Wildguzzi.com
General Category => General Discussion => Topic started by: larrys on June 15, 2021, 07:28:37 PM
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I can't seem to get them bled. Had a parking lot mishap that resulted in the banjo fitting on the hose breaking. I had a new brake line made at a local hydraulic shop. I had rebuilt the master cylinder and the caliper just last year. I replaced the line and back bled it with a Motive Products power bleeder til no air bubbles were appearing in the reservoir. No brake and no joy. I then did the old method of filling the reservoir, putting a discharge hose on the caliper bleeder fitting, cracking the bleeder and letting fluid flow through by gravity. Ran two full reservoirs through the system and still no joy.
I am at my wits end. Have been wrenching on bikes for fifty years and never have had this difficulty with bleeding brakes of any kind.
Could the caliper be somehow air bound? If so, how do I fix that? It has to be still full of fluid as I haven't removed it from the bike. Its a single bleeder type.
The NH rally is this weekend. Am screwed if I can't figure this out and get it fixed.
TIA.
Larry
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Are you talking the right caliper only and front master cylinder, or the left caliper and foot brake?
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I've been going over a'98 EV I picked up.I had a hard time bleeding the right front caliper.I discovered the lever was hitting the switch gear and not returning all the way.I moved the brake reservoir away from the switch gear and was able to bleed the brake.
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Right front disc, front master cylinder.
Larry
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My "old method" is to squeeze the lever, maybe multiple times, to build some pressure in the line, and then crack the bleeder on the caliper, and close it before releasing the lever. It can be a little like playing Twister. I have had single bleeder calipers (from new) that needed the pistons pushed all the way back in after an initial bleed to get the last bubbles out.
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The bikes that don't work, I take caliper off & put a wrench between pads then set the thing and line up on a box on a table so it goes up w/line from master. As you pump it up tap on line & fittings w/wrench. Caliper must be higher than master for air to go up.
This always works for me, a PIA to take line loose and all but it works.
I just spent the $ years ago & got a bleeder that works off my air compressor.
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You could try pushing the pistons as far into the caliper as they will go and wedging them in place before bleeding
It reduces the volume for air to hide, just remember to pump the brake before riding
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First thing I do when they give me trouble is push the pads/ pistons all the way in with a screwdriver and wedge them there, less volume for the master to overcome.
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I tried all the stuff that you guys suggested. Everything points to the master cylinder being FUBARed. Will be taking the car to NH Friday.
Larry
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Is the piston returning all the way out when the lever is released? If it is not, the fluid cannot refill because the hole from the reservoir is not cleared. Maybe the piston is bent or is not installed correctly. I have seen this to be an issue.
I use a long clear tube from the bleed nipple back to the m.c. to keep the fluid in circulation. A few zip ties or wire to hold in place and to keep it from dropping out and making a mess. I can see the bubbles coming out and know when the system is full and free of air.
Water is a friend when cleaning up. It brake fluid is easy to clean off surfaces with straight water and a few rags.
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For shits and giggles try tying the lever back to the handgrip with a bungie cord or zip strap overnight, this has cured many a spongy lever for me, may not work for you but at this point what have you got to loose? DonG
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Yes, the lever has full travel. I don't have a spongy lever, I have no brakes at all, nada. I squeezed the pucks in the caliper all the way in, I've bled the system both ways with a pressure bleeder from the bottom and gravity from the top several times. Ordered a master cylinder rebuild kit, will go from there.
Larry
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One thought besides the air bubble is the lever has traveled into an area which has had little use and picked up a bit of crud. Maybe you take the Master Cylinder apart and clean it. It may resolve your issue or you may find it needs a rebuild.