Brake master cylinder diaphragm busing

[aquamantx]

Ok so cleaning up rear master. have the new kit for the innards but as we all know there is always something not available. Some guidance on the plate/busing that sits under the diaphragm. Super important, or just shape holder for the diaphragm? mines a little crusty and have cleaned. Should I just smooth out with a skim coat of jb weld or does someone have a source.

[DEEBS11]

No new parts available. This used unit can be cleaned up.

https://www.ebay.com/itm/116227307390?_skw=yamaha+XS+rear+master+cylinder&itmmeta=01JMRYS03PTN1PBE3JK4MFWGX1&hash=item1b0faff77e:g:l9EAAOSw11pmd32T&itmprp=enc%3AAQAKAAABAFkggFvd1GGDu0w3yXCmi1edFmA%2FNesyGaQ6e2OLsmkPb0%2FUQ6fXzLWnRnN890%2F6TuDY5IumWLfSAcCYpwwzYGaxC7%2F%2B%2FzEZWflCFxJCcw7ITKUMYjwEBcbyg%2FNjJKlszaYpGr9A7LlJ%2F1327BK5wmHdFHTLlv4i1oibZbSNYDDvbaT3abk2XNTFniFZ45TZGVuchUBW4iIhuxOl34%2FdRqrfeaWwsKJ5RW2DeFq0sTcKSqhnYEDvRA8lGGqd9sVSACqsf1hzzWZhzh9R%2F9yTxZf8R4KpWddpfrP3SVkyYI04GeW%2BscFtlqoYzgVnzKRHR0tRGM7%2Fb6jqr53LLrGkdZw%3D%7Ctkp%3ABk9SR4SC5J6mZQ

[aquamantx]

Appreciate the find. Mine was pretty crusty under the rubber but the rubber is still good. keep it for back up..

[LAB3]

Remember, it's the rubber that does the sealing not the bushing. I'd just clean it up and use it as is.

[Radioguylogs]

I'm with LAB3. I usually just hit them with a wire wheel and reuse them.

I think JB Weld is asking for trouble being uneven and susceptible to chemicals.

I'd pick POR15 if anything.

[jetmechmarty]

I'm with LAB3. I usually just hit them with a wire wheel and reuse them.


I'd pick POR15 if anything.

I believe POR15 is solvent based. Zinc plate it.

[Radioguylogs]

I believe POR15 is solvent based. Zinc plate it.

No solvent will dissolve POR15.

Zinc plating is better if you can manage it.

[cajun31]

Just wanted to throw this out there Yambits : Master Cylinder Parts for Yamaha XS1100 1978-1980

[aquamantx]

Ok so master rebuilt with new kit but the darn thing doesn't want to return. Followed instructions and made sure seals went in the proper direction. Any thoughts? Silver lining, I'm getting decent in removing a rear master cylinder.

[bikerphil]

The "cupped" side of the seals face towards the brake hose, and the inner seal needs to go over the inner shoulder as shown in the following pic...

[aquamantx]

Mine are facing that way. Spindle is a little different. spool sides in ok but sticks on return. I'm going to see what original seals do again,