Custom brake fluid reservoir venting?

[Zerb]

So. I want to make a custom aluminum brake fluid reservoir, just so I can powdercoat it

But, before I do that. I need to know if the cap needs to be vented somehow. There is a dude who makes custom reservoirs and when I asked him if he vented the caps he said no. But, I must ask the collective here regardless so I don't end up not having brakes at 140+.





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[speeding-g60]

hygroscopic fluids attract water/moisture. we discussed this.

if you must do this, please use quality components, such as:

http://summitracing.com/parts/wil-260-12697

or

http://.summitracing.com/parts/wil-260-12696

you know i am about saving money. but stopping is worth the coin spent

or even some from Jamar..... fancy a triple? ok they have it.

http://www.pacificcustoms.com/jamar-mcrr1300.html

[Zerb]

We did. But those options are all killing the idea I'm shooting for here. As pictured above. There are plenty of caps available as pictured above. But I'm still up in the air if a vent is needed. Those I posted. Don't vent. And are on many cars. And they don't have issues. But they aren't drag cars. So I want to be sure here.


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[speeding-g60]

no vent.

the system is bled with the cap off, under vac or pressure (or both depending) so once the system is set its set.

the cap can be solid, in my opinion, and it should not affect the performance of the system.

pushing the brakes down HARD even, cant take that much fluid out of the reservoir i do not think. not enough to suck in the reservoir, otherwise they wouldnt mostly all be plastic.

get what you want to get, but make sure it is a sealed setup. internal bladder i dont think is super needed for your application.

and make your mind up, boy. show car or go car!!!! (i had to LOL)

[All_Euro]

...and make your mind up, boy. show car or go car!!!! (i had to LOL)

Nothing wrong with going fast AND looking pretty

[PRY4SNO]

Hmm

What kind of pressures does the brake system work under in the first place? I mean, there's only so much volume of fluid to be displaced in a moment of time... which is why Aaron's comment about plastic tanks holds water IMO.

FTR... I do like the looks of the custom aluminum reservoirs, but not at the expense of punishing fools on the road right now.

On the other hand, what about when it gets super cold? I notice in extreme winter weather random Audi cars I've driven need brake fluid (and coolant lol) added in cold snaps. Could venting alleviate this problem?

[Mcstiff]

If it is vented your fluid is going to absorb water. Old systems have ways to release pressure but newer designs use a rubber diaphragm in the cap to allow for pressure equalization without atmospheric contamination.

[elaw]

IMHO "no vent" does not make sense. Take a close look at the factory cap... it's got a vent!

The fluid level doesn't drop very much each time you press the brake pedal, but over time as the pads wear it does drop as the pistons move farther out in the calipers. When that happens, you either need a way to admit air to take up the extra space in the reservoir, or eventually a vacuum will form and the brakes will start doing weird things. You also have to accommodate the fact that both the air and the fluid in the system expand & contract with temperature changes.

Another poster mentioned that newer systems have a diaphragm in the cap... that's a great idea and it's interesting to hear that the Europeans are doing it. But it's not exactly a new idea... American cars had them going back to at least the 1950's.

But what the others have posted about the fluid absorbing moisture is true also... that's why you change the fluid periodically.

[my2000apb]

fwiw my Tilton res. has breather caps

http://tiltonracing.com/product/3-chamber-plastic-reservoir/



and they do sell just the caps if needed
http://tiltonracing.com/product/reservoir-cap/

[Zerb]

fwiw my Tilton res. has breather caps

http://tiltonracing.com/product/3-chamber-plastic-reservoir/



and they do sell just the caps if needed
http://tiltonracing.com/product/reservoir-cap/

Good info. But. I now need something to weld onto the top of a can. That will accept that cap.

Or. I use the cap and threaded bung I have. And drill a wee hole in the cap and get a diaphragm underneath it.

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[speeding-g60]

i have the same Tilton triple setup. with the same lids and i even have a spare i got to mod for the Motive bleeder if needed. (and FWIW the caps on VW/Audi cars are identical, just sealed and yellow )

and what do ya know, mine has the same tiny hole in it, and yes it does vent as you can blow thru it.

making a diaphragm for the cap would be simple. with thin rubber, cut out a circle like you would make a round gasket but dont cut the inside circle.

VIOLA.

[speeding-g60]

so now, you are looking for something like this: (this one is steel bung, aluminum cap)



Art Morrison rear end filler cap assembly.

https://www.artmorrison.com/rearends.php

EDIT: actually, something like this then.

http://www.summitracing.com/parts/mez-pn6550

[speeding-g60]

or this:

http://www.summitracing.com/parts/vpe-11291

[Zerb]

That's precisely what I have. The vibrant piece.

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