Britbike forum Forums British motorcycles in general British motorcycles in general Free play amount in hydraulic brake lever?

First, this question is in regard to my Brit power special "Project 39-1/2" which has Brembo brakes from a 1985 Cagiva. The rear brake bleed out quickly, firm pedal. The front brakes are dual disc. The front lever has 4 inches of total travel, lever ball to handlebar. Now it has been bled but still has 1-1/2 travel before it comes up against the hydraulic pressure. At that point the lever feels firm. Is 1-1/2 inches too much play, is it normal, or does it need to be bled out better?
Thanks
Al

Have you got twin discs fitted to a single disc master cylinder?

Which master? Free play is usually the clearance between the pushpin and the piston.
You should check the Ducati forum to see if these calipers can be bled without removing them. Some calipers will leave an air pocket unless oriented correctly.
The AP master has a small hole between the banjo bolt or male hose end and the piston chamber. You cannot get this air out without pointing the hose end sharply down. Of course any part higher than the reservoir will trap air.
Firm - hard solid or still squishy?

This is why I prefer mechanical brakes.

Another thing to check, are the calipers square to the discs? When you pull the brake lever do the calipers move? Try unbolting the calipers and put a lump of 5mm or 6mm metal plate between the pads and try the lever again

is it same master that came with brakes ? ( or at least the same Master diameter )

if you have mixed and matched one master with a different area of brake calipers
the force and distance moved by the calipers changes .

What's the area of the master cylinder ?
and
What's the area of the disc brake calipers ?

Okay, I'm back. Thanks for all your replies.
Andy - Good points. The master cylinder and dual discs are from the Cagiva, so they belong together. The calipers are shimmed to center them on the disc per Cagiva shop manual.
DM - Right, there's a small allen screw to adjust the pushpin to the piston. The free play I have begins at the pushing of the piston. Right now it has 1-3/4 inches at the ball end (when pushing the piston), that leaves 2-1/2 inches with hydraulic pressure. When reaching this point the hydraulic pressure feels quite firm.
Irsih - Drum brakes would have been simpler, that's for sure. I could have opted for one of those 4 shoe jobs (the Benelli Tornado has 2 shoes per side, I think). But then I wouldn't have alloy wheels. There was some compromise here, for sure. But I don't think even affordable drum brakes would have cost me less - I would have needed spokes and (alloy) rims.
Quinten - So as above, yes, the master belongs with the dual discs. The rear brake is also from the same donor bike. I don't know the diameters offhand but they are a matched set and should work well.

So, these questions having been dealt with, is the 1-3/4 free play at the lever end too much or normal? It is certainly possible that I may not have got all the air out of the system - even though the lever feels firm after the free play.
Following is a photo of the forks - all Cagiva except the steering stem, damper and headlight brackets. Trees, forks, sliders and even the fender are from the Cagiva.
Thanks
Al

Added note - the Cagiva workshop manual does not mention needing to remove any parts in the bleeding process. But that doesn't mean there isn't a better way.
Al

Hi Al, I have a Ducati Darmah 1981 [as well as some brit stuff], what you have looks to be the same as mine, 280mm rotors, brembo etc. The measurements you give are fairly similar to what I just found, your handlebar angle also seems the same. I was advised and then found it so, to remove m/c and lever[ as a unit of course] and tilt it up, ball end in the air , as much as possible but keeping fluid still in reservoir ,then bleed.[ as DMadigan suggested] An assistant is most likely needed. Hope that's a good explanation. You won't have any complaints with these brakes compared to drums. Not modern big floating discs multi pot calipers but pretty good 80's style.Photos of your bike when it's done please. Good luck Eric

Hi Al.

I havent read it all. Air pockets as other suggest could be an issue. But also, try clamping the lever as hard back with a cable tie as it will go overnight and try again.

Seems to work for many.