Why am I having such a hard time bleeding?

[Road_Clam]

Cripes, i've been flushing an bleeding from brakes on motorcycles for the past 25 years without too much trouble (some inherantly take patients), but my '87 GSX-R has gotten to be the biggest friggin PIA to date ! I recently completely rebuilt the front 4 piston calipers with brand new OEM piston/seal kits. I am thinking a have a caliper piston that must be air bound. If I pull the brake lever, it almost goes to the bars, if i do like 3 quick pumps the brake action is rock hard ? If I wait 10 min., it get soft again. I've mighty-vac'd the lines for almost 3 hours, and i'm not getting any better brake action. Any thoughts ?

[Calvin Blackmore]

your new seals have revealed what was a marginal master cylinder seal?

[Joe Nardy]

Try removing the calipers and pushing the pads as close together as possible before fitting the calipers over the rotor. I had a similar issue when I rebuilt my GS front calipers and someone posted this idea here. For some reason the pads tend to pull back to the point they were at when you fit them onto the rotors. I placed the calipers so just the leading edge of the pad was fitted onto the rotor. I then slowly pushed the pads in using the brake lever and then slid the calipers the rest of the way on. My brake lever was instantly rock solid. I know of at least one other forum member who has successfully used this method to firm up the brake lever.

Thanks,
Joe

[Calvin Blackmore]

Try removing the calipers and pushing the pads as close together as possible before fitting the calipers over the rotor. I had a similar issue when I rebuilt my GS front calipers and someone posted this idea here. For some reason the pads tend to pull back to the point they were at when you fit them onto the rotors. I placed the calipers so just the leading edge of the pad was fitted onto the rotor. I then slowly pushed the pads in using the brake lever and then slid the calipers the rest of the way on. My brake lever was instantly rock solid. I know of at least one other forum member who has successfully used this method to firm up the brake lever.

Thanks,
Joe

Man I did that once and had to split the calipers cos I got to excited and jammed the pistons together............
it did get the things bled though as I recall

[hikermikem]

Try removing the calipers and pushing the pads as close together as possible before fitting the calipers over the rotor. I had a similar issue when I rebuilt my GS front calipers and someone posted this idea here. For some reason the pads tend to pull back to the point they were at when you fit them onto the rotors. I placed the calipers so just the leading edge of the pad was fitted onto the rotor. I then slowly pushed the pads in using the brake lever and then slid the calipers the rest of the way on. My brake lever was instantly rock solid. I know of at least one other forum member who has successfully used this method to firm up the brake lever.

Thanks,
Joe

I've posted that trick before... in fact, i just did it again last week when i put new SS lines & rebuilt calipers & MC on the front of my 1100. As Joe mentioned, just squeeze them tight enough so you can push them back on over the rotor - this always fixes that spongy lever.

[Road_Clam]

Interesting idea. Thanks, i'll give it a try!