Tech Talks Presented by Park Tool is a monthly video series hosted by Park Tool's own wrench whisperer, Calvin Jones. The series covers the A to Zs of some of the most prevalent repair jobs, with the fifteenth episode showing you how to cure sticky brake pistons.
The disc brake has been one of the most important products of the last few decades, but they're far from perfect. Like most things, they require some love every once in awhile, and if you don't give them some attention, they can work poorly or even start slowing you down when you don't want them to. When brake pistons don't retract back into the caliper, it's often because of a corrupted surface on the piston that rides back and forth on the seal. And if it gets really nasty, one or both of the pistons may decide to stop moving altogether. Park Tool's Calvin Jones is here to show you how to use a strip of cotton and some solvent to fix those troublesome pistons.
Fixing Sticky Caliper Pistons
Need more Calvin in your life? Episode #1 - Tubeless tire installation and conversion Episode #2 - Saving that bent disc rotorEpisode #3 - Derailleur hanger alignmentEpisode #4 - Shimano and Crankbrothers pedal serviceEpisode #5 - Trailside wheel repairEpisode #6 - Trailside chain repair Episode #7 - Derailleur limits and cable tensionEpisode #8 - Derailleur setupEpisode #9 - Fork wiper seal replacement Episode #10 - Clipless pedal setupEpisode #11 - New cleat setupEpisode #12 - Top 5 next level shifting issuesEpisode #13 - Fixing cassette playEpisode #14 - Gearing hacks
Stay tuned for more mechanical how-to videos with Calvin returning on the last Thursday of every month to show you the easiest way to get the job done. Want to know more? Park Tool's how-to section
has you and your bike covered. www.parktool.com
I explain: on my avid trail I installed aftermarkets pads with the included spring. After 2 months I had a sticky piston problem.
I completely disassembled the caliper and overhauled it. After 2 months, happened again on the same caliper.
Comparing the spring to the OEM I noticed that the OEM was stronger and stiffer compared to the aftermarket.
So I just replaced the pad spring with the OEM (without cleaning or lubing the pistons) and never had a single sticky piston again.
IMHO spring has a very important role in the health of your caliper piston(s). Check it before loosing your s**t trying to solve the problem.
Pistons are designed to creep out of the seal to take up pad wear and give consistent lever throw.
Imagine the impact of a strong spring causing full return on worn pads - loads of free stroke on every lever pull.
This is a warranty issue, if this is what is happening to you. Fyi.
I have MY17 Guide RS's, so the levers have the new res. piston assembly that doesn't expand in warm weather.
Furthermore, I even know which pistons in the caliper don't move. I noticed it the last time I bled them :-)
Thanks anyway though, I'm sure some people still don't know that the lever thing is a warranty issue, as SRAM have been really quiet about it, as it's due to heat, so not everyone's affected.
They are the new model, I'm aware of the lever piston assembly issue that plagued the older models, I don't live in any kind of hot climate so we're not really affected by it.
And lastly, I have seen which pistons do not extend when pressing the lever.
3 pistons move, 1 stays put. And it's like that at both ends.
Yeah they just leak and you can’t repair any part of them.
Actually, I didn't technically replace them with Shimano XT's or XTR's.
I kept using the Exiler 5's until I retired the bike. The new bike came with Shimano XT components. Then from there I decided to upgrade to XTR just to deck the bike out in full XTR bling.
From what I've read and from hearing about SLX they are just as good just a little heavier and made with cheaper parts. My buddy rides SLX and has never complained about them.
My personal experience was not good when it came to Elixer's. I tried the 3 that came stock on my bike and then the 5's and same issues.
Still, good video, useful to know.
"What are you doing?"
"Flossing my brakes."
"Jim, I think it's time we move on, my friends say it's weird that you floss your bike."
Bingo! We have a winner!
Also can the Mods not just put a poll under the video for the Left vs Right piston?
It is only the higher level bike nerd that gets their panties in a wad over sticky pistons. If they aren't seized they are fine.
Power spraying your bike!
I know what I'm talking about. I maintain a fleet of bikes. I've had to replace calipers a few times because once a seal is compromised it isn't worth fixing. It isn't like rebuilding a caliper to a car/truck. The seals are too small on bicycles service and expect it to work properly again.