Topic: Master Cylinder pitting... too much? (picture)

[nomad]

I'm trying to decide if this is simply too much pitting to make it not worth it to rebuild.  Should I go ahead and use it, would I be better off trying to find a used one in better shape or should I simply go with a new aftermarket MC?  This is the first time I've ever torn into a MC and I'm just not sure of what I'm looking at when it comes to corrosion.

[K5owner]

Can't really tell from the picture. I'd try to clean it up a little. If you don't have a hone; you can clean it up a bit by cutting a chop stick to about 8", make a slit on one end. Get some 1500 grit wet/dry paper and cut a piece off about 1" in width. Stick the middle of the paper in the slit, and roll it until it will fit in the bore. Add water & RPM (drill motor), and check it after a few cycles.

[nomad]

I took a brass bore brush, hooked it to a drill, ran it through there extensively with some cleaning solvent.  Then I cleaned it with some simple green, then warm soapy water.  I then polished it with a cotton bore cleaner (again with a drill) and Flitz polishing compound.  Would 1500 grit do any more than that?  I thought the brass brush was fairly agressive.

[K5owner]

If you can feel the depth of the grooves; how deep would you say they are?

[nomad]

If you can feel the depth of the grooves; how deep would you say they are?

They don't "feel" deep, but again, not knowing what I've got, my "not deep" might be an experienced person's "craters."  I made up a 1500 grit/ bamboo stick contraption (good idea btw).  I'm going to go see if it'll do anything more.

[Tugboat]

That looks pretty pitted... too much and the new rubber cup you put in there won't seal, and then you're out $$ for the rebuild kit and STILL may have to buy another one. Give it a go w/ the 1500 and if it doesn't clean up any better, I'd try for a replacement.

[nomad]

It looks a tad better after the 1500 grit, but not substantially.  Crap.

[Tugboat]

The good news is that the MC off almost any 70's jap bike will work.

[lucky]

It should have NO pitting at all.

[nomad]

If no one replies to my "wanted" ad, I guess I'll have to go with a new one.   

[nomad]

Does anyone know of a company that can re-chrome the lining?  Is it even possible to do and stay within specs for a rebuild?

[Tugboat]

Replace it for $20
http://www.ebay.com/itm/HONDA-1976-SOHC-CB750-CB-750-FRONT-BRAKE-MASTER-CYLINDER-LEVER-PERCH-1-/380406005911?pt=Motorcycles_Parts_Accessories&vxp=mtr&hash=item5891f70097

[Blitzburgh207]

I've got a spare too if you want it. PM me if interested. 

[nomad]

After breaking down one master cylinder and finding all that pitting, I started to open another one, but it was rusted all to hell around the circlip.  I got a third MC, broke it down and found it to be in good enough shape to rebuild.

Question... the other two MC's might be salvageable if they were re-sleeved by a shop that does that sort of thing, but with what I would guess would be a fairly costly process, is it better to just toss them in the trash?  I know for a fact the one isn't rebuildable as it is and I'm about 90% sure the other one isn't either.  I'm definitely not going to sell these things.

[crazypj]

As long as the bore where seal fits is good, pitting where the circlip or boot fits isn't a problem.
 Pitting on the bore means it's scrap, unless you get a brass/bronze sleeve installed.
 The bore was never plated