Key Takeaways

The following are the key takeaways from this article:

  • The flywheel is a metal disc installed along with the crankshaft in the engine.
  • It provides uniform power to the alternator, holds the clutch plate, and turns on the engine.
  • A typical flywheel comprises a housing, springs, planetary wheels, ring gears, bearings, and a support disc.
  • The common problem in a flywheel is wear and failure due to improper maintenance and bad driving habits.
  • The common symptoms of a bad flywheel involve a vibrating clutch pedal, difficulty changing gears, a burning smell, and a chattering noise.
  • The typical cost to replace a flywheel can be between $550-1000, depending on the car model.

Introduction

You might have seen a heavy metal disc in your engine, usually with the crankshaft.

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This heavy metal disc is around an inch thick and weighs around 10-40 pounds depending upon the car model. This is called a flywheel, designed to store the rotational momentum produced by the engine and deliver the power to the vehicle in a smooth form.

Consider rotating a crankshaft with muscle power, where more muscle power is applied at one stage than the other resulting in more power produced by the crankshaft. The same is the case in the engine, where the driver acceleration rate varies with the power produced by the crankshaft (1). So, a flywheel is designed, resulting in a more consistent rotation of the crankshaft. This article will further shed light on the role of the flywheel in the car, its major parts, problems, and symptoms of a bad flywheel.

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Role of Flywheel in the Car

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As discussed above, a flywheel’s first role is to store the rotational momentum and provide smooth power to the car. Another role of the flywheel, in particular the manual transmission cars, is to provide a smooth and flat friction surface to grab the clutch plate.
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Generally, when the driver releases the clutch pedal, the clutch plate comes in contact with the flywheel, which is then grabbed by the smooth flywheel. In automatic transmission cars, the flywheel is sometimes called by different names (1). It can be a flexplate in the automatic transmission vehicle to provide smooth power. That is why the flexplate is thinner and lighter than the flywheel. Flexplate also has small holes in it because it does not function to hold the clutch plate (3).

Similarly, when the driver pushes the start button or turns the key to start the engine. The starter motor pushes a gear mesh with the flywheel allowing the starter motor to start the engine. So, the flywheel is an important vehicle component that provides smooth rotational motion and holds the clutch plate in manual transmission vehicles.

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Important Parts of a Flywheel

Following are some important parts of the flywheel:

Springs

The flywheel comprises two-phase springs bent in parallel. The spring functions to alleviate uncertain frequency ranges.
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The outer arc of the spring is adjusted when the engine is operating and vice versa (3).

Flywheel Housing

The purpose of a flywheel housing is to hold the wheel component inside it. It is solid and made up of heavy-duty metal to prevent the accumulation of dirt, water, etc., in the inner components of the flywheel.
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So, the flywheel components sit inside the housing and work to provide uniform power to the alternator (1).

Planetary Wheel

Planetary wheels comprise small gears fixed on the flywheel bracket. When the bracket operates and rotates, the meshing with the ring gears produces a meshed-up motion with each planetary wheel (1).

The gears revolve and rotate, producing a meshed motion to deliver power to the alternator.
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Ring Gear

The ring gear is fitted to the outer side of the flywheel. Some flywheels are fixed with the help of an interference fit produced by heating the ring gear using the principle of thermal expansion. In other flywheels, the ring gear is meshed up like normal gear.

Bearings

There are two types of bearings inside a flywheel that are radial and axial bearings.

The axial bearings function for weight compensation. The radial bearing functions to alleviate the parasitic radial forces created by the generator/alternator.
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So, both bearings function for the smooth movement of the flywheel and deliver uniform power to the alternator (4).

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Support Disc and Flywheel Sliding Shoe

The support disc is placed inside the flywheel to support the parallel bent springs and their movement (2).

They alleviate sliding and wear/tear during the flywheel movement. The same is the function of a flywheel sliding shoe with a convex radial portion that prevents sliding during the flywheel movement.
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What Causes Flywheel Problems

Although flywheel is made of sturdy metals such as chromium aluminum, bad driving habits and improper maintenance can cause problems.

