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.
@@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.
This was super informative! I always thought the pistons moved back because of the vacuum in the chamber when it is pushed out, but it was the seals that were doing the jobs all along~
This method fixed my "rub" problem pretty quickly. I had a piston that wasn't retracting as far as the one on the opposite side. I used alcohol and a foam swab and copied the method in this video and repeated again, total of twice on each side. Reinstalled the pads, mounted the wheel, and problem was fixed. The swabs, especially on the first application were pretty black. 2nd application not as much, but I noticed right away that the pistons were in unison with one another. Brakes can get pretty dirty. Gotta clean them up once in a while. Thanks Park Tool for the great solution. 👍
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.
That was a great presentation. Very detailed with cut away parts. I had squealing brakes but after 3 repeated pad/rotor cleaning and scuffing it still squealed. After your video I checked the pistons and found they moved very little and did not retract. Followed your procedures and now they move properly. Voila! The squealing is gone. Big thanks guys.
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.
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.
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!
@@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.
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
Another Tip: Keep an old set of pads around as a maintenance pad set. Allows you to push the pistons back in without damaging the piston faces if using a flathead screwdriver/chisel/etc.
Was wondering if it was necessary to invest in the parktool piston press that they use here. I tend to bodge it with my metal tyre levers and always scratch the surface.
Simplest and least damaging is the box end of a cheap 10mm wrench. I say cheap because expensive ones have a huge width. Cheap ones will drop between the pucks. And if you have old Hayes post mount brakes, the box won't break the post
@@s31720 I use a wooden paint stir stick. They are firm enough to do the job, soft enough not to damage the pistons. Stick one through the caliper and pull with both hands
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.
You guys are absolutely AMAZING, THE BEST. I LOVE YOU. Im kinda newbie and dumb about bikes and such. Especially whole brake system was kinda hard to understand for me, but i wanted to fix myself. I was reading some articles etc, few videos and it didnt help me at all.But every each one of your videos is so well made, nicely and easy explained.. Only thank to your videos, i got it all now. I fixed everything i needed. Simple, easy and compared to some services very cheap. Thanks so much. Amazing job, good luck fellas.
Tomi Saaranen it sure beats watching todays politics ....but then its our duty to know what is happening out there because we live in dangerous times . I'm new to hydraulic brake calipers without the internet id be stuffed. its these dam pistons that confuse me . my shimano pistons from 2014 models are just plastic looking black ones without any rubber Orings? all the others iive seen have ceramic white pistons and rubber orings. so on striping the caliper and opening it I thought I may have lost the white ceramic ring part but no there isn't any white ceramic on this model just a black one?
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. 😆😆
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.
@@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,
@@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.
(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 ...
Thanks for making this fun to watch as well as informative! You guys are great. And it really helped that you talked about one caliper moving less than the other because I have this exact same thing going on. Thanks for the help! And I'm subscribing to this channel now.
I think this helped with a brake centering issue I was having. My rear wheel was almost rubbing on one side with more daylight on the other, but the rotor was centered in the caliper. After adjusting the caliper or pressing in pistons it would just happen again later. Today fixed the sticky piston on one side and now I see even daylight on each side. Maybe the better-moving side was squeezing out too much each time I tried resetting brake alignment, while the sticky piston wasn't out enough yet. I don't know if it would actually work that way, like I think it would have to almost slightly and temporarily bend the rotor from one side while braking for the piston to remain stuck out too much. I'm running thought experiments in my head while tired and I'm a maintenance newb anyway. Maybe I did something else that fixed the centering... but I think it was this.
Muchas gracias por su aporte! Realmente se agradece, es simple y me parece que está muy bien explicado. Tanto la animación como el capiller recortado es de mucha ayuda para entender como funciona el sistema. Saludos desde Argentina. Comenzaré a seguirlos.
Great video, very comprehensive. From my experience water and mild soap works better to remove both brake fluid and mineral out. Furthermore, I would also mention how the reservoir works and how it gets isolated by the master piston before pressure build-up. Many people still think adding more fluid to the system than intended will reduce the dead stroke.
Best way that I have found to clean the pistons is to use a nylon tube brush. Then lube with mineral oil or brake fluid, then push back, clean, re-install.
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.
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!
Wow, thank you so much :)) I've been told to use silicon grease to lube the piston. But know, thanks to you guys, i know that i can use brake oil to both clean and lube the piston (and also know how the system work too). P/s: i know with mineral oil is fine, but i don't think you should use the same method for DOT fluid braking system, cuz DOT oil is a little bit too harmful.
amazing video!! i was just thinking, ok i know how to bleed Hydraulic brakes.. but what's actually inside? Cause something ain't right with mine. Good info thank you
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 👍👌☺️
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.
I had this problem last night. All the fluid came out of the front brake. I was worried I would need to replace the caliper, but now I will clean the system first. Thanks for the video... What is the life of the seal? I have 3,600 miles on my Inokim oxo scooter.
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...
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?
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.
I always wondered how hydraulic brakes self adjusted. It's beautifully simple. Great explanation!
