Motorcycles feature multi-plate clutches, meaning that you can find a set of plates inside the clutch assembly. The majority of these clutches are wet clutches that run in an oil bath while a few bikes feature dry clutches. However, the latter is pretty rare. Although motorcycle clutches are actually very simple units (a set of plates in a metal basket) they require continuous attention and maintenance.
If you would like to find out more about motorcycle clutches, this post is for you.
We at PowerSportsGuide have compiled the basics about this mysterious unit under one roof!
Basics of the Motorcycle Clutch
Which Type of Clutch is Used in a Motorcycle?
Modern motorcycles feature a multi-plate clutch, which can transmit a lot of torque to the transmission. What’s more, the lever of a multi-plate clutch can be easily operated by hand. There are two main types of these motorcycle clutches, which are the wet and dry clutch systems.
Besides regular manual motorcycles, more and more “clutchless” semi-automatic and fully-automatic motorcycles are coming on the market.
Why is a Multi-Plate Clutch Used in Motorcycles?
The five main reasons why a multi-plate clutch is used in motorcycles are as follows:
- It features a small and compact design
- It has the capacity to transmit high torque
- It runs more smoothly and quietly
- Easier to operate by hand
- Lightweight
The main reason why motorcycles feature a multi-place clutch is that they are small and compact in size.
Unlike cars, motorcycles offer a very limited space for the engine. Therefore, using single-plate clutch with a large diameter is not possible on motorcycles.
This is where multi-plate motorcycle clutches come into play.
They are much smaller than the single-plate clutches you find in most cars, so they fit perfectly into a motorcycle engine. What’s more, they are much lighter as well, which is also a great point on a bike.
Despite its small dimensions, a motorcycle clutch can deliver a lot of torque as it is spread over several plates. On top of that, a multi-plate motorcycle clutch can be easily operated by hand.
What is the Clutch in a Motorcycle Used For?
Simply put, a motorcycle clutch has one main use: it can fully or partially separate the engine from the transmission. It comes in handy when you are shifting gears or want to start the bike. The clutch is a key part of any bike as it allows the bike to start with a low RPM and ensures smooth shifts.
This is important because unlike electric motorcycles, internal combustion motorcycle engines don’t offer much torque at low speeds.
So, when you want to start a regular motorcycle, an adequate engine speed must be maintained to prevent the engine from stalling.
This is where the clutch comes into play!
Thanks to its design, a motorcycle clutch can “slip” (progressively engage), so you can feed the bike engine power while maintaining the required engine RPM.
Finally, it results in a controlled and smooth start.
Without a clutch, shifting would not only be more difficult but the bike could also stall any time you stop. Therefore, a clutch is a must on any motorcycle!
How Does the Clutch Work on a Motorcycle?
A motorcycle clutch works in a simple way. The clutch assembly is between the engine crankshaft and the transmission and controlled by the clutch lever. The clutch features a set of plates, which are pressed against each other to transmit engine power towards the transmission. Pulling the clutch lever reduces friction between these plates, which also reduces power delivery.
The main parts of a motorcycle clutch are as follows:
- Outer basket
- Inner basket (or inner hub)
- Pressure plate
- Clutch pack: friction plates and metal plates
- Springs/bolts
The outer basket is geared to the crankshaft so it’s spinning all the time when the engine is running.
The other main part of the clutch, the inner basket (known as an inner hub), is attached to the transmission’s input shaft.
These baskets fit into each other while the clutch pack is inserted between them. The clutch pack is a set of metal plates and friction plates stacked in layers, like a layered cake.
The friction plates are attached to the outer basket while the steel plates are attached to the inner basket.
On top of these layers, you can find the pressure plate. As its name suggests, the pressure plate keeps the plates tight.
If you pull the clutch lever, you actually decrease the pressure on the pressure plate and finally the plates. This means that the outer basket can’t transmit force to the inner basket.
If you slip the clutch (compress the lever partially) the plates can transmit some engine power, but not all.
Releasing the clutch lever completely causes the clutch to engage, so the plates start to work together transmitting all the engine power.
Think of the motorcycle clutch as a water tap. When the clutch is engaged it means that the tap is open, so the water (engine power) can flow freely. But disengaging the clutch (pulling the lever) is like closing the tap. The water flow stops, as does engine power. When the tap is partially open it causes the water to just trinkle, which corresponds to the sliding of the clutch.
