Front brake problems

MEDMUNDS · 03-05-2012, 01:55 PM

Hey i have a 2007 komoto 250 i just replaced my steering neck bearings but in the process when i did that i disconnected my front brake cable and when i reassembled everything and i bleed the front brake and get all the air out with a mityvac brake bleeder and i do acouple manual bleeds i cant get my front brake to get any pressure built up so i rebuild the master cylinder and and rebleed the system and still nothing and its starting to piss me off :( anyone have any solutions or can help for me?

FastDoc · 03-05-2012, 02:13 PM

If it was working before you must have air in the system still I think.

I also use the vac and it usually works but since air rises and you're 'pulling' fluid from below try what we do to bleed airplane brakes.

PUMP the fluid from the bleeder nipple out the master cylinder. I bet this will restore function.

MEDMUNDS · 03-05-2012, 03:15 PM

ok ill give that a try

MEDMUNDS · 03-06-2012, 01:56 PM

well i tried reverse bleed it like you said and still nothing i pumped a whole bottle through the system and still nothing some how i royally screwed up the front brakes

MEDMUNDS · 03-06-2012, 01:58 PM

could the rubber boot in the master cylinder be a problem? maybe its not sealing and getting the pressure built up? idk...

Weldangrind · 03-07-2012, 12:02 AM

If that was the case, you'd think that the master would leak. The good news is that entire assemblies (including the master, lever, hose and caliper) can be had for cheap on eBay.

Azriel_Strife · 03-07-2012, 12:45 AM

The air is probably trapped in the front caliper.

Take the lid off the master cylinder

remove the caliper from the fork, and make sure the portion where the hose attatches is pointing UP. remove the brake pads from the caliper and while the hose is oriented so the air can escape, push the caliper back in with a C clamp or some channel lock pliers. this will force all fluid and air from the caliper. (keep bleeder nipple closed on the caliper, keep an eye on the master cylinder for overflowing when you push the caliper back)

once this is done, put the pads back in and re-attatch the caliper. you can then pump the master until the caliper fills with fluid, make sure to keep the master filled while pumping the caliper.

Weldangrind · 03-07-2012, 12:53 AM

Never thought of that. I wonder if it's helpful to remove the caliper bolts (leaving the hose attached), turn the caliper upside down and then right side up again. Maybe air got trapped where it can't get out via normal bleeding.

It works for gassy infants.

Azriel_Strife · 03-07-2012, 01:03 AM

This is a common fix on the old CB400's, yank off the caliper and push it back. Same idea for cars with stubborn/stuck bleeders.

MEDMUNDS · 03-07-2012, 01:06 PM

ok coool yea i give that a try and see what it does i hope this fixes it thanks for the help

MEDMUNDS · 03-07-2012, 02:12 PM

YAY!!! ok brake is fixed now. THANKS!!!!!! a bunch everyone for your help im so relieved now that it is taken care of..

FastDoc · 03-07-2012, 02:33 PM

Great news.

I'll tell you what some people here really know things! :P

MEDMUNDS · 03-07-2012, 02:45 PM

LOL that they do and im glad i can come here and get that awesome knowledge and wisdom!

Weldangrind · 03-07-2012, 09:22 PM

Azriel_Strife came up with that one. Awesome tip!

Azriel_Strife · 03-07-2012, 10:06 PM

Haha, thanks guys. saw this a lot on the old CB400's, the same can happen to any disc brake system, particularly front ones.