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The common flywheel problems include wear/tear and failure. As discussed above, the flywheel holds the clutch plate when the pedal is released. So, the major cause of flywheel wear/tear is an improperly aligned clutch plate or a faulty one.

Many drivers do not replace the clutch plate when worn to save costs. However, not doing so causes wear/tear on the flywheel, which will cost double to replace both the clutch plates and the flywheel (2).

Similarly, internal engine component problems, such as crankshaft problems, camshaft problems, etc., cause the engine to start rough. Rough and idle engines can adversely impact the flywheel’s planetary wheel and ring gears (1). Finally, an overheated engine can also cause damage to the flywheel surface. Overheating can result in metal cracking and wrapping, impacting the flywheel surface. Overheating can also happen due to a slipping clutch creating friction impacting the metal surface of the flywheel.

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Symptoms of a Bad Flywheel

The following are some common symptoms of a bad flywheel:

Vibrating Clutch Pedal

As discussed above, the parallel springs alleviate the vibrations produced due to engine movement. In addition, the clutch pedal is usually smooth and can be pressed easily (5).

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When it starts vibrating, it can signal that the springs mounted within the flywheel are either malfunctioning or are mounted incorrectly. So, these springs cease to alleviate the unwanted vibrations.

This can also happen due to a worn disc unable to alleviate the vibrations.

Difficulty in Changing Gears

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In a manual transmission, the drives are supposed to change the gears themselves. However, if the flywheel is worn out, it will result in frequent clutch disengagement.

If you are unaware of manual transmission driving, the driver has to properly press the clutch pedal to engage the clutch while changing the gears. If the driver cannot do so, the gears may not be properly engaged (5). So, a worn-out clutch plate/flywheel will wrap, causing problems in changing the transmission levels.

Burning Metal Smell

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Another common symptom of a bad flywheel is a burning metal smell. As discussed above, the engine and frequent clutch slippage can cause the flywheel metal to melt, resulting in a non-uniform flywheel surface.

The drivers, in this case, will sense a burning smell near the wheels or under the hood. This is a sign that the clutch is frequently slipping. And if the problem still needs to be rectified, the clutch might stop working.

Chattering Noise

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If the driver hears a chattering noise when engaging the clutch, it is a sign that the flywheel is worn out and the clutch is slipping.

This chattering sound can also be due to a distorted clutch disc and an indication that the dowel pins in the flywheel are damaged.

Cost to Resolve Faulty Flywheel Problems

The following table illustrates the cost of resolving the faulty flywheel problems:

Common Flywheel ProblemsCost to Resolve the Flywheel Problems
Worn out Flywheel$550-1000 to replace the flywheel
Worn-out Clutch Plate$500-800 to replace the clutch plates
Bad Flywheel Bearings$50-200 to replace faulty flywheel bearings
Bad Springs$70-130 to replace the bad springs. However, you might have to replace the flywheels if the springs are not available in the market.

Conclusion

A flywheel is an important component in manual transmission cars that provides uniform power to the vehicle. It combines springs, flywheel housing, ring gears, planetary wheels, etc., to provide uniform power and alleviate vibrations due to engine component movement. However, bad driving habits, worn-out clutch plates, and an overheated engine can cause damage to the flywheel impacting its function.

FAQs

If the damage to the flywheel is minor, you can drive with it. But it is advised to change the flywheel as driving for long distances with a damaged flywheel can cause clutch and internal engine component problems. This can eventually result in the car not starting at all.

In automatic transmission cars, a flywheel is replaced with a flexplate. The flexplates are lighter, thicker, and have holes in them. It is because the flex plates do not hold the clutch and only function to deliver smooth engine power.

A faulty clutch will not impact flywheel performance all of a sudden. However, the rapid slippage will result in flywheel overheating. This impacts its surface in the longer run. Similarly, a faulty clutch will also result in improper gear engagement impacting the driving experience.

References