Tech Spotlight - Brake Piston Balancing

May 6, 2014 at 0:09
May 6, 2014
by Nate Collins  
 
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Pinkbike and BikeCo.com are excited to bring back the mechanical “how-to’s” with the new Tech Spotlight articles that you can (usually) expect to see on the last Tuesday of every month. Joe Binatena, BikeCo’s owner and world class mechanic, will help walk riders through a variety of tasks, from basic jobs to more advanced work that you'll be able to read about in the future. We aim to provide readers with a gauge on difficulty and risk for these projects, and also encourage you to post any questions in the comment section below when it comes to things that need more explaining.




Brake Piston Balancing


The caliper houses the hydraulic slave cylinder and piston system that clamps the pads down onto the rotor. Modern brakes typically employ either two or four opposing pistons, and a big factor in getting the most performance boils down to symmetry in the piston's power and stroke - this service is aimed at achieving exactly that. Whether you have brakes that have been in hard use for many seasons or a set that's straight out of the box, balancing pistons will increase your brake performance and longevity. New brakes typically only need to be balanced, but brakes that have been in service will likely need to be cleaned and then balanced.

The performance advantage of the steps described below have been proven on the race course, trail riding and commercially through BikeCo.com and other highly capable mechanical resources. As with any type of service, make sure you have the appropriate confidence and skill required to successfully complete the job before you start - you can be seriously injured or even killed if your brakes aren't working properly! Don't attempt this service if you have any doubts about your abilities.

uneven pistons cause poor pad wear

Note how the uneven piston travel in the caliper has the pads sitting at an angle. This can cause power loss and premature pad wear.



Symptoms of unbalanced pistons:

• Long lever throw. This can be from one of the pistons not moving as intended, with the extra throw required to drive the operating piston across the gap left by an ineffective piston.

• Stiff lever throw but low power. Assuming that there is no fluid contamination of the pads or rotor, this condition is typical of a higher friction coefficient needed to drive the pistons. Slow pad return is often a telltale sign of excessive friction. If you apply the brakes and note that one or more of the pistons is slow to return after lever release, you could have contamination that is keeping the piston from returning smoothly.


Important points to remember:

• Mountain bike brake pads are easy to contaminate, and contaminated pads lack power and will be noisy. Contaminants can include any sort of cleaner, lube, grease, and even the oils naturally on your skin. Bottom line, don't let anything touch the pad's braking surface.

• Pistons can be easily damaged, so do not pry directly onto the piston material. You're far better off utilizing an old set of “dummy” brake pads to protect your pistons - slide them into place anytime you need to relocate the pistons.

• Commercial brake cleaner may be used to clean pistons but DO NOT allow brake cleaner to contact pads - mountain bike brakes do not generate enough heat to burn off commercial brake cleaner. After using commercial brake cleaner BikeCo will thoroughly rinse the caliper with an ammonia based window cleaner.


cocked piston

Cocked pistons like those shown above can eventually cause seal issues or even crack while being used.



Cleaning Steps

• Remove your brake pads and put them in a safe place where there is zero chance that they'll be contaminated - it's mind blowing how far some lube or cleaner can travel when over-sprayed. Install your old dummy pads to protect the piston surfaces.

• In order to protect your bladder within your master cylinder, uncap the bleed screw to open the hydraulic system. A Shimano brake bleed cup is a great tool to minimize bubble ingress while still providing an open system. If you utilize the bubble bleed, we suggest opening the system when servicing pistons or replacing pads. This is a good time to review brake fluid condition - if the fluid is roached or you have air in the line you should complete a full service brake bleed.

• It's now time to assess piston movement. This is often the moment of truth for those who have been fighting brake performance issues. Squeeze the lever slowly and only part way through its stroke so as not to drive the pistons completely out of the caliper. This could be a concern if your dummy pads are well worn, and you might need to insert an old rotor between them in order to keep this from happening.

• Is one piston not moving at all? This means that you have a frozen piston that may require you to rebuild the caliper, but there is a trick to try before resorting to that. Start by applying pressure on the functioning piston (you remembered to install your dummy pads, right?) while pumping the brake lever gently. If you're lucky this may provide enough leverage to break the sticky piston free.

Uneven Pistons

Uneven pistons in a four piston caliper.