03-05-2012, 01:55 PM	#1
MEDMUNDS Join Date: Jan 2012 Location: El Dorado, Kansas Posts: 83	Front brake problems Hey i have a 2007 komoto 250 i just replaced my steering neck bearings but in the process when i did that i disconnected my front brake cable and when i reassembled everything and i bleed the front brake and get all the air out with a mityvac brake bleeder and i do acouple manual bleeds i cant get my front brake to get any pressure built up so i rebuild the master cylinder and and rebleed the system and still nothing and its starting to piss me off :( anyone have any solutions or can help for me?
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03-05-2012, 02:13 PM	#2
FastDoc Join Date: Mar 2009 Location: Southeastern Washington desert Posts: 14,761	If it was working before you must have air in the system still I think. I also use the vac and it usually works but since air rises and you're 'pulling' fluid from below try what we do to bleed airplane brakes. PUMP the fluid from the bleeder nipple out the master cylinder. I bet this will restore function. __________________ Happy to serve.
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03-07-2012, 12:02 AM	#6
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	If that was the case, you'd think that the master would leak. The good news is that entire assemblies (including the master, lever, hose and caliper) can be had for cheap on eBay. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
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03-07-2012, 12:53 AM	#8
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Never thought of that. I wonder if it's helpful to remove the caliper bolts (leaving the hose attached), turn the caliper upside down and then right side up again. Maybe air got trapped where it can't get out via normal bleeding. It works for gassy infants. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	0

03-07-2012, 02:33 PM	#12
FastDoc Join Date: Mar 2009 Location: Southeastern Washington desert Posts: 14,761	Great news. I'll tell you what some people here really know things! :P __________________ Happy to serve.
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03-05-2012, 03:15 PM	#3
MEDMUNDS Join Date: Jan 2012 Location: El Dorado, Kansas Posts: 83	ok ill give that a try
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03-06-2012, 01:56 PM	#4
MEDMUNDS Join Date: Jan 2012 Location: El Dorado, Kansas Posts: 83	well i tried reverse bleed it like you said and still nothing i pumped a whole bottle through the system and still nothing some how i royally screwed up the front brakes
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03-06-2012, 01:58 PM	#5
MEDMUNDS Join Date: Jan 2012 Location: El Dorado, Kansas Posts: 83	could the rubber boot in the master cylinder be a problem? maybe its not sealing and getting the pressure built up? idk...
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03-07-2012, 12:45 AM	#7
Azriel_Strife Join Date: Mar 2012 Location: Chilliwack BC, Canada Posts: 32	The air is probably trapped in the front caliper. Take the lid off the master cylinder remove the caliper from the fork, and make sure the portion where the hose attatches is pointing UP. remove the brake pads from the caliper and while the hose is oriented so the air can escape, push the caliper back in with a C clamp or some channel lock pliers. this will force all fluid and air from the caliper. (keep bleeder nipple closed on the caliper, keep an eye on the master cylinder for overflowing when you push the caliper back) once this is done, put the pads back in and re-attatch the caliper. you can then pump the master until the caliper fills with fluid, make sure to keep the master filled while pumping the caliper.
	0

03-07-2012, 01:03 AM	#9
Azriel_Strife Join Date: Mar 2012 Location: Chilliwack BC, Canada Posts: 32	This is a common fix on the old CB400's, yank off the caliper and push it back. Same idea for cars with stubborn/stuck bleeders.
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03-07-2012, 01:06 PM	#10
MEDMUNDS Join Date: Jan 2012 Location: El Dorado, Kansas Posts: 83	ok coool yea i give that a try and see what it does i hope this fixes it thanks for the help
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03-07-2012, 02:12 PM	#11
MEDMUNDS Join Date: Jan 2012 Location: El Dorado, Kansas Posts: 83	YAY!!! ok brake is fixed now. THANKS!!!!!! a bunch everyone for your help im so relieved now that it is taken care of..
	0

03-07-2012, 02:45 PM	#13
MEDMUNDS Join Date: Jan 2012 Location: El Dorado, Kansas Posts: 83	LOL that they do and im glad i can come here and get that awesome knowledge and wisdom!
	0

03-07-2012, 09:22 PM	#14
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Azriel_Strife came up with that one. Awesome tip! __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
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03-07-2012, 10:06 PM	#15
Azriel_Strife Join Date: Mar 2012 Location: Chilliwack BC, Canada Posts: 32	Haha, thanks guys. saw this a lot on the old CB400's, the same can happen to any disc brake system, particularly front ones.
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