Ok lets play Dr. House...motorcycle edition...need brake help...

[makenzie71]

Okay it's a 2006 GSXR600.  No front brake pressure.

No air in the system unless it's in the line that crosses over from caliper to caliper.

I bled all the connections and no air escaped, just brake fluid.

Pumping the lever builds pressure, after pressure builds it stays good until the bike rolls.

Rolling the bike as little as three feet and there is no brake pressure.

Rotors are not warped.

All gaskets are intact and sealing.

If I pump the lever and build pressure and then hold the lever down it does no bleed off.


I've never encountered anything like this...any ideas?

[mach1]

could the MC have internal leakage bleeding back into the RES, you wont see any leaks or a drop in fluid level. are you saying pressure builds you hold the brakes and move the bike and it fades out or you build pressure release the lever move the bike and pull the lever and nothing. this happened to my truck I would build pressure in the pedal pedal is fine then I drive the car when coming to a stop car stops fine then i release then reapply and nothing. It came out to be the seal on the rod in the mc was leaking.
If you do have air it will be in the highest spot which would be the cross over line. what method are you using to bleed the brakes?

[makenzie71]

I don't think it's air in that cross-over because the air would compress...I know what air in the system feels like.  When pressure builds, it's good.

I can build pressure with the lever, then release the lever.  If I pull it again it's fine for any given period of time, unless I move the bike.  The pressure begins bleeding off the once the bike starts moving.  If I move it a foot, I loose a little lever play before the brakes bind.  If I move it three feet it goes to nothing and I have to pump the lever to build pressure again.

[Pigeonroost]

Let's see; House always starts with the most unlikely stuff and works his way to the obvious just before his patient crokes.  So; did Ya check the tire pressure?  How about checking the chain tension?  Did you use a new crush washer on the oil drain plug the last time?  Maybe the spark plugs are fouled.  Well; I don't see how it could possibly help, but maybe, just maybe, you should bleed-purge the old brake fluid using the old tried and true pump-hold-bleed technique and new in spec brake fluid from a new sealed container.  Now, I need some more pain drugs becuase my leg has a boo-boo....   

prs

[makenzie71]

As said, brakes have been bled....every joint and seal.  It's not a matter of old fluid or it wouldn't ever build pressure.

[mach1]

could the seal around the piston be leaking. explain when the bike is still its fine not moving but i the piston or housing is worn when you move thw bike the piston moves a lil and if the seal is bad then air or fluid leaks out. I know you said the seals are good but maybe the caliper or calipers are shot.

[makenzie71]

By seals I mean the crush washers on the banjo fittings.  There was no fluid around the pads or I would suspect the pistons off the bat...I will be investigating it further, though.

[makenzie71]

Ok I put a mic on the rotors and the right rotor has a .005" variance from one side to the other and the left rotor has a .075" variance on three axises...which is to say the left rotor is warped all to hell.