Brake piston stuck

[Stardog]

Does anyone know how to unstick this brake piston? One piston will pump up all of the way and one refuses.

[fixxervi6]

No clue, but that would explain some really crappy feeling brakes

[DarcShadow]

When in doubt, try a hammer.

[Stardog]

No clue, but that would explain some really crappy feeling brakes

And that is only one side. Once I get this one figured out I get to check out the other side.

[milesmiles]

Could be that it's not getting fluid to that one

[Stardog]

Well it moves a little bit, just not much. I would assume that they share the same internal reservoir since a caliper only takes one line in and one bleed point.

[shilka99]

Do you have a bench vise that the caliper will fit into? If you can position it correctly, use this to compress both pistons and push them both back into the caliper body. then see if both move freely - but a new seal kit would be a very good idea regardless.

[Stardog]

Do you have a bench vise that the caliper will fit into? If you can position it correctly, use this to compress both pistons and push them both back into the caliper body. then see if both move freely - but a new seal kit would be a very good idea regardless.

I do have a vice that I could do this with. Should the pistons go until the are pretty much flush with the rest of the caliper? As long as I do not apply an unreasonable amount of force is there any such thing as pushing them in too far?

[shilka99]

all you need to do is free that one piston - i would try pushing both in a little, remove it from the vice then pump the master cylinder to see if both pistons move. if not, put it back in the vice and push them both back in a little further. repeat until both pump out as they should or the piston moves all the way in. If that happens, eBay is your friend for a new caliper (real cheap)
Use soft jaws so you dont damage anything, and be real careful not to overtighten the vice.

[Stardog]

Well, I went out and pushed the popped up piston in by hand and held it in place by hand with a rag while I pumped the lever. The second piston came up but it is at an angle compared to the other one and can not come up all of the way. It doesn't look right to me. I think something might be out of whack. The previous owner told me that he had the calipers professionally serviced but did not know how good of a job they did because the brakes still sucked. Let me see if I can get a pic...

[Rhino]

The correct solution is to buy a GSXR front end.

[Stardog]

Here we go.

[Stardog]

The correct solution is to buy a GSXR front end.

Perhaps.

[Striple]

The correct solution is to buy a GSXR front end.

That would make the bike ineligible for racing in the superstock classes, which may interfere with future goals...

[shilka99]

Dont worry too much about the angle - the pads align the pistons when in use. You just need the pistons to move evenly with every pump of the lever. Does this happen now or is one still stuck?

[Stardog]

No, the movement is uneven and weak. Here is a video. Never mind the beer cans.

[youtubell][/youtubell]

[nitzer]

Yeah...that's not good IMO. It would cause uneven pad wear and loss of braking since only 1 piston would be doing 70 of the work. Who knows, maybe the other piston wouldn't even move when a load was put on it. Personally, I would get a new caliper. Just me...

[Dragonfly]

If you want to use the same calipers,remove the brake lines from the caliper. Get something to catch the fluid that will pour out. Take the caliper and used compressed air (air compressor with a rubber tip nozzle), shoot air into the caliper were your brake line connects to it. This will blow the pistons out of the caliper completely. Buy a caliper rebuild kit and replace the o-ring/seals.
Or go to eBay or Craig's list and replace the entire caliper (probably your cheapest and easiest fix).

[Stardog82]

I dunno about bike calipers, but for the 'stang, a caliper costs around twenty bux.

[Stardog]

I am picking up a pair right down the street for $60. Hopefully they will clean right up and work.

[Stardog]

I think I am also going to try to deglaze the rotors.

[shilka99]

Are you saying you're buying another set of calipers? What guarantee do you have that they are better than yours? If it were me I would just buy the rebuild kit and that will give you as new calipers.

[Stardog]

I bought another set and cleaned/installed the right hand which was the one that I already knew was screwed up. It feels much better now. I am going to do the same with the left hand tomorrow. Afterwards if I am still not happy then I will try my hand at rebuilding the original parts. I have never rebuilt calipers so having a spare set in case I screw something up royally is not a bad thing and all of this is teaching me a lot about my brake system which is cool. I know a lot more than I did this morning. If I rebuild the ones that came with the bike do I need any brake specific tools to install the wiper seal? The small O-ring in the top seems to go in to place by hand without issue. It looks like that one is just to keep grime off of the wiper.

[Rhino]

Do like some of my BRC students and just stop Fred Flintstone style.

[DLSGAP]

I had a front brake failure at Cresson a few years back on the zx10.. Not a good feeling when you've just passed a cmra buddy you've been chasing and have the throttle pegged. Let off the gas and grabbed the lever... Straight to the bar with no resistance.


Thank god for the slipper clutch