• If your pistons are moving but sticky, you will need to assess the level of cleaning they require. Riders who run their brakes into the ground, put extreme heat through the system, or who are generally hard on components, may use commercial brake cleaner. Less aggressive riders may simply use ammonia based window cleaner to get the job done.

• Start by pulling the brake lever in order to expose the pistons. Take a close look at the pistons and inner walls of the caliper - is there burnt debris and filth everywhere? If so, utilize a commercial brake cleaner by spraying it across the pistons and then completely cleaning the same area with window cleaner. However, if your pistons and caliper aren't suffering from any build up you can use a gentler ammonia-based window cleaner. Push the pistons back into their bores only when the area has been cleaned properly, and then check to see if they each travel evenly. Repeat this process until your pistons drive and retract freely. DO NOT lubricate the pistons. Remember, DOT systems are designed for DOT fluid and mineral oil systems designed for mineral oil - mismatching any fluid as a "lubricant" may lead to failure.



Piston Balancing Steps

Both sets of brakes photographed for this article were straight out of the box and had never been used, yet both had piston balance issues that could cause power loss and uneven pad wear, so don't assume that your calipers are working perfectly just because they're brand new. Balanced pistons provide better lever feel, even brake pad wear, and are much easier to mount onto your bike. Those with a touch of OCD will need to remember, however, that absolute symmetry isn't possible in all cases. Ideally, you want the pistons evenly exposed, with near equal stroke and power application. If you’re starting with brakes offset in the caliper but driving with equal stroke and power, the goal is to simply reset the natural location.

Offset Piston Reset

Begin to balance the pistons by driving both back into their bores. A butter knife works well for this job because it's not too stiff but is sturdy enough to get the job done. As always, make sure that your dummy brake pads have been installed - never push on the pads you intend to use.



• Begin by resetting both pistons into their bores - insure that you have the bleed screw cracked and your dummy pads installed. If they drive out evenly when you pull the brake lever, you're golden. If one drives more aggressively, apply slight pressure to it to retain its position while allowing the slower piston to advance towards it until both are even with each other. Take your time and don't pull on the brake lever too hard; remember that going slow will get the job done correctly.

Pressure on free piston to break other pistons loose

We're applying pressure to the moving piston in order to balance the system.



• If your pistons are not sticky but will not balance, it's a sign of another issue: end of service lifespan. At the very end of a brake's service life the pistons can often develop grooves across the cylinder barrel. These are typically too minute to see or feel but can be measured with machinist tools. What does this mean? Basically, brake pads wear quickest from new to approximately the fifty percent mark, and due to heat cycles and other variables the brake pad material hardens, producing less bite and heat capacity, while allowing the pistons to stay in a slightly cocked position. The pistons will then wear slowly over time where they make continued contact with the O-ring, something that can create a groove around their circumference, and they can end up wanting to always return to the same resting position because of this. Typically brakes at this level of wear will not center, or if they center they will tend to jump out of alignment as the piston's friction changes and resets which side’s groove they set into.

Even and clean

Clean, even, and balanced. These brakes will offer optimum performance when installed.



Disclaimer: Many of our tech tips ARE NOT factory approved service techniques. Riders should evaluate their skills prior to attempting any published tips. Knowledge base is needed to define success or failure after any tip procedure – if you doubt your understanding of any system described in our tech spotlight work with a professional resource. All systems on a bicycle should be considered critical – riders risk injury or possibly death with improper service or application. Be safe and enjoy your riding.


We hope that you found tips in this that will help you better maintain your ride. We will look forward to future instalment of Tech Spotlight here on Pinkbike on the last Tuesday of each month. If you have an idea that you would like to see covered, please e-mail Nate@BikeCo.com to let us know what issues you’ve had that can’t seem to be solved and we will put Joe on the task.
www.bikeco.com
Must Read This Week






