Topic: In need of 77-78 cb750f rear master cylinder

[hapakev]

I started a rebuild of my rear master cylinder and found the rubber boot full of rust/dust.  not good. so I started to remove the snap ring, which is rusted to the push rod washer thing and stuck in the groove.  snap ring pliers bent. parts of the ring broke off, the thing is v ery well seated in there.  i am out of ideas and about of pen lube.  I am giving up for the night.

Does anyone have a spare laying around that they would be willing to part with?  I am so close to getting her back on the road.  I would really appreciat some help.  I could not find anything in parts for sale.  Please help.
I am in Ca 92630

[BeSeeingYou]

I think the 77-78 is a bit different than the 76F that I have but here is what I did.  While mine was not rusted the plunger was stuck.  First I squirted some Deep Creep in the inlet port and into the inlet from the reservoir.  I then heated it up with a heat gun and then pushed the plunger further in to depress the spring more.  After a few minutes it popped apart.  My next option if that did not work was to blow compressed air into the inlet port.  As a last resort I though about drilling into the plunger and tapping it for a small bolt and using that to pull it out.

But it sounds like you still need to get the C clip out.  Keep the plunger depressed if it is not stuck.  This will take a bit of pressure off the washer c clip combo.  Maybe with a small drill bit you can drill some holes in the exposed bit of c clip and break it up.  Try http://www.tricountymotorcycles.com if all else fails.  Before I was able to salvage mine I found one for the 76 there. 

[hapakev]

the spring must hade been that rust dust because there is no pressure on the push rod coming through the washer.  maybe the plunger is also dust, but I tried to drill the snap ring and it just dulls the bits.  I think its hardened steel.  It really sucks.  I was looking for the push rod mechanism so that if I destroy the washer to get it out, I coud replace it.  It looke like its discontinued, does anyone know if the OEM Honda rebuild kit comes with one?

[BeSeeingYou]

When I received my rear master cylinder kit the pushrod was included as well as the boot and washer.  It was not that clear in the parts diagram.

[BeSeeingYou]

The stuff in the boot may be just a combination of brake fluid and dirt.  Mine had a bit of  red mud in it but only minor corrosion.  The plunger is aluminum so that should not corrode.  The plunger was originally very stuck and I had to hit it with a hammer and screwdriver to move it about 1/4 inch.  After that I was able to push it further in by pushing with the screwdriver.  The spring may still be intact but it is just stuck like mine.

[hapakev]

do you recall what kit you used for the rebuild?  Mine did not come with the pushrod but it is not OEM

[754]

Snap ring wont move till you put some heat to it, the heating and cooling will break it free.

any other you find.. usually same problem.. that is iF you find one..

[hapakev]

that is my next step, that you for the encouragement

[BeSeeingYou]

The kit was OEM 45530-377-305.  On the 76 the diagram shows the boot as a separate item and not available but it came with the kit.  It also shows the pushrod as being included but not available separately  The parts diagram for the 77-78 is a little different with a differing part number. The pushrod does not show to be included and is listed unavailable as a separate item.  The boot seems to be included. The pushrod has the same part number for the 76 and 77-78 so I would think it the same.  It is obliviously available.  I even suspect these kits are interchangeable but I am not sure.  If you exhaust all possibilities I can send you my old one.  It is perfectly serviceable, not new and shiny but it is not badly corroded.