Brake master cylinder ports

[sinannasirli]

Hi All
I have a 1969 K10 suburban with booster setup..
I have just bought a new master cylinder from classicparts and a booster from cardone..
When installing, the mechanic installed the rear port to front brakes and front port to rear brakes.. eventhough i insisted the cylinder is front-fron rear-rear setup.(info given from part supplier)

What possible effects would it have? Shall i insist to him to change them back?

Regards

Thank you

[geezer#99]

It could likely be good.
More info needed.
Do you have drum brakes or disc/front and drum/rear?
Pics always help of what you got.

[Bigdav160]

Drum brakes will have a residual check valve, usually located in the outlet port, that maintains a small amount of pressure on the wheel cylinder cup seals.

Disc brakes do not

[tdangle]

My understanding is that on C/K 10 you are correct front to front, back to back, for C20/K20 it is reversed

[sinannasirli]

Originally Posted by geezer#99

It could likely be good.
More info needed.
Do you have drum brakes or disc/front and drum/rear?
Pics always help of what you got.

Sorry forgot to tell you, this is a drum/drum setup.

Actually i am driving now with ports reversed and not much difference to me..
Is there any risk involved?

[sinannasirli]

Picture.. sorry that it is upside down

[geezer#99]

Looks fine!
No problem running it like that.
No risk involved.

Is the pedal firm or soft feeling?
Will it lock up all four tires in a panic stop?

[Caddylackn]

There are two circuits in the master cylinder. The primary circuit on the master cylinder is nearest to the firewall and should go to the front brakes since this does the majority of stopping power on the truck under normal driving conditions. The secondary circuit should go to the rear brakes. Most cars are set up this way if they don't have a proportion valve (P.V.). If either circuit fails, a port is uncovered in the master cylinder and both circuits are linked together so the car can stop. I don't know why a C10 is reversed, but a C20 is designed for more weight so it is set up correct. If you have the factory P.V. from a later model with disc brakes it doesn't matter as much which is the front as either circuit can take over inside the P.V. if one fails. Since your master cylinder is drum/drum both circuits have the pressure residual valve. If your car stops fine now with a load, I would say there is no risk. Your C10 should have been set up this way from the factory.

[sinannasirli]

Originally Posted by geezer#99

Looks fine!
No problem running it like that.
No risk involved.

Is the pedal firm or soft feeling?
Will it lock up all four tires in a panic stop?

Pedal is quite soft actually but stops well

Panic stop locks wheels yes..

[geezer#99]

Some people might prefer a harder pedal but if you’re happy with it just enjoy it!

[sinannasirli]

Originally Posted by geezer#99

Some people might prefer a harder pedal but if you’re happy with it just enjoy it!

I would want a firmer pedal, but after the new booster it gone soft..

Thank you all for the messages..

[sinannasirli]

Originally Posted by Caddylackn

There are two circuits in the master cylinder. The primary circuit on the master cylinder is nearest to the firewall and should go to the front brakes since this does the majority of stopping power on the truck under normal driving conditions. The secondary circuit should go to the rear brakes. Most cars are set up this way if they don't have a proportion valve (P.V.). If either circuit fails, a port is uncovered in the master cylinder and both circuits are linked together so the car can stop. I don't know why a C10 is reversed, but a C20 is designed for more weight so it is set up correct. If you have the factory P.V. from a later model with disc brakes it doesn't matter as much which is the front as either circuit can take over inside the P.V. if one fails. Since your master cylinder is drum/drum both circuits have the pressure residual valve. If your car stops fine now with a load, I would say there is no risk. Your C10 should have been set up this way from the factory.

That is actually our biggest debate..
He tells me primary piston shall go to front brakes, i am telling that all the setups i have seen and also what parts salesman told me was opposite..
Wonder why chevy selected the “odd” way..
Thanks

[Rickysnickers]

Flipped your photo. I am no expert, but I suspect the front is for the front and the back is for the back. Also, I'd take into consideration the info the person who sold you the part as well.