141 Comments

  • + 121
 All this talk of brakes is really slowing me down.
  • + 27
 The better you brake the faster you go
  • + 29
 I need a brake
  • + 13
 Again?!! You should STOP this.
  • + 4
 Have a brake at your lbs if you still having issues.
  • + 78
 Im an avid user of brakes
  • - 11
flag superbikes (May 6, 2014 at 2:58) (Below Threshold)
 Your takeing the ...pist...on )
  • + 19
 One way to pad out the comments section
  • - 19
flag Scrobb (May 6, 2014 at 3:18) (Below Threshold)
 I bet Stevie Smith has uneven brake pistons
  • + 30
 The caliper of this article is excellent...
  • - 8
flag MCMbiker (May 6, 2014 at 6:35) (Below Threshold)
 Wire you guys still doing this pun jokes?
  • + 2
 Julie Magura needs bleeding every... not going there sorry
  • + 39
 I put WD40 on my brakes. It helps me go really fast.
  • + 2
 ^GT85 is cheaper...
  • - 10
flag L4teski (May 6, 2014 at 7:15) (Below Threshold)
 Brakes just slow you down
  • - 5
flag dirtworks911 (May 6, 2014 at 8:00) (Below Threshold)
 Reighley guys, I'm kenda getting tired of all these bike puns.
  • + 1
 Im learnin to just lever it out...........
  • + 2
 Tired? Then take a brake
  • + 1
 I had to dust off my note pad for this.
  • + 4
 I Hope you will stop with these puns.
  • + 0
 Dot com
  • + 4
 stop it
  • + 15
 Yea it is time to put endo to this
  • + 8
 im weelie done with this
  • + 6
 puns, really? give me a brake...
  • + 5
 When fixing your brakes do you bleed from the nipple?
  • + 3
 Couldn't stop reading during my lunch break.
  • + 2
 Steve815 - where I live we remove the air from the system by bleeding from the knob
  • + 3
 The puns are unstoppable! Brake it up.
  • + 5
 These puns are leaving me in a hayes!
  • + 1
 When my avids gets moody every 3 weeks. But once I bubble bleed it, it back to normal.
  • + 0
 Okay just STOP now...
  • + 0
 Hammm - I would like to point out gently that the word stop is related to braking...
  • + 0
 Really?
  • + 2
 No one stop you from braking the combo.
  • + 3
 Hammm - Captain Obvious needed to march in as a form of disclaimer. I am happy I changed to stiff hose.
  • + 2
 Wait we need to dab this down.
  • + 3
 A good clean brake is all this conversation needs. Otherwise it will just bleed out and eventually stop.
  • + 2
 the magic is working very well on this post! Seems we have the right formula
  • + 3
 I was out testing yesterday and only got to reply this am - i thought this line of comments was pretty good... thanks to everyone - it was nice to wake up with a smile - very punny.
  • + 1
 Really guys! Stop hitting my nipple with your pads. They need a brake.
  • + 27
 Yet another maintenance job I almost certainly need to do, but know I'll never find the time to get done...sigh.
  • + 20
 Using isopropyl alcohol and Q-tips is my go-to when cleaning pistons; and is way cheaper than brake cleaner. After that I drip a drop or two of mineral oil (for Shimano) or dot fluid (for Avid and Hayes) on the side of each piston, push them back in the caliper with a tire lever, and finally isopropyl alcohol the caliper all over. I've never had an issue with pads getting contaminated doing this and the pistons glide much better than if you just push them back in dry.
  • + 0
 so, i have an m820 saint set, the time arrived to change pads. which side should i open, the bleed screw down at the caliper or on the top, at the lever? If the lever, and i am correct, i also need to attach the bleeding funnel with some oil, so if i push the pistons back into their bores there would not be any backpressure, cause the oil can move upwards the funnel? Smile
Thanks for the tips!!
( i can bubble bleed them, never changed oil, or pads so im a first timer Big Grin )
  • + 4
 I've been using brake cleaner for over 10 years with amazing results. Not sure where the author gets the notion that you shouldn't use it on pads. It essentially gives your brake much more stopping power. Oh, and brake cleaner evaporates leaving no residue. I've been told this by welders who use it to clean metal parts.
  • + 1
 Riejuspike, When replacing your pads on the saints, you shouldn't need to open up any screws when pushing your pistons back into the caliper (that is if you never bled them, bubble bled or full bled.) If you have bled them as your pads have worn down, you will need to open a screw. Undo the top screw, the lever side screw and attached this special Shimano bleed cup ( www.jensonusa.com/!BJz-XYzUl4TW5!qsZmXF9w!/Shimano-Disc-Brake-Bleed-FunnelStopper?utm_source=FRGL&utm_medium=organic&gclid=CjkKEQjwkKKbBRDwk8uzi8y7jb0BEiQA71zrXCH01aPEllq1kp6b9bTG-xYo1cBC5c2zF9Za3NAFuIXw_wcB ) This cup will keep you from dropping any oil on the ground as you reset your pistons. Reset you pistons and put a bleed block in (you can use your new pads as a bleed block but for best results, use one of the yellow bleed blocks that came with your brakes.)
  • + 2
 Once you bleed block is in, I would recommend doing a full bleed to get new mineral oil in your lines but you don't have to. To bleed the brake, attach your syringe that is full of mineral oil to the nipple of the bleed bolt on the caliper (remove that black rubber dust cap to allow it to attach well.) Open the top bleed screw and thread on that bleed cup from the link above. Once the cup is in place, pull back on the syringe of the caliper end 2-3 cc/ml to get any bubbles out and then push the oil through the caliper til it starts coming out of the lever bleed hole/bleed cup. Do this til all the bubbles leave. The last step is probably one of the most important. With your bleed cup still attached to your lever, squeeze your lever slowly, then faster and faster. You should see bubbles coming up from the lever. Do this til they stop and then tilt the brake lever at a 45 degree angle (riding angle) and squeeze your lever some more. This gets rid of all the air bubbles and makes your saints feel amazing. If your brakes start feeling spungie, fill the cup about 1/3 full, thread it on your lever, and pump your lever all over again.

