A snowmobile clutch works very much the same as the clutches in scooters or many automatic-transmission cars. This is because all these vehicles have similar transmissions, known as CVT (Continuously Variable Transmission).
CVTs have three main parts, the primary clutch, the secondary clutch, and the belt.
If you want to learn more about how a snowmobile clutch works, this post is for you. No fluff or useless affiliate links, just the solid info you need!
If you want to know how to remove or maintain your sled’s clutch, don’t miss our step-by-step maintenance guide!
How Does a Snowmobile Clutch Work?
How does a snowmobile clutch work?
Snowmobiles feature a type of pulley-based CVT transmission that consists of two clutches. These clutches (also known as pulleys) are connected with a belt. The engine crankshaft directly drives the primary clutch. It has two sheaves; the stationary sheave, which is attached to the crankshaft, and the movable sheave. The latter engages the belt while moving in and out depending on the engine’s RPM.
These two sheaves are held apart by pressure while the RPMs are low. At a certain RPM, the centrifugal force generated by the clutch weights forces the movable sheave towards the stationary sheave.
This engages the clutch and allows the belt to rotate, which starts transmitting power to the secondary clutch.
The secondary clutch is connected to the jackshaft, which takes the power to the chaincase.
The primary clutch closes when the snowmobile reaches its maximum speed. At this point, the belt spins faster, at the same RPM as the engine.
This stepless transmission offers a vastly different experience from a manual or regular automatic transmission.
This is because it is based on the engine’s RPM, so the system can simply switch between “gears.” It results in easy handling and a smooth riding experience.
If you want to see how a snowmobile clutch works, don’t miss this informative video:
What are the Primary and Secondary Clutches on a Snowmobile?
The primary and secondary clutches on a snowmobile are parts of the CVT transmission. The primary clutch is driven by the engine crankshaft while the secondary clutch drives the jackshaft. The two clutches are connected with the belt, which drives the secondary clutch depending on the engine’s RPMs.
Parts of Snowmobile Clutches
What does Changing Clutch Weights do?
The clutch weights generate a centrifugal force while the engine crankshaft is rotating. This force increases as the engine’s RPMs increase. At a certain point, this force moves the moving part (sheave) of the primary clutch towards the stationary part. Once the clutch engages, the belt starts to rotate the secondary clutch.
What are Clutch Sheaves on a Snowmobile?
Simply put, clutch sheaves are the two main parts of the primary clutch. The movable main part of the clutch is called the movable sheave, while the fixed one is the stationary sheave.
What does a Helix do on a Clutch?
The helix is the part of the primary clutch that separates the moving sheave from the stationary sheave. The geometry of the helix is important as this determines how fast the clutch engages and starts the sled. The general rule is the steeper the angle it features, the faster it shifts.
Aftermarket helixes are available with different geometries. If you want to change your sled’s character, you can consider replacing the helix in your clutch.
What does a Clutch Spring do?
Clutch springs can be found in the primary and secondary clutches. Their main purpose to dampen the engagement to make it smoother. Their additional benefit is that they help reduce the engine RPM’s fluctuations. You can learn more about clutch springs from this informative video:
What does a Clutch Kit do on a Snowmobile?
Simply put, a snowmobile clutch kit contains aftermarket performance clutch parts. If you are looking for snowmobile clutch tuning, these kits are for you. They offer faster acceleration, a longer belt lifetime, and a significant improvement in back shifting.
You can make good use of this kit if you use your snowmobile in extreme conditions, have made performance modifications, you regularly ride with heavy load, or your track is heavily studded.
What’s Included in a Clutch Kit?
Snowmobile clutch kits include all the necessary components you need to tune your clutch. These are usually the following parts: springs, clutch weights, helix, and the buttons. However, the contents of kits may vary from each one to the next.
Always double-check the description before you make your purchase!
What RPM Should a Snowmobile Clutch Engage?
As a rule of thumb, a snowmobile clutch should engage around 3500-4200 RPM. Unfortunately, there is no fixed number for this since the exact RPM varies from one model to the next. Regarding stock full-size snowmobiles, the engagement is usually around 3800-4000 RPM.
Conclusion
The clutch is a key part of every snowmobile. This unit transfers power from the engine to the jackshaft. Simply put, a snowmobile clutch consists of three main parts: the primary clutch, the secondary clutch, and the belt.
The primary clutch is driven by the engine crankshaft. At a certain RPM (around 3500-4200), the primary clutch starts to rotate the belt which transmits the power to the secondary clutch.
The secondary clutch drives the jackshaft, which transfers the power towards the other parts of the drive train. The primary clutch has some key parts, which are the clutch weights, the helix, and the spring.
When it comes to snowmobile clutch tuning, you can choose among several clutch kits on the market. These contain high-quality aftermarket parts to make your clutch more durable.
References:
https://adventure.howstuffworks.com/outdoor-activities/snow-sports/snowmobile1.htm
https://www.startinglineproducts.com/clutch-kit-polaris.htm
