scott_m_mil

I'm looking to upgrade the single reservoir master cylinder on my 66 to the 67 style dual reservoir master. I currently have 4 wheel manual drums, with no intention on changing it anytime soon. I have located the correct 67 MC.

From what I understand, typically you would disconnect the front brake line from the existing distribution block and plug it directly into the new MC. You would then plug the left over hole on the dist. block. Then you run a line from the new MC to the dist. block. This line would power the rear brakes.

Here is my question:

Do I need to keep the distribution block just to run the rear lines? Is there a proportioning valve in there that is required?

I need to replace the line that runs from the dist. block to the rear brakes anyway, so I'm hoping to just run a new line from the MC to the rear brakes. That is unless I need the dist. block to proportion the line pressure.

Thanks,
Scott

67t5ponycoupe

Use the proprtioning valve/splitter to go to the front brakes not the rear. The fronts have a line going to the left and right wheels, those stay plugged into the block. You will need a new line from the master to the block. Disconnect the rear brake line from the block and plug it. Run the rear brakes directly to the master. I use a joiner fitting for this. I don't run a proportioning valve on the back brakes but I think most will say you should. My brakes work fine without it. Remember to use the push rod from the old master not the one that comes with the 67 master. If you can do a double flare it should be easy for you.

kalli

no idea which one you are getting, but the following would apply to plumbing a dual master
a) the outlet at master that is closer to the firewall (so to say the rear one) is the one that goes to the _FRONT_ brakes
b) a proportioning valve (should you use one) goes between master cylinder forward port (the one further away from firewall) and the rear brakes
c) if you don't use a proportioning valve then you just plumb the rear brake lines to the forward port of master (further away from firewall)

now for the distriibution block
Before you change you have one line from the master to the distributon block.
from there you will have: one to front left wheel, one to front right wheel and one to rear wheels (1 line for both). the rear wheels use the same line until you meet the rear axle.

So when you change it over to dual, then
- you plumb the rear brake line straight into the master cylinder (the forward port further away to firewall)
- the line that went from master cylinder to distribution block now goes from the master cylinder rearward port (the one closer to firewall) into distribution block.
- and then empty port in distribuition block (where rear line was) will have to be blocked

So in short:
- move the rear line from distribution block into the master cylinder port that is further away from firewall and block the empty port in distribution block
- the original line from mastre to distr block now goes into the other port in master (the one closer to firewall)

Again: REAR brakes go into FRONT (further away from firewall) port of master cylinder!

scott_m_mil

Thanks for the help guys. That's pretty much what I was thinking would happen. I was also aware of which reservoir is for which set of brakes.

Now the decision it whether or not to use a proportioning valve for the rear brakes. Do you guys know if the standard distribution block actually proportions the rears?

Thanks,
Scott

Oxnard Montalvo

From what I understand the proportioning valve is only needed in a disc/drum system because the drums require residual pressure.

kalli

i believe as well for disc drum only as well.
however when done just go to a safe carpark or something and floor the brakes. when the rear locks up before the front does get a proportioning valve. otherwise don't. you will feel it easier when it's wet outside. wet car park is the easiest way to figure this out ;-)

2+2GT

I use a gravel road. Much less excitement. The front wheels should lock before the rears. If you have disc fronts and drum rears, a proportioning valve is mandatory. Drum brakes will lock before there is even enough pressure for the discs to do much.

scott_m_mil

My brother and I actually just discussed the same idea. Plumb the breaks, hit them and see what happens. I will be sure to post back with everything I do.

Thanks again,
Scott

Oxnard Montalvo

Fixed.

scott_m_mil

That just depends on how well the line plumbing goes