Your truck, SUV, or that performance car’s torque and power are determined by the powertrain it has. The powertrain consists of the engine and drivetrain.
And the drivetrain consists of front and rear differentials, axles, transfer case, driveshaft, wheels, and transmission. These components are responsible for providing the torque and power your performance car, SUV, or truck needs to move forward and backward.
One of the essential components of the powertrain we fail to mention above is the flywheel. If it fails, it will cause several adverse effects on other powertrain components.
Now, you may be wondering what does a flywheel do, and what the heck is it. This article will unveil three functions of a flywheel and bad flywheel symptoms.
What is Flywheel?
A flywheel is a mechanical device that uses the conservation of angular momentum to store rotational energy; a form of kinetic energy that is proportional to the product of its moment of inertia and the square of its rotational speed.
A flywheel is a heavy wheel attached to a rotating shaft to smooth the transfer of power from an engine to a machine.
In automobile engines, the flywheel serves to smooth out the pulses of energy provided by combustion in the cylinders and provide energy for the compression stroke of the pistons.
The inertia of the flywheel opposes and moderates engine speed fluctuations and stores the excess energy for intermittent use.
In order to effectively counteract speed fluctuations, a flywheel is given a high rotational inertia; i.e., most of its weight is far from the axis.
A wheel with a heavy rim connected to the central hub by spokes or a web has high rotational inertia. Many flywheels used on reciprocating engines to smooth the power flow are made this way.
However, the energy stored in a flywheel depends on both weight distribution and speed; if the speed is doubled, the kinetic energy is quadrupled. A rim-type flywheel will burst at a much lower RPM than a disc wheel of the same weight and diameter.
For minimal weight and high energy storage capacity, a flywheel can be fabricated from high-strength steel and designed as a conical disc, thick in the center and thin around the rim.
In automobile engines, the flywheel serves to smooth out the pulses of energy provided by combustion in the cylinders and provide energy for the compression stroke of the pistons.
The larger the rotational inertia of the flywheel, the smaller the changes in speed resulting from the intermittent power supply and demand.
How does Flywheel Works?
To understand the working we must first understand the working principle of the flywheel first.
The basic working principle of a flywheel is that it absorbs rotational energy during the power stroke and delivers that energy during other strokes ( suction, compression, and exhaust).
The energy equation depends on the angular velocity and moment of inertia of the flywheel.
Thus, it is obvious that the energy stored in a flywheel will increase with the increase in weight, size, and angular velocity.
Working method:
- The electric motor gives power to the flywheel at the very initial stage.
- This movement causes the piston to move and burn fuel inside the combustion chamber.
- Once the power stroke is activated the flywheel draws power from the power stroke and uses it for the other three strokes.
- In this way, It helps in stabilizing the rotational movement of the transmission system.
Parts of Flywheel
Following are the parts of a flywheel:
#1. Flywheel Housing.
The flywheel housing is solid and sits outside of the flywheel. The flywheel is the part of the engine that rotates and delivers power to the alternator.
#2. Springs.
The flywheel is consists of two-phase bent springs in parallel. The outer arc is adjusted to raise the spring when the engine is operating. The soft outer arc spring only serves to improve the uncertain resonance frequency range.
#3. Planetary Wheel.
A planetary wheel consists of many planetary gears fixed on a flywheel bracket. When the flywheel bracket is operated by a screw and rotates, the meshing with the outer ring gear produces a compound motion composed of each planetary gear revolution and rotation.
#4. Axial and Radial Sliding Bearing.
While the axially acting bearing serves only for weight compensation, the imbalance or parasitic radial forces initiated by the motor or generator unit must be compensated by
radial Bearings.
#5. Ring Gear.
A ring gear is fitted to the outer diameter of the flywheel. It is usually fixed to the flywheel with the help of an interference fit, which is produced by heating the ring gear. So, the thermal expansion enables it to be placed around the flywheel.
#6. Support Disc.
As the name suggests, the support disc is attached inside the flywheel to support the two-phase bent springs and other components of the flywheel.
#7. Flywheel Sliding Shoe.
Sliding shoes preferably have a convex radial outer portion bearing on the inner wall of the flywheel. In this area, they are preferably manufactured to promote slip and suffer minimal wear and tear.
#8. Flywheel Cover.
The flywheel cover is commonly made of chrome. This chrome-plated flywheel cover will prevent dust from getting into the internal functions of the flywheel, due to which it is running poorly.
Where is the Flywheel Located?
How well your vehicle drives, how much power it has, and how much torque it can generate are all determined by its powertrain. The engine and the drivetrain together make up the powertrain.
The drivetrain includes the transmission, axles, transfer case, driveshaft, wheels, and differentials (both front and back). These parts generate the torque and horsepower required to propel your car.
The flywheel is one of the essential parts of the powertrain. The failure of the flywheel can have far-reaching consequences on the rest of the powertrain.
Functions of Flywheel
Almost all types of automobiles have flywheels because they serve various purposes. Below are the functions of the flywheel in an automobile engine:
#1. Engine Balancing.
Because the pistons are offset from the center of the crankshaft, vibrations and wobbles occur. This is also because each piston fires at a different angle.