I love the new Shimano braking system because you can literally bleed a brake in 2-3 minutes and never have "weird" results like you may have with other brands.
  • + 1
 Heres a very "intense" youtube video on everything I just said:

www.youtube.com/watch?v=o2c6ezHY0A4#t=86
  • + 7
 @dirtworks911

the only piece of your advice I'd take issue with is using DOT or Mineral Oil to "lubricate" the pistons

neither are lubricants but corrosive brake fluids, and both actually cause the piston seals to slightly swell (this is designed into systems and prevent fluid leaks under high pressure)

initially, using DOT or Mineral Oil makes it easy to reseat the pistons as they press back easily into the caliper bay.

However, it then causes more drag on the piston / seal interface. It seems like a quick fix but often make piston imbalance worse. I have seen many mechanics in my workshops make this mistake until we've educated them Smile

the correct lubricant to use is high-temp silicon grease, Avid have their "Pit Stop" variant and Hope use "Hunter" for example. This does require a caliper rebuild to install properly, but ensures a long working life and good piston balance.
  • + 3
 Thanks Hampsteadbandit. Thats some good info to know!
  • + 1
 Correct. Also been using it for years.
  • + 1
 yes, I asked for some info bits, but you wrote down the whole procedure! Smile thanks by the way
i did a bubble bleed in the past only with the cup in the lever, and some lever squeeze
now, i have worn pads, so i will attach the cup to the lever, and push the pistons back, put the bleed block in place, and give the system a fresh fluid, than good to go!
I love shimano's pure easyness too Smile
thanks
  • + 2
 We suggest opening the bleed screw when moving pistons to insure you don't pop a bladder - arrange the bike so the bleed screw is level with the ground and if you like utilize an open reservoir such as the Shimano cup.

We don't suggest lubricating pistons unless you do a full tear down to avoid (which means the system was very dirty or had a more severe issue) if you do a full tear down it is up to you.

MTB brake pads contaminate so easily we do not suggest anything but ammonia based window cleaners - we've seen issues commercially with just about everything else...

Thanks for the comments - there's some good advice in them above!
  • + 1
 @Nate-at-BikeCo-com

thanks for your input

normally I'd use Iso Alcohol to clean the rotor and caliper bay. We also have access to commercial "bike specific" disc brake cleaners like this product:

muc-off.com/clean/56-disc-brake-cleaner-5037835913002.html

Do you guys have this product in the US? Any experience with it?

I've used it on customers bikes and my own bikes without any issues as a service item, especially after washing the bike when soapy detergent gets onto the rotors and brake pads.

if a bike comes in, like yesterday a Specialized Crosstrail Disc where the customer used a spray chain lubricant and contaminated the rear brake, I degreased the rotor with Iso Alcohol and replaced the pads after cleaning the caliper bay.


the normal procedure for an uncontaminated bike would be to dose the rotor and pads with the Muc-
Off spray, wipe the rotor clean with a clean, dry rag and then ride the bike up and down the street, applying the brakes, until the brakes stops squeaking.

