Technical Getting Rid of Dot 5 Brakes Fluid

Unless you have a way to get the dot 5 from its container to the master without contacting the air then there is moisture in it, part of the problem with it so that it is not hydroscopic so if moisture is present it will collect at low points such as calipers, if the brakes get hot enough then the moisture will boil and oops no brakes. If it’s impossible to get moisture in a system with dot 5 then why do they give wet and dry boiling points? The wet boiling point is the point the fluid boils with three percent water by weight. Dot 5 is also slightly more compressible with will result in a slightly spongy pedal.


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I see that Wilwood now sells their own version of dot 5 fluid. They do not recommend dot 5 for hi-temp racing applications though.

 

pulled this today off Wilwoods website.

NOTE: Only use fresh un-opened fluid. Once opened, use immediately. Do not store opened bottles or cans, or reuse old fluid.

Due to a high-performance brake system's extreme operating temperatures, standard parts' store brake fluid is not recommended. Never mix brake fluids of different DOT classifications.

Dry Boiling Point
Of critical importance is the brake fluid's dry boiling point - the temperature at which a brake fluid will boil in its virgin non-contaminated state. The minimum dry boiling point temperature is 401° F for DOT 3 fluid, and 446° F for DOT 4. All Wilwood brake fluids exceed these standards, with Hi-Temp° 570 rated at 570° F, EXP600 Plus rated at 626° F, and XR Race-Only at 645° F.

Wet Boiling Point
Moisture enters your brake system through condensation, weather, ambient humidity, or washing the exterior. Glycol based brake fluids are hygroscopic (they absorb moisture), and over time the boiling point is gradually reduced. The DOT 3 minimum wet (roughly 4% water absorbed) boiling point temperature is 284° F, DOT 4 is 311° F. All Wilwood brake fluids exceed these wet boiling standards, with Hi-Temp° 570 rated at 313° F, EXP600 Plus rated at 417° F, and XR Race-Only at 432° F.

DOT 5 Silicone Fluid
Silicone DOT5 fluid is often used in classics, show cars, and pre-ABS Harley-Davidson motorcycles to prevent corrosion. Silicone fluids have a neutral PH and do not attract moisture like DOT 3 and DOT 4 fluids and is paint-safe if spilled. However, DOT 5 is not compatible with glycol-based DOT 3, DOT 4, or DOT 5.1 fluids, and will turn to gel if mixed. Wilwood does not recommend using silicone-based DOT 5 fluid in racing applications because it is prone to aeration and foaming under normal braking conditions, providing a spongy brake feel.

Flushing
Whenever you add fresh fluid to your existing system, it immediately becomes contaminated, lowering the new fluid's boiling point. For maximum performance, use a high boiling point fluid and flush the system thoroughly. For street cars, flush and refill the fluid every year. For race or track driven cars it can be beneficial to change the fluid after every race weekend, especially after racing in the rain, severe temperature use, or brake fluid boiling.

 

I love these brake discussions ...

The brake system draws atmospheric moisture, no matter what fluid is being used. Talk to GOD. HE can explain it.

The DOT 3, 4 and 5.1 are hygroscopic by design to absorb the water. That is why brake fluid is changed (should be) every two years. DOT 5 shuns the water and it eventually puddles at the lowest point in the system (gravity), leading to corrosion and boiling fluid @ the calipers and wheel cylinders on hard repetitive brake applications and further reducing the boiling point.

DOT 5 aerates with aggressive brake usage. Unless you reverse bleed, the system will have to sit for a period to have the air come up to the MC.

There is no argument. That is a fact.

WILWOOD BRAKE FLUIDS - https://www.wilwood.com/BrakeFluid/BrakeFluid

WILWOOD FIVE DOT 5 SILICONE BRAKE FLUID - https://carsuppliesdepot.com/product/wilwood-five-dot-5-silicone-brake-fluid/