But it will cost you absolutely nothing extra.
But what about the clutch itself? What does it consist of?
And what’s the difference between a “wet clutch” and a “dry clutch?”
In this blog post, you’ll discover:
- The 4 main components of a motorcycle clutch
- Differences between wet and dry clutches
- How long a motorcycle clutch typically lasts
- What the “friction zone” really is
Prefer to get this information in podcast form? Listen to the 30 Minute Motorcycling Podcast episode about the clutch and clutch friction zone:
Why Do You Need to Disengage the Engine from the Rear Wheel?
If you didn’t have a clutch, the only way to change gears would be to come to a complete stop. This would be fine for first gear, but not so for any higher gears.
Have you ever tried to pull away from a stop in fifth gear?
Clutch Operation – Hydraulics vs. Cable
Hydraulics
And just like hydraulic brakes, the lever for the clutch isn’t as stiff when you squeeze it compared to a cable-operated clutch.
However, it also means that you need to renew and replace the transmission fluid every now and then.
Cable
It’s not hard to see why – compared to hydraulic clutches, cable-operated clutches are much simpler to maintain.
This means they don’t require you to buy any additional fluid for the clutch to work.
However, the clutch cable will wear out eventually, and when it does, you’re in for a clutch cable replacement job.
What Does a Motorcycle Clutch Consist Of?
The clutch hub
It’s these spines that make it possible for the hub and the input shaft to rotate together and for the clutch to move freely back and forth along the shaft.
If the clutch couldn’t move freely along the input shaft, it might not disengage fully.
Do you have a clutch hub for an older bike? Then you should know that it might contain asbestos, which is toxic to inhale.
Clutch plates
Aside from a pressure plate, clutch plates are either friction or steel, which sit between the housing and the clutch hub.
The smaller the clutch, the more plates it will contain.
The two types of plates alternate between one another – i.e., if you’ve got four friction plates, you’ve got four corresponding steel plates as well.
While you’re riding your bike, the two plate types are pressed together by either a set of coil springs or by a large diaphragm spring.
As you pull the clutch lever in (e.g., shift into second gear), the pressure plate separates these two plates – either through a cable or through hydraulics.
While the clutch is disengaged, these friction plates press the clutch hub against the flywheel, which transfers the power from the engine to the transmission.
Diaphragm or coil spring and pressure plate
Diaphragm spring
Coil springs are cheaper to make, although they can cause clutch drag or slipping if the tension is uneven.
Also, the more a coil spring is compressed, the stiffer the clutch lever will be.
Another alternative is the diaphragm spring, which gets its name because it resembles a diaphragm.
Compared with the coil spring, the diaphragm isn’t as stiff when you pull in the clutch (apart from the first few compressions when the diaphragm is brand new).
Clutch housing
Wet vs. dry clutch
Outside of MotoGP, however (and a couple of Moto Guzzi models, most road motorcycles use the wet clutch type.
Why do road motorcycles use wet clutches?
- Increases the clutch lifespan
- Reduces noise
The oil for the clutch also serves as a type of coolant to prevent the clutch from burning out.
If you’d like to know more about the differences between wet and dry clutches, check out this video from the Motorcyclist Magazine YouTube Channel:
How Long Does a Clutch Last?
On the flip side, if you don’t look after your clutch properly, it’s only good for as little as 8000 kilometers (5000 miles).
What is the “Clutch Friction Zone?”
But what is the “friction zone” from a mechanical point of view?
As you begin to release the clutch and connect the engine to the rear wheel, the clutch’s rotation must match the engine’s rotation.
If you roll on the throttle and let go of the clutch too early, the engine will receive an insufficient amount of power and you’ll stall it out.
Anyway, between “fully engaged” and “fully disengaged,” there’s a clutch zone where the rear wheel begins to get power from the engine.
Once you find this zone, you’ll experience that the bike will begin to move forward – albeit slowly.
As you probably already guessed, this is what the “friction zone” is – it’s the point where the engine will begin to transfer power to the rear wheel.