Here’s a great video on how a motorcycle clutch works:
What is the Difference Between a Dry and Wet Clutch?
The main difference between dry and wet clutches is that the latter runs in an oil bath. In contrast, dry clutches, as their name implies, run completely dry without any lubrication. Consequently, a wet clutch is always hidden in an enclosed housing.
Which is Better a Wet or Dry Clutch?
Many motorcycle riders claim that wet clutches are far better than dry clutches, and with good reason. Wet clutches last longer, require less maintenance, and are less noisy than dry clutches. Since they run in an oil bath, wet clutches are less prone to overheating. What’s more, they are also easy to use thanks to their wide friction zone. That’s why nearly all modern motorcycles feature a wet clutch!
Are you wondering what the advantage is of having a dry motorcycle clutch? In short, not much.
The main idea behind dry clutches is that it’s much easier and faster to fix or replace. That’s why these clutches were initially developed for racing purposes and commonly used on GP bikes.
But over years this technology moved from racetracks to the streets, so today you can also find dry clutches in a couple of production motorcycles.
Despite their disadvantages, some riders love dry clutches as they offer a unique experience.
Since a dry clutch doesn’t need to be sealed it is usually visible on some bikes. This gives the bike a cool and unique appearance.
But beyond design issues, a dry motorcycle clutch is much easier to work on, and doesn’t contaminate the engine oil either.
What is a Motorcycle Auto Clutch?
A motorcycle auto clutch is a special aftermarket clutch assembly. In a nutshell, an auto clutch is designed to automatically handle the clutch based on the engine’s RPM. If a bike features an auto clutch, it can be started or stopped without depressing the clutch lever.
So finally an auto clutch on a motorcycle works like a semi-automatic transmission, but just in first gear! It’s really convenient especially in city traffic.
On the other hand, to shift into higher gears you still have to use the shift lever and the clutch just like on any other regular bike.
The most well-known motorcycle auto clutch manufacturers are Rekluse, Hinson, Revloc, and EFM Auto Clutch.
Where is the Clutch Lever on a Motorcycle?
The clutch lever is placed on the left side of the handlebar on each motorcycle. To disengage the clutch, you have to fully squeeze this lever against the handlebar with your left-hand fingers. Releasing the lever causes the clutch to reengage.
(Next to your right hand you can find a similar lever, which is the front brake lever.)
On many bikes, the clutch can be controlled mechanically, meaning that the clutch assembly and the clutch lever are connected with a cable. Other bikes feature a hydraulic clutch, in which the clutch is operated by fluid pressure.
It seems on the newest bikes hydraulic motorcycle clutches are becoming more and more prevalent.
How do You Use the Clutch on a Motorcycle?
To properly use the clutch of a motorcycle, you always have to close the throttle first. Then, fully squeeze the clutch lever with your left hand against the handlebar. Always use all four fingers for safety reasons! After shifting gears, you must always carefully release the clutch.
Depressing the clutch lever causes the clutch to disengage, meaning that the engine can’t transmit power towards the transmission.
When you shift a bike into first gear and start to release the clutch lever, at a certain point the bike begins to move. This point is when the friction zone starts, which is known as the “engagement point.”
(If you want to learn more about gear shifting on a motorcycle, don’t miss our step-by-step guide, or just check out this tutorial video:)
What is the Friction Zone on a Motorcycle?
The friction zone on a motorcycle refers to a specific section of the clutch lever movements. It starts at the engagement point (when the clutch starts to transmit power) and ends when the clutch is fully engaged (all power is delivered).
When your bike is in gear and you’re slowly releasing the clutch lever, at the engagement point the clutch start transmitting engine power to the transmission.
This point is easily recognizable, as in this moment the bike starts to move. This is when the friction zone starts.
Releasing the clutch lever allows it to deliver more and more power, and finally all the engine power reaches the rear wheel.
This is when your bike’s friction zone ends.
When Should You Use a Motorcycle Clutch?
As a rule of thumb, you should use the clutch on your motorcycle in four instances:
- When you start the bike
- When you stop the bike and want to let the engine run
- Every time you shift gears
- If you want to maneuver the bike very slowly (“riding the clutch”)
As a rule of thumb, you should use the clutch on your motorcycle when you shift gears.
