fast brakes

Disc Drilling
The same effect can be seen by drilling holes in the discs, but this takes away some of the heat absorbing mass. Too many holes can be counterproductive and can also weaken the disc. Because of the possibility of the discs bursting when mounted on the secondary shaft, the International Snowmobile Racing rulebook used to ban drilled discs for safety reasons. This is not a big concern with the discs mounted on the drive shaft since the burst force is reduced by 75 percent. ISR now allows drilled discs in order to improve the "gas planing" situation.

Lately, some different brake discs have entered the market. These discs have a large, overlapping saw tooth shape on the inner and outer diameter. The main function of this shape is to remove the hot gas layer to let the brake pads grip.

After my excursions off various racetracks due to inadequate brakes, I am in favor of thick over-designed discs, preferably with internal cooling passages. By keeping the discs cool, the chance of hot gases building up between the disc and the pad is drastically reduced.

This brings me back to the photo shoot at McCall and Arctic's new and very substantial brake disc. When you jump on a ZR 900 with 150 hp stock and haul across the lake at top speed, it is nice to know that this brake is probably over-designed. It sure beats the sick feeling you get in the pit of your stomach as the brakes fade away when you need them the most.

This story appeared in the December 2003 issue of American Snowmobiler magazine