brake caliper is still sticking shut. - Yamaha YFZ450 Forum : YFZ450, YFZ450R, YFZ450X Forums

Kenny Lampe · 01-29-2012, 11:50 AM

I just rebuilt it. Bleeds out properly. I dont understand what it could be. Please help

nickmell · 01-29-2012, 06:19 PM

mastercylinder probably.

Kenny Lampe · 01-29-2012, 08:48 PM

Do you think a rebuild kit would solve this problem? Could I have hurt it by pressing in the pistons without the cap of the mastercylinder off?

ctown208 · 01-29-2012, 08:50 PM

i dont think so we do that on cars all the time, how r u bleeding it?

Kenny Lampe · 01-29-2012, 08:56 PM

gravity bleed and the old pump the brake and loosen the bleeder valves method

nickmell · 01-29-2012, 08:57 PM

Did you rebuild the mastercylider or the caliper, If you had the lid on the resivior and pressed the calipers piaton in, like when you replace pads. it will build pressure on not release it, which could be the problem.

Kenny Lampe · 01-29-2012, 08:58 PM

and its only the front left side thats not releasing properly.

Kenny Lampe · 01-29-2012, 08:59 PM

rebuilt the caliper

Kenny Lampe · 01-29-2012, 09:00 PM

so nick i blew the mastercylinder?

nickmell · 01-29-2012, 09:06 PM

Possibly, if the one side is still working though it may not be, I would take the lid of the master cylinder and try it first. You don't want to push the caliper piston in while the lid. Is tight. If you don't the glass will explode and you will say bad words. I learned the hard way.

Kenny Lampe · 01-29-2012, 09:13 PM

ive already tried re bleeding and pressing the pistons in with the lid off of the master cylinder. bleed it off at the master cylinder and the calipers.
should i just get a new master cylinder or rebuild mine? I dont know what part of the darn thing that could go bad!LOL Im UP IN ARMS! Been riding a while now with this problem and it needs to be off my back..

nickmell · 01-29-2012, 09:23 PM

You can usually find used complet mastercylinders for cheper than the rebuid kits. If you pull yours apart and clean all the parts up it may fix it. They can sometimes get stuff in them.

Kenny Lampe · 01-29-2012, 09:26 PM

also, if the mastercylinder is pushing fluid to 1 caliper wouldnt you have fluid to both? I need to figure out what causes the pressure on the pistons for them to release

Kenny Lampe · 01-29-2012, 09:28 PM

is it the diaphram in the mastercylinder that does that?

nickmell · 01-29-2012, 09:40 PM

Ther is like a little aluminum piston that has some fancy shaped o rings on it. They are wedge shaped so one way pushes and one way releases.

01-29-2012, 11:50 AM	#1 (permalink)
Kenny Lampe Member Join Date: Dec 2011 Posts: 33	brake caliper is still sticking shut. I just rebuilt it. Bleeds out properly. I dont understand what it could be. Please help

01-29-2012, 06:19 PM	#2 (permalink)
nickmell Senior Member Join Date: Aug 2010 Location: Oakland MD Posts: 1,720	mastercylinder probably. __________________ “Speed has never killed anyone, suddenly becoming stationary… that’s what gets you.” - Jeremy Clarkson

01-29-2012, 08:50 PM	#4 (permalink)
ctown208 Moderator Join Date: Oct 2011 Location: Caldwell Idaho Posts: 512	i dont think so we do that on cars all the time, how r u bleeding it? __________________ 2012 yfz 450r

01-29-2012, 08:57 PM	#6 (permalink)
nickmell Senior Member Join Date: Aug 2010 Location: Oakland MD Posts: 1,720	Did you rebuild the mastercylider or the caliper, If you had the lid on the resivior and pressed the calipers piaton in, like when you replace pads. it will build pressure on not release it, which could be the problem. __________________ “Speed has never killed anyone, suddenly becoming stationary… that’s what gets you.” - Jeremy Clarkson

01-29-2012, 09:06 PM	#10 (permalink)
nickmell Senior Member Join Date: Aug 2010 Location: Oakland MD Posts: 1,720	Possibly, if the one side is still working though it may not be, I would take the lid of the master cylinder and try it first. You don't want to push the caliper piston in while the lid. Is tight. If you don't the glass will explode and you will say bad words. I learned the hard way. __________________ “Speed has never killed anyone, suddenly becoming stationary… that’s what gets you.” - Jeremy Clarkson

01-29-2012, 08:48 PM	#3 (permalink)
Kenny Lampe Member Join Date: Dec 2011 Posts: 33	Do you think a rebuild kit would solve this problem? Could I have hurt it by pressing in the pistons without the cap of the mastercylinder off?

01-29-2012, 08:56 PM	#5 (permalink)
Kenny Lampe Member Join Date: Dec 2011 Posts: 33	gravity bleed and the old pump the brake and loosen the bleeder valves method

01-29-2012, 08:58 PM	#7 (permalink)
Kenny Lampe Member Join Date: Dec 2011 Posts: 33	and its only the front left side thats not releasing properly.

01-29-2012, 08:59 PM	#8 (permalink)
Kenny Lampe Member Join Date: Dec 2011 Posts: 33	rebuilt the caliper

01-29-2012, 09:00 PM	#9 (permalink)
Kenny Lampe Member Join Date: Dec 2011 Posts: 33	so nick i blew the mastercylinder?

01-29-2012, 09:13 PM	#11 (permalink)
Kenny Lampe Member Join Date: Dec 2011 Posts: 33	ive already tried re bleeding and pressing the pistons in with the lid off of the master cylinder. bleed it off at the master cylinder and the calipers. should i just get a new master cylinder or rebuild mine? I dont know what part of the darn thing that could go bad!LOL Im UP IN ARMS! Been riding a while now with this problem and it needs to be off my back..

01-29-2012, 09:23 PM	#12 (permalink)
nickmell Senior Member Join Date: Aug 2010 Location: Oakland MD Posts: 1,720	You can usually find used complet mastercylinders for cheper than the rebuid kits. If you pull yours apart and clean all the parts up it may fix it. They can sometimes get stuff in them. __________________ “Speed has never killed anyone, suddenly becoming stationary… that’s what gets you.” - Jeremy Clarkson

01-29-2012, 09:26 PM	#13 (permalink)
Kenny Lampe Member Join Date: Dec 2011 Posts: 33	also, if the mastercylinder is pushing fluid to 1 caliper wouldnt you have fluid to both? I need to figure out what causes the pressure on the pistons for them to release

01-29-2012, 09:28 PM	#14 (permalink)
Kenny Lampe Member Join Date: Dec 2011 Posts: 33	is it the diaphram in the mastercylinder that does that?

01-29-2012, 09:40 PM	#15 (permalink)
nickmell Senior Member Join Date: Aug 2010 Location: Oakland MD Posts: 1,720	Ther is like a little aluminum piston that has some fancy shaped o rings on it. They are wedge shaped so one way pushes and one way releases. __________________ “Speed has never killed anyone, suddenly becoming stationary… that’s what gets you.” - Jeremy Clarkson

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