Front Brakes Problem

[J///Kidd]

Story:
Got new tires. Had to remove front wheel to get them mounted. Had to remove front calipers to get wheel off.
Got the wheels back, attached the front wheel and attached the calipers. I finally get done bleeding the brakes (Speed Bleeders) and I'm getting clear fluid and no bubbles out of any of them. However, the calipers barely squeeze the pads in....not even enough to keep the wheel from spinning.

What did I miss? What did I do wrong and how can I fix it?

Thanks.

[squiggy]

However, the calipers barely squeeze the pads in....not even enough to keep the wheel from spinning.

On both calipers?

That would be very odd to have that happen to both at the same time. I suspect you may have to disassemble, hopefully only one caliper, to repair it. Or first you can take the pads off the caliper, crack open the speed bleader, compress the caliper piston (use a rag for the fluid that comes out), close the bleeder, install the pads, install the caliper, then see what it does. You may have dislodged the piston, caused the piston to become cockeyed, but that seams like a long shot.

Hopefully it's just a mildly stuck piston.

[Trackerrrr]

Did you remove the brake hoses when you removed the calipers? If so you still have air in the lines somewhere, mostly likely up at the master cylinder if you bled all four bleeders on the calipers. Try pumping up the master cylinder and then cracking the banjo fitting on it momentarily to expel any trapped air. Bleeding the MC is a PITA.

[Black_peter]

What bike is this?

[J///Kidd]

This is on my '95 Katana 600.

I'll try releasing the banjo fittings and see what happens. If that doesn't work, I'll probably start from scratch (ie. take the lid off the reservoir and then disconnect the two lines to the calipers and let it ALL drain - I didn't take the lid off the first time and had most of the fluid left in the reservoir even after I disconnected the caliper lines - I'm thinking some air did get trapped up in that area).

[DreKat]

romove the bleeder valve and squeeze the brake and see if fluid come out.

[Black_peter]

This is on my '95 Katana 600.

I'll try releasing the banjo fittings and see what happens. If that doesn't work, I'll probably start from scratch (ie. take the lid off the reservoir and then disconnect the two lines to the calipers and let it ALL drain - I didn't take the lid off the first time and had most of the fluid left in the reservoir even after I disconnected the caliper lines - I'm thinking some air did get trapped up in that area).

So you did disconnect the lines. OK you don't have to remove the lines, I also don't suggest you go there yet, yet.
What could have happened:
Air in the master cylinder. Very hard to get out.
Air in the splitter (I assume you have the splitter) very hard to get out.
Any time you get air in the lines it is hard to get it all out.
Speed bleeders in this case are not helping out. In this case they are preventing the hard-core bleeding you need to do.
I also suspect you drove the piston into the caliper, you might have cocked a piston as squiggy mentioned but more likely you gummed up the caliper with all the gunk that was on the outside of the pistons and possibly damaged a seal or three..

Honestly? I would disassemble the calipers, if you're very careful and you have no damaged seals you can clean everything (with brake fluid) and reassemble. Then put the stock bleeders in, us the syringe or mity-vac to pull fluid down the lines. until you feel the system us at least full..
Pump up the MC then crack the banjo at the MC, this is the only why I have found to get the air out of the MC. You then need to bleed until there is no air. Then I suggest pulling the lever to the bar and tying it there (wrap cord around the lever and bar while holding the lever tight)
Leave it like that at least over night, then bleed again.

[J///Kidd]

romove the bleeder valve and squeeze the brake and see if fluid come out.

I did. It does. Even comes out WITH the bleeder valves. It acts like the calipers are full (as far as bleeding) but it doesn't seem to be pushing enough fluid for them to squeeze. It is happening on BOTH calipers so I believe the problem is in the line before it divides...which leave a little line from the reservoir to the splitter. Figure at this point the issue has to be there. I just don't know if I'm fighting an uphill battle trying to fix it as is or if I should just drain everything except the calipers and start again (or if that would just be adding more potential issues).

Terms question:
Master cylinder - where is it and how to I "pump" it?

[ctandc]

You need to start at the master cylinder and work down.

Pump up the lever on the master cylinder. While holding the lever in, crack the banjo bolt on the master cylinder loose, then quickly tighten it. Try this several times.

You can also go to Harbbor Freight or Autozone or Advance and pick up a Vacuum pump / bleeder for cheap. They are helpful.

BTW.....you don't have to disconnect the brakes lines to get the calipers off the rotor so you can remove the wheel. Just take the two bolts off that mount the caliper. And then slide the caliper off the rotor and zip tie the rotors to the fairing stay or tie them up so they don't hang on the brake lines.