This seems to return the system to full power. I've done this numerous times on my Devinci, Banshees and Stumpjumper for years and gone mountain biking with no brake issues.
  • + 2
 @hampsteadbandit: sorry to reply to a really old thread, but regarding stuck pistons, would 3M 08946 Clear Silicone Paste work for lubricating a stuck shimano slx piston? it says that the service temperature is up to 400 deg F
  • + 2
 @xeren:

should work fine. you don't need much. wipe the caliper clean with Iso alcohol afterwards. Hope use Hunter silicon grease, Avid have their (rebranded?) Pit Stop silicon grease.
  • + 1
 @hampsteadbandit: awesome, thank you!
  • + 2
 @xeren: make sure to pull the brake pads out and put them where they won't be contaminated no matter what you use. if the pistons aren't hopelessly seized a couple dabs of shimano mineral oil on the pistons and driving them in and out will typically work as well. make sure to open the bleed port before you manipulate the pistons to avoid damage on the bladder.
  • + 1
 @Nate-at-BikeCo-com: thanks nate, does opening the reservoir at the lever work as well, or does it have to be the caliper bleed screw? i've definitely pushed pistons in without opening either port several times in the past, i hope i haven't damaged anything
  • + 2
 @xeren: sorry i wasn't clear - the opening the bleed screw on the lever is perfect. it is very important to open that, especially if you have been bubble bleeding the system while the pads have worn (essentially topping it off). When you drive the pistons back in you will displace some of the fluid - if the system is 100% full it can pop the small bladder in the master cylinder.
  • + 1
 @Nate-at-BikeCo-com: yikes! good to know. i'll definitely make sure to open the reservoir next time. thanks again!
  • + 7
 "Both sets of brakes photographed for this article were straight out of the box and had never been used, yet both had piston balance issues that could cause power loss and uneven pad wear" - oh look Avid's ... what a surprise!
  • + 5
 ....or maybe they were just staged with a little help of a tire lever.
  • + 2
 The cocked pistons were staged for photos for sure. Both brakes were slightly offset out of the boxes - but more notably one piston was driving harder on both sets of example brakes.
  • + 2
 One thing that people sometimes overlook is keeping the rotor straight. Sometimes you can get a brake that is quiet, yet the rotor is bent and pushes pistons back into the caliper, so the feel can get REALLY inconsistent. I got to a point when I thought I must have toasted the brake, inspected it, and didn't find a fault, yet I had to pump the brake up all the time. Turned out the rotor was bent quite hard, but not enough to stop the wheel when trying to spin it (as it has pushed the pistons in already).
  • + 3
 Excuse my ignorance , but what does "insure that you have the bleed screw cracked" mean ??. I know what a screw is and I know what condition something has when it is cracked , but I don't think that is the meaning here...
  • + 2
 I think they mean open when they say cracked
  • + 2
 Thanks!, never heard that expression before ...
  • + 4
 Open just a tiny bit "cracked open"
  • + 3
 It's a good feature but I can't see the logic of opening the bleed screw to push/retract the pistons. All you'll do is create a vacuum in the master cylinder when the pads are fully extended and introduce air into the system.
  • + 6
 North American expression, used such as, "Oh, that one's going to stink, crack the window." would mean that I farted and it's going to smell badly and you should open the window slightly to allow for ventilation of the noxious fumes.
  • + 2
 Sorry for the slang but they've got you covered! Open the bleed screw.
  • + 2
 "• Begin by resetting both pistons into their bores - insure that you have the bleed screw cracked and your dummy pads installed. If they drive out evenly when you pull the brake lever, you're golden. If one drives more aggressively, apply slight pressure to it to retain its position while allowing the slower piston to advance towards it until both are even with each other. Take your time and don't pull on the brake lever too hard; remember that going slow will get the job done correctly"

-so open the bleed screw,
-then pull the lever to see pads drive out evenly??

