Topic: brake woes

[hymodyne]

evening,

the plunger on the brake lever is jammed in to the hilt of its housing. I've romoved the circlip and the spring retaining ring but the internals won't budge. I've used heat and penetrating fluid. the same is the case with the caliper (for a '76 550 by the way)puck is jammed in below the level of the housing, compressed air does not dislodge the piston or caliper. compressed air does however release oil, maybe transmission oil from the threaded opening for the the brake line. these are parts from an outdoor salvage heap. everything's stuck, time to get replacements?

hymodyne

[phylo101]

Ummm, it IS a plunger.... remove the bolt and line from the other end, and put a soft drift of some sort into the other end of the mastercylinder! I used a soft five inch nail with the point ground off and dressed round.Whatever you use, make sure it doesnt foul the threads when you begin to hammer.....

AS for the caliper....it IS possible on a Four to connect everything up, then very slowly you CAN bleed the system by hand, pumping soooooo slowly at the mastercylinder. Do it with the caliper loose and dangling, and kick it every so often to make sure the air gets to the top of the caliper and up into the brake line as you pump. This way of blleding up an old Honda system is an acquired skill, but it does work and the hydraulic system in the end, once air-free, pushes FAR harder than compressed air...Hell, thats why its on the bloody bike! lol lol

phylo

[Bob Wessner]

When driving the internals out of the master cylinder, in addition to making sure you don't damage the threads at the hose end, make sure you don't score the sides of the bore itself.

[cjackel]

You should be able to find parts for your K8 at a Honda Dealer.

The K8 isn't as collectable as the older SOHC4 750s but
it's the newest (and last) and Honda usually have the common
wear item parts. They also can order them.

My local dealer had the master cylinder diaphragm and plastic "washer"
in stock. I wouldn't be surprised if your local dealer had the rebuild kit,
which shows in the fiche as item #9, if I remember. It includes all of
the rebuild parts.

You can see the fiche at www.powersportspro.com

[hymodyne]

ok, i've pushed out all the internals in the master cylinder... now on to the caliper...is there any way to dislodge the caliper pad without the rest of the system being in working order?

hymodyne

[Bob Wessner]

I used a small grease gun. Make sure the bleeder valve is closed and gently screw a few threads on the grease gun into the outlet where the brake hose attaches to the caliper then start pumping. Mine eased right out. You need to clean up some grease in there afterwards, but no big deal. If the piston is pitted or corroded, replace. And you will need to replace the piston seal which should be available from a Honda dealer. Also be sure to clean the groove that the piston seal sits in really well, including the corners around the circumferance. The seal has to sit in there square and flat.

[Quail "Owner of the comfortable k8"]

I know this may a dumb question because it is what I always do first and assume others do the same. Have you just loosened the 2 bolts holding the caliper to the bike about 1 inch and pump the m/cylinder to push the piston out.  If not you will have to bleed the caliper if you still have it unhooked, but that takes all of 5 minutes.  if it has grease and stuff in there it will not matter.  If it still does not want to come put the heat to it and hold pressure on it, ( I just pump it up and then zip tie the handle to the throttle.  The heat and pressure will make it come out.)  This will also tell you the condtion of your m/cylinder, if it leaks it needs rebuilt/replaced.

[hymodyne]

the grease gun did it!
this site and its members are very helpful!

hymodyne

[Bob Wessner]

Glad it helped. Wish I could say I dreamed the trick up myself, but I learned it here.

[jgary]

Hymodyne, what did you use to push out the master cylinder internals?  After nearly a week I finally got the circlip and retaining ring free, and am at the same point of trying to get the rest of the guts out.  Long nail, as described, or something else?  Thanks!

John.

[hymodyne]

I used a thin bolt, keeping the threaded part away from the sides. a makeshift dental pic (sharpened tang of a small file) served to dig out the crud and reveal the spaces for the circlip and retaining spring.

hymodyne