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brake bleeding

Old 02-17-2007, 10:45 AM
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brake bleeding

hello to all, after recieving the calipers from birdoprey I've been trying to bleed the brakes with no luck I have fluid to the bleed nipples and all the banjo bolts but I have no stiffness to the lever and my caliper pistons will not close the pads to the rotors how do I go about getting pressure to the system??? thanks in advance,Neil
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Old 02-17-2007, 12:08 PM
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First, describe what you did. What are the calipers and what is the master cylinder? What did you do to bleed them?

In the meantime, bleeding requires patience. Most people think it ought to be done before it is. Start with the farthest caliper first. Sometimes it is helpful to tap the calipers with a screwdriver handle when bleeding to dislodge bubbles.
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Old 02-17-2007, 12:27 PM
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I installed s/s lines, new pads, and stock calipers. never touched the stock master cyl. after installing everything I added new fluid and pumped the brake lever all day I have fluid at the bleed valves but no firmness at the lever the pistons are not pushing out in the calipers I can spin the wheel and hold the brakes all the way in and nothing I went back through everything and applied thread sealent as to make sure there was no air leaks I'm at my wits end any-one want to buy a 99 hawk with out front brakes!!!!!!
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Old 02-17-2007, 02:05 PM
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Youre bleeding with the master reservoir full and cap OFF correct? We used a vacuum pump to pull fluid through the SS lines on my install, and then bled from there...made the process faster. it does take a lot of bleeding with a line install, and I actually bled the crap out of mine, then rode it around, then bled it again and got a marked improvement...had a little more air in the system.
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Old 02-17-2007, 02:45 PM
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I just did the rear with much better results I installed the pads then pumped the brakes to seat the pads then drained the system added the new line added fluid and bled the brakes in 10 minutes. So how can I pressurize the front system to seat the pads to the rotors?? just pumping the brake lever does not seem to be enough?
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Old 02-17-2007, 03:10 PM
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I don't know if it will work with the s-hawk, but I had the same problem with
an old cb750f supersport, and I opened up the bleeders for a while and let gravity do the work for me. I took a while but, eventully I was able to bleed
the system.
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Old 02-17-2007, 03:15 PM
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will cracking the bleeders allow enough pressure to seat the pads to the rotors??
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Old 02-17-2007, 03:26 PM
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Youre not going to depress the calipers one bit until the system is pressurized...and when there's a large amount of air in the system, there's not sufficient pressure. Gravity bleeding IS a possibility....to do this just crack the bleeders open on the calipers and leave the master reservoir full, with the cap off. It will slowly draw the fluid down....but I DO MEAN SLOWLY.

As I said, I used a vacuum pump until I started getting fluid, then began bleeding as normal until I got pedal and there were no visibly air bubbles in the stream. (use a piece of clear hose slipped over the bleeder and run into a jar with some brake fluid in.....lets you see any air bubbles youre pushing out)
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Old 02-17-2007, 04:35 PM
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Forget whether the pads are touching or not. That's not relevant to bleeding. When you're well enough bled, they'll tighten. It seems to me that you're not filling up the calipers. Try keeping the bleeders closed and pumping the system (master cap open) until you get pressure. Then crack the bleeders to let air out and go again.

If you just leave the bleeder open, it will be almost impossible to fill the calipers.

Its also not impossible that there is something wrong with your lines.

When everything is closed, can you pull the lever to the bar? How many times?
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Old 02-17-2007, 04:43 PM
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I luv using a mity-vac (about $30 at auto parts store) to get the system up and running PDQ. Then a couple of the traditional hold lever/open valve gets it firmed up.

