One of the most frequently ignored areas of performance on todayâ€™s snowmobiles is the hydraulic brake system. Hydraulic brakes definitely reduce the amount of effort required to get a sled to slow down compared to the old cable-actuated systems, but they are not a service-free system. Which begs us to ask the question, have you ever had the brake fluid replaced on your snowmobile? Has it ever been bled? And itâ€™s how old?
Each snowmobile manufacturer will provide their specifications as to frequency of total brake fluid replacement, and these recommendations should be followed for maximum brake system effectiveness. As we reach the higher levels of performance, many high-end riders will have their brake system bled for two reasons; first, and most common, is to remove any air bubbles in the system. Air is compressible, and its presence in the brake system results in a spongy feeling lever.
The second purpose of bleeding brakes is to ensure the hydraulic system remains free of moisture. All glycol-based brake fluids are hydroscopic, meaning they absorb water. Even the smallest amounts of water absorbed into the system will dramatically lower the boiling point of the brake fluid. Frequent bleeding of the brakes purges the system of contaminated fluid, reducing the possibility of unexpected brake failure. This is more of an issue with race sleds and those that require frequent and heavy use of the brakes, as in mountain sleds that see steep inclines and heavy use of the brakes, but any sled fitted with hydraulic brakes can suffer unexpected loss of braking if the fluid is ignored. The water in the fluid turns to steam, and the brakes can simply fade to the point of â€œlever to the barsâ€. This is a very serious situation, thus the need to be aware of brake fluid contamination.
At a minimum you should be visually inspecting the brake fluid, which should appear clear to golden in the master cylinder. A cloudy, murky or muddy appearance indicates the presence of contaminants and/or water. Be sure to use ONLY the proper brake fluid as specified by the manufacturer to avoid compatibility issues and to maintain as high of a boiling point as was designed into the system.
Any sled over a couple years old would benefit from a bleeding as a precautionary measure. Dealers we contacted stated every 2500 miles or two years is a good point to be doing preventative service, but be warned that most factory service manuals state the brake fluid should be replaced annually! Sleds used in extreme environments where braking is heavy and frequent should be doing this at least annually. If your brakes should ever feel spongy, the system should be inspected immediately by a qualified technician. Point is, donâ€™t just forget about your hydraulic brake system on your snowmobile.