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No front brakes

  • Thread starter Thread starter Mike
  • Start date Start date
M

Mike

Guest
So I started putting my bike back together today. Put the front brakes on, and they are useless. There's no effort on the lever, and the caliper doesn't move. There's plenty of fluid in the reservoir (snapped one of the screws trying to check). All I did when I had it apart was take the caliper off the wheel and set it aside. Never disconnected any lines or anything, so there shouldn't be any air in the lines. Where should I start looking?
 
Try pumping the lever several times. You will have moved the pads back when you pulled the caliper and they'll need moving back in to position.
 
I've pumped it repeatedly. Nothing changes. With the caliper off, the pads are barely moving.
 
Tear down the system (caliper and master) and maintenance them properly. Most likely air got into the system somehow but consider that a sign. Replace the brake line while performing the maintenance. Brakes are nothing to monkey around with.
 
What Ed says. If pumping doesn't bring them back then you have disturbed something. If you haven't serviced the calipers and MC for a while you'll be surprised what gunk you might find in there.
 
Got the caliper off, the piston will not move. I'm trying nothing but muscle to get it out. Will WD40/PB Blaster/Acetone-ATF ruin anything inside here?
 
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Not really since you'll want to replace those seals anyway. If you have an air compressor you can try to blow out the piston with that just be careful you have it pointed in a safe direction. Or you can use a couple of screwdrivers to act as levers to pull it up (stick under lip of piston and work it out).
 
Nm, got it.

Methinks I found the problem

955cb21a.jpg
 
Alright, I'm completely at a loss and about to lose my mind.

Got the caliper cleaned out good and back together. Took the master cylinder apart (as much as you can at least, not really a whole lot to take apart) and cleaned it good. I know that the connection between the caliper and the reservoir is good because when I pushed the piston in, it shot air bubbles up in the reservoir.

But I'm trying to refill the reservoir and I'm clearly doing something wrong. When I pull the brake handle, it doesn't seem to be pushing fluid down the line. I know the piston is working because I checked it when I removed the master cylinder.

The reservoir is full, but everything else is empty. I tried pumping the brakes with the bleeder open and with it closed, no difference. Even tried sucking on the line connected to the bleeder and the amount of fluid in the reservoir didn't change.

What am I doing wrong?
 
Did you take the MC piston out when you cleaned the MC? Plus did you clean the tiny hole and the even smaller hole that makes the tiny hole look big?
 
Go buy a Mitey-vac at autozone or something. Makes life MUCH easier. As to your problem, usually when you disassemble a MC, you need to "prime" it on reassembly to make sure you get all of the air out of, or it won't push any fluid. There are half a dozen different ways people do this, most involve quite a mess ;). A Mitey-vac will make it both easier and less messy.

You didn't say: did you strip the mc and use NEW bits inside? And did you absolutely assure you cleaned out both little ports inside? There are two. One is tiny, and the other is reaaaaally tiny. That's the pressure return port and if it's plugged with gunk, it will cause your brakes to lock up.
 
Another person to recommend tearing the MC COMPLETELY apart and cleaning/replacing the piston cup set.
 
Basically yeah. There are directions, but it's pretty easy to figure out. I recommend putting plumbers tape around the bleed screw threads, for a good seal. And make sure the fluid level in the m/c doesn't empty.
 
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