Piston Stuck?

[b5driver]

Today I dropped my bike off at the shop because it sounded like the rear brake rotor needed to be straightened. It turns out that one of the pistons in the rear caliper is stuck. I'm riding an 07 Yeti 575 with Juicy 3's that I bought in September.

My question is, is this a wear and tear item? Is this common with Avid brakes? The mechanic at the shop I dropped it off at said that this is usually caused by age or from really slamming on the brakes hard. Obviously the bike and brakes are fairly new, so that rules the first one out. I don't go too fast since I'm relatively new to moutainbiking (or at least I ride that way) so I'm thinking that I'm probably not guilty of the second scenario. Also, I'm a bigger guy (around 200 lbs.) and I'm running on 160mm rotors. Is it possible that I should be using something a little bit bigger (or maybe a burlier setup) and that the combination of my weight and the brakes somehow caused the piston to lock up?

From the searching I did here, it appears that there might be an easy fix and that all I have to do is swab the piston with some WD40 and gently work it out and then it might be ok. The mechanic seems to think that he needs to replace the piston and any other parts so he is going to contact SRAM tomorrow to see if they will warranty it. I've never been one to turn down new parts, but couldn't they (or me I guess) just try the fix above and maybe that would do the trick?

[Rockinthecasbah]

IF its stuck out its possible that the pads wore too thin but thats not really a rotor issue maybe you smoked the pads and caused them to wear fast but its more likely that they just got to thin and/or out of adjustement side to side and locked at full travel. It should be an easy fix.

[b5driver]

Originally Posted by Rockinthecasbah

IF its stuck out its possible that the pads wore too thin but thats not really a rotor issue maybe you smoked the pads and caused them to wear fast but its more likely that they just got to thin and/or out of adjustement side to side and locked at full travel. It should be an easy fix.

I think he said that the piston was actually stuck in. I'll have to check.

How long do pads last? I usually only ride once or twice a week and I haven't had the bike that long. Hopefully, they don't need to be replaced that often?

[project_d]

Shop guys (and girls) should chime in, but sounds like BS to me. I know the piston can get stuck, but I think it's usually from use over a long period of time (much longer than the amount of time you've had them), or from use in adverse conditions (mud, sand). I talked to a friend, and he used the WD40 trick once, and it worked for him. If SRAM doesn't warranty it, then try that.

[jschwart73]

What I've always done with motorcycle calipers and pistons is the WD40 trick to get the piston out and then use emery cloth to *GENTLY* work the sides of the piston to free it up. You're barely removing material, just enough to free up the piston's fit to the caliper.

[Rockinthecasbah]

I dont see how it could be stuck in if it was working properly before sounds like BS, pads last way longer then that I was thinking of the piston being over extended in stuck because it was rubbing .

[RacinJason]

It is really unusual for the piston to stick with the juicy 3,5,7s. Those brakes are some of the most reliable brakes we have used. Easy set up and a solid feel. WD40 or liquid wrench can free up that piston.
I have also used Murphy's Mystery Oil. When the pad wears down to metal it heats up the piston. When that happens it expands in its sleeve and can lock up/seize . Sometimes it is temporary .
Those are great brakes.
On the other hand if you where talking about the Avid Code brakes it would not be unusual. I have had a lot of trouble with those darn things. Where do I start.
When they work they are great . Have a shop set them up for you .
The path ,Bike Co ,Adrenaline,Switchback. And no I don't get anything for telling you about those shops I just know they are great people.

[dutch]

The piston on my Hayes nines is a bit stuck right now. The culprit seems to be dirt and grime around the side of the piston. To (quick) fix it I took the caliper off of my fork, swabbed the hydraulic brake fluid around the extended piston (had to pry it out just a bit), and then pushed it back in. Its only a temporary fix as my rotor is also out of true and I think my quick release skewer might be bent, but it has worked ok so far.

I think the culprit for me was riding el prieto, I rode through some silty mud and also smacked the rotor and left fork leg on a rock while nearly going otb through a rock garden.

Next in the works for me is a rebuild of the front brake. From what I know, I doubt that you'll need to warranty the piston, but a rebuild and cleaning might help out a bit.

hope that helps.

[b5driver]

Thanks for the advice everyone. I'll talk to the shop today and see if the fix might be a little simpler than what they're saying.

[bjammin]

The culprit usually is the rubber O-ring that is used to retract the piston back into the caliper. When they get nicked or worn they loose their ability to do their job. A thorough cleaning will do the trick. Once the pads are removed, carefully pull the lever to extend the pistons. Apply a very small amount of light oil (tri-flow works best) around the pistons and carefully press them back in place with a 9mm open-end wrench. Wipe down everything VERY WELL! Put everything back together and check out your work.

[b5driver]

Originally Posted by bjammin

The culprit usually is the rubber O-ring that is used to retract the piston back into the caliper. When they get nicked or worn they loose their ability to do their job. A thorough cleaning will do the trick. Once the pads are removed, carefully pull the lever to extend the pistons. Apply a very small amount of light oil (tri-flow works best) around the pistons and carefully press them back in place with a 9mm open-end wrench. Wipe down everything VERY WELL! Put everything back together and check out your work.

Thanks. Since I'm the least mechanical person in the world, I will be sure to suggest this to someone else.

[OldDogDan]

[quote=bjammin;172687]The culprit usually is the rubber O-ring that is used to retract the piston back into the caliper. When they get nicked or worn they loose their ability to do their job. A thorough cleaning will do the trick. quote]

Hey Ben,
If the o-ring's nicked or worn, I'd think you'd want to replace it...? But maybe save that for a later full rebuild if cleaning works for now.
Dan

[bjammin]

[quote=OldDogDan;175356]

Originally Posted by bjammin

The culprit usually is the rubber O-ring that is used to retract the piston back into the caliper. When they get nicked or worn they loose their ability to do their job. A thorough cleaning will do the trick. quote]

Hey Ben,
If the o-ring's nicked or worn, I'd think you'd want to replace it...? But maybe save that for a later full rebuild if cleaning works for now.
Dan

True.

[DHS]

[quote=OldDogDan;175356]

Originally Posted by bjammin

The culprit usually is the rubber O-ring that is used to retract the piston back into the caliper. When they get nicked or worn they loose their ability to do their job. A thorough cleaning will do the trick. quote]

Hey Ben,
If the o-ring's nicked or worn, I'd think you'd want to replace it...? But maybe save that for a later full rebuild if cleaning works for now.
Dan

agreed. if still stuck. i've had good luck using compressed air to get stuck pistons out. the tri-flow trick works well.
if you can get a hold of the Grimeca piston grease. that worked even better. its actually dot fluid based, so won't mess up a bleed.