The mity-vac has many other uses as per the instruction booklet. Mine's about 8 years old and looks like hell due to brake cleaner (it's plastic, DOH) but it still works. Don't forget to do you clutch too while you're at it.
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Old 02-17-2007, 06:15 PM
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I know what you're going through. Crack the upper hose just like you would the bottom bleeder to get the master cylinder primed and then to remove air in the hose. Wait a second or two between cracks. The air will rise to the top. Keep doing it until you stop seeing air come out of the top then bleed the calipers as usual. Some new bike actually have a bleeder on the master cylinder for this reason.
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Old 02-17-2007, 08:41 PM
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hi neil. don't this just bite! I've had the best luck letting gravity do the work. and I put goodridge lines on those calipers with no sweat. glad to see you rechecked your connections, I must admit that I put both crush washers on one side of the banjo at one caliper and that kept it from working at all. I just take the cap off the m/c, open a bleeder on one caliper and let it drain a couple of reserviors worth of fluid then do the other caliper. but don't let the reservior run dry. good luck.
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Old 02-17-2007, 11:25 PM
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I had all sorts of trouble getting my hydraulics up after my recent tear down. I had to do the front calipers and the clutch and neither were cooperative. Gravity was not my friend and based on my experiences and observations I challenge you to do an experiment using DOT 4 Synthetic BF. If you take a clear tube you can see why gravity will not work with this product. First, the fluid when confined to smaller spaces is like jelly. It's surface tension is so strong that it will not run down hill. It just sits there in the tube. You can partially fill a clear tube with DOT 4 and hold it up vertically with both ends open and the **** just sits there. It is this same surface tension what will not allow it to be pumped into new braided lines by the master cylinders. Another experiment: release the hydraulic line for the brakes or the clutch and put your finger over the hole where the banjo bolt goes into the MC. Squeeze on the lever and you'll shoot fluid all over. Remove your finger and squeeze the lever you get nothing. It comes out a little but as soon as you release the lever it sucks right back into the MC. It will move small air bubbles around easily if the space is mostly fluid and a little air. If the lines are new or have been drained the fluid will not displace the air. I gave up on mine and got a little trigger style vacuum pump and literally pulled the fluid into the lines and calipers. For the clutch I pressurized the system from the bottom up. The vac kit has the containers and fittings to make this possible although it leaked badly forcing fluid up into the MC - but it did work and worked very well. I've worked around brake fluid most of my life but I have never seen anything behave like this DOT 4 synthetic.

If you're having trouble getting the old-timey methods to work there is a cheat. If you have a shop that services several different kinds of vehicles you can probably scare up some DOT 3 brake fluid. You can use it to "prime" the lines but you can't leave it in there. This stuff is real runny and will work with the gravity method. Pumping up bare lines is still going to take a millenium so gravity might be the best bet. (the purests are wiggling in their chairs) Drain the MC as best you can with a syringe or by pumping it out with the lever. Fill with DOT 3 and begin your gravity feed - pour it into the MC just as the level drops away until you notice a steady stream out of the other end (caliper or slave). Allow the MC to drain nearly completely out. Close the bleed screw and fill the MC with DOT4 and start a normal bleeding process squeezing the lever and evacuating the air/fluid at the bleed screw. By the time the system is thoroughly bled you can be reasonably sure that the DOT 3 has been replaced by the DOT 4. I grant you this is not the preferred method but if you can't afford a $45 vac and need to get your lines back up it will work.
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Old 02-18-2007, 06:41 AM
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thanks guys I actually drove twenty minutes into town to by a vacuum bleeder and was talked out of it he told me I had a pressure problem not a vacuum problem as I had fluid at the bleed valve? of course he tried to tell me my master cyl. must be shot to!!! I'll pick up the bleeder tommorrow and try that. I guess the fluid is just not filling the caliper and the vacuum bleeder will force fluid in correct?
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Old 02-18-2007, 08:20 AM
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Neil, I never bled brakes in my whole life and got a Mity-Vac and did it right first time. Those things work.
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Old 02-18-2007, 08:39 AM
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just curious, I took the pads out while doing the gravity thing to keep fluid off the pads any-ways when squeezing and releasing the brake lever I can see fluid moving around the caliper pistons this could be from all the fluid that has ran down the calipers what else could this be??
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Old 02-18-2007, 08:41 AM
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Tapping on the calipers has been mentioned, but not on the lines, so I had to speak up.

For one thing, bring a friend over. When you're the one to squeeze the lever and crack the bleeders on the calipers, it sucks.

Two, you have got to spend time tapping on every single part of the brake system, from the top banjo bolt down along the lines and on to the calipers. There are air bubbles that are not gonna want to go anywhere unless either 1) you are moving fluid through the lines with some pressure (which apparently is not the case), or 2) you are tapping the lines to get the brake fluid to coat them, thus releasing the air bubbles (which can then much more easily be pumped through).

Aight, good talk. I'll see you out there.
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Old 02-18-2007, 08:47 AM
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Originally Posted by sprhawk neil View Post
just curious, I took the pads out while doing the gravity thing to keep fluid off the pads any-ways when squeezing and releasing the brake lever I can see fluid moving around the caliper pistons this could be from all the fluid that has ran down the calipers what else could this be??
Oh boy. Second thing's first. Get a vinyl tube on your bleeders, so you can keep the pads against the rotors for when you finally get pressure. Really this isn't necessary, but it would suck for the pistons to pop out because you weren't paying attention when you got pressure finally. (Good thought about keeping the pads clean though).

And first thing's second: you are not supposed to be seeing fluid oozing out from behind the pistons. Unless you've managed to drip brake fluid all over the place, and that's what it is, it's probably time for a caliper rebuild. I'm pretty sure the seals are cheap, and it's not an overly-complicated process.
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Old 02-18-2007, 08:51 AM
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thanks scooberhawk, I will try tapping on the lines to. I've also got some air out of the top banjo by pumping then holding then cracking. My biggest fear is that I have no lever feel I could pump this thing for two hours and never increase firmness there is nothing there the rubber seal around the master cyl and brake is torn would this matter my clutch is the same way and has never made a difference but I have never bled that either
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Old 02-18-2007, 08:55 AM
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anotherthing that ive had work for me(before my mighty vac) was get a syringe and fill it with fluid, then back feed it from the caliper to the mastercylinder.
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Old 02-18-2007, 10:43 AM
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Thanks to all I'VE GOT BRAKES!!!!!!!!!!!!!!!! I cleaned everything and through in my old pads and pumped and cracked to no end and it worked!!! I'm still buying a vacuum bleeder tommorrow and will redo the prosess but I will seat the new pads first HA HA!!!!!!!!!!!!!! now I'm starting my ape cct swap so I'm sure you'll hear from me soon!!!!!!!!!!!!!!!!!!
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Old 02-18-2007, 05:16 PM
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whatever you do for the ape swap, make sure you put the piston you are working on at TDC before you take out the old tensioners.
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Old 02-18-2007, 08:25 PM
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Originally Posted by AZZKIKER View Post
whatever you do for the ape swap, make sure you put the piston you are working on at TDC before you take out the old tensioners.
And, correct me if I'm wrong, but I believe it is possible to not be at TDC, even if the flywheel seems to indicate it. I'm pretty sure others have made this mistake and suffered consequences.
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Old 02-18-2007, 08:40 PM
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True, the piston and flywheel both pass TDC four times. Only once on a compression stroke. Pull the plug out, stick your finger in the hole and tell a buddy to spin the back tire. There's no doubt about it.
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Old 02-18-2007, 11:39 PM
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Originally Posted by nuhawk View Post
True, the piston and flywheel both pass TDC four times. Only once on a compression stroke. Pull the plug out, stick your finger in the hole and tell a buddy to spin the back tire. There's no doubt about it.
Might be a good idea to use a popsicle stick or something similar. If your finger gets stuck, it ain't going to be pretty.
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Old 02-19-2007, 03:17 AM
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To get down that long hole you'll need something longer than a popsickle stick. Try a part of a metal hanger or something like that. I think I understand about the finger thing. That's just to see if you have air coming out of the cylinder. Still, not a hugely bright idea, especially if you're not in control of the motor spinning.
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Old 02-19-2007, 07:38 AM
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I don't know about the size of your fingers but I haven't been able to get my finger in a spark plug hole since I was 10. You simply cover the hole with your finger to feel the compression. That's like the sound of air hissing past your fingertip. Once you know you're on the compression stroke you can use the marks to line it up at TDC.
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Old 02-19-2007, 01:30 PM
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Say, while we're on the subject... Is there anything wrong with turning the motor backwards to get it where you want it?

I'm guessing if you do, you want to be going in the correct direction when you stop, as it could make a difference in cam chain slack...
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Old 02-19-2007, 01:47 PM
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You can turn it backwards but go past mark and then turn it in the right dir untill mark lines up. there is slack in every motor its not much but its there.
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Old 02-19-2007, 10:04 PM
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brake bleeding

Neil:

I had the same problem with the front brakes when I bled them. With the cap off the master cylinder and with the bleeder valves closed, keep the brake lever squeezed and loosen & bleed the air out of the Bajo bolt connecting the brake lines to the master cylinder. (Make sure you keep a rag under it to keep brake fluid off the paint). I had the same problem when I bled the brakes and changed fluid. I wasted an evening trying to get pressure back until I read this same trick on a Harley site.
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