Mountain descents are widely used for brake testing in both the United States and Europe. In order to demonstrate the high temperature capability of silicone-based brake fluids mountain descents, preceded by extensive track testing, were carried out at the Stilfser Joch in northern Italy and the Gross-glockner in south central Austria.
A Volkswagen Rabbit was used as the test vehicle since its size, weight, engine displacement, and brake system configuration are typical of current and future vehicles.
All test requirements were met with ease. The limiting factor was found to be compressibility of the silicone fluid and the ratio of master cylinder displacement to caliper and wheel cylinder volume. The effects of compressibility, although measurable in some braking systems, were found to be significant only at temperatures where a conventional fluid in normal use would vapor lock.