The Filthy Motorsports 80 Series Land Cruiser has been testing and abusing Crown Race Gears since 2015
While one might not think that slow speed technical rock crawling and trail running could break a ring and pinion gear set, the repeated shock loads, even if relatively small, will cause a standard gear set to fatigue, micro-fracture, and then ultimately fail. Most automotive gears, including aftermarket gears, are designed and engineered for street and highway use where torque and forces are applied slowly. Gears for this application are made hard and strong for a long wearing life but this makes them brittle. While even the lowest quality gears would last five lifetimes under typical everyday use, when you subject gears like these to repeated shock loads off-road, they will not last long.
On the trail, every time a tire impacts an obstacle like a rock or tree stump, the drivetrain binds up to apply power to the tire. Then, when the tire drops off the other side of the object, the drivetrain temporarily unloads before binding up again when the tire comes back into contact with the ground. These small shock loads happen thousands of times each trip and add up over time, eventually resulting in ring and pinion gear failure.
Crown Race Gears are engineered to withstand this type of abuse by starting with a steel alloy that is heat treated and then cryogenically treated to be as tough (flexible) as possible so that it can absorb shock loads, yet have a very hard case (surface) to ensure a very long wear life. This ideal gear case hardness transition is difficult to achieve, yet it is the key to making a ring and pinion set hold up to off-road use while also promising a full usable life.
Because many gear failures begin with micro-fractures forming at the gear tooth root, Crown Race Gears go through two separate shot peening sessions that increase the gear density in those critical areas. This process has shown to improve the usable life of gears by about 75%, and has become a standard requirement for most aerospace components.
In addition to heat treatment and shot peening, Crown Race Gears are cut using 5-cut helical gear geometry that uses a sliding motion to transfer power through the gears instead of a pushing force that stays at the center of the ring gear teeth where it increases the likelihood of pitting and micro-fracturing. To take full advantage of the 5-cut gear geometry, Crown Race Gears are REM ISF finished for an aerospace grade smooth surface that, when lubricated with full-synthetic gear lube, reduces friction and power loss by almost 40%.
By increasing gear toughness, creating a desirable case hardness transition, and using an aerospace gear finish, Crown Race Gears are stronger, tougher, and more efficient than any other ring and pinion gears available today and making them the ideal choice for any rock crawler or trail runner.