Tandem master cylinder (1 Viewer)

[Bolifart]

Not mine, but a good explanation of why you NEED a proportioning valve:

"A Proportioning valve is required on vehicles that have disc brakes on the front wheels and drum brakes on the rear wheels. Disc brake pads are normally in contact with the disc, while the drum brake shoes are normally not in contact with the drum. If the pressure was not proportioned the disc brakes would engage before the drum brakes when you depress the brake pedal.


The Proportioning valve compensates for this, allowing the drum brakes to engage first before the disc brakes. The Proportioning valve does not allow any pressure to the disc brakes until a pre-determined pressure has been reached. The pre-determined pressure is low when compared to the maximum pressure in the braking system, this allows the drum brakes to engage before the disc brakes engage. Having the rear brakes engage first provides the control and stability needed to stop your vehicle safety.


The proportioning valve reduces the pressure to the rear brakes. Whichever type of brakes your vehicle has, the rear brakes require less pressure than the front brakes.


If equal braking force were applied to all four wheels during a stop, the rear wheels would lock-up before the front wheels. The proportioning valve only lets a portion of the amount of pressure to the rear wheels thus preventing rear wheel lock-up."

Thank you.
I just got a two reservoir MC. Se attached photo. Do they sell proportioning valves that can be installed with the MC I purchased?

 

[brian]

Brake Proportioning Valve for '76 to '80 Land Cruiser FJ40

OEM style brake proportioning valve for '76 to '80 Toyota Land Cruiser FJ40. Prevent rear brake lock-up and bring back your brake performance. Reproduction of OEM part # 47150-14010. Plug and play replacement for your original valve. For vehicles with stock front disc / rear drum brakes setup...

www.cityracerllc.com

i recently replaced my 40something year old original with one of these.....brakes are so much better now.

and while youre there, why not..... Dual Diaphragm Disc Brake Booster for Land Cruiser FJ40 FJ55 FJ60

also recently went with one.

 

[reddingcruiser]

You should be able to use an OEM proportioning valve like @brian. Otherwise, you can order a Wilwood valve from Summit, Jegs, etc.

 

[1911]

That appears to be an 80 series dual circuit brake master. (Don't 80s have 4 wheel discs? I forget).

FJ80's did not have rear discs; the FZJ80's did I believe.

 

[reddingcruiser]

FJ80's did not have rear discs; the FZJ80's did I believe.

FWIW, I have an FZJ80 FF disk brake rear axle in my 40.