front master cyl question

[emzdogz]

Was wondering why a front master cyl, that has sat for a long time off the bike, would be "stuck" such that I can't get the lever to push in and out etc. Its like once the little brake light switch touches, it won't go any farther after that.

I have 3 different ones I could use and wouldn't you know, the "stuck" one is also the one that looks the most decent. LOL. The ones that looks like crap, the levers pump right in and out.

Was just wondering if anyone else has encountered this? An absolutely stuck front MC?

thx!
Em

 

[Travis]

What does the fluid look like in the reservoir? I've seem them stuck but not so much that you can't free them up and rebuild them.

 

[emzdogz]

hi Travis, there's no fluid in there...and no banjo bolt or brake line on....

 

[J ray]

My master cyl had the same problem when I bought my xs; bone dry and stuck. What I did was to remove it from the bars, pull the rubber boot (carefully), pull the piston retaining circlip then tap the piston out from other end(carefully) with an aluminum rod, the piston was totally oxidized with furry white shit, the piston fluid ports were clogged also. I cleaned it all off and out (a braided copper wire works good for the piston ports) being careful on the O.D. of the piston. Clean the rubber cups in penetrant, clean the resovoir. Blast it all with air and put it back together with brake fluid as a lube. Check the bore too it may need honing if it it looks risky.
This worked for me and I didn't have to replace any parts. Of course you'll have to bleed the system. The caliper may need attention too if that's dry.

 

[inxs]

- more stuff you never really wanted to know

- the problem is that the various metals and semi-metals have different electropotentials, on one hand this causes galvanic corrosion with the metal having the lower potential suffering the most damage, on the other hand when oxygen is introduced into the system enhanced redox reactions accelerate oxidation or 'rust' compounding the damage...this is why when you have say both iron and alu, or 2 different alu alloys together, although they both suffer damage one, alu or the alu alloy with the lower potential, will be more severly affected as it loses electrons more readily

- similarly your alu cases oxidise in air when not protected by lacquer against the salts

 

[jservant]

very smart guy!!

 

[Gordon]

Aunty!!!
Hey you, how are ya these day's? Burned up my Ironhead two weeks ago, should have gone a lot slower home than running about 110-120 for a hundred fifty mile's. No ticket's, but burn't the ring's out of 'er.
Anyway, back to your problem. You can use a grease gun( lever type, not the pistol grip type) and get a metric fitting at Advance Auto or Auto Zone, Put the fitting in the hole where the Banjo Bolt goe's, and pump away. Lever type gun's produce up to 10,000 psi, and that will push just about anything! When the track's on a bulldozer are adjusted, they loose a bolt and use that method on a cylinder built for that purpose. Same idea, just make sure that all grease is out of the caliper before reassembly. I do believe the thread size for the Banjo is 10mm by 1.25 pitch. And you won't have to worry about too much pressure, because as soon as the piston is out, the grease holds it so it won't fly away or hurt your finger's like compressed air will.

 

[sgallaty]

also brake fluid after it absorbs h20 has a bad habit of crystallizing.

 

[DogBunny]

I worked on several master cylinders with stuck pistons this week, and I agree with everything that has been said.

I would not worry too much about saving that rubber boot. If the piston is stuck, then the spring and circlip are probably very rusty, and the boot will probably be almost impossible to get off without destroying it, but all of that stuff comes in the Mikes rebuild kit.

Once you get the circlip off, drip some penetrating fluid where it was, put some more penetrating fluid through the banjo bolt hole, and the stuck piston should tap out pretty easily as described before. Don't try to tap it out without removing the cicrclip.

 

[emzdogz]

hey everyone, thanks for the info. Gordo, so sorry to hear about the Sporty. So you just need to put new rings or do you have to re-hone cyls and all that stuff? anyway, good luck!
That master cyl, I sh_t-canned it. I actually still have pieces of it. Was unable to establish which rebuild kit went to it. I did push the piston out.
Anyway, got one almost just like it - a 12.9 mm one.

NOW I see the 'new and re-vamped' Mike's has some really cool new MC's available - would have gotten a diff one if they been available. oh well.

 

[Gordon]

Emmer's, I got the whole kit and kaboodle, cylinder's, piston's, ring's for a song. All brand new stuff, US made, andthey look great. Should be back up by next weekend.

 

[emzdogz]

that's great news!!! still wanting to see a pic of that thing....