Topic: front brake prob..

[NGL_BrSH]

I searched my face off.. tried lots of different things.. and can't figure it out.

My bike sat a really long time.. the brake fluid eventually dried up out of the m/c res.

I added new fluid.. freed up the piston in the m/c.. i can bench bleed the m/c with my finger and it will pump fluid out and then draw new from the res...

Once connected to the line it won't bleed.  It's driving me nuts.. If i stick my finger over the caliper hole, press the brake lever.. I barely feel anything.  So i figured maybe an "air cushion" in the line or something.. I was very patient and did this for about an hour and the res took about 2cc of fluid! blah.

So after more research someone recommends filling the m/c, leaving the cap off, opening the bleed valve at the caliper and let it work the bubbles up.

I left it like this overnight... not a single drop of fluid made it's way through. 

What do you think i'm dealing with here?

I've done brake jobs on dirtbikes before with no prob but this is diff because the line isn't a solid line as you know.  It connects to the head tube bracket where the brake sensor is attached then down to the caliper.

I can't hear anything leaking anywhere and there is no fluid escaping along the path or down by the caliper.

any help would be greatly appreciated.  Thanks.

[bryanj]

"freeing up" a master that has been that dry just wont work, you will have to totaly strip and fit new seal kit, also the caliper after that amount of time will need stripping and cleaning out with new seal.
it is also probable that the lines are clogged with crystaline residue clean or replace but remember you only got one neck to break.

On reassembly you will have to bleed plenty of fluid out of the master using the finger technique, one i have described many times before then re-connect and bleed athe complete system

[bozo4onion]

+1. Kits are cheap. Caliper seal cheap even from Honda. Piston is $60 if you need one. Bleeding is still tricky and not like other bikes or cars I've done. I used a cheap vacuum pump from Harbour Freight (on the bleed nipple) and used bits and pieces of different methods found here. Good luck.

[Bob Wessner]

it is also probable that the lines are clogged with crystaline residue clean or replace

I agree, you can clean, inspect and rebuild both ends, but who knows what's in the lines. Additionally, who knows how old they are. I replaced mine along with the rebuild, it's worth the peace of mind.

[Steve F]

+1 on the vacuum pump....couldn't be any easier.

[NGL_BrSH]

excellent advice and i'm totally a poor (cheap) guy.. but like you said "I only have one neck to break." so for peace of mind i'll rebuild.

I could have bought a new 1000s Sport ducati by now in the nickels and dimes i've dumped into this thing

[Bob Wessner]

I could have bought a new 1000s Sport ducati by now in the nickels and dimes i've dumped into this thing

I don't know what a good equivalent would be for vintage bikes, but rag baggers call sailboats, "Holes in the water into which one pours money."

[NGL_BrSH]

aaaaaaaaaah..

so i went to hondaparts-direct, oldbikebarn and various sites and clearly they all use teh same fiche.

If you feel so inclined you can replicate my issue.  No master cylinder rebuild kit for 1975 CB550K1?!

the parts i need apparently are #33 part on the fiche.. which of course is missing from order section on all websites.

Can i use the one for the CB550F?  very aggrivating.  I don't think i'll ever be able to ride this thing.

[TomC]

Hi Bob
     When I did the brakes on my CB400F1 Honda had dated the brake lines. So they are only thirty two years old.

it is also probable that the lines are clogged with crystaline residue clean or replace

I agree, you can clean, inspect and rebuild both ends, but who knows what's in the lines. Additionally, who knows how old they are. I replaced mine along with the rebuild, it's worth the peace of mind.

     I the future I plan to go to SS lines.
          TomC in Ohio

[bryanj]

same master kit for 400/500/550 fours + 500 twin and single disc 750 to 76, probably get one from one of the aftermarket suppliers like dennis kirk, caliper seal from honda

[NGL_BrSH]

they all exclude 1975 for some reason.. I dunno... I really wanna get this baby rolling... (and stopping)

[NGL_BrSH]

as a follow up.. i went out there is morning to blow off some steam.

Looked in the res and it was down about a few cc's.. so for giggles.. i put my finger over the caliper hole and squeezed the lever.. a fair amount of fluid came out this time.. murky but fluid just the same.  So i repeated this about 30 more times.. until all the little air bubbles had come out and the fluid got to that nice golden brown color.  put the bleed screw back in and proceeded to bleed the brakes like normal.. IT WORKS!  not only does it work.. it works GREAT!   Stiff lever after about 1/4 lever movement.

With that being said.. how easy is it supposed to be to push down on the front forks?