4th wheel Kits for Rear Axle
From factory, Yamaha Japan built sleds have only 3 wheels on the rear axle. This 3 wheel set up puts extra load on the solo wheel. If the solo wheel were to fail the sled is no longer mobile. By running a 4th wheel kit the load is evenly distributed on the rear axle, and should any one wheel fail the sled can still be ridden.
The SR Viper and Sidewinder sleds only run a 2 wheels on the rear axle and is known as the tri hub. Beings the two wheels are bolted together if one of the wheel bearings fail, essentially the whole assembly fails. This makes the sled inoperable, and tri hub failures can even cause track and rail damage.
Some will claim better cornering and handling, but my take is 4th wheel kits are an insurance policy to help ensure the sled does not leave you stranded on the trail.
All 03-09 sleds, & all year Phazers & FX Nytro....$40
All 2010-2015 Mono Shock II Apex and Vector......$50
SR Viper & Sidewinder models....$65
The Viper and Sidewinder 4th wheel kits utilize used standoffs from Yamaha Japan rear suspensions. The used standoffs allows us to keep the cost down on these kits. Kit includes includes (2) new wheels, (2) used standoffs and applicable hardware. Photo below shows how to assemble these kits.