the outside surface?

[@joecanuck3751]

I'm no expert so take this with a grain of salt ... one issue is that the brakes can get really hot this will cause oil and grease to become more viscous and travel to where you don't want it.

[@alanlemap]

And cheap imprecise engineering. It's plastic bike parts as opposed to high end aeronautical parts. ? My guess only.... But yes, not ideal.

[@harry-eto]

You guys would make a dream team children channel hosts!

[@dineshhanda2301]

Wonderful video as usual. Thanks Calvin, thanks Trueman

[@peglor]

Perfect until right at the end where they said to move the caliper if the brake pads remain uneven. Just hold back the active pad with a screwdriver or similar and pump the brake and it'll center up fine. It's a 'feature' of the more recent Shimano brakes unfortunately, causing wandering bite point - sorted in a couple of minutes every month or so as the pads wear.

[@Henrymayday]

Great educational info! Feels like a father and son video 😀

[@lukepatrick6196]

I dont even have disc brakes and I watched this

[@erikkjelland5719]

Dude, that is dank

[@nickmihai]

Dude, this is nice to know when you have that :))

[@twintyara6330]

Nice, you have eyes

[@ПсихологНиколайЛу-ч2з]

You guys are brilliant!! Thank you!

[@KOL630]

Excellent explanation guys thank you.

[@mountainbiketim]

I let the piston fallout. No bueno. Great video guys and very informative. I have these same brakes so very helpful for my situation. How often should the seals be replaced? My brakes are about 8 years old and have about 12,000 miles.

[@audiofella5066]

The more i learn about hydraulic brakes the more I love my cable actuated BB7's!!!!!!

[@CameraRestore]

you couldn't make it better!! Thank you!

[@FollowThatDale]

Excellent as always. Thanks!

[@franckth186]

If that is not a top notch tutorial.. what is ? Thank you guys, i always wondered what was going on!!

[@kendobson9009]

Cheers fellas. Sorted my sticky pistons out nicely! Great advice :-)

[@KeepOnRollinFilms]

Very, very helpful. Thank you guys!

[@kenoliver8913]

My tip: Put ONE of the pads back in as a temporary stop to prevent pushing the piston out too far. Take it out and then clean your pistons.

[@David_SPN]

I made a mistake, I pressed too hard and the pison came out, I put it back on but it caught air. and after a while I started to lose the mineral oil from the Shimano hydraulic brake. Please help me and explain to me how to proceed to put the piston back so that I do not lose mineral oil again. Thanks!

[@HarveyLMiller21]

@@David_SPN Bleed the brakes. Once the piston falls out you can't prevent loss of fluid while air enters the system.

[@Rudas2007]

This was really helpful. Thank you.

[@auxsin]

What if my 1 side piston went out and really hard to pushed back even with hard force? No movement at all.. what should i do?

[@ironman1518.]

GREAT explanations! Thank you both!

[@forrestegan]

Very helpful video!! I’m new to hydraulic brakes, recently replaced rotors and pads on my mountain bike…the front brake was rubbing, now it’s not!! Keep up the great work!!

[@maxishappy]

I used this tutorial because when braking in the back the brake rotor bend to the side of the wheel and it's hard to push the piston back on shimano brakes

[@hochiminh902]

You two are the best.

[@MaquinasDePalomitas]

Ohhh wow!!! Nice about the rollback!!!

[@corsomagenta]

Excellent work. Thanks y'all!

[@philklepka6933]

So this is the video ive seen when seth talks about you too and shows the seals clip!!!

[@BrendonMacintosh]

Have you made a video on how to replace the the seal on on the master piston in the hand lever assembly?

[@Awkward_Fox]

Researching brake maintenance, and its a culture shock to see no social distancing now... Thanks Covid. Also, Great Guide as usual!

[@parktool]

Oh the good old days of no social distancing. Thanks for watching!

[@jacobclark89]

I don't know about roll back cuz the pads use a spring to retract them. I noticed that the stock ceramic pistons in the Shimano xt calipers seem to be not polished and were abrasive so I use the upgraded pistons to make the seals last , brake fluid leaking on the pads / disc can kill .

[@stayathome2]

So these guys are wrong? I think the purpose of the spring is so the pads don't rattle, similar to a car.

[@jacobclark89]

@@stayathome2 the pistons move more than just the roll back from the seals

[@XavierBetoN]

You know the content will be heavily educational when you hear about seal sounds au au au au

[@mrmostchill]

Really helpful. What if the piston is completely stuck tho?

[@michaelpearce6982]

Should i do this before a bleed and what if I'm alone?

[@honestmcgyver]

Apologies if you already have separate videos but surely a sram one and a separate Shimano one?

[@Timyoo78]

Very informative! Thanks

[@twosons5290]

Informative and entertaining. Thanks

[@Oldvelocette]

Quality video. Thanks for posting

[@ghost_control3276]

thank you guys! Gonna go do my front brake now its sticky, found out the hard way.. on a ride.. i fell over the bars! hahaha i love my bike!

[@pondacres]

This is great, thank you much!

[@BikingVikingMTB]

Awesome tutorial i never bew this but will clean my pistons next time 🤟

[@stresaoutdoor]

Ciao ! :-) On braking systems that have worked a lot, I prefer to open the brake caliper, replace the gaskets, and reassemble everything. The question is: when reassembling the pistons, which lubricant is best to use? Is brake fluid sufficient, or is there a specific grease ? I usually overhaul systems with mineral brake fluid, other times with DOT fluid. Grazie ! :-)

[@joserobertobernalvera7863]

I just bled the brakes and cleaned the pistons, but I get the feeling that the pistons are not returning properly, what possible fault could they have? Thanks!!!!

[@Piplodocus]

*thinks* I probably shoukd have watched this 5 years ago when it first came out! 😂

[@kierancoia84]

Amazing video

[@kisilvan]

Great info thanks

[@seanhammon6639]

It might not be a 'lazy seal' but air in that side that isn't moving.

[@esiasonR77]

So I pushed the break lever all the way and I leaked a lot of fluid like you said not to do before watching this video . What do I do now , refill fluid ? Or did I screw up bad?

[@mpl1700]

thanks for this explanation. I have & question, when a piston leaks, will there be oil on the brake pads ?

[@parktool]

Yes, that is one area. Remove the wheel and pads, now look and feel for oil around the piston itself.

[@mpl1700]

​@@parktool I removed it, and I see that air bubbles emerge from one side of the piston, so I think this caliper has to be replaced or, I can open it and adjust/fix it ...what is your advice ? thanks a lot

[@alaingagnon23]

Fantastic intel!