bleeding the lockheed caliper

I put in new seals (three o-rings) in the caliper. I decided to fill the caliper before mounting it on the bike. Because of it's design it is a real bear to get fluid into the inboard puck. NEVER rely on the bleeder valve to get out all the air. I tried using a long syringe to reach into the back of the caliper but no cigar. What really works is....1st, make sure the rear puck is not all the way in the back where it will block off the fluid. I had the caliper on the bench with the bleeder valve at the highest point and removed it. I filled the outboard puck and capped it off with a bolt, making sure it was completely full and no air. With an eye dropper I dropped a few drops of fluid into the bleeder hole and it would not budge. Using a thin rod to reach all the way to the back of the MC I worked it back and forth watching the small bubbles come up slowly one by one. This process took at least 30 minutes of carefully teasing out each little bubble all the while wondering why Lockheed didn't supply a second vent for the rear puck or at least inform the public what a bear it would be to fill the back of the caliper.
Sorry I can't report on how well the method works....the brand new bit of hardline...did I say BRAND NEW?....failed to seal. I found an old one and solved that problem. Now the bargain basement caliper I bought has refused to work so that goes into the trash too. The old story...get what you pay for.

With recalcitrant master cylinders, I have found that a pressure bleeder used from the opposite end - from a wheel caliper - works well for me.

i can't recall having any problems or issues w/ the conventional bleeding method on the Mk2 - hose off the bleed nipple into a container of brake fluid. a bit wasteful, but that's the nautre of the beast. come to think of it, i due for a fluid change about now.

seattle##gs said:

1st, make sure the rear puck is not all the way in the back where it will block off the fluid.

Click to expand...

This requirement depends on how the back of the piston is machined, aftermarket can have a flat back which will block the fluid from entering.



But properly machined there should be a recess on the outer edge.

I was looking at the empty caliper and thinking about how the fluid flows to the inboard puck. I have seen many times that the caliper seems to be stronger on the outboard side and pushes the disc - actually bending the disc - towards the wheel. It seems to me the passageways do not provide an easy route for the air to get out even under pressure. I found the air really clings to the alu, it took a long time to fill the inboard puck drop by drop and coax each bubble to the surface. I turned it this way and that and gently rapped it with an alu hammer to dislodge air bubbles. I'm guessing that squeezing the lever at the master cylinder doesn't automatically remove all the air from the inboard side. And reverse bleeding by forcing fluid up the hose to the MC only clears the line, not the caliper.
Just offering this as a possible, partial, reason for the poor performance of the stock system. I can't give results yet because of the junk master cylinder...I will probably bite the bullet and get the CNW Brembo MC next week. This way of pre filling the caliper deserves more investigation. Next time someone rebuilds a caliper give it a try and see what happens. I used a thin rod from the hardware store in the hobby section.

As Kommando says, a lot of aftermarket stainless pistons aren't machined properly, apart from the missing step as in the photo, the surface finish of them can look ok but hold the pistons off the disc, so much so it gives the same symptoms as air in the system. The original pistons have a polished chrome finish, so the piston can slide through the seal.