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.
@@adriansue8955 yes thanks so it is a two sided story.. The pressure side and the relaxing side. Nice to get more understanding
@@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.
This was super informative! I always thought the pistons moved back because of the vacuum in the chamber when it is pushed out, but it was the seals that were doing the jobs all along~
Best explanation of a very common and eventual problem for most anyone. Great visuals!
This method fixed my "rub" problem pretty quickly. I had a piston that wasn't retracting as far as the one on the opposite side. I used alcohol and a foam swab and copied the method in this video and repeated again, total of twice on each side. Reinstalled the pads, mounted the wheel, and problem was fixed. The swabs, especially on the first application were pretty black. 2nd application not as much, but I noticed right away that the pistons were in unison with one another. Brakes can get pretty dirty. Gotta clean them up once in a while. Thanks Park Tool for the great solution. 👍
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,
Excellent Park Tool®. We need more of these. Kudos to the graphic artist
Solid info guys!
The illustrations and animated graphics are incredibly well done. Give that man a raise! 😀👍
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.
Had a sticky seal on my wife’s recumbent trike. Was able to unstick it with the help of your video. Thanks guys!
That was a great presentation. Very detailed with cut away parts. I had squealing brakes but after 3 repeated pad/rotor cleaning and scuffing it still squealed. After your video I checked the pistons and found they moved very little and did not retract. Followed your procedures and now they move properly. Voila! The squealing is gone. Big thanks guys.
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.
For this you should use the bleed port in the caliper, so that dirt from the bottom of the whole system is not going up.
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.
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!
@@David_SPN put it back and then bleed the brakes
@@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.
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.
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
I never knew this!! Amazing and extremely underrated comment.
Best bicycle maintenance tutorials i've seen, thanks guys :)
Fantastic video!
I’ve just performed this job after shying away from it for years!
Thank you!
Great instructions, explanations (including graphics). Helped us getting hydraulic break pistons cleaned and brake pads replaced! Thank you!!
Another Tip: Keep an old set of pads around as a maintenance pad set. Allows you to push the pistons back in without damaging the piston faces if using a flathead screwdriver/chisel/etc.
Use plastic tire levers :)
Ha. Good idea. I keep my plastic levers in the road kit. Have the Park metal levers that've never let myself down.
Was wondering if it was necessary to invest in the parktool piston press that they use here. I tend to bodge it with my metal tyre levers and always scratch the surface.
Simplest and least damaging is the box end of a cheap 10mm wrench. I say cheap because expensive ones have a huge width. Cheap ones will drop between the pucks. And if you have old Hayes post mount brakes, the box won't break the post
@@s31720 I use a wooden paint stir stick. They are firm enough to do the job, soft enough not to damage the pistons. Stick one through the caliper and pull with both hands
I love this guy talk. Looong and simple at times.
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.
Very informative on how to correct those sticky pistons. Thanks
You guys are absolutely AMAZING, THE BEST. I LOVE YOU. Im kinda newbie and dumb about bikes and such. Especially whole brake system was kinda hard to understand for me, but i wanted to fix myself. I was reading some articles etc, few videos and it didnt help me at all.But every each one of your videos is so well made, nicely and easy explained.. Only thank to your videos, i got it all now. I fixed everything i needed. Simple, easy and compared to some services very cheap. Thanks so much. Amazing job, good luck fellas.
2:43 *alcohol for our alcoholic friends*
Funny guy! :))
I came to the comments for this
Lol wanted, to write same thing ;)
..that is ethanol !. Surely a cheaper and better option would be isopropyl alcohol and save the ethanol for a G&T?
Could i also use regular brake cleaner or lighter fluid for the cleaning part?
Great tutorials guys! But mostly I just watch these for entertainment!
It's Tomi again ;-p
Tomi Saaranen it sure beats watching todays politics ....but then its our duty to know what is happening out there because we live in dangerous times . I'm new to hydraulic brake calipers without the internet id be stuffed. its these dam pistons that confuse me . my shimano pistons from 2014 models are just plastic looking black ones without any rubber Orings? all the others iive seen have ceramic white pistons and rubber orings. so on striping the caliper and opening it I thought I may have lost the white ceramic ring part but no there isn't any white ceramic on this model just a black one?
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. 😆😆
Killer video, a huge step I've been neglecting. Sorry wifey...gonna be in the garage tonight!
Thank you for the info. Learned a lot on how to clean my disc brake pistons.
You guys sure "sealed" the deal with this video.
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.
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.
@@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,
@@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.
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!
Just did on my 4 pistion SLX brakes...I hope my feel as good on the trail as they do in the garage
(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
...
Brilliant video, I had a lazy seal, was really messing with my head until I watched this. Many thanks guys.
Best explanation ever.
Now we know what's going on!
As usual: great educational video! Keep them coming, please.
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!
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.
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.
Agree, this will prevent unintentional oil transfer and pad/disc contamination.
great info, well done! just felt like this vid was made to entertain toddlers
You just gotta love these guys.
Thanks for making this fun to watch as well as informative! You guys are great. And it really helped that you talked about one caliper moving less than the other because I have this exact same thing going on. Thanks for the help! And I'm subscribing to this channel now.
nothing better than scientific explanation, massive thank you
I think this helped with a brake centering issue I was having. My rear wheel was almost rubbing on one side with more daylight on the other, but the rotor was centered in the caliper. After adjusting the caliper or pressing in pistons it would just happen again later. Today fixed the sticky piston on one side and now I see even daylight on each side. Maybe the better-moving side was squeezing out too much each time I tried resetting brake alignment, while the sticky piston wasn't out enough yet. I don't know if it would actually work that way, like I think it would have to almost slightly and temporarily bend the rotor from one side while braking for the piston to remain stuck out too much. I'm running thought experiments in my head while tired and I'm a maintenance newb anyway. Maybe I did something else that fixed the centering... but I think it was this.
Nice tutorial, I have a lazy seal on my front brakes and now I'm Confident to tackle the problem.
Great explanation. Most people think the pistons slide in and out of the seals.
Muchas gracias por su aporte! Realmente se agradece, es simple y me parece que está muy bien explicado. Tanto la animación como el capiller recortado es de mucha ayuda para entender como funciona el sistema. Saludos desde Argentina. Comenzaré a seguirlos.
Great video, very comprehensive. From my experience water and mild soap works better to remove both brake fluid and mineral out. Furthermore, I would also mention how the reservoir works and how it gets isolated by the master piston before pressure build-up. Many people still think adding more fluid to the system than intended will reduce the dead stroke.
Thanks for your help. I just bought a maintenance stand so I can fix everything myself, with your help.
Great information in this video. Thanks for taking the time to produce this .
So working on your bike's brakes is a two person job! Awesome!
Excellent as always. Thanks!
Best way that I have found to clean the pistons is to use a nylon tube brush. Then lube with mineral oil or brake fluid, then push back, clean, re-install.
Excellent explanation guys thank you.
you of the Park Tool are very well understood know what they do and the tools are appropriate
This was not the video I intended to watch... but I'm glad I watched it. You guys are solid af. lmao :)
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.
Great video. This is the problem to my hydraulic brake now. Thanks
Frank zappa Making the magic happen. Loved the seal btw
Hell of a compliment guy. 👍
This are superb tutorials/info! Thank you
Thanks a lot, that’s what i was looking for to fix my hydraulic break 👍🏻
So lovely maintenance ❤️
Thanks guys... this cleared up alot of questions I had.
Great tips, sorted out my sticky brakes in no time
Exactly what my pistons are doing on a used bike I bought.
This might have saved me a trip to the bike shop!
Fantastic videos! Congrats!! Super useful!!
3:36 Recommend you *_do not_* insert Q-tip into container but instead pour small amount of mineral fluid into small (Dixie) cup.
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!
@@David_SPN you will have to bleed it from scratch.
Nice diagram of how the seals work
Great tutorial guys, thank you!
Wow, thank you so much :)) I've been told to use silicon grease to lube the piston. But know, thanks to you guys, i know that i can use brake oil to both clean and lube the piston (and also know how the system work too).
P/s: i know with mineral oil is fine, but i don't think you should use the same method for DOT fluid braking system, cuz DOT oil is a little bit too harmful.
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!.
You two are the best.
Wonderful video as usual. Thanks Calvin, thanks Trueman
Excellent video!! Thank you!
Ohhh wow!!! Nice about the rollback!!!
Great info thanks
Thank you
amazing video!! i was just thinking, ok i know how to bleed Hydraulic brakes.. but what's actually inside? Cause something ain't right with mine. Good info thank you
You guys are brilliant!! Thank you!
Amazing video
you couldn't make it better!!
Thank you!
Gold video!
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 👍👌☺️
Good, very good, extremely good. I just bought a ph-1 p set to help subsidize the education system.
Thanks Jose!
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.
Dropping knowledge like it's nothing. Thank you :)
thank you so much park tools
Nice demonstration guys...
I had this problem last night. All the fluid came out of the front brake. I was worried I would need to replace the caliper, but now I will clean the system first. Thanks for the video... What is the life of the seal? I have 3,600 miles on my Inokim oxo scooter.
great! really helpful !!! Thanks guys really enjoy the maint. tutorials.
Good tips.
I’ll be employing those at work soon.
Thanks.
Cheers fellas. Sorted my sticky pistons out nicely! Great advice :-)
Thank you guys! Subscribed!!
Fantastic intel!
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...
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?
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.
And cheap imprecise engineering. It's plastic bike parts as opposed to high end aeronautical parts. ? My guess only.... But yes, not ideal.
If that is not a top notch tutorial.. what is ?
Thank you guys, i always wondered what was going on!!
Really a goed explanation
right on the spot! this is what i am searching for.
Excellent work. Thanks y'all!
I just got a new bike, my first set of hydraulic disc breaks so this is going to help allot.
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
Ty for ur time to upload this video.. ty guys
This was really helpful. Thank you.
Very, very helpful. Thank you guys!