Topic: 1972 350F front brake sticking

[JHAT76]

Well since I am a novice at this I thought I would ask before I start unscrewing things.  Recently when I squeeze the brake lever the front brake will stick.  This can last several minutes or even a day.  Before I start does this signal the need for a whole new cable?  Is there a spring in there that I can easily replace without replacing whole cable?

Just looking for a starting point.

JHAT

[crazypj]

It's hydraulic not cable (or at least should be)
 Most common fault is corrosion under the piston seal and pivot rusted.
After that, the return hole blocks up in master cylinder (it's only about 0.012"- 0.03mm)

[flybox1]

^+1
Time to service your piston and MC.
Remove your caliper arm from the fork keeping the lines attached, and use the MC to push the piston out.
watch it puke out all over the place. wear gloves.  DOT3 is not good.
new fluid, piston seal, maybe even a new piston and MC rebuild.  only getting in there would tell.

[goldarrow]

My 750F0 had a front sticking brake, I took everything apart and clean everything including inside the caliper, all good after all said and done.

[bryanj]

If its a drum brake cable yes, if its a disc brake  caliper piston pitted/sticking; caliper pivot pin siezed; master cylinder return hole blocked

[JHAT76]

OK o I am giving this a shot.  Sorry if I should ignorant, but I truly am.  I the brake apart.  The pads are pretty rusted around the edges, piston looks pretty good, and the inside of mc wasn't too gunked up.  It came apart fine but just to practice I attempted to put the piston back in.  When I do this it acts like it doesn't want to go in.  Was wondering if there is a special technique?  Do I need to flush out the cylinder more?  I can't seem to get the brake line loose from the cylinder due to stuck bolt.  Do I fight it off to get more fluid out of cylinder/.

Thank you for any reply

[Deltarider]

Time to service your piston and MC.

Piston yes (cleaning and checking pivot pin for free travel is often enough), MC not necessarily.
I'd start to check if pivot pin moves freely, then the piston and then maybe the MC (last). Don't start with taking everything apart at the same time.

[steam-powered man]

you are saying you got the caliper piston out?  if not, do so.   

don't put the piston back in until you remove the rubber seal and clean the groove completely.  all the hardened crappola must be scraped clean, fab whatever tool you wish.  clean the flat surface, and upper/lower corners.  replace the seal, order from local honda dealer, $11. 

remove the master cylinder cap, then push the caliper piston back in.  if it won't go back in the relief hole in the m/c reservoir may be plugged.  use a guitar string to clean it out.  no need to remove the brake line.       
   

[JHAT76]

Ok so now I have truly botched it.  I played around with piston after it was out to see how it would fit back in and now it is wedged.  The caliper is still hanging on bike.  After blasts with wd40 and PBNJ Blaster I can't get that Damon boot loose to get caliper off.  Any hints on powering the bolt off?  At least then I can attempt to unwedge piston or even just buy new.

[flybox1]

Post up a picture of how it's stuck....