FJ40 Brake master Cylinder help

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May 3, 2010
MS Coast
Hey gang,
My 75 FJ40 (built 5/75) has the infamous leak at the rear of the master cylinder and will not hold pressure (original unit and been sitting for 2 yrs with previous owner). I am having trouble findng a rebuild kit and even a place to get a mildly priced rebuilt unit from. I'd prefer to rebuild this one myself, to save money and for the fun of it (i've rebuilt many in my day), but I cannot find a rebuild kit. Does anyone have any suggestions as to where i can source a rebuild kit and even a rebuilt unit? I believe these particular units were common to the USA in 1/75 to 12/75 productiond FJ40's. Any help is greatly appreciated. This is the only thing stopping my 40 from being road worthy once again and I'm itching to get it on the road again.
swap it out to a taco or fj60 unit and be done with it .
Duh... :doh: I hate to say I wasn't thinking, but obviously wasn't. Will I be able to use the brake booster on the 75 or will I have to swap that out as well? I can easily get a setup off a 94 4 runner.
I'm also using a fj80 master on my 72 40, get one at auto part store for under $100.00, will fit booster but check pre-load, may need to adjust or shim master to booster. Also if you don't have disc brakes and think you may upgrade in future the 80 master will work great.
I run the same 94 non abs land cruiser master on my 74 with stock booster and drums all the way around , stops great .
Sorry to fire up an old thread but when you say master cyliner leak at the rear do you mean where there appears to be a factory casting dent? As mine appears to be passing a lot of air from there i'm curious.


never mind. turns out there's no o-ring in the brake booster between the master cylinder.... the stuff people forget to put in amazes me.
Sounds like you have a leaky booster. There shouldn't be any air escaping, and I don't think an o-ring will do anything for you.
Are you having to put a lot of pressure on the pedal to brake?

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