STICKY:Piston

[dyna-ti]

Sticky piston on a mono mini
one side sticks out and seems reluctant to return.
any ideas whats causing this?
I thought a bit of bleeding but it seems to be one side only
Doesnt appear to be a serious prob,im sure either a service or a bleed will sort it out
Im only used to the C2's so a non-adjustable calliper is new to me.
Any help you chaps can offer would be great help.

Nicer looking than the C2's

 

[Enid_Puceflange]

I would try cleaning the pistons up a bit bud,

dont strip it down, just get it off the fork leg, remove the pads and get the pistons out a little (not too far or your in a world of hurt) .

Get a basin of hot soapy and clean up around the pistons with a toothbrush and a little brake cleaner.
Then when its all dry, apply a tiny smear of copper grease around the pistons (while its exposed) then return them to their normal position.
this should free them up and resume normal service.

It might work, but worth a try nonetheless

Gc

 

[dyna-ti]

I dont have any 'brake cleaner'
any recommendations :?

Oh God,there goes another tooth brush
just as well i buy them in packs of 4

 

[Enid_Puceflange]

Dont tell anyone i suggested this, so keep it quiet.......

(Wd40) seems to remove most old stubborn pooh, just make sure you get it all off before applying copper grease dude

Gc

 

[currie]

i have this same problem with my mono minis, i bought them when they first came out and they have never worked as good as my old minis!

i have tried this and it didnt work for me.

anyways, i dont have the massive torx driver and i was so fed up i have taken mine into the LBS to have a full strip down.

will see how it goes!

 

[Enid_Puceflange]

Coool,

Keep us posted when you get them back from the shop to see if there is any noticable difference dude

Gc

 

[dyna-ti]

Thanks for the help

 

[FairfaxPat]

I have XTR calipers and the same thing happens to mine now and then. I use a Q-tip and alcohol to clean the piston-just squeeze the levers a little bit when there are no pads in there, so the piston travels a little farther than usual, taking care not to squeeze so hard the piston pops completely out, this exposes the grime that has built up on the piston wall and you can then clean it off. I then apply a light coat of brake fluid to the piston wall and then push it back in. If one of the pistons is stuck in, as often happens, I push the other one in and hold it in with a wrench or screwdriver, then squeeze on the brake lever, forcing the stuck one out past the layer of grime holding it-then clean it off and lube it. Works like a charm every time!

 

[dyna-ti]

Ok
I'll try that

Do you need the little spring clip when you take the pads out
ive seen it included with the mono but dont know what its for or how important it is[i dont have one ]

Ok to use gt85 on a q-tip or could that contaminate anything :?

 

[FairfaxPat]

I'm not familiar with GT85, I just use ordinary rubbing alcohol for a cleaner and, on my Shimano brakes, I use their brake fluid, which is a red colored mineral oil, to lube the piston sides before I push them back in. Some bicycle hydraulic brakes use different fluids, and I'm not sure what yours uses, but whatever it is, I would use that as a lube. Also, since it is easy to over extend the pistons and pop them out of their bores, I hold a thick beer coaster in the middle to prevent this happening when squeezing the lever to get at the dirt. On Shimano brakes and Avid's, there is a little H shaped spring that holds the two pads in the right alignment and inserts with them, partially holding them in place, but I'm not familiar with the system on your brakes.