The function of a flywheel in this situation is to suppress the side-to-side motion. This is achieved because of the heavy weight of the flywheel.
#2. Engine Start.
The flywheel plays another role while starting the engine. The gear teeth on the flywheel are attached to a starter motor. This starter motor is controlled with the car key, so when the car is started, the starter motor turns the flywheel.
Immediately, the engine spins, and the combustion effect continues to turn it. The starter motor’s Bendix gear retracts, allowing the flywheel to spin freely.
#3. Drivetrain Stress Reduction.
By stabilizing the engine’s movement, a flywheel can perform this additional function. It also smooths out the engine’s speed and reduces wear and tear on the drivetrain components.
The flywheel also limits the wear between the transmission shaft and the driveshaft. These two are attached with a universal joint.
#4. Engine Speed-Soothing.
The crankshaft generates power by converting the jerky piston movement into rotary motion. the rotational speed of the crankshaft is constant, and the engine runs smoothly.
This is because the mass of the flywheel applies inertia, which keeps the engine crankshaft spinning between each piston firing.
#5. Weight Manipulation.
The weight of a flywheel determines the performance of an engine. We design the weight based on the vehicle’s performance. Heavier flywheels allow the engine to work under loads, which may cause the engine to bog down.
Large trucks or trailers work well with heavier flywheels, while sports cars and some commercial vehicles work well with lighter flywheels.
Materials used for making Flywheel
The materials used for making a flywheel are:
- Cast Iron
- Steel and
- GFRP
Let’s understand one by one in detail,
Cast iron
Traditional flywheels are made of cast irons. The major advantage of cast iron is that it is cheap. There is minimum or no need for machining as it can directly be used after casting operation.
They also act as great dampers and absorb vibrations. They also have few disadvantages such as, they have sudden failure and they also offer poor tensile strength.
Steel
Nowadays flywheels are made of high-strength steel as they offer better tensile strength and are corrosion resistant.
They are also very durable and do not undergo failure very easily. Steels are considered to be a better option when compared to cast iron.
GFRP
GFRP stands for graphite fiber-reinforced polymer. This is considered to be the best choice for making flywheels for modern-day cars and automobiles.
They offer a great density and tensile strength and are perfect for making flywheels.
Types of Flywheel
Following are the types of flywheel used in vehicle:
- Solid disc flywheel
- Rimmed flywheel
- High-velocity flywheel
- Low-velocity flywheel
#1. Solid Disc Flywheel.
The Solid disc flywheel is a type of flywheel. It is used in a single flywheel thresher is made of cast iron. The solid disc flywheel is equipped with a flywheel hub and disc.
In the design calculation of a solid disk flywheel, various parameters are used as inputs. This includes the dimensions of the solid disk flywheel. Also, resulting functional values are calculated.
#2. Rimmed Flywheel.
The rim-type flywheel will explode at a much lower rotary speed than a solid disc-type wheel of equal weight and diameter.
For minimal weight and high energy-storage capacity, a flywheel can be formed of high-strength steel and produced as a tapered disk, which is thick in the center.
#3. High Velocity Flywheel.
In these types of the flywheel, the high-velocity flywheel has a velocity between 30000 rpm to 80000 rpm. That can also be adjusted up to 100,000 rpm.
They have magnetic levitation bearings and require little maintenance. These are light in weight when compared to a low-velocity flywheel according to size/capacity. They are more expensive than a low-velocity flywheel.
#4. Low Velocity Flywheel.
In these types of the flywheel, the low-velocity flywheel has a velocity of 10000 rpm. They are heavier and bulky than the high-velocity flywheels.
They require time to time maintenance and do not use magnetic levitation bearings. Their installation requires special concrete construction to carry its weight. They are more affordable than high-velocity flywheels.
Symptoms of a Bad Flywheel
The symptoms of a malfunctioning flywheel include slipping gears, difficulty in changing gears, a burning smell, a vibrating clutch pedal, clutch drag, and difficulty starting the gear.
#1. Slipping gears.
There are a number of potential causes of gear slippage, but one of the most common is a faulty flywheel. When the flywheel is malfunctioning, it is unable to produce the required torque to prevent the gears from slipping.
Wear and tear, damage, or even a flaw in the flywheel itself are some of the potential causes of this.
#2. Difficulty changing gears.
Gear-shifting issues may be caused by a damaged flywheel. The gears may shift irregularly if the flywheel isn’t functioning correctly. There are a number of possible causes for why shifting gears could be challenging with a damaged flywheel.
One explanation is that the flywheel does not exert enough force on the gears, which makes it difficult for them to mesh.
#3. Burning smell.
An indication that your clutch isn’t operating properly or isn’t being used appropriately is a burning smell coming from underneath your car.
It results from clutch plate wear and tear, which may be brought on by a deformed flywheel that generates excessive heat and friction. If you don’t swap out your flywheel, the clutch will probably stop functioning.
#4. Vibrating clutch pedal.
There can be an issue with the flywheel if your clutch pedal is vibrating. There are a number of plausible explanations for why a faulty flywheel generates a vibrating clutch pedal.