Clutchless shifting is not recommended because it can damage the transmission or the clutch.
Do You Hold the Clutch in When Starting a Motorcycle?
On some motorcycles, you have to hold the clutch when starting the engine, while on others this is not the case. Finally, it always depends on the make and model. Most modern motorcycles feature a sensor to check if the transmission is in neutral. If not, you can’t fire up the engine. But besides this safety feature, more and more bikes require you to pull the clutch as well to start the engine, even if it’s in neutral.
Many riders find this feature annoying, as on these bikes they need to use both hands to fire up the engine. This could be a hassle when gearing up!
Finally, don’t forget that many bikes can’t be started as long as their kickstands are down.
Do You Pull the Clutch When Braking on a Motorcycle?
As a rule of thumb, you have to pull the clutch when braking on a motorcycle just before it completely stops. But when you slowdown from higher speeds, it’s not recommended to hold the clutch. Instead, shift through the gears one by one and let the bike slowdown in each gear. This trick is known as an “engine brake.”
This is important because holding the clutch when riding leaves the rear wheel without any power. this can end in risky situations as you never know when you will need to speed up again.
Best practice is to shift into the lower gear, wait until your bike slows down in this gear, then shift down again.
Repeat the process until you reach first gear, and make sure to always stop the bike in first gear. (Never shift from second gear into neutral!)
Before your bike completely stops you need to pull the clutch to prevent the engine from stalling.
Is it Bad to Hold the Clutch on a Motorcycle?
Is it bad to hold the clutch on a motorcycle? This is a typical question of many beginners and the answer is that it depends. The general rule is that holding the clutch for a long time is always bad as it can lead to various types of clutch damage. But for a short period you can hold the clutch without any issues. For instance, holding the clutch at a stoplight is a common practice that many riders do.
But if you have to wait at a railroad crossing or you’re stuck in traffic it’s highly recommended that you shift into neutral and not keep the clutch lever depressed.
Holding the clutch too long can be harmful in many ways as it holds the clutch assembly and the clutch cable under tension. Finally, this may end in a stretched/broken clutch cable or some other type of damage.
On top of that, it’s hard on your left wrist too!
Is Riding the Clutch Bad for a Motorcycle?
Riding the clutch on a motorcycle means keeping the clutch lever at the engagement point when riding. This helps you control the speed of the bike by using the throttle and the clutch. In most cases, riding the clutch is done in first gear.
As a rule of thumb, riding the clutch is bad for any motorcycle if you do it at a high RPM. However, in situations when you need to move the bike at very low speeds, riding the clutch is considered normal use and won’t cause any damage.
For instance, you can use this practice if you have to maneuver your bike in a parking lot.
Just make sure to apply a little throttle while riding the clutch and keep your speed low.
Related Questions
Are All Motorcycle Clutches the Same?
Although most bikes feature a multi-plate wet clutch, this doesn’t mean that all motorcycle clutches are the same. Some manufacturers use dry clutches like Ducati, BMW, or Moto Guzzi. What’s more, the latter uses a single-plate motorcycle clutch! Thanks to Moto Guzzi’s longitudinal V-twin engine design, their engines can accommodate this large-diameter, “car-like” clutch.
Why Don’t Cars Use Wet Clutches?
Cars don’t use wet clutches as they have plenty of space to accommodate a larger diameter single-plate dry clutch. Besides, in a car the clutch is operated by foot so the higher spring tension is not an issue. However, it’s good to know that dual-clutch cars as well as certain racing cars also use multi-plate wet clutches.
Do All Motorcycles Have a Wet Clutch?
No, contrary to popular belief not all motorcycles feature a wet clutch! Although dry motorcycle clutches were developed for racing purposes, you can see this technology on a few street bikes as well. But to the greatest regret of many fans, dry-clutch motorcycles are slowly disappearing.
What is a Slipper Clutch on a Motorcycle?
The slipper clutch on motorcycles refers to a special clutch design originally developed for racing motorcycles. Today you can find this type of clutch on many production motorcycles as well. The main advantage of a slipper clutch is that it can reduce the negative effects of engine braking. This means that the slipper clutch helps riders keep the line even during hard engine braking. Besides, it can also prevent the engine from over-revving.
