Remote Reservoirs | Mounting Height

[Padawan]

All,
I'm unable to find any information explaining how a remote reservoir works. This will help me understand the height in which they need to be mounted in relation to the master cylinders.

Is it based on gravity or suction, I've been told both answers, I'm trying to understand the fluid dynamics that are in play?

Does the remote reservoir have to be higher than the master cylinder?

Do I need to buy remote reservoirs with vented caps?

https://www.amazon.com/DNA-Motoring-TANK-CLU-001-Aluminum-Reservoir/dp/B07K9F54VK/ref=sr_1_3?dchild=1&keywords=aluminum+brake+reservoir&qid=1617590953&s=automotive&sr=1-3

Does anyone have any articles to read?

I'm working on brake and clutch remote reservoirs.

Thanks...

[NAZ]

Gravity fed. When getting conflicting info it's best to call Wilwood and have them explain how a reservoir works and why it's mounted above the M/C.

While direct vented caps are still available, it's best that the caps do not vent directly to atmosphere as atmosphere contains water vapor and non-silicone brake fluid is hydroscopic and will absorb moisture out of the air, and that's a bad thing (lowers boiling point and can cause corrosion). A good reservoir has an elastomer diaphragm between the fluid and vented cap so pressure is equalized without exposing the fluid directly to atmosphere.

I like a rather large volume reservoir and the plastic see-through are more practical than the fancy aluminum or chrome ones. A larger brake fluid capacity makes bleeding easier as you don't have to stop as often to top-off. The larger capacity also gives more time for you to catch a leak before one of the systems fail. And the see-through style makes checking fluid level easy. But if you're mounting the reservoir(s) external such as a hot rod with no hood, the plastic ones look ugly.

[Padawan]

Gravity fed. When getting conflicting info it's best to call Wilwood and have them explain how a reservoir works and why it's mounted above the M/C.

While direct vented caps are still available, it's best that the caps do not vent directly to atmosphere as atmosphere contains water vapor and non-silicone brake fluid is hydroscopic and will absorb moisture out of the air, and that's a bad thing (lowers boiling point and can cause corrosion). A good reservoir has an elastomer diaphragm between the fluid and vented cap so pressure is equalized without exposing the fluid directly to atmosphere.

I like a rather large volume reservoir and the plastic see-through are more practical than the fancy aluminum or chrome ones. A larger brake fluid capacity makes bleeding easier as you don't have to stop as often to top-off. The larger capacity also gives more time for you to catch a leak before one of the systems fail. And the see-through style makes checking fluid level easy. But if you're mounting the reservoir(s) external such as a hot rod with no hood, the plastic ones look ugly.


So does the bottom nipple need to be above the master cylinder with all lines above the master cylinder or just the fluid within the reservoir needs to be above the master cylinder where the lines could be routed below and back up to the master cylinder?

[NAZ]

The fluid will seek a common level; so any part of the fluid in the reservoir that is higher than the M/C will always want to feed the M/C as the column that is higher has more weight than the fluid that is lower. However, any part of the fluid in the reservoir and hose between the reservoir and M/C that are below the level of the M/C will not feed the M/C so if you mount your reservoir with half of the fluid below the M/C you have just cut your usable capacity in half. You can simulate this with a length of clear tubing and water.

On some race car brake systems the cars have such a low profile that the M/C is mounted below the calipers and must use a residual pressure valve to prevent gravity feed from the calipers to the M/C and reservoir.