Rear Brake Pedal Travel

@sidewise, to answer your specific question, when I do the refilling of any master cylinder with brake fluid, I fill it all the way up, as full as possible, without causing a spillage. Put the reservoir in place, reinstall the screws, and wipe away any brake fluid that is around the edge or rim of the reservoir.  So to answer your question, just FILL IT UP.

Regarding the excessive travel of the rear brake pedal....Man, I hear ya.

It is a battle to get 100% of the air out of the system, when having added a sidecar brake to the equation, and feel that you have a really good rear brake pedal. Luckily for us, those front brakes on your ST-1100 are the monster brakes that all motorcycles should have, and they are unaffected by the sidecar brake lines, except being a Linked Braking System.

Try, and try again, to vacuum of push any air out of the sidecar brake fitting, and if you are as satisfied as can be, then just have to live with hitting your rear brake pedal once, to SET it, then a second time to engage the brakes fully.

That is where I have settled....pump my rear brake pedal once to set it, then hit it a second time to really engage the rear brake and sidecar brakes.

I found a small adjustment can be made to the pedal height by lengthening the rod going to rear master cylinder.
It's a start and I don't have to buy anything but sure is PITA to get too.

Posted by: @sidewise

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I found a small adjustment can be made to the pedal height by lengthening the rod going to rear master cylinder.
It's a start and I don't have to buy anything but sure is PITA to get too.

It should have been obvious as I did a similar adjustment on my V-Star 1100 Classic a few years ago but I didn't think of it as everything is hidden under plastic and aluminum on ST1100. After making the adjustment to the brake pedal, all seems much improved. I think I'll leave it here for now as riding season is soon drawing to a close in the NE USA. Maybe I'll give it another tweak for the spring.

Miles

Same problem here, too much brake travel. I have tried the work round of putting pressure on the brake pedal overnight and that has made a difference, i will repeat the process after a few days to see if there is any further improvement. No sign of fluid leaks on the floor afterwards,fluid level good. The next step will be to see if i can adjust the pedal itself, with limited ankle movement i definitely agree with Sidewise statement. Seems to be a common issue.

Both of you  should  also  check the  thickness of the  brake  pads in the sidecar  brake  caliper,  and....the bike rear brake  caliper.  I like  starting with  brand new  thick brake  pads, whenever  possible,  and before  installing the new  brake  pads in either  caliper,  I  exercise the  caliper  piston (s) in and out, lubing the  seals on those  pistons, lubing  up all contact points on the  calipers,  and the contact points on the  new brake pads, so that  everything  proves to me that  it all functions smoothly and  correctly.  In doing  all this,  part of working  the caliper  pistons  in and out  forces the brake fluid forward and  backwards  through the  hose and  rear master cylinder.  When all is done, all back together,  new pads in place....I  generally  end up with  as good  of brake  pedal  as I am going to get. 

Brakes/clutch flushed at 133962 replaced with Dot4 now at 139000plus. My thoughts have been drifting towards the sidecar wheel so i will start with that because it is easier for me to deal with. Not sure of my ability to examine the rear wheel just yet. I know its an assumption but the condition of the sidecar brakes should give me a decent guesstimate of the rear wheel as the previous owner also replaced the rear tire @ 134976 so the brake pads were likely checked then. I have not really used the rear brake so far so everything 'should be' in good condition but maybe a bit stiff from lack of use. As you commented when i was buying the wing it does look like everything has been done. =) i can always ask the last owner.

Posted by: @none

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Brakes/clutch flushed at 133962 replaced with Dot4 now at 139000plus. My thoughts have been drifting towards the sidecar wheel so i will start with that because it is easier for me to deal with. Not sure of my ability to examine the rear wheel just yet. I know its an assumption but the condition of the sidecar brakes should give me a decent guesstimate of the rear wheel as the previous owner also replaced the rear tire @ 134976 so the brake pads were likely checked then. I have not really used the rear brake so far so everything 'should be' in good condition but maybe a bit stiff from lack of use. As you commented when i was buying the wing it does look like everything has been done. =) i can always ask the last owner.

Steve, wasn't the previous owner...previous to the one you bought from, wasn't that Varn Cummings ? If so, then yes most everything was done, and done correctly. But if in doubt, I can call Varn Cummings, as I have him on speed dial.

Yes it was Varn and i can confirm with him if i need to. Previous owner i bought from was Jeff Kramer and he commented that he had done everything =) if i remember correctly you have pictures from my emails with him including his notebook

sorry, ive been locked out of the forum for a while. typical.

have you considered a master cylinder with a larger diameter bore? that would move the same amount of brake fluid with less pedal travel?

lots and lots of cylinders are available from china, cheap enough that you can experiment. i mounted a british girling front brake caliper onto a suzuki disc set up using a 14mm chinese master cylinder/hand lever. works fine for a lightweight british 650 (280 pounds) race bike.

im sure something is available in a similar fashion for a rear cylinder that could be adapted

@kevin I have actually been thinking of something as simple as a small block screwed onto the brake pedal itself. I have yet to investigate the possibility of changing the angle of the pedal, assuming it is on a spline. having a sidecar in the way does not help=) Push comes to shove i could always unbolt the sidecar and lift it off the chassis, chuckle!

or exchange the whole thing for a watsonian with a built-in brake pedal!

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this really is only an option for a right-shift bike.  i wouldnt be coordinated enough to handle two brake pedals on the same side.

im still building the tug, to tell the truth, so i dont know how well this thing actually works.