What is a Dual Mass Flywheel and What Does it Do?

Think of a flywheel in a car like a big spinning disc. When your car’s engine runs, it doesn’t give out power smoothly all the time. Sometimes it gives more power, and sometimes less. The flywheel helps by acting like a storage for spinning energy. When there’s extra power, it spins faster and stores that energy. Then, when the engine isn’t giving enough power, it uses the stored energy to keep things running smoothly. This way, the flywheel helps make the car’s power feel steady and smooth, whether you’re speeding up or slowing down.

In its most basic form, a flywheel is a mechanical device specifically designed to efficiently store rotational energy. Flywheels play a pivotal role in smoothing out the engine’s power pulses, providing a smoother ride and helping with gear shifts.

What is a Dual Mass Flywheel?

The dual mass flywheel (DMF) takes the concept of a traditional flywheel further by incorporating two primary components: the primary flywheel attached to the engine and the secondary flywheel connected to the transmission. These two are separated by a set of springs that act as “cushions” and dampers that absorb and mitigate the vibrations and torque fluctuations from the engine before they reach the transmission. This design significantly reduces noise, vibration, and harshness (NVH) levels, making for a smoother and quieter driving experience, particularly in vehicles with manual transmissions. This way, by the time the power goes from the engine to the part of the car that helps change the gears (the transmission), it’s nice and smooth, without any of the roughness or jerks it started with.

How Does a Dual Mass Flywheel Work?

The DMF operates on the principle of vibration absorption and torque smoothing.

A dual mass flywheel works like a smart buffer between your car’s engine and its gearbox.

The components: The dual mass flywheel consists of two primary sections, known as masses. The first is directly connected to the engine, capturing its output, while the second is linked to the transmission, which ultimately drives the wheels.

What does it do? The key to the dual mass flywheel’s effectiveness lies in its ability to absorb and dampen the vibrations and erratic power surges from the engine. This is achieved through a sophisticated system of springs and dampers located between the two masses. These components work together to cushion and neutralise the irregular forces and vibrations before they can be transmitted from the engine to the transmission.

What does this mean for the driver: By smoothing out these fluctuations, the dual mass flywheel ensures that the power delivered to the transmission is steady which leads to smoother acceleration, improved gear shifts, and a reduction in noise and vibration. The overall driving experience is significantly enhanced, making for a more comfortable and controlled ride.

How Do I Know if My Flywheel is Going Bad?

Here are several symptoms that might indicate a failing DMF:

Unusual vibrations or rattling noises, especially during idle or acceleration.

One of the first signs of a failing dual mass flywheel is an increase in vibrations and noise, especially when the engine is idling or during acceleration. Since the flywheel’s primary role is to dampen engine vibrations, its failure means these vibrations are no longer effectively absorbed, resulting in a rougher ride.

Difficulty in engaging gears, or a noticeable increase in clutch pedal vibration.

The smooth transition between gears can be compromised. Drivers might find it harder to engage or shift gears, which can be particularly noticeable in manual transmission vehicles. This happens because the synchronisation between the engine and the transmission is disrupted.

A ‘spongy’ feeling clutch pedal or a noticeable change in the pedal’s engagement point.

The dual mass flywheel works closely with the clutch system. When it fails, it can cause the clutch to perform poorly, leading to slippage or difficulty in engaging the clutch.

In severe cases, especially if the flywheel’s damage is significant, it can lead to engine stalling. If you encounter any of these symptoms, it’s advisable to have your vehicle inspected by a professional to determine the root cause.

How Long Will a Noisy Dual Mass Flywheel Last?

The lifespan of a DMF can vary widely based on driving habits, vehicle type, and maintenance routines. Generally speaking, once a dual mass flywheel starts making noise, it’s an indication that the internal components are wearing out or have already suffered damage.

If you continue to drive without addressing the issue, you might get a few thousand miles out of it, but this is highly variable. In some cases, the flywheel might fail suddenly, leading to immediate and potentially more costly issues. Early intervention can prevent further damage to the transmission and other drivetrain components, saving you from more extensive repairs down the line. We recommend you get it checked by a professional as soon as possible!

What Happens When a Dual Mass Flywheel Fails?

Failure of a DMF can lead to a host of issues, affecting not just the driving experience but also potentially causing damage to the transmission system. Common consequences include increased vibration and noise, difficulty in changing gears, and in severe cases, complete loss of power transmission between the engine and the wheels. It’s a situation that requires immediate attention to prevent further damage and ensure safe driving conditions.

How Much Does it Cost to Replace a Dual Mass Flywheel?

Replacing a clutch and flywheel in the UK can be a costly affair, mainly due to the complexity of the work and the parts involved. On average, the cost to replace a clutch and flywheel can range from £500 to over £1,000, depending on the vehicle make, model, and the labour rates of the garage. You can get a fair price based on the make and model of the vehicle and postcode on ClickMechanic.

Marketing at ClickMechanic

Louanne is a marketing and communications professional in the automotive tech industry currently at ClickMechanic, boasting over 5 years of experience.

Louanne’s work at ClickMechanic might revolve around branding and customer engagement, but her passions extend far beyond the marketing sphere. A true foodie at heart, she loves exploring diverse cuisines and talking about her culinary adventures across the world. Her writing prowess shines through in her car-related blog content, where she offers invaluable driving tips and practical car repair advice.

In her Suzuki Jimny 4-wheel drive, Louanne combines her sense of adventure with her automotive know-how, transforming every drive into a lesson and a pleasure.