Dear Motor Age,
Your recent Backfire about synthetic brake fluids was great (September, November 2007), but after 10 years of racing we found that synthetic fluids break apart at high heat and pressure and do not go back to a normal fluid state when cooled down, resulting in very bad brake pedal.
The fix is to flush the system clean and use a quality DOT 4 brake fluid. Also, synthetic is not recommend in ABS systems because of high internal pressures and small passages. On the plus side, synthetics normally do not mess up paint jobs.
Thanks,
We've met other racers who expressed similar experiences with synthetic brake fluid and decided to return to DOT 4. We've met others who've chosen to stick with synthetic fluid because they really do need the higher boiling point. But they usually rebuild the brake system and change the fluid several times throughout the season, so they don't see the problems described in Nick's letter. Those racing stock cars equipped with ABS don't use synthetic fluid, because it tends to foam during the repeated rapid pressure spikes of ABS activation, and foamy fluid is not uncompressible.
Nick's letter accomplishes two things. First of all, this is hopefully the last time we need to discuss synthetic brake fluid. This letter also shows the value of real-world experience with the products you read about in this magazine and how important (and easy) it is to share your hard-won knowledge with each other. E-mail me directly at [email protected].
Thanks for writing, Nick.