[Black_peter]

I did. It does. Even comes out WITH the bleeder valves.

Fluid will come out even if there is air. The key is this:
An air bubble can compress, IE get smaller under pressure. With the bleeders open the pressure in the system is low, so the fluid in the MC (Master cylinder, more later) will push against the bubble. The bubble might compress a little but the bubble will push on the fluid going to the caliper pushing fluid out the bleeder. Now in a perfect world, the bubble will move and keep moving until it reaches the bleeder and comes out. I hate to break this to you but we are not living in a perfect world. What can happen is after the fluid stops pushing the bubble creeps back up the line (bubbles like to move up, right?) and stays in the line or the splitter or where ever it is. Now once the bleeder is closed, and your testing the brakes, the fluid pushes on the bubble. the fluid after the bubble has to move the caliper piston however instead of that, the bubble compresses. This absorbs all the force of the fluid from the MC and the caliper pistons don't move or at least without enough force to clamp the rotor.

Pulling the lever to the bar and tying it there over night can allow the bubbles to creep up the line and into the fluid reservoir..

I just don't know if I'm fighting an uphill battle trying to fix it as is or if I should just drain everything except the calipers and start again (or if that would just be adding more potential issues).

You are, getting the system free of air in your situation can be very hard. I spent at least a week when I switched to SS lines getting the brakes to work again. But draining adds air and air is the enemy. Do not drain!

Terms question:
Master cylinder - where is it and how to I "pump" it?

The Master cylinder is the cylinder attached to the brake lever. It is called the Master because the pressure it creates is sent to the "Slave Cylinder" in this case the caliper. Odd that we call brake caliper cylinders "pistons" or "calipers" only in hydraulic clutches do we call the second cylinder the Slave..
Pumping it up means to squeeze the lever to the bar several times then hold it.. While holding it you break the banjo loose. Not so easy I know..

You need to start at the master cylinder and work down.

Pump up the lever on the master cylinder. While holding the lever in, crack the banjo bolt on the master cylinder loose, then quickly tighten it. Try this several times.

Yes, as I mentioned. Just be careful.. Like I describe above.. You have to be holding the lever..

You can also go to Harbbor Freight or Autozone or Advance and pick up a Vacuum pump / bleeder for cheap. They are helpful.

Or a syringe like in my how-to (link below) In both cases you are pulling fluid from the caliper bleeder all the way from the reservoir. This works better then pumping from the top because you only move a few CCs of fluid when you pump, but with the syringe or the vacuum pump you can pull 10 times as much fluid, this will help to really pull that air bubble out. If you can find one of those big syringes (I have some that are like 150 ccs.
It is also critical that you don's allow the reservoir to empty!

BTW.....you don't have to disconnect the brakes lines to get the calipers off the rotor so you can remove the wheel. Just take the two bolts off that mount the caliper. And then slide the caliper off the rotor and zip tie the rotors to the fairing stay or tie them up so they don't hang on the brake lines.

you might has to "wiggle" them a bit to push the pistons back slightly so you can make that turn around the rim..

My bleeding how-to:

http://katriders.com/vb/showthread.php?t=60280

My post on hydraulics:

http://katriders.com/vb/showthread.php?t=69982

[J///Kidd]

Follow up:

THANKS TO ALL AND EVERYONE! Again, this site has allowed me to be able to afford to keep my bike by sharing the knowledge I need to complete these jobs.

Air in the master cylinder!!! I went out this morning, took the cover off the reservoir and tied the brake lever to the handlebar. I returned 6 hours later, tapped the calipers and lines and master cylinder with a rubber mallet (gently). I then pressurized the master cylinder like everyone has explained, held the lever in, and loosened the banjo bolt. I spurted a bit and fluid came out and I tightened right back up before releasing the lever. After that first time, I noticed after I had pressurized it, the brakes bit! I did this 5 or six more times just to be sure and to make sure I just heard fluid coming out. To be on the safe side, I re-bled the calipers! What a difference in the amount of fluid coming out per squeeze!

As of right now, the front brakes actually seem to be better than they were before I undertook this. Tremendous gratitude to all who helped and had the patience to explain things!

-John

[Black_peter]

Today you are a man my son!

[squiggy]

Today you are a man my son!

bar mitzvah time.



From what I read in the past, like this thread, I bought a bleeder banjo bolt and speed bleeder for the brake master cylinder.

[J///Kidd]

Today you are a man my son!

So THAT'S what that feeling is

Thanks again!