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Staggies

5th Gen brake Issues....again

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Picked up a 2000 7 years ago that was a project bike when I got it. I went pretty hard for the first few months but life caught up and it ended up sitting until this spring.  I am so close to having it road worthy except for the brakes.  I have bled the hell out of the front brakes and can't get them to build up enough pressure.  I have done the bleed process from the front back to the PCV valve.  I stopped short of the rear caliper because the lack of pressure in the front is driving me up a wall.  I have pulled the calipers off and given them a good cleaning without doing a full rebuild. I have the rebuild kits on the way, but I would like to get it on the road soon.  I live up north, and once you get into September, you really never know when riding season will come to an end.  I have noticed that if I press the rear brake pedal, and then pump the front lever a couple of times, the  front brake pressure is there. I can release the rear pedal and still have the pressure.  The pressure goes away once I release the front lever.  I honestly don't know what else to do other then a full rebuild of the front brakes. I am not worried about doing it, I was just hoping I could get the bike on the road (safely), and then do the brakes in the winter.  Any suggestions?

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Outer bleeder on left, front caliper
Outer bleeder on right, front caliper
Center bleeder on right, front caliper
Center bleeder on left, front caliper
Remove left front caliper and tilt about 10 degrees
PCV bleeder at rear of gas tank
Re-install front, left brake caliper
Center bleeder on rear brake caliper
Outer bleeder on rear brake caliper

Finish by performing traditional bleeding process at all points, ensuring brake lever and pedal feel solid.   Since brakes are linked pay attention to whether you need to work the front lever or the foot pedal.   Once done, cycle the brakes a bunch.  I also park my bikes with a strap holding pressure on the lever for a few days after changing fluids.  Strapping the lever took out some sponginess I never could get by bleeding alone.

 

Oh, and if you are using a Mighty Vac, it will suck air around the bleeder threads.  Some folks put teflon tape on the threads, others replace with speed bleeders.  Obviously this isn't the issue if you do it the old fashioned way and pump the levers.

 

If that doesn't take care of it, the true mechanics on VFRD will help you sort out the issue.

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Remember the brakes are only linked mechanically. The front is a separate system hydraulically.

 

Master cylinders can be a real bitch to get air bubbles out.

 

Don't "bottom out" the master cylinder. You can damage the seal.

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I have bled the brakes in the correct order, even removing the front left caliper. I did stop at the rear brake because I don’t think bleeding the rear caliper at this point will help fix the front brakes.  I intend on finishing the process once I have the front brake issue resolved unless it will actually make a difference on the fronts. Using a vacuum bleeder almost felt pointless because it didn’t move enough fluid and it was pulling air from around the bleeder valve. I have speed bleeders on the way to help simplify this process as well.  Maybe there is just some air stuck in the master cylinder that I can’t get out. I will be leaving for the weekend, so maybe I will pull the strap the front lever in for the weekend with the master cap open a little bit and let it sit. See if the air will work it’s way out over the long weekend. 

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34 minutes ago, Staggies said:

I have bled the brakes in the correct order, even removing the front left caliper. I did stop at the rear brake because I don’t think bleeding the rear caliper at this point will help fix the front brakes.  I intend on finishing the process once I have the front brake issue resolved unless it will actually make a difference on the fronts. Using a vacuum bleeder almost felt pointless because it didn’t move enough fluid and it was pulling air from around the bleeder valve. I have speed bleeders on the way to help simplify this process as well.  Maybe there is just some air stuck in the master cylinder that I can’t get out. I will be leaving for the weekend, so maybe I will pull the strap the front lever in for the weekend with the master cap open a little bit and let it sit. See if the air will work it’s way out over the long weekend. 

You don't  have to leave the cap open.  If any air works its way up, it will move to the top of the reservoir.  In fact, leaving it cracked open will allow moisture into the system and that's a bad thing. 

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Maybe the problem with the front brakes is not hydraulic. I've certainly been able to put a rear pad in slightly wrong and catch the backing spring, which kept pushing the pad off the disk and made for awful feel. I'd suggest you check some basics, that the pads springs are in the right place, the pads are correctly fitted and the sliding pins for the calipers are moving freely.

 

It is quite correct that there is NO hydraulic connection between the front master cylinder and the rear so what you do with the pedal should not affect the brake lever. Pushing the pads against the front discs with the pedal will however affect how much movement is needed for the lever to start applying some pressure. 

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So I wrapped the front brake lever while

I was away for the long weekend. Came home and it was the same. Speed Bleeders arrived yesterday so I installed those and bled everything again. Still no better. So I replaced the pads, slide seals, and cleaned what I could without completely removing the calipers. Greased up everything and put it back together and the brakes are great now. The brakes were the final battle. I had all of the plastic painted and will be picking it up this evening. Hopefully I will have this machine on the road this weekend. Thanks again! 

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Welcome to the asylum Staggies from your neighbor state to the east. We'd love to see a picture of your machine to prove you are not a figment of your imagination.

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