I don't think this will work with bleed screw open
  • + 2
 He is refering to the lever bleed screw, so the master piston will still seal and generate pressure. I think you crack it to avoid pressurising the reservior when you push the pistons back in.
  • + 1
 Blehed's reply is exactly right. with the bleed screw cracked your master cylinder will drive the slave cylinder still - but when you apply pressure to the piston to reset them it will ease the load on the bladder. Again thanks for the comment and the thoughtful reply to the comment.
  • + 1
 'Use your set of dummy pads" -with an obviously brand-spankin-new set of pads in the photos.

"Clean, even, and balanced. These brakes will offer optimum performance when installed." -but the pads are way too close together to fit a rotor in there.......herp derp.
  • + 2
 Brand new brakes - we didn't clean the system with anything that would attack the pads. We left the pads close for the photo so it was easier to see they are even. Your points are valid though.
  • + 1
 Overall good article addressing a problem that tech-savvy mechs know all about Wink on the other hand I'm not so sure I think it's such a good idea to post this kind of stuff on the interwebs for all double left handed wannabe pro mechs to try at home...
  • + 1
 Good point - we try to have a decent disclaimer on it all. If nothing else I like to know what the problems might be before I take my car to the mechanic - so if its just for information we hope some riders can review the problem with their resource if they don't feel confident doing the service themselves.
  • + 1
 I have a question...

Wouldn't uneven pad wear, or even "Piston unbalance" typically be caused by an improperly centered caliper? Where one piston has to move farther in order for the pad to contact the rotor? Therefore causing the closer pad to contact the rotor sooner, apply more pressure sooner, thus causing that pad to wear faster?

And since every modern brake ships with a pad spacer in it, designed specifically to prevent "Piston imbalance" (or whatever term you invented) in that it is typically the correct thickness to allow a rotor to pass through and the pads to retract enough not to rub - I find it strange that you had these issues.

Just spitballin'
  • + 1
 yeah.. im sitting here reading this and telling myself "ive never had this issue."
  • + 1
 Even with evenly spaced brakes I suggest checking that both pistons are driving equally hard from the manufacturer. That is more what we were referring to with "piston imbalance"

The slot opening for the rotor will typically balance itself when you apply the brakes a few times (it's very hard to say add a mm and keep it - brakes are designed to accommodate pad wear)
  • + 1
 When the pistons don't go back in I toss the brakes. Now I will try the cleaning of the caliper. maybe I will get some life out of my huge tossed brake collection. Its worth a shot . Thanks for the tip. The only cleaner I trust is pure alcohol. I think most cleaners use detergents. Detergents are the worst thing to have on your brake pads.
  • + 1
 "mismatching any fluid as a "lubricant" may lead to failure" - that's not true. there is a good lubricant for brake pistons, it's called "bremszylinderpaste" (ATE brake cylinder paste is compatible with DOT 3, DOT 4 and DOT 5.1 brake fluids). www.ebay.de/bhp/bremszylinderpaste
  • + 3
 But not mineral oil...
  • + 4
 i really wish the bigger brake companies would switch to mineral oil (with the exception of shimano... cause, well, you know).
  • + 1
 Total nonsence. Brake cleaner is excellent for pads. 1 remove and clean the pad with soap 2 cover in spray brake cleaner and leave for 2 mins 3 spray once more till wet looking 4 using a lighter burn off the fluids on the pad taking any rogue oils and residues with it leaving a smooth clean dry ceramic behind Piston balancing is down to the seals. Once contaminated oil is ruled out stiff pistons will almost never free up without a seal replacement. The article above mearly spread the fear of unequal pistons
  • + 1
 Great guide, thanks. I always though that the pistons on my Formula RX brakes engaged at different times to increase the modulation. I know this is a feature on some breaks. After reading this I think ill have a shot at trying to balance them.
  • + 1
 You can have two top level mecanics using diferent tecnics to make the same job. Very nice article. This article make me understand why Pink Bike is like a bible to me. No more tripping Waki-shity-leaks and more teck twesday and teck spotlight please
  • + 5
 leave waki out of this!
  • - 3
 Waki cocksuker??? Should love moto and stinky smoke and that noize braaap that irritate everyone
  • + 3
 someones a little butt hurt they cant get their drawings on the front page of PB
  • - 2
 My drawings? Dont have it. Front page??? For what? Show me? Dont need that...have tons of photos edited in websites and magazines... have tons of trophies and medals... I dont want to be famous do you?
I just dont like wakistuff like many others that do coment there dobt understand why PB do that...
Everyone has his own taste. Im not a keyboard jokey
  • + 1
 I have a question/problem. One of my pistons on Shimano Saints won't go all the way in the caliper. What to do?
And is it possibile, that uneven pistons go "too much out" on the one side and that causes oil loss?