How does a slipper clutch work? When the bike is decelerating and the rear wheel starts to drive the engine, the pressure plate can move slightly away from the plates. This reduces the pressure on the plates and allows the clutch to slip.
Finally, the slipper clutch does the same job when you pull the clutch lever a little bit. But for your convenience, this special clutch handles it automatically for you.
This results in lower engine RPMs and fewer engine brakes during deceleration. On top of that, the rear wheel is less likely to lock in case of aggressive engine braking.
Which Motorcycles Have Dry Clutches?
The most well-known dry clutch motorcycles are arguably the Italian Ducatis, but you can also find a dry clutch in Moto Guzzi, and BMW motorcycles. Besides, a dry clutch is commonly used on MotoGP bikes as well.
Does Ducati Still Use a Dry Clutch?
Yes, Ducati still uses dry clutches, but not on all of their models. In the past, dry clutches were much more prevalent on Ducatis, but today more and more models come with a wet clutch.
Why Does Ducati Use a Dry Clutch?
Ducati probably uses a dry clutch because of marketing considerations. This Italian manufacturer is well-known for its custom technical solutions like oil cooling or special L-twin (angled V-twin) engine layouts.
Does Harley-Davidsons Have a Wet Clutch?
Although vintage Harleys featured a dry clutch, it’s safe to say that all new Harley-Davidsons come with a wet clutch. The last dry-clutch Harley was manufactured in 1984.
What is Feathering the Clutch on a Motorcycle?
Feathering the clutch is a riding technique that is also known as “riding the clutch.” Feathering the clutch means keeping the clutch at the engagement point. This means you can control the speed with the throttle and the clutch lever together. This trick is often used to maneuver the bike slowly but feathering the clutch at high speeds is definitely not recommended.
Can You Burn Out a Motorcycle Clutch?
Yes, unfortunately you can burn out a clutch on a motorcycle. Poor riding techniques and doing stunts can easily burn out motorcycle clutches in a short period of time. If you want to avoid burning your clutch out, always use the clutch reasonably. This means never letting it slip too long and never feathering it at higher RPMs.
Can You Burn Out a Wet Clutch?
Although they are more durable than dry clutches, wet clutches can easily be burned out as well.
Which is Better a Hydraulic or Cable Clutch?
Motorcycle clutches can be controlled with a cable as well as hydraulic levers.
Many riders say that cable motorcycle clutches are better as they are less expensive and much easier to work on. On the other hand, they require much more maintenance, which typically means lubricating the cable and adjusting its tension. This is why many other riders prefer hydraulic clutches. These systems require much less attention as long as they don’t leak. But unfortunately hydraulic motorcycle clutches are much more expensive and harder to repair.
There are pros and cons on each side, so the final decision often boils down to personal preferences.
Conclusion
The clutch is a key part of every motorcycle engine. It helps you shift the bike safely to cut engine power from the rear wheel whenever you want. What’s more, the clutch also contributes to smooth starts.
The clutch assembly is geared to the engine crankshaft and connected to the transmission, so these parts are typically built into one unit.
The clutch is controlled by the clutch lever, which you can find on the left side of the handlebar.
The clutch is engaged if this lever is released, so the clutch can transfer engine power towards the transmission.
Depressing the clutch lever causes the clutch to disengage. In this state, the clutch separates the engine from the transmission. Therefore, the motorcycle can’t move even if it has shifted into gear.
There are a set of plates inserted inside the clutch assembly. When the clutch is engaged, these plates are pressed against each other to transmit the power.
When you disengage the clutch you actually relieve the pressure on these disks, so they can’t transmit power.
This is our short motorcycle clutch review. We hope you find it useful!
References
https://bikeadvice.in/ducati-dry-clutch/
https://www.cycleworld.com/how-does-motorcycle-clutch-work/
https://www.motorcyclecruiser.com/transmitting-power-your-clutch-system/
https://www.bestbeginnermotorcycles.com/how-to-operate-a-motorcycle-clutch-brakes/
https://travelzone.bestwestern.com/how_your_motorcycles_clutch_wo/
https://www.motorcyclistonline.com/cable-vs-hydraulic-clutch-whats-difference/
