What is a Slipper Clutch in Bike and What are Its Parts?

India has one of the largest two-wheelers markets. Hence, technological advancements and conveniences have always come in rapidly, and a slipper clutch is one of the basic features available now in most bike models. 

Let’s find out more about this device, how it works, its pros, cons and more in detail.

A motorcycle slipper clutch, also known as back-torque limiter or assist slipper clutch, is available in most high-performance bikes. This device aids in flawless downshifting into corners by gradually disengaging the clutch basket from the clutch centre as per the amount of back torque. 

This feature is similar to a manual clutch in a bike but helps reduce wheel hop effect when downshifting at corners and aims to prevent damage in transmission by creating controlled slippage of clutch plates against each other.

The device is placed between the transmission and the power mill. 

Usually, the clutch assembly and the crankshaft turn in higher speed during engine braking when compared to the rear wheel. In manual clutch, this speed difference creates skids and loss of traction as the rear wheel slows down. 

However, a slipper clutch works differently. The pressure on the clutch plate decreases as the rear wheel slows down. This mechanism allows clutch plates to slip. 

This controlled slippage tuned down the torque transmitted to the rear wheel, preventing it from locking up.  

A slipper clutch consists of multiple components such as springs, pressure plates, clutch hubs, and plates. 

1. Clutch Hub: It is attached to the crankshaft and moves it. 
2. Pressure Plate: It is attached to the clutch cable. It aids in engaging the clutch by getting pulled towards the hub. 
3. Clutch Plates: They are placed between the pressure plate and the hub. It transmits power from the engine to the rear wheel. 
4. Springs: They hold the plate in place and apply enough pressure for the clutch to engage.

Slipper clutches are preferred over manual clutches, mostly in high-performance or superbikes. Here are the reasons why: 

1. Smooth Rides: Slipper clutches disengage and engage the gears properly and smoothly. This results in less bumpy gear shifts and smooth rides. 
2. Swifter Lap Times: While racing, slipper clutches aid the riders to achieve faster lap times. It allows a rider to brake later and carry higher speed through corners. 
3. Enhanced Grip: The slipper clutch prevents locking up of the rear wheel. This lets a rider maintain control during quick downshifts. 
4. Less Wear & Tear: Controlled slippage of clutch plates reduces pressure on the gearbox. This results in reduced wear and tear on the bike and other components.

There are primarily three types of slipper clutches. Here are the details of them below:

1. Electromagnetic Slipper Clutch

This is the most advanced and complex type of slipper clutch. As a result, it is also more expensive. It uses an electromagnetic coil to adjust the pressure on the clutch plates. 

Once the coils are energised, it creates a magnetic field. The field attracts the clutch plates by reducing their pressure and allowing them to slip smoothly. 

2. Hydraulic Slipper Clutch

Hydraulic slipper clutches employ a hydraulic piston to adjust the pressure on the clutch plates. When the engine braking torque is high, this piston moves forward. This process reduces pressure on clutch plates and allows them to slip against each other smoothly. 

This mechanism is more complex compared to a mechanical slipper clutch but requires less maintenance and is more consistent.

3. Mechanical Slipper Clutch

Mechanical slipper clutch employs a combination of balls and ramp to achieve slip. The balls get pushed up the ramps once the engine braking torque is high. This forces the clutch plates to slip against each other. 

This type of slipper clutch is less complex and reliable. However, it requires regular maintenance for proper functioning, with balls and ramps cleaned and lubricated. 

There are multiple advantages of slipper clutches. They are as given below: 

1. Slipper clutches help in reducing rider fatigue and enhance the riding experience. These clutches smoothly engage and disengage gears. This results in less jerky rides and smoother riding experiences. 
2. The slipper clutch gives riders better control over their bikes, especially during rapid downshifts. It prevents locking up or skidding of the rear wheel, and reduces the chances of your bike losing control.
3. Slipper clutches reduce the pressure on the transmission system and other associated components, lessening the wear and tear of the bike. This, in turn, lowers maintenance costs and enhances the bike's longevity. 
4. While racing, riders can achieve faster lap times with a slipper clutch, allowing them to brake later and go on at higher speed through the corners. This feature can offer racers a competitive advantage on the track.

Along with the advantages of slipper clutches, you should also know their disadvantages for an informed decision. These are: 

1. Slipper clutches have a more complex mechanism and consist of more parts when compared to manual clutches. This is why they are costly to manufacture and purchase. Hence, if you are going to buy a bike with a slipper clutch, it might cost you extra. 
2. Slipper clutches lowers engine braking during rapid downshifts. This can hamper the sense of control an experienced biker enjoys over their bikes. This is also why some bikers prefer bikes with manual clutches over slipper clutches. 
3. Additional weight and complexity of the slipper clutch can increase the bike's weight, hampering the overall performance and handling of the vehicle. 
4. Slipper clutches need periodic maintenance, such as cleaning, lubrication and inspection, to ensure proper functioning and longevity. 

Proper installation of slipper clutches requires a little bit of mechanical knowledge and experience. However, it is a pretty straightforward process. The process is as follows: 

• Disassemble the clutch assembly.

• Install the slipper clutch. 

• Reassemble the disassembled parts. 

Besides, following the manufacturer's instructions and using the necessary tools and lubricants are essential during the process. 

Maintenance of a slipper clutch is paramount to ensure its longevity and optimal performance. Maintenance includes periodic cleaning, lubrication, and inspection of the clutch assembly. 

If there is any sign of damage, you should contact a technician at the earliest and replace them if necessary. 

Here is a list of the top bikes in India with slipper clutch: 

• Bajaj Dominar 400

• TVS Apache RTR 200 4V Race Edition 2.0

• TVS Apache RR 310

• Yamaha R15 V3.0

• KTM RC 390

• KTM Duke 250

• KTM Duke 390

• KTM 390 Adventure

A slipper clutch is mostly available in larger-displacement wheels. However, a few smaller displacement models include this feature. You should not rely on this feature for overriding downshifting. It can only help correct rider input but is not a safety feature.