Thanks for the answers
  • + 4
 I pissed on my brakes evenly and nothing changed
  • - 2
 Thats funny
  • + 1
 You weren't drunk enough.
  • + 4
 Ya I'm probably not going to do this
  • + 1
 What I have found for getting 99% pure Isopropyl Alcohol, is to order it from your drug store. Just got a new pint last week for $7.00. Should be good for the summer now.
  • + 1
 yep works fantastic !!
  • + 3
 i found the easiest way to clean my breaks… I got rid of Avid's.
  • + 1
 My brake cleaner evaporates, not sure if it leaves any residue. IPA evaporates and so does buffsol i use them with great results
  • + 2
 Welcome back, Tech Tuesday!
  • + 1
 Where is the delicious pics of Emily Batty? Without them this is all wooplaw!
  • - 4
flag mudmandhbrazil (May 6, 2014 at 12:25) (Below Threshold)
 Wrong site buddy. Go to xxx sites man. This is a mtb site. She is a princess anyway
  • + 1
 Rotating the pistons (1/4 turn) will extend their life and, in some cases, improve balance dramatically.
  • + 1
 My brakes don't work well because I never bleed them, I've wrecked on them a ton, and they're like 6 years old.
  • + 1
 Whatever the case, fix it so it brakes!
  • + 1
 * but didn't give any advice on solving the matter
  • + 1
 The originality of these puns are beginning to fade.
  • + 1
 Squeaky Shimano brake when coming to a stop?
  • + 2
 Try some aluminum tape on the back of the pads backing plate. It acts as a damper (sound insulator). Make sure the backing plate is clean, use brake cleaner on a clean rag and wipe it over and over again till it is. Trim off any tape that is going past the edge with a razor blade or a fresh X-acto knife by putting on a flat surface and tracing the backing plate. This usually does the trick for any brand of brakes.
  • + 1
 Cool thanks ill give that a shot tonight.
  • + 1
 does this also the cause of squealing brakes?
  • + 4
 Squealing brakes can be cause by a few things. Most common cause is dirt on your rotors. Simply rub isopropyl alcohol on them with a clean rag. You should see dirt on the rag when you are done. If it continues to squeal, chances are, your pads are contaminated. You can either sand them down with fine grit sandpaper and burn them with alcohol to get rid of all the contaminates, or just place them. Note: Organic pads aren't able to burn like metal ones and you will just need to replace them.
  • + 2
 dirtworks911 Simply? Make sure you have a quality isopropyl alcohol with no "magical" additions that supposedly improve it's ACTION and makes it better than those "other" products on the market. Burning with alcohol... if you have a rebreather, then you are welcome to make an attempt with little chance of success. Most pads contain toxic substances DO NOT burn them if only for your own sake.

Pads are very porous, they will suck most contaminants very deep. You can clean a rotor to a certain degree but as a base rule contaminated pads should be thrown away immediately to save yourself time, frustration and eventually money. If you used contaminated pads for longer time throw the rotors away as well. It will be cheaper than contaminating new pads with shit that sits in the rotors and doing it all over again. Bicycle pads and rotors are not motorcycle or car brakes - they are many times smaller thus the effects of contamination have more impact on their performance.
  • + 6
 WAKI, I was just giving some simple, basic advice on what my shop and I do to help our customers get rid of brake noise on their well-maintained bikes. It certainly isn't a "cure all" for every brake squealing situation, but 9 times out of 10, it works. WAKI knows a lot and comments on most things on Pinkbike so he's a good person to follow. BUT... If you don't have the money to spend on "other," more expensive products, stick with the high 90% or more isopropyl alcohol and a clean rag. If your pads are dark and discolored, they are contaminated. Take them into your local bike shop and get their opinion if they can be decontaminated or not. If you know dot or mineral fluid got on the pads, more often than not, it is best just to replace them and possibly your rotors as well.

