Many of today’s snowmobiles use a rising rate skid frame out back, but due to cost of manufacture, they have an archaic, falling rate, front A-arm design for the front suspension. The ski shocks can lose mechanical advantage over the front spindles as the shock strokes towards bottom, getting weaker as it runs out of travel, not stronger as we would like. Ideally, we would like it soft up around sag, when we are just going down the trail, and get stronger as we jump or pitch the sled into a corner and the ski shocks stroke closer towards bottom.
The OEMs then may compromise with a spring that is a bit strong up around sag, which can adversely affect ride comfort, just so it isn’t WAY too soft when we drop into a washout or land a small jump near shock bottom.
A dual rate spring set up allows us to now have a progressive spring support package that can start soft, with great ride comfort and grip at the top of stroke around sag, then get STRONGER as the shock nears bottom, which makes the performance/comfort window bigger, not more focused towards one or the other. All in all, a dramatic improvement to the safety and handling of your snowmachine, reducing bottoming, body roll and in some cases eliminating inside ski lift altogether.
Dual Rate springs explained video
