Effects Of Driven Clutch Helix Ramp - Polaris 2003 Pro X Service Manual

CLUTCHING

Effects of Driven Clutch Helix Ramp

A larger helix angle will allow the clutch to upshift at a lower engine RPM. Less side force will be exerted on the
moveable sheave and the clutch will upshift more rapidly. During backshift, a lesser helix angle will backshift more
easily and keep engine RPM higher. A larger helix angle will make it harder to downshift and will load the engine,
resulting in lower RPMs.
If all other variables are kept constant, a helix change with a lesser angle will result in slower upshift and faster
backshift. Engine RPM will remain higher. A helix change with a greater angle will result in faster upshift and
slower backshift. Engine RPM will be lower.
The drive clutch controls upshift, while the driven clutch controls backshift through the angle of the helix. The
factory helix will work well for most rugged cross country races, while a helix with a lesser angle may work better
for high speed ice cross country races.
Because backshifting is not important in drag races, most of these racers experiment with larger helix angles for
the fastest possible upshift. Multi-angle helixes are sometimes used by racers who need a good holeshot. A
multi-angle helix reduces to a smaller angle as the clutch shift out and RPM is increased to match the HP curve
of the engine. This is particularly true of engines with narrower powerbands.
Oval and snowcross racers need a good holeshot and a quicker backshift for good response out of the corners.
Helix angles may require a change depending on individual tracks. Depending on performance requirements,
continuous radius, compound angle, and straight angle helixes are available. Once again, experimentation is the
best method of determining what will work best for your application.
Fully shifted
out
Continuous Radius
4.10
Stopped
Fully shifted
out
Stopped
Compound Angle