| The most important link of a racing brake system | | | | be over 392F. This is mainly applied to brake fluid |
| is the brake fluid. Sometimes this gets overlooked | | | | for OE passenger cars however there are |
| because the choice of the brake fluid may be | | | | independent labs that can perform this test on |
| political or based upon price being the brake fluid a | | | | Racing brake fluids. |
| consumable. Here the key factors to look at to | | | | 4. Compatibility: One of the most important tests |
| make the best choice: | | | | that the brake makers carry out to validate a |
| 1. Compressibility: This is crucial in order to take | | | | brake fluid is the compatibility to the rubber |
| full advantage of the stiffness of the calipers. If | | | | components such as seals, dust boots, master |
| the fluid loses compressiblity the driver will feel | | | | cylinders parts and pieces, etc.. The test runs |
| spongy pedal and the modulation of the braking | | | | hundreds thousands cycles which simulate the life |
| power gets worse. It is important to look at the | | | | of the brake components, it involves many |
| curve of Compressibility vs. Temperature - | | | | procedures to make sure all the components |
| supplied by the fluid maker - to see the | | | | meet the specification at the end of the test. |
| correlation of the stiffness and the caliper | | | | Another important characteristic of a brake fluid is |
| temperature. The consistency of the brakes | | | | the hygroscopicity which is the measured as the |
| performance at high temperature is what's | | | | % of water the fluid absorbs when exposed to |
| desirable to accomplish. The flatter that curve the | | | | moisture. This is crucial expecially for Stock Cars |
| better. | | | | where the teams change calipers and master |
| 2. Dry Boiling Point: This is the temperaure which | | | | cylinders in the garage to test several brakes |
| the fluid boils at when it is unopened. Nowadays | | | | combinations. The more water is absorbed the |
| this values range around 600F which is pretty | | | | more it loweres the brake fluid boiling points. This |
| remarkable however if the caliper temperature | | | | can be tested in a lab as well. |
| goes up in the 500F range, problems to the seals | | | | Last but not least is the chemical composition of |
| might occur, as well as the aluminum loses | | | | the brake fluid that might include toxic substances |
| strenght. | | | | that are may not legal by the local government |
| 3. Wet Boiling Point: This is a DOT procedure. The | | | | so the fluid itself can be banned. Most fluid |
| DOT4 specification mandates the wet point must | | | | chemical compositions are patented. |