brake master cylinder leaking

[935Baby]

Hello,

does somebody know, where can I buy repair kit for brake master cylinder? I have ABS version manufactured by TOKICO bore diameter is 23,81mm (15/16").
Nissan original repair kit (pistons with seals) under number: 46011-44F26 (original number was 46011-41F26) is not possible to order - out of stock :-(
Part number for whole cylinder assembly is: 46010-41F10 possible to order for 300pounds!!!

My car was stored for 7years at my garage and was not driven during this time. Brake fluid was last time changed in 2011. So brake fluid is 7years old (maybe even 10).

Now my BMC (brake master cylinder) looks like seals are leaking-perished.

My question is: Can old (7years) brake fluid be agressive to seals (O-rings) and damage them?

I was always thinking, that old brake fluid can only absorb moisture a that´s it. Not to become acid which is killing O-rings
In year 2008 I was rebuilding BMC, I had to put new seals inside. I bought seal kit from company FRENKIT or AUTFREN (do not remember exactly)

I did use DOT4 brake fluid (Castrol or TRW). What type of brake fluid do you use?

[jay1017]

Best bet would be to get a used BMC. I’ve not seen one fail before so that’s very strange, potentially because the car isn’t getting used?

Personally I use dot 5.1 in my s13, best stuff you can get. Brand doesn’t really matter but mine is from Toyota.


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[ANDY black s13]

looks more like a chemical reaction from something being spilt onto the BMC from above,
that yellow coloured stuff is not brake fluid reacting with the aluminum, it is something else (not sure what tbh) but that is not brake fluid
If the seals had failed during the lay up period the fluid leak would be below the BMC body and run down the front of the servo
and bubbling up the paint as a sure sign it is brake fluid,
it's not natural for a leak to travel upwards and defy gravity from a container with no pressure

[935Baby]

looks more like a chemical reaction from something being spilt onto the BMC from above,
that yellow coloured stuff is not brake fluid reacting with the aluminum, it is something else (not sure what tbh) but that is not brake fluid
If the seals had failed during the lay up period the fluid leak would be below the BMC body and run down the front of the servo
and bubbling up the paint as a sure sign it is brake fluid,
it's not natural for a leak to travel upwards and defy gravity from a container with no pressure

Hi Andy, it is for sure brake fluid leak. I have spoken with guy, who repairs oldtimers and he told me, that he knows this. In brake cylinder there is slight pressure, so if seal fails it can leak-out. As it vaporize, it creates "salt" crystals. For sure there was nothing been spilt over BMC.
As you say about paint corrosion, it is visible on this picture, that paint on brake booster is at bottom corroded. There is also theory, that in the past, when I have replaced seals inside of BMC, I did accidentaly used kit for NABCO 22,22mm and that is maybee why did seal started to leak

Does somebody of you know, where can I get repair kit for TOKICO brake master cylinder? Size 23,81mm.
Seals (O-ring) kit or Tandem brake master pistons assembly.


I don´t trust to used brake master cylinders as I had alread problem with them it the past and had to reseal used unit.

[Phoenix]

Definitely a brake leak. If you're struggling to find a rebuild kit I have a known working spare one here after I took it off the car to replace it with a BM57 because of brake upgrades to the car

[935Baby]

Thank you Phoenix for you offer. I will try to get new seals or repair kit.

[935Baby]

Hello, I would like to ask if any of you have some new ideas where to get new seals for Tokico BMC? Or new repair kit? From Nissan Czech Republic it is not possible to order due to production stop. All previous tips here above were not successfull. Inclulding some tips sent by personal messages.

But I have some new fresh tip, regarding Subaru Impreza BMC swap:
I heard, that certain BMC from Subaru Impreza does fit to 200SX S13. They are also from Tokico company and its straight fit. Does somebody have some experiences with this swap? I am afraid, that it can affect function of ABS and overall brake ballance. But I have heard, that with this Impreza BMC, braking performance of 200SX S13 is improved.

[alanjuggler]

if you're LHD - get one from a 240sx.

as mentioned on the amayama page here:

https://www.amayama.com/en/part/nissan/4601127c26

they do offer a seal kit - Miyaco TK-9183

though I'm not sure why you'd bother since RockAuto list loads for LHD applications along with the 300zx ones if you want to change it.

https://www.rockauto.com/en/catalog/...+cylinder,1836

[935Baby]

USA rocks :-) Look what I have found in California, one new Tokico BMC is already on its way to me :-) It is same Part Number for 200SX S13 ABS :-)
https://www.ebay.com/itm/Tokico-Brak...72.m2749.l2649

[935Baby]

Thanks alanjuggler :-) I should see it before I did order the whole BMC from ebay :-)