Rear brake part?????

[Fearthepack]

1.Small washer bottom left corner where does it go? I could not find it on tear down....



2. Both diaphragms won't retract and stay must be replaced yes/no....

3. front master, does the small end of the spring go in 1st?...

[Ken Talbot]

Check out the tech tip for a front master cylinder rebuild here. Though not exactly the same, they are very similar.

I think that washer goes on just under the snap ring.

Be sure you have the forward seal in the right place, and the cup on the right way around.

[mack]

M/c

On the plunger close to the pointy end you'll see a flange with holes in it. The little washer goes against that and the thinner of the rubber gaskets goes against the washer. Make sure the middle gasket is installed first, it's the thicker of the two and ensure the larger diameter is facing the pointy tip. The little metal nipple goes over the end, then you put the narrow end of the spring on the metal nipple. Coat the M/C bore and rubber gaskets with brake fluid before assembly into the bore to lubricate. Insert then install horseshoe clip then c-clip then rubber boot.

[Fearthepack]

Mack you da man thank you i can follow those instructions.....

[mack]

Sorry

Took me awhile but I finally found this one I'd made earlier.
https://youtu.be/neMSmI34iGg

[Fearthepack]

Even better seeing is believing.....PO did not assemble correctly.... Mack both my diaphragms are fully extended are they still usable? will brake fluid on them help in any way? Can I add the video to my main build thread?

[Fearthepack]

Not sure why the video is not in the tech tips area..... you nailed it. Seems simple but when PO has it installed wrong you end up doing a lot of second guessing on orientation of each replacement part. Thanks again.

[mack]

not

sure what you mean by "fully extended". They will be snug around the plunger and in the bore but with brake fluid they should slide easily in and snap back out like mine did in the video. If it doesn't move freely then clean and polish the bore. I have a bunch laying around here someplace. PM me if you need a couple and don't want to buy a whole kit.
Sure you can use the video. I made it public, anyone can use it. I'll be up loading a bunch more in the future and they will be public as well.

[Fearthepack]

The rubber diaphragm under the lid and retaining ring wont lay flat like yours in video its extended into the bowl.

[mack]

Do you mean

the wrinkled circles? or are you saying that the diaphram itself will not seal around the edges of the top. I had one leak once when the diaphram didn't seal around one of the screw towers on the reservoir side. You could probably make a thin seal with grey ultra gasket maker after you've bleed out the brake lines. If you keep it thin and let it set before you torque down the lid it should work. I'd try a bit in a very small container of sorts and let it set up, then emerse it in brake fluid to see how it responds. It never really hardens, but remains rubber like. You'll need a tube anyway if your going to do the usual required maintenance on the drive shaft/ final drive spines so it wouldn't be a waste if the brake fluid breaks down the rubber like quality. Option one of course would be to fill it and test it before you install the m/c on the bike. Just sitting it upside down it may not leak but once the fluid is under pressure in the reservoir, if there is way to leak, it will find it and you'll know for sure.
I'm sorry I don't have any of those laying around. As I said before. These are very hard to find in good shape. I do have a few retaining rings. If it's bent you can staighten it easy enough.

[Fearthepack]

Yes the rubber with rings mine stays in this position in the pic...

[mack]

Cleaning

Yikes!!!!!!Take that thing out and clean it properly!!!!An ultra sonic cleaner will do wonders.

[motoman]

EvaporRust......throw the whole thing in....will NOT affect anything BUT the rust....guarenteed.

[Fearthepack]

EvaporRust......throw the whole thing in....will NOT affect anything BUT the rust....guarenteed.

I agree... used it in gas tank worked like a charm

BUT... does anyone think the rubber is salvageable?

[3Phase]

BUT... does anyone think the rubber is salvageable?

Make sure the cylinder bore is good. Evapo-Rust will clean up the diaphragm, take the rust right off of it but I wouldn't trust it for the working guts in the master cylinder, that'll need a kit.

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