Blown a master cylinder piston?

[bentwrench]

I need an opinion or a hundred on the front brake master cylinder for my 82 XS400.

I was replacing the front brake pads, and pressing the piston back in using my patented "get a c-clamp and squeeze down on the old pad" method, when I heard a pop, and the piston slid right back with no issues.

No leaks in the system, I was stupid for not having the lid off the master cylinder, but now I get no pressure when I press the brake lever. Is there an easy way to check the master cylinder piston, or did I likely cause a problem somewhere else?

 

[63-Coupe]

Doesn't sound good but have you tried bleeding it yet?

 

[bentwrench]

That's the next step, I suppose. I opened the master cylinder and fluid splashed everywhere - all the fluid from behind the piston.

Nice car, by the way.

 

[drewpy]

you may have "flipped" the seal. either way I would take the MC apart to check. Can't mess about with brakes IMHO.

 

[63-Coupe]

You probably know already but don't get any of that brake fluid on any paint. If you do, get it off immediately.

I agree with Drewpy, a master cylinder is one part you want to be absolutey sure about. Don't know what your level of expertise is but if you are not sure about how it is supposed to be put together or what may be busted find someone who knows what they are doing.

That car is my "Other" toy.

 

[bentwrench]

Yeah, it felt like something rubber popped, and a flipped seal would make sense.

Brake fluid was wiped up immediately. The tank was off the bike being sanded, so at least there was no threat to the new paint.

I'm jealous of your other toy.

 

[bentwrench]

Ugh - the circlip holding the piston in is brutal!

 

[drewpy]

oh yes, I forgot about those.
done two as well. At least its easier to put it back together

 

[bentwrench]

i'm about ready to drill it out - my circlip pliers won't fit into the holes.

 

[drewpy]

i'm about ready to drill it out - my circlip pliers won't fit into the holes.

use a long nail, ground down and flick one of the ears inwards and up. if it rotates, use another to stop it. 2 pairs of hands is good.

 

[bentwrench]

Drewpy, if you were here, and a woman, and really hot, I would kiss you.

Problem solved.

 

[drewpy]

ugh!

btw I'm going to see one of your most famous Canadians on thursday....

RUSH

 

[bentwrench]

Nice. I'm sure the audience will by 90% geeky looking guys, all rocking out completely to Tom Sawyer.

I've been one of those geeky looking guys before.

Rush is awesome.

 

[drewpy]

don't knock it, my daughter, heard them today thought they were good and she's 16!!

I prefer 2112, hemispheres (recorded in Wales, UK) and all the early stuff!

 

[xs400neophite]

The nail trick is the way to go!! Soooo much easier then snap ring pliers!! Actually I used a probe and probably small toothpick screwdrivers would work too. Whjat about honing the MC? is it necessary? or a thorough cleaning with a stiff bottle brush sufficient?

 

[bentwrench]

I didn't hone - just cleaned with brake fluid and a pipe cleaner, then replaced the MC innards.

Glad it worked for you too!