custom master cylinder reservoir vent/breather ideas?

I didn't like the "plastic" reservoirs on my brake and clutch master cylinders and decided to weld some homemade aluminum ones on. picture show'em pretty good, i used 1 1/4" NPT br*** plugs for the caps.
I originally wasn't sure if i needed vents or not..... any thoughts on not using vents?

i had issues with my welds leaking, then i jacked up a fitting and line. So i'm alittle nervous about really cranking down on the br*** NPT caps. with them pretty tight brake fluid does push up around the threads currently, i think as the fluid warms up it happens the most.

so i've got these little 1/8" NPT plugs i'm thinking about drilling very small holes in the shape of a "T" and putting down into the the filler plugs, hoping to alow air to go in and out, but let fluid drain back down.....

i'm really looking for ideas,
maybe some kind of miniature vents or something?

couple pics;

 

I had an idea about using "breathers" like used on axles and transmissions, but i've never see it done before

 

Rubber diaphram required,
Fluid is thus sealed from the outside air,
while the space above the diaphram is vented to outside.

Try looking at a motorcycle mastercylinder might find the parts you need.

 

The thing is, is brake fluid will absorb water, water is in the air. So the best thing to have would be a rubber diaphram that will keep the air from the fluid but still flex like a boot to allow the fluid to go to the clutch/brakes. But you know, on older cars their was no diaphram, just a vent in the cap. What you have looks good, I would make sure you have a vent and if you can't keep the air from the fluid, just change the fluid every year or so.

 

I've thought about making a round rubber disk and bolting it to the bottom of the br*** cap, but i just can't see it really sealing good. but if it kept air out most of the time and helped keep fluid from coming out the vent i guess that would be a plus.

i might look into motorcycles or autos with round caps to find the correct size rubber. thanks for the ideas............

 

I'd be more worried that you just wasted the bore of the master by welding on it like that...... I would have plumbed the master to a custom made reservoir mounted to the firewall before welding to the master....

 

I dis***ebled the master cylinders prior to welding and don't think i harmed the bores at all. everything went back together fine. I have drove the car since and the brakes work great (except for the brake fluid leaking from the br*** cap threads.)

well, i got some master cylinder rubber cap things and trimmed to fit the bore of my reserviors. also drilled acouple small vent holes, pictures show pretty good.

suppose to be dry and sunny tomorrow, can't wait to give her a test drive.