Front Master Rebuild Uh Oh!

[Guest]

I recently rebuilt my front master cylinder and my calipers. Got it all pieced back together and my plunger in the master only has about 1/4 in of travel. So I cant bleed my brakes and my brake lever is just flapping back and forth. Did I put the c clip on the plunger in the wrong place and the plunger is too deep in the bore?

[Dogma]

The c-clip doesn't go on the plunger. It goes into the bore after the plunger.

I'm having trouble imagining how you may have put it together another way. Perhaps something is stuck on a piece of debris you missed. I don't know, but something is clearly wrong inside.

[Big T]

You'll have to pull the MC apart and see what you did wrong

[gs1000emt]

Your right it is not on the plunger. Im not sure what I did. It does not have much travel at all though. Guess I'll have to tear it back apart. Had a hell of a time putting that clip in so the fun starts again. Thanks guys.

[Big T]

Be sure and use some silicone lube on the rubber bits when you re assemble it

NAPA has it in those little .99 packs, hanging on a rack

[eil]

In case you need a reference for the proper order of the MC guts:



The spring goes towards the brake line and the circlip goes toward the brake handle. Ignore the two pieces on the far right and replace them with the new dust boot. The little nub on the seal between the spring and piston goes into the hole on the spring.

When I put mine back together, I lubricated the bore and piston with new brake fluid. Silicone works too and probably is a better idea if the MC isn't going back on the bike right away. Don't use engine oil or anything made of petroleum.

[gs1000emt]

Oh thanks! I think I have the spring turned around the other way. Would that cause it to not have much travel? I did clean the bore real well and lubed all parts and bore with brake fluid while assembling. Should I use the silicone brake lube on only the rubber parts?

[Big T]

You can use the silicone lube on any of the parts, as it is compatible with any brake fluid

It provides a better seal initially , making easier bleeding

Just get the thumb sized pack, it's more than enough

[jwhelan65]

Sounds like you might have the plunger oring on backwards, it is tapered to seat like in the photo above.

[gs1000emt]

Which piece is the plunger oring?

[jwhelan65]

Which piece is the plunger oring?

The one dead center in pic above

[gs1000emt]

Ok thanks. I'll check it out.