01 ST1100 ABS No brakes!

Breaks felt soft, both lever and pedal. It got worse and worse by time I made it home (2.4 miles). Sitting in the drive I could pull the lever all the way in. Backed the bike into the garage and that's it. I hadn't the time to do any checking. But plan on checking the fluid level in both reservoirs and if the level is good, check for any blown fuses.
Any culprits or usual suspects here? 226k on the clock.


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When is the last time you changed the fluid?

With 226K on the clock, the calipers may need to be rebuilt... cylinders sticking?

If the lever has gotten soft, then there is air in the system, might be low on fluid. (I'll just keep guessing until I get it right)

Sorry, I just haven't checked anything yet. I may have a few minutes in the morning. I haven't had any problems till now. I was going to change the fluid this winter season since I don't know when it was last changed. Mark might know, if he sees this thread, he might join in.


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Fluid should not be too old, couldn't hurt to flush but it was all done prior to last seasons start.
Weird, first UP and now you, it is an epidemic.

Thanks Mark for the info. I'll post later when I check it out.


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John, I would look for wet areas and see if a line has loosened up. Or refill and pump to see if you can see it leaking. To loose the peddle and lever,the fluid has to be going somewhere. Good luck.

My thoughts exactly. Hope it's something simple.


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Master cylinder...(?) BTDT

Both master cylinders at the same time? Very unlikely. Either master cylinder by itself wouldn't result in the symptoms described. Neither would any of the fuses.

I wonder if I imagined the pedal being a problem. The pedal seems okay, but I can pull the lever all the way back. Appears to be plenty of fluid up top.


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Start with a thorough bleed John. That may be all it is.

STurgisSTeele said:

I wonder if I imagined the pedal being a problem. The pedal seems okay, but I can pull the lever all the way back. Appears to be plenty of fluid up top.

Click to expand...

Given that it sounds like its just a problem at the lever, and not the pedal, then go back to John's comment about the master cylinder. If fluid is leaking past (whatever creates the seal) so it can't generate any pressure, I think that would be consistent with the symptoms you're describing. Haven't had to rebuild my non-ABS master cylinder so I can't be more specific about the details, but that sounds like a good place to start looking. Maybe someone else who has rebuilt the MC can chime in with more specifics.

I've had master cylinders go out on cars before, and its exactly as you describe, the pedal goes to the floor without applying the brakes. Fortunately in those cases I was able to pump it a few times to get enough pressure to stop the car.

IINM, your master cylinder rebuild kit:
45530-MAJ-G41 PISTON SET, FR. MASTER CYLINDER
about $42

Thanks fellas. Sorry for the delay in response. First chance I've had since being in Indy foe a wedding. Will be home later today and order the kit.


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Kit has been ordered. Thanks John for the part number.

John OoSTerhuis said:

Master cylinder...(?) BTDT

Click to expand...

Agree, but considering mileage/age I'd go for a precautionary complete overhaul of the brake system, incl. both masters and all 3 calipers... and give the brake hoses a good visual while at it.

Good idea. Too bad I didn't think of this when ordering. Maybe I'll be able to combine orders if the first hasn't been already done. Thanks for the advice.


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Installed the master cylinder rebuild kit, pulled new fluid through both sides, and bled both sides, though there wasn't any air bubbles. But when the diaphragm, that plastic piece, and the cap were reinstalled, there still wasn't any pressure at the handle when applying pressure. The handle pulls back as easily as when the cap and other pieces were removed. I don't see any leaks. And I believe I have all the air out. So I'm back to how it was when I lost the front brakes.
Any thoughts on what it might be or what I should look at or test?
TIA



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