Brake fluid. Oh boy. Brake fluid is like beer, spark plugs & oil. Ask 10 guys & you’ll get 13.5 opinions.
I have my own philosophy about brake fluid, based on my racing experience.
My brake fluid strategy is this:
a. Run a brake fluid with a slightly higher boiling temp than you need.
b. Flush the brake fluid regularly for optimum performance and less problems.
c. Spend as much as you need to achieve “a” … so you don’t have problems.
d. Don’t spend more money than you need, so doing “b” doesn’t feel wasteful.
I share some real world examples. Some may surprise you.
In our 1100# USAC Midgets, they corner so well, with such corner speeds, the amount of braking is very low. After a 40 lap main event, our crew pyro’s the rotors immediately & the hottest brake rotors are around 300°-350° on our fastest cars. If the rotor temps were hotter than that … we had driver or handling issues … and the car’s performance was off.
For these cars we used Castrol GT LMA brake fluid with a dry boiling point of 446°. We changed it during service before every race weekend & never had a problem. It cost about $10 a quart. Not $10 a pint … a quart.
In our 2550# NASCAR Modifieds we ran modern high travel/low roll suspension set-ups that required softer braking for optimum corner speeds. After a 40 lap race, the front brakes would read 450°-500° and the rear brakes 300°-350° … again on our fastest cars. Higher brake temps meant problems. For the Mods, we ran Wilwood 570° brake fluid, costing about $10 for 12oz, replacing it during service for every race weekend. Never a problem.
For the 2900# NASCR Late Models, optimum brake temps were 600° front & 400°-475° rear. We typically ran Motul 600 here … about $18 a pint … & changed it in between every race weekend.
In the GT1 & Trans Am cars, the braking is intense & you can’t mess around. You’re braking hard, often & for a lot of laps. Brembo LCF 600+, AP 660, Motul 660, Wilwood EXP 600 & Endless RF-650 are the brake fluids that work here. Way more money. Still changing it every race.
Why change the brake fluid so often?
a. Heat affects it, braking it down a bit.
b. Moisture kills the boiling point.
Yes moisture gets into “sealed” brake systems. Condensation forms inside the brake lines. Add heat to that & you get steam. Just 3% moisture content drops most brake fluids boiling point in half. Racers & teams that don’t change the brake fluid often enough have braking problems. Fresh brake fluid performs closer to the dry boiling temp. Older brake fluid performs closer to the wet boiling point.
I am not suggesting you change your street car brake fluid this often. Unless you run hard at the track. If you take your “street car” and drive it hard at a road course race track … it is now a race car. For sake of safety & track performance, you’ll want good brakes with no fade.
Castrol SRF is crazy expensive, but is the best at resisting moisture saturation. This is the best brake fluid for guys that don’t want to change it as often & can justify the price. You can see this in the chart below … Castrol SRF has the highest rated wet boiling point.
The “wet boiling point” is a test where the fluid is left exposed for a set time & then tested. The “dry boiling point” is when the brake fluid is new & fresh out of the container.
Thanks for the break down Ron. I typically flush my brake system before each season and then give them a good bleed before each track day the rest of the season. Really makes a huge difference.
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Rod Prouty
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Anyone use this brake fluid?
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