brake master cylinder question

1948 Pontiac
Master cylinder extremely difficult to get to.
Drilled and tapped fill cap, attached hose running to a reservoir mounted high up on the firewall. Reservoir is a salvaged clutch reservoir.
Question: Seems to work OK, but, system is kind of sealed. I assume there is no air within the top of the master cylinder.
Is this a problem?
Comments, suggestions appreciated.
Ivan Vegvary

On 8/15/2014 1:37 PM, Ivan Vegvary wrote:
> 1948 Pontiac
> Master cylinder extremely difficult to get to.
> Drilled and tapped fill cap, attached hose running to a reservoir mounted high up on the firewall. Reservoir is a salvaged clutch reservoir.
> Question: Seems to work OK, but, system is kind of sealed. I assume there is no air within the top of the master cylinder.
> Is this a problem?
> Comments, suggestions appreciated.
> Ivan Vegvary
>

I don't know the answer to your question but for a zillion
reasons you ought to develop the habit of regularly purging
the whole system with new fluid on classic cars. Brake fluid
is hygroscopic and corrodes master cylinders if left a long
while. Your vehicle is not dual-diagonal so a rusted through
brake line is a serious matter. Etc.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

Ivan Vegvary wrote:
> 1948 Pontiac
> Master cylinder extremely difficult to get to.
> Drilled and tapped fill cap, attached hose running to a reservoir mounted high up on the firewall. Reservoir is a salvaged clutch reservoir.
> Question: Seems to work OK, but, system is kind of sealed. I assume there is no air within the top of the master cylinder.
> Is this a problem?
> Comments, suggestions appreciated.
> Ivan Vegvary

As long as the new reservoir isn't kept full and the hose is 3/8" or so
it should be fine. The reason for the "extra" room is so that as the
fluid heats up and expands it doesn't apply the brakes for you!

I second the idea of keeping fresh fluid in there, and if possible
updating to a dual split system. Should be easy using a master from a
dual drum vehicle.

--
Steve W.

Ivan Vegvary > wrote in
:

> 1948 Pontiac
> Master cylinder extremely difficult to get to.


Shouldn't there be an access-panel set into the floorboard? Back then, such
things were meant to receive constant attention, and provision was usually
made for just that.


> Drilled and tapped fill cap, attached hose running to a reservoir
> mounted high up on the firewall. Reservoir is a salvaged clutch
> reservoir. Question: Seems to work OK, but, system is kind of sealed.
> I assume there is no air within the top of the master cylinder. Is
> this a problem?


You're fine. No air is no problem at all. If the brakes continue to work
properly, then your fix is good (and a good idea).
But it's not "correct"; you may get frowny-faces from purists at your next
show.


--
Tegger

On Friday, August 15, 2014 2:37:50 PM UTC-4, Ivan Vegvary wrote:
> 1948 Pontiac
>
> Master cylinder extremely difficult to get to.
>
> Drilled and tapped fill cap, attached hose running to a reservoir mounted high up on the firewall. Reservoir is a salvaged clutch reservoir.
>
> Question: Seems to work OK, but, system is kind of sealed. I assume there is no air within the top of the master cylinder.
>
> Is this a problem?
>
> Comments, suggestions appreciated.
>
> Ivan Vegvary

Studebaker actually offered a remote reservoir for its cars with the under floor master cylinder, so I don't see the issue with your setup.

If you used a clutch reservoir the cap should have a bellows with a hole in the cap on the atmosphere side of the bellows, so again, no problem.

nate

Nate, thanks for the info and your time.
Ivan Vegvary

On Monday, August 18, 2014 2:25:51 AM UTC-4, Ivan Vegvary wrote:
> Nate, thanks for the info and your time.
>
> Ivan Vegvary

Another thought. Unless you drilled through the vent hole in your old cap for the fitting (presumably this is a typical Jeep/Studebaker underfloor MC with the metal cap, and you used a right angle NPT to hose barb fitting?) you will need to find how the old cap is vented and fill the vent with a loctited grub screw, braze, solder, etc.

nate

Drilled through center of cap and threaded 1/4" NPT. Installed barbed fitting.
Ivan Vegvary

On Monday, August 18, 2014 9:29:39 AM UTC-4, Ivan Vegvary wrote:
> Drilled through center of cap and threaded 1/4" NPT. Installed barbed fitting.
>
> Ivan Vegvary

The typical old American MC that I'm thinking of had the vent hole on the side of the hex of the cap. May want to have a look at that before you fill it up with fluid, so it doesn't leak out and down the side of the MC/frame rail.

nate