Front brake is super mushy in feel

M

MXP1MP

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Nov 14, 2000

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• Jul 23, 2002

• #1

I know that YZ's don't have the greatest of lever feel in the front brakes but damn! mine is super mushy. I've tried bleeding it many times with it on the bike still. I can get some of the feel back in the lever but its no where near what it was like when it was new. The pads are brand new dunlopad with two rides on them. After I bleed the brake it still feels mushy and after a good amount of pressure was applied while ridding it last time the lever feel just got worse. After I bleed it it would start getting feeling/pressure at about half way from the bar. This still isn't acceptable but now it pulls right to the bar with very little pressure. There are no leaks and no air trapped in the line from what I can tell. I'm wondering if maybe my master cylinder or cable some how died or something in the master cylinder went out? Cause before I changed the pads and before all of this started happening I was ridding at a low speed and grabbed the brake at about half to the bar it would be a full pressure then all of a sudden I felt it given and it sounded like it made this "chunk" sound then it pulled to the bar the pressure was like half of what it was before. Bleeding doesn't seem to help much what else can I check?

 

J

jmics19067

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Jan 22, 2002

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• Jul 23, 2002

• #2

I would look at possibley the little screw that adjusts the lever itself stripped out or loose well something along those lines . Or I would suspect the inside of the master cylinder is bypassing.

 

I

IrishEKU

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• Jul 23, 2002

• #3

Check the plunger on the master out. You should have a hard time trying to depress it with just your finger. If it pushes easily the master is shot or at least the plunger is. jimics had a good thought with the travel adjustment too.

 

M

MXP1MP

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Nov 14, 2000

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• Jul 23, 2002

• Thread starter
• #4

I tried adjusting the screw on the lever it doesn't help the brake I can feel it grabbing when it should but the lever pressure is way off. I feels like the brake is working at half its potential. I can't get it to lock up untill I pull it all the way to bar with a good amount of pressure. Maybe the piece were the bolt pushes into (whats it called..) on the master cylinder died? It doesn't feel like it though. Maybe air is some how getting into the system or some how trapped? I highly doubt it cause the frist time bleed the brakes I only got out 3 air small air bubbles and non afterwards tapping on the line etc didn't make anymore pop out. This is bummin me out cause I rely on my front brake alot.

 

bclapham

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Nov 5, 2001

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• Jul 23, 2002

• #5

have you tried bleeding from the bottom up? i went to the cr route on mine but i am still not happy, but i think i need pads.

 

M

MXP1MP

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Nov 14, 2000

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• Jul 23, 2002

• Thread starter
• #6

No I haven't tired it yet I'm gonna clean my bike off and check the plunger tonight. Wouldn't bleeding backwards be alittle messy? I got the rear brake working great doing the regular more common technique. I want my CR brakes back :)

 

I

IrishEKU

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• Jul 23, 2002

• #7

Originally posted by MXP1MP
Maybe the piece were the bolt pushes into (whats it called..) on the master cylinder died? It doesn't feel like it though. Maybe air is some how getting into the system or some how trapped?

Click to expand...

That's the "pluger" I talked about. It is usually a couple of o-rings and a metal "compressor" that acts as a plunger.( if my memory of hydralics is off correct me!)If you think it's shot remove it and clean it out. I am talking about the whole master cylender(sp). You would be suprised as to where dirt get's lodged! Personaly after draining the whole system and bleeding in new fluid, I would deffinatly(sp) think about a new Master cylender.

 

M

MXP1MP

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Nov 14, 2000

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• Jul 24, 2002

• Thread starter
• #8

Well I checked the plunger it feels fine it takes a good amount of pressure to push on it. I am I suppose to be able to wiggle it around a tiny bit? I'm gonna try rebleeding it again tonight.

 

J

jmics19067

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• Jul 24, 2002

• #9

look up in a website those parts microfiches. See if the O rings and /or seals for the plunger are available, and think about rebuilding your master cylinder. If it costs 10$ to rebuild or 100 for a master cylinder I would try it seeing if I could fix it. what is the worse thing that can happen? It doesnt work youhave that problem now. And the 10$ that you spent is easily worth the knowledge of how the thing actually works.

It is quite possible you only ruined an O ring inside making the master cylinder bypass. Keep everything CLEAN and organized, only use brake fluid and clean lint free rags and/ compressed air to clean the parts. when you have carefully reassembled the m/c bleed the cyinder before you hook up the brake line< fill up the cylinder hold your finger over the outlet port and pump it a couple of times>.
Remember now that this is a brake system , of anything that you can make shorcuts on this is not one of them!!!!!!!! Dont be afraid/humiliated /too cheap to get a mechanic to help you if you need it. Not only is it a lot cheaper to pay a mechanic than the emergency room but it doesnt quite hurt as much either :D

 

S

Shift-MX

Member

Feb 10, 2002

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• Jul 24, 2002

• #10

I had problems bleeding my brake ( 98 rm 125 ) so i toke the caliper off the bike completley (sp?) tipped it upside down and bleed it. There was air in the caliper which i couldnt get rid of bleeding it normaly.

 

M

MXP1MP

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Nov 14, 2000

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• Jul 25, 2002

• Thread starter
• #11

Well tried bleeding it again last night once with it still installed, that didn't really work then removed it and it didn't make much of a difference. Tried bleeding it backwards still the same no air bubbles came out, but it's not pushing much fluid out when you pump up the brake. Only small amounts of fluid is coming out I really think now its going to need to be rebuilt. If the cable/hose is going out you think that might cause it as well? In a recent wreck the metal part of the cable where it bolts into the master cylinder got bend slightly maybe it killed the cable? but its only bent every so slightly, it got bend down so it's kinda got a slight U shape to it. Or do you think maybe the impact may of pushed the lever to hard into the plunger damnaging it?

 

J

jmics19067

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Jan 22, 2002

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• Jul 25, 2002

• #12

take a good look at the hose. Pump up the brake a few times and see if you can see the hose swelling. Sometimes the inner liner of the hose can go bad and yet the outer liner keeps it from being an external leak making basicly a balloon. If there is no mechanical damage no external leaks and the hose isn't swelling up it would have to be inside the master cylinder.

 

7

70 marlin

Mi. Trail Riders

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Aug 15, 2000

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• Jul 26, 2002

• #13

Old hose'es can get spongy feeling. I'd go for the rebuild & hose with new sealing washer's. cheap insurance. good luck