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Re: brake calipers spongy feel
Does all the usual tricks include wrapping a thick bungee cord around the brake lever and leaving it overnight? That should force any residual air bubbles to the top of the system where the master cylinder should replace them with fluid.
If that does not work try installing some new bleed screws, even speed bleeders.
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About the only ways air can get into the system is either a leak somewhere, or the master cylinder is too low on fluid, but it REALLY has to be low for this to happen.
When you installed the new caliper, did you use NEW sealing washers for the banjo fitting? Finally, when you bleed the brakes make sure that the caliper is oriented so the bleeder valve is at the highest point. I have bleed the brakes before on one bike and had a problem getting all the air out. Turns out the caliper was positioned so the bleeder was towards the lower part of the caliper. I had to rotate the caliper in order to bleed the air out, then reposition it correctly when done.
It means there is air in the brake line. If the fluid gets too low in the brake cylinder air gets pumped into the system when the brake is applied. A loose fitting or bad seal is usually why the fluid gets low. Fix the leak then add fluid and bleed the system of air. First bleed the master cylinder at the lever. There should be a bleeder valve on the cylinder. Put a clear rubber hose on the end of the bleeder valve. Run the hose into a container so the brake fluid doesn't get on paint or plastic parts. The fluid can mess up the finish. Now squeeze the brake lever several times in rapid succession then hold the lever in without releasing it. Open the bleeder valve slowly and fluid and air bubbles will come out of the valve. Close the valve BEFORE releasing the lever. Do the same thing multiple times until only fluid comes out of the valve. Do not let the cylinder run out of fluid while bleeding. If it does, you have to start all over again.
Now do the same procedure on the wheel caliper.
Understand that the master cylinder and / or the wheel caliper may need new seals. Please rate my answer. Thanks!
You still have air bubbles trapped on the fluid hose, going to the brakes. To get rid of them, pump three times, hold the brake grip, unscrew the breathing tap down on the brakes, let it bleed, seal it and pump again. During all this procedure, you must always have the fluid reservoir on the steering bar, full, and closed to create pressure downwards. If done right, should have it in no more than 20min.
try using a line locker close to master cyclinder ,lever should go rock hard if it has no air in system,work line locker down lines to see if lever stays hard. also check the lever travel to make sure that lever is pushing on master cyclinder plunger as a lot of after market levers dont have correct casting and have to travel in a long way before brakes work even when system is bled. also check to make sure calliper carriers are not bent and pads not sitting square on rotors. hope this helps
Larry.. the symptoms you describe are exactly what would happens when your primary seal fails, the purpose of the primary seal is to generate and hold pressure, it is located just under the little hole in the reservoir and is a little rubber seal that pushes the fluid down the line and when it fails the fluid leaks by the seal making the brakes feel spongy... replace the seal and you should have your brakes back
the master cylinder is not bleeding back. there is a presure hole, in front of that there should be a small hole, if it is clogged it won't re lease pressure. mine was the same way. i took a.010 drll bit used to clean torch tips, with a hand chuck and turned it with my fingers,i felt it break thur and i stopped. this is with the piston removed!!! then i held atube on it and blew smoke thur it . i could not do that before.
the brakes would then release.
late ri decided to make the hole a little bigger.,and i didn't feel it break thur and drilled clear into the bore and ruined the master cyclinder. you have to pry off the pastic resivor to do this i used a wide blade putty knife. replace with a new o ring.
Your $7 bleeder kit typically has a near useless one valve in it. Forget the kits such as these, they usually make things confusing for you.
Firts, make sure all teh brake lines are tightly connected and in good condition. If the flexible lines are over 5 years old, conside getting new ones made/fitted. Stainless/braided lines look good but are NOT necessary for any road bike.
All you need is a long piece of clear hose line (fish tank air line tubing usually works well) that fits the top of the bleed nipples very firmly. The hose should be long enough to hang over your handle bars, or be suspended by a wire or string so that the open end is higher than the master cylinder. You can use two such hoses and do both front calipers at the same time if you wish.
First, manouver the handle bars so that the top of the master cylinder is as level as possible, even to the point of undoing the grip clamp and rotating the whole assembly around the handle bars a bit. Then fit the clear hoses to the caliper bleed nipples.
Remove the top of the master cylinder reseviour and make sure the fluid is topped up. Watch this level the whole time, it is important that the fluid level never get below half full or you risk reintroducing air into the brake lines again. Never reuse old fluid, and always filter any new fluid that has been in the brake system before (run it through a new fuel filter if you are that hard up for money) you reuse it.
Then crack open the bleed nipples on the calipers so that you see fluid start to rise up the hoses ( which is why you want clear hoses). You can pump the lever a few times to get things happening quicker, just watch the master fluid level!
Keep pumping the lever and topping up the fluid level until the level in the tubes is at the same level as the master cylinder. Leave the bleeder nipples open and leave the bike alone for an hour.
After an hour, close the bleeder nipples and top up and refit the master cylinder reserviour cover.
Use a jar under each hose to catch the fluid, remove each hose from its bleeder and let the fluid drain out into the jar. Ditch the used fluid.
Reset the grip to its proper position if it was moved and test the brakes. Pump the lever two times and then release the lever for a few minutes ( at least 1 minute) If the brakes are still soft or wont hold pressure ( if you still have to pump the lever to get pressure, dont ride the bike!) then suspect worn master cylinder or buggered seals.