There are basically two types of 4-wheel drive available on ATVs these days.
The first is part-time 4WD like you see on Yamaha, Suzuki, Honda, Arctic Cat and Kawasaki.
With these systems, you can select whether or not you want to be in 4×4 by flipping a switch.
There’s also a diff-lock switch that enables the front wheels to be locked so power is transmitted evenly left to right. This is great technology and definitely is capable of getting the job done.
An alternative and widely used system is full-time 4-wheel drive and this setup is used by Polaris and Can-Am.
Full-time or All-Wheel Drive means you can leave the vehicle in 4×4 mode all the time or you can select to leave it in 2WD.
There’s no penalty through the handlebars with increased effort when you’re in 4×4.
Can-Am, uses a viscous coupling (trade name: Visco-Lock) that senses when 4WD is needed, automatically engages it and then automatically locks up the front left and right wheels for maximum traction.
The Polaris system operates nearly exactly the same except it doesn’t use a viscous coupling. Polaris uses a mechanical “hilliard” system in the front differential to automatically select 4WD and also to apply locking to the front differential.
The system can sense when more traction is required and it allows both automatic differential locking and auto 4WD selection on the fly.
From a pure user-friendliness perspective, the Polaris and Can-Am 4×4 systems are pretty cool.
No fear going into a mud hole that you may have forgotten to engage 4WD and now you’ll lose momentum. Just nail the throttle and hang on – you’re guaranteed to be in the correct mode.
We really like the part-time systems out there and they are so refined nowadays, you’d almost have to be an idiot to mess things up with them.
However, full-time 4WD is just too good to ignore.