Motorcycle clutches come in two different styles, wet and dry. If you’ve ever heard a motorcycle at a stoplight clattering and sounding like a tractor, then you’ve probably heard a dry clutch motorcycle. Classic Ducati motorcycles have a unique sound to due their extensive use of dry clutches. In more recent years, Ducati has switched over to wet clutches.
So what does a clutch do? What’s the difference between a wet and dry clutch? Which one is better for your motorcycle?
What does a Clutch do?
The clutch is a device which uses friction to transfer power from the engine to your rear wheel. Engaging the clutch will allow power to be transferred to the tires, but disengaging the clutch disconnects the power transfer. This allows you to stop your motorcycle and still have the engine running. For more specific details on clutch operation and troubleshooting check out our guide here.
Wet clutches are the more popular of the two different types of clutches. The reason they are called “Wet” is because the clutch is immersed in engine oil. The purpose of bathing the clutch plates in the oil is for cooling. Clutches rely on friction which creates lots of heat. The cooling capacity of the engine oil enables the clutch to take abuse of stop and go traffic and whatever other hooligan activities we throw at our bikes.
One key advantage to a wet clutch is that they generally have a wide friction zone. The friction zone is the section of the clutch lever’s travel from the initial engagement of power being sent to the rear wheels to the point where the clutch delivers all of the engine power to the wheel. Throughout this friction zone, the clutch is slipping but still delivering some portion of the engine’s power to the wheel.
This friction zone is key for new riders learning how to ride. A wide friction zone enables easy control of the clutch slippage which in turn helps riders start from a standstill smoothly. If you’ve never ridden a motorcycle, a wet clutch is the easier to learn on than a dry one.
Another key benefit is that they are durable and last a long time. The actual mileage that you get out of your clutch will vary depending on the type of riding you do. City riding takes a toll with start and stops but so can other types of riding like burnouts.
There are downsides to wet clutches too. The first is that the clutch can get your engine oil dirtier faster. The clutch uses friction plates which wear over time. This dust will get into the oil dirtying it. The oil filter should do a good job of keeping your oil clean, but it might require more frequent replacements than if you had a dry clutch.
The other disadvantage is that wet clutches aren’t as efficient as transmitting engine power as a dry clutch. This is because the oil creates resistance to the engine’s rotation reducing the power sent to the rear wheel.
The main reason a motorcycle would use a dry clutch is to increase efficiency of the motor’s power delivery to the rear wheels. Ducati is famous for high performance motorcycles and they have history of using dry clutches for performance reasons. This is also why you will only see dry clutches on motogp race bikes. Every little advantage helps racing.
Dry clutches also have a much narrower and sudden engagement point compared to wet clutches. This could make learning to ride on a dry clutch harder than a wet one.
Today the dry clutch has reduced in popularity because the wet clutch is quieter, easier to ride, and generally more durable. Some owners put on aftermarket clutch with extra cutouts for increased air cooling. While this helps keep the clutch cool, it also increases the noise.
However, if you still want to experience a dry clutch motorcycle, Moto Guzzis, classic BMW flat twin engine powered bikes, and select Ducatis like the Panigale V4R still offer dry clutches.