One possibility is that the engine vibrations brought on by the bent flywheel are causing the clutch pedal to vibrate.
#5. Clutch drag.
The clutch may drag if there is too much inertia in the flywheel. The flywheel tries to continue spinning at its pre-acceleration speed as the engine and vehicle accelerate. The entire system will drag if the clutch tries to seize the flywheel too rapidly and it resists.
#6. Difficulty in starting a car.
Because it might stop the engine from turning over, a damaged flywheel can contribute to starting issues. This frequently results from a seized flywheel, which won’t turn even when the engine is started. The starting motor may experience issues as well.
#7. Engine stalls.
A rotating part of the engine called the flywheel stores energy and aids in a smooth start-up. The engine may stall and idle unevenly as a result of a damaged flywheel. This is due to the faulty flywheel’s inability to retain sufficient energy or to enable a smooth startup.
What Causes Flywheel Damage?
Understanding what causes a flywheel to break is key to preventing early failure. Here are the main culprits behind flywheel damage in both manual and automatic vehicles:
Common Causes:
- Improper Maintenance: Faulty clutch installation or a malfunctioning starter motor can lead to misalignment and flywheel issues.
- Clutch Problems: A slipping or worn clutch transfers excess heat to the flywheel, which may lead to cracked flywheel symptoms.
- Rough Driving Habits: Aggressive shifting, riding the clutch, or driving in the wrong gear can cause flywheel wear symptoms over time.
- Excessive Heat: Often the result of a slipping clutch, it causes warping or even cracks—common damaged flywheel symptoms.
If you’re driving an automatic transmission, note that what causes flywheel damage in automatic cars can include torque converter misalignment and starter gear engagement issues.
Design Considerations When Customizing Car Flywheels
When manufacturing car flywheels, there are factors that you need to consider, particularly for custom ones. They are critical for obtaining a delicate balance of performance, reliability, and durability.
Material Selection
Generally, car parts manufacturers use high-strength and durable materials to withstand the vibrations and tensions this mechanical device experiences while the engine runs.
However, enhanced responsiveness and driving at higher speeds are prioritized for high-performance and racing vehicles. Therefore, such vehicles may utilize lightweight but strong and robust materials.
Precision And Accuracy
In custom flywheel designs, high precision and accuracy are essential. Therefore, machinists must use manufacturing methods that guarantee these parts’ dimensional accuracy.
Consequently, the go-to manufacturing process for such customization is CNC machining, which includes a combo of turning, drilling, and milling operations.
These processes ensure the meticulous crafting of these parts, high standards, and the overall efficiency and reliability of the fabricated flywheels.
However, when dealing with bulk-volume production, you may need to consider other methods, such as die casting and stamping. These processes are beneficial, creating high-precision parts, and are cost-effective for large-volume manufacturing.
Surface Treatment Options
Besides selecting the right manufacturing processes and ensuring the precision of these parts, you may also need to employ quality surface treatment options when customizing flywheels.
These post-processing options include coatings or suitable heat treatments. They prove effective for reinforcing the flywheels and reinforcing them to thrive in harsh environments that flywheels may be exposed to.
Clutch Compatibility
Ensure that whatever flywheel you select to manufacture for your vehicle perfectly matches its clutch system.
Even though you are customizing and improving the vehicle’s flywheel, clutch compatibility is vital. Ensure it integrates seamlessly with the car’s clutch so you can benefit from a seamless driving experience.
Benefits of Using a Flywheel
The flywheel’s unique properties make it an attractive component for various applications. Some of the key benefits of using a flywheel include:
- High Power Density: Flywheels can store a large amount of energy relative to their size and weight, making them ideal for applications where space is limited.
- Low Maintenance: Flywheels have few moving parts and don’t require lubrication, reducing maintenance costs and increasing their lifespan.
- High Efficiency: Flywheels can achieve high efficiency, often exceeding 90%, by minimizing energy loss during storage and release.
- Scalability: Flywheels can be designed to meet specific energy storage needs, making them suitable for a wide range of applications, from small-scale power tools to large-scale industrial systems.
Challenges and Limitations of Flywheels
While flywheels offer numerous benefits, they also come with some challenges and limitations:
- Material Constraints: The design and material selection of a flywheel are critical to its performance and lifespan. Materials must be able to withstand high-stress conditions and maintain their structural integrity over time.
- Energy Loss: Although flywheels can achieve high efficiency, they are not immune to energy loss. Friction, heat, and other forms of energy loss can reduce the flywheel’s overall performance.
- Cost and Complexity: Flywheels can be complex and expensive to design and manufacture, particularly for large-scale applications.
How Much Does It Flywheel Replacement Cost?
On average, flywheel replacement cost is anywhere between $600 to $1,100. You can save yourself a lot of coins if you did the replacement by yourself but only attempt that if you’re an experienced mechanic.
The replacement cost of a flywheel can range considerably. There are some flywheels that cost under $50 while others cost as much as $400 or more.
It all depends on what type of car you drive, how durable the flywheel is, and whether the part is an exact OEM replacement or aftermarket. In addition, clutch and/or release bearing replacement may also be necessