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MathProf

Bleeding front brake problems.

20 posts in this topic

I ripped the front caliper off the front end in a recent HS. The brakeline was pulled off the caliper and the caliper flew out in front of the bike.

I have put it all together with a new front brake line, but I'm not getting any brake pressure. I have straightened out the line and pushed brake fluid from the caliper through the brake cylinder. I removed the plunger from the brake cylinder, thinking air was trapped in there. I also worked the plungers in the caliper. There is no fluid dripping out of the system, but then there is no pressure.

The brake worked fine before the race so I don't think a seal is bad, but that's my next direction.

Have I missed something????? :applause::bonk:

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I use a big ass syringe to suck through normal way, but you filled the line the right way.

I have seen workshops that use vacuum pumps to bleed their brakes. How easy would that be?

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I don't have a vacuum pump.

I have tried to pull fluid out the bleed screw on the caliper with my B.A syringe, and I get air but I can't tell if the air is coming from around the

bleed screw, from the connection on the syringe, or from the caliper.

I'm going to try again tommorrow, but something is going to give because the weather is getting warmer and I hear Rabbitt Valley calling my name. :applause::bonk::cry:

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pull the caliper off and hold it above the reservoir when you try to bleed it.you may need a second set of hands.the air trapped in lines will find it easier to go up then down.I had to rebuild my cylinder recently and this is the only way it would bleed without a vacuum pump.

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That is one way I hadn't tried.

I'll give that a try first thing tommorrow

Thanks for the idea.

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Try pulling in the lever and use a bungy-cord or tape to keep it pulled in overnight. This lets the air work its way up the line and past the plunger. This works great for getting the last of the tiny air bubels out.

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Nope, pulling in the lever closes the port in the master cylinder. No air can get past the piston with the lever pulled.

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Still just air in the system. The master cylinder displaces a very small amount of fluid, so bleeding is slow. One other option is to remove the master cover, open a bleeder and allow gravity to do its job, but keep the master full of fluid. Other next best option is to either vacuum the air out from the bleeder or pump brake fluid into the bleeder and push the air out backwards. Otherwise, just keep doing the old pump and burp method, it will eventually take hold. Been there, done it, ran into the same deal.

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Invest in a $25. Mityvac Brake bleeder. It is the best way to bleed and change your brake fluid! A must for any KTM owner front brake bleeding and a great tool for our WRs rear brake bleeding as well.

33160_lg.jpg

:applause::bonk::cry::cry::cry::p

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Those are useless on KTM brakes and no good for flushing out and changing the fluid. One you have a vaccum bleeder you wont go back to pump and release for an hour to change out fluid. :applause:

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Invest in a $25. Mityvac Brake bleeder. It is the best way to bleed and change your brake fluid! A must for any KTM owner front brake bleeding and a great tool for our WRs rear brake bleeding as well.

33160_lg.jpg

:applause::bonk::cry::cry::cry::p

Agreed. I think I bought mine cheaper than that though.

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I have been there. It's a pain in the ass and takes patience.

With the top off the master cylinder, jiggle the hose ,watch for bubbles then sqeeze the brake,repeat several times.

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Those are useless on KTM brakes and no good for flushing out and changing the fluid. One you have a vaccum bleeder you wont go back to pump and release for an hour to change out fluid. :applause:

I will have to look around here to get one of those now! The cheapest ones I have seen are about $200. I haven't really looked though.

Those work on the WR brakes don't they?

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I have been jiggling and refilling for a while. :applause:

I was hoping that I had forgotten some obvious thing.

Something has been working because I'm getting a clicking sound from the caliper that wasn't happening earlier. Something wants to work.

I'll guess keep trying tommorrow, I've had enough for today. :bonk:

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I bought my Mityvac for $16. years ago. I am sure you can find it for about $20 at Pep Boys/Autozone etc. Works great on all motorcycle brakes. Brake fluid traps moisture and air over time and flushing the system once a year with the vaccum bleeder takes only 10 minutes per brake. :applause:

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I bought a mityvac just for bleeding motorcycle brakes but so far it don't work worth a damn. I just changed my front brake line and have pulled at least a quart of fluid through the system and still have no pressure at all. Some how the air is staying trapped in there and won't come out, it's very frustrating. :thumbsup:

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