Front Brake Problem 2nd Try........

[Slammer]

In my first post "Front Brake Problem" I didn't explain correctly the symtoms. The brakes aren"t locking up under braking, they are building pressure while riding and quickly applying themselves until you have to stop. When this happens there is no play at all in the front brake lever and the only way to get the brakes to release is to bleed them. At first I thought there might be to much fluid in the system but before selling the bike my wife and I rode it alot with no problem. After the first lockup we bled each caliper twice and did not add any fluid but they locked up on the next ride. After bleeding the tire rolled free with no noise. We pumped the brake then rolled it with no drag or noise. It seems if the calipers were dragging you would hear or feel  something while rolling the bike with the engine off. Just try to get a direction to go in to rid this problem.

Slammer

[Chrisj CMA]

Is there any chance some WRONG fluid was added to the system?  This can cause a reaction that will do just what you are experiencing

[Ricky-D]

The characteristics of disc brake systems will seem to cause the brake pads to remain in contact with the rotor after brake pressure has been released.  This will usually cause a bit of rubbing noise but no actual braking effort so the rotor will be free to rotate.

The problem you are experiencing

"It seems if the calipers were dragging you would hear or feel  something while rolling the bike with the engine off"

is perfectly normal.

The other problem

"The brakes aren"t locking up under braking, they are building pressure while riding and quickly applying themselves until you have to stop."

seems to have abated. More than likely there was air in the caliper that was expanding due to the heat generated, which caused the problem and bleeding the calipers removed the captured air.

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[Slammer]

Thanks......I think we will rebuile the master cylinder and calipers.

[Mr.BubblesVRCCDS0008]

I've had cars that the rubber hoses start breaking down inside and start acting like check valve letting fluid only travel under pressure to the caliper but not back to the master cylinder. Only fix is new hoses.

[Mr.BubblesVRCCDS0008]

I'm sorry I'ld be lying if I said I knew. Not sure, if they do then problem will not be with the lines. I'm sure somebody on the board will chime in with the imfo.

[Valkpilot]

Hello, Mr. Bubbles.

Does a Valkyrie brake hose have a teflon tube going down the center?  Many Hondas do.

Thanks / Pluggy

Valks do not, at least the '98 lines I cut open don't: http://www.valkyrieforum.com/bbs/index.php/topic,19915.0.html

[Blackduck]

The master cylinder piston has to come right back to uncover the port in the cylinder body, this allows any pressure in the system to bleed off. Possible problems are blocked port, lever not returning properly, faulty piston seal or dirt/corrosion between the piston and body.
Cheers Steve

[Slammer]

thanks for the  info

[Ricky-D]

The master cylinder piston has to come right back to uncover the port in the cylinder body, this allows any pressure in the system to bleed off. Possible problems are blocked port, lever not returning properly, faulty piston seal or dirt/corrosion between the piston and body.
Cheers Steve

This is a very cogent post and should be considered significant to the original posting.

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[rayjay]

"The master cylinder piston has to come right back to uncover the port in the cylinder body,...". One culprit, but if the master is clear and you have checked the calipers think about replacing the lines to the calipers. A very rare occurrence, but I've seen the inside of an "older" flexible brake hose start to come apart and keep the pressure from being released on an older HONDA motorcycle as well as a car. The hoses on both the mid 80's motorcycle and car were about 15 years old at the time of the problem and the previous owners had allowed the calipers to hang from the flexible brake hose while they were fixing things. I did learn one way to check for this was to reverse bleed the caliper, i.e. pump the brake fluid up from the caliper to the master after draining the fluid from the master cylinder's reservoir. If there is a problem you should hit a point where the fluid builds up enough pressure to where you can not pump anymore in. Once this happens, crack the top banjo bolt and see if that releases the pressure. If it doesn't you have found your problem is the lines, if it does you have found your problem is the master cylinder.

P.S.: A word of warning, do NOT reverse bleed any car or bike with anti-lock brakes without checking to see if reverse bleeding will destroy or hurt the anti-lock system. For example some Jaguars, Astons, and Cadillacs use a Teves system that is prone to being damaged by reverse bleeding. You will have a very expensive problem if you do this. The system may not work and you will have a very expensive repair of the system if you catch it early or the car if the system fails on the road and you hit something. Always remember 1) good judgement comes from experience and most experience comes from bad judgement, and 2) I have a Jaguar XJ-S and have had a lot of "experience" from it.