Master cylinder question

[Johnl48]

Not to sound like a dope but my mechanic is giving me conflicting info
On a stock drum brake set up does the reservoir in the master cylinder closest to firewall go to the rear brakes or front brakes ?

[Accelo]

Reservoir location may be reversed on the 3/4T trucks.
Others will have to confirm this.

[72c20customcamper]

Originally Posted by Accelo

Reservoir location may be reversed on the 3/4T trucks.
Others will have to confirm this.

Mine is reversed but it has discs brakes . First picture is my 72 second is my 68 With a disc conversion but the lines are in the same orientation rear reservoir goes to the rear brakes

[72c20customcamper]

Picture of the factory setup rear reservoir goes to rear brakes

[Johnl48]

Service manual says front reservoir goes to front brakes but he insists the "front" reservoir is closest to firewall not front of truck and the first reservoir (closest to firewall) always goes to front brakes ?

[72c20customcamper]

He’s wrong

[Keith Seymore]

Originally Posted by Johnl48

but he insists the "front" reservoir is closest to firewall not front of truck and the first reservoir (closest to firewall) always goes to front brakes ?

So - is the tailgate on the "front" of the truck?

What does "front" mean to this guy?

K

[72c20customcamper]

Here’s a diagram may not be a C10 but GM did them all the same pertaining to drum brakes .

[72c20customcamper]

I would be looking for a new mechanic

[Johnl48]

Based on what I read the "early" gm master cylinders were front/front rear/rear so having said that will a new after market M/C retain that ?

[72c20customcamper]

Originally Posted by Johnl48

Based on what I read the "early" gm master cylinders were front/front rear/rear so having said that will a new after market M/C retain that ?

If it a direct replacement part then yes it will

[Keith Seymore]

Originally Posted by Johnl48

Based on what I read the "early" gm master cylinders were front/front rear/rear so having said that will a new after market M/C retain that ?

Normally it is the later disc/drum masters that go the other way.

The smaller reservoir in the front of the master going to the rear brakes allows for more hood clearance in the event of a sloping front end.

M/L Van shown as an extreme example.

K

[Rust_never_sleeps]

If he's been underneath, he's probably right, but just have him show you. Too many variations

Mine was rear reservoir --> rear drums, but IIUC, the valving in the distribution block(NOT a combination valve) could be set up either way.

[Rust_never_sleeps]

Originally Posted by Johnl48

Service manual says front reservoir goes to front brakes but he insists the "front" reservoir is closest to firewall not front of truck and the first reservoir (closest to firewall) always goes to front brakes ?

There are plenty of excellent mechanics with dyslexia. Their spatial reasoning is extraordinary, but the words do get tangled up sometimes