Also WAKI, I am curious, what in metal pads that makes them toxic?
  • + 2
 Squealing brakes, not only caused by dirty components which are easy to clean, but an out of line rotor with caliper, or a rotor that is deformed so that it has to bend when the pads make contact... depending on what system you have, a proper caliper setup (not just 'pull the brake lever') where you follow this guide, then fit the caliper and align it by eye with the rotor and a true rotor should cure it. Also the pad material will make a difference... I used to use brake lube behind the pads but now use a micron layer of Molybdenum Disulphide behind the pads before bed in.
  • + 3
 One guy here boiled his pads: put them into a pot of boiling water, weight them down so they stay submerged and with the brake surface facing up and supposedly the high temperature makes contaminating oils fluid and the fact that oil is lighter than water pushes the water into the porous pad and in consequence the oil out and it will swim on the surface and your pad will be clean. Never done but sounded convincing as a way to decontaminate pads.
  • + 1
 dirtworks, sorry for sounding so "high-horsed"... there are many cheap degreasing products out there that for some unexplainanble, or rather unreasonable reasons contain more stuff than just isopropyl alcohol. You don't need to buy stuff like motorex but I meant it is worth making sure that you get a simple freaking isopropyl alcohol and in the world full of unnecessary waste bullcrap that is not that simple. 20 years ago you were going to department store and you got a transparent glass bottle or a silver spray can with "Isopropyl Alcohol" writing on it, now you get Clean> 5000 or "Brake doctor master Pro"with logo designed by marketing experts, it contains 10 more ingredients and is virtually worthless because it removes old crap from it and puts its own instead..

About the toxicity of brake pads - I got this advice from a bloke who is a car mechanic and occasionaly rides bikes. He says that these days brake pads don't contain as much crap but they still work with them with mask on their face. He says that he just wouldn't risk. My bike mechanic does not recommend burning pads either. They are not that expensive to replace.
  • + 1
 Ahh and BTW, I am having all this negative attitude because I used cheap car brake cleaner and it turned my brakes even worse than they were.
  • + 1
 Use clean streak on them. I just lightly sand the rotors and pads, clean them off with clean streak and wipe them down with a clean rag. Like brand new again. I have no idea why the recommendations in this article say not to use any bike brake cleaner on our bike brakes. In my experience, isopropyl does not work near as well. To the point that I use to chalk it up as a myth when working in a shop as a mechanic.
  • + 2
 My 2 cents here:

Squealing brake noise typically from overheat. Look for black marks on rotors. We suggest flooding with ammonia based window cleaner (spray entire rotor), then resurface with wet/dry sandpaper approx 200 grit. Do this a couple times, then go ride the bike with the brakes applied to burn it off. Typically this gets you going.

Honking brake noise (more like a goose) is typically pad contamination. I have seen many was people try to correct this over the years - some with much more risk than others... If I contaminate pads (and occasionally it happens to everyone) I replace them. Yes I work at a shop, yes I suggested you buy something but for me - the cost of a set of brake pads typically isn't worth the amount of time it takes to try to correct them or the extreme irritation if they didn't get corrected after that much time!
  • + 1
 got my friend here says overheat too because there was definitely blueish/black marks on my rotors. He suggested that i should change a bigger size rotor (180/203) because the 160 im currently running now is not enough to stop (he said im going too fast and that rotor cannot handle it)
  • + 1
 Your friend is on the right track if you are consistently overheating brakes. The reasons for staying smaller on rotor size are both weight and bite (initial power). I used to run 180 / 180 on 26" bikes but found the 7" rear (180mm) provided too much bite and lead to brake hop. I went to 160mm rotors and just service them more often.
  • + 1
 really? thanks for your comment. Will change to 180mm up front first, see whether it will stop the squealing sound
  • + 1
 How badly would this affect brake power if the pads were unbalenced?
  • + 1
 No idea about power but my unbalanced rear brake pistons make my pad drag and the rotor bend while braking and cause uneven wear on the pads.
  • + 1
 Yes THIS is what this article is telling you how to sort
  • + 0
 Hahaha!! Funny to see what happens to Avid
  • + 2
 Exactly. I just bleed my non-Avid brakes once a year and life goes on. Had them for 6 years now with no problems.
  • + 0
 I too am not an Avid fan....................of Avid..............get it?
  • + 1
 Probably should do this
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