Need HELP!... 2001 YZ125 Front Brake Not Working

[Lubeboy]

Just bought an 2001 YZ 125... knowing the front brake was not working... figured no biggy, I can fix... well I can't fix...

I have tried to bleed every which way I can... I have sucked plenty of fluid through the bleed... so we have fluid.

The calipers don't move and I never get any pressure... when we bleed, we get fluid just oozing out.

Any advice?... Can I get a master cylinder rebuild kit?... can the freaken master cylinder be out?

 

[SpDyKen]

Just like rear suspension linkages, etc.; hydraulic brake systems fail when not maintained. You may know that (most)brake fluids are hydroscopic, absorbing water (from the water vapor in the air) if you leave the cap off. Well, even with the semi-sealed system on your bike, It still happens over time. Thus, your fluid is a milky blend of water & brake fluid, with the water accelerating the corrosion process. A complete disassembly, thorough cleaning, and rebuild, with new rubber seals will have you as good as new. Be thorough in cleaning, and meticulous in eliminating all air from the pressure system. Good luck!!! :ride:

 

[Lubeboy]

Are the calipers rebuildable on these? Looks like they aren"t... so should I be rebuilding both master and calipers?

 

[shadow171]

where is fluid leaking from? I'd start there, that's where your problem is most likely at. I would consider doing both since you already have to drain and replace your fluid. Then you know that the whole system is good to go.

 

[SpDyKen]

ABSOLUTELY! The caliper piston may well be "frozen" to the caliper. Dirt, water, etc. deteriorate those seals also. You need to clean it ALL spotlessly! You'll have a better understanding of hyd. brake systems when your done. But remember, air is lighter than brake fluid.

 

[Lubeboy]

Does anybody know how exactly you remove the current calipers?... Since I will get new ones, do I just rip the old ones out at any expense (keeping the walls in tact).?

 

[SpDyKen]

1. Get a service manual.
2. Read it carefully.
3. Follow the directions.
4. Keep your cool; no violence necessary. :nod:

 

[Lubeboy]

1. I have a service manual
2. I can read
3. I can follow directions (have rebuild my RD400 calipers).
4. I hate rebuilding calipers!!!

Key is, the RD 400 has removable and replaceable calipers, you just change the seals... on this, it looks like you have to change the calipers all together.

 

[QKENUF4U]

should be not difference between the two. two bolts hold the calipers on the RD and two bolts hold the calipers on the YZ.
pull the brake line (all your fluid will run all over the floor so be ready with a pan), put a thin piece of wood between the pistons and the caliper body, stick an air nozzle in the brake line opeing and pop the pistons out, one may come out before the other so youll have to push it back in a little and hold it so that you can get the other one to pop out. WATCH YOUR FINGERS
you manual should tell you all about doing this job. (as long as its a FACTORY SERVICE MANAUL)
you can get the seals/rebuild kits at your local bike shop and i just use a wire wheel to clean up my piston bodies. use lots of brake fluid when putting it back together (caliper and resivoir)
good luck :cool:

 

[Lubeboy]

Went to the dealer today to order the master cylinder and caliper rebuild kits... he said "don't bother"... just make sure you are bleeding through the top... these YZ have lots of problems with bleeding.... so I didn't order the parts, tomorrow I will spend the day with bleed and tap issues... if this doesn't work, I will order parts online...

 

[Gibby]

Trust me you will be bleeding for hours they are a pain in the ass. So don't give up easily and good luck. I had this problem about a month ago. I raced all season and they worked fine, then I left my bike in the garage for about a month went to ride it and had no front brakes(very little). They worked fine when I parked it. I don't know if from sitting water might have settled to the bottom or what. But after a couple of hours I had them going again. I took a syringe and sucked out all the old fluid, filled up the master cylinder and did it again a couple of times. Then bleed, bleed, and bleed some more. There is probably a easier way but that worked.

 

[Lubeboy]

Bleed, bleed, bleed... tap, tap, tap... no pressure... worked on it for 20 minutes... then bleed, tap, bleed.... still seeing very small air bubbles... decided to put my suction pump on the bleed screw.... pulled some fluid through... then back to bleed, bleed, bleed... tap, tap, tap... lots more air bubbles... then air bubbles stop and when I pull the brake lever you see fluid squirt up from hydraulic reservior... so I said, one more time.. bleed, bleed, bleed... then PRESSURE, PRESSURE, PRESSURE... IT FREAKEN WORKS!!!... NOW, my brake is draging a bit.... I need to get some laps on and see if it lets go... thanks all.

 

[Gibby]

Told you it was a pain in the ass :)