1966 Deville master cylinder

[mario]

Hi all:
I am installing that master cylinder in a "brand X" car replacing a single circuit "fruit jar."
Can anyone tell me which port goes to the front drums?
The one closest to the firewall, or the one closest to the radiator?
Thanks in advance.
Mario Caimotto

[Poncholover]

Unless you have some sort of hermaphrodite, front port always to front brakes.

[mario]

Thank you for the reply.
I, too thought that, until I saw this on another forum:

".. I just looked at an original 1962 Cadillac this past weekend, which was the first GM car to have a dual master cylinder. It had the port closest to the booster operating the front brakes and the one furthest away operating the rear brake..."

I don't know if that is right or wrong. That is why I asked. I was hoping to get a response from someone that can look at his stock, unmolested 66 deville.
Ciao,
Mario Caimotto

[D. Mailan]

Looking at my 1966 deVille, the line farthest from the booster follows the frame to the rear of the car. The line closest from the booster goes to a y and spits towards the two front brakes. Hope this helps

Derick

[mario]

derick:
thank you for taking the time to do this for me. this is the way the caddy engineers designed it.

mr. snodgrass:
i do not question your thoughts on what you stated. i, too believed that in a drum/drum system as there is so many disagreements on this, i wanted to see how the original setup was.

it is kind of funny that your handle is poncholover as that is the car i am replacing this fruit jar on, 1964 grand prix.

over on that other site, there are links that state the 1967 master cylinder on that car is as you stated - the closest to the firewall goes to the rear brakes.

now that i am using a 66 caddy master cylinder it should be installed the way those engineers designed it.

i am using that particular one as the outlet ports are away from the inner fenders (as you can see from derick's photo,) whereas the pontiac has the ports next to the inner fender.

by the way, both vehicles have the same size wheel cylinder diameters and main bore diameter.
thank you everyone for all your assistance.
ciao,
Mario Caimotto

[Roger Zimmermann]

Not the same year, but on my '72 de Ville, the master cylinder has a large reservoir at the front for the front brakes; due to the piston diameter, front brakes are using more fluid during the brake application. At the rear (near the firewall), the reservoir is small and is for the rear drums.
Therefore, there is no set rule.

[Big Fins]

Hey, Goomba, the M/C on the '69 Fleetwood, has two equal reservoirs and a disc/drum set up. The front goes to the front and the rear to the rear. So, I have to agree with Roger, there is no set rule.

[mario]

roger:
does your car have front discs/rear drums of drum/drum
that would explain the different size reservoirs.

fins:
with all the different opinions and with no set rule, that is why i asked. i didn't trust the thought that front brakes were fed by the front (closest to the radiator) reservoir. i wanted to find out from an original installation (thank you derick.)

some said that the master cylinder pistons were different sizes or had holes drilled in them to offset the pressures inside of the master as kind of a pressure regulator to one side of the braking system over the other. 
ciao,
Mario Caimotto

[Roger Zimmermann]

roger:
does your car have front discs/rear drums of drum/drum
that would explain the different size reservoirs.

If you read my text, you will see that I have discs in front and drums at the rear. I believe for 1972 front discs were standard. From the pictures, the old master cylinder had almost equal reservoirs; the new master cylinder has obviously a larger one for the front brakes.

[mario]

Roger:
Funny you should say that, as I did read your post. Nowhere did I read that you had DISC brakes, just larger front pistons,, and rear drums.
Sorry for misreading your post.
Ciao,
Mario Caimotto

[Roger Zimmermann]

You are right, Mario: the word "disc" is not on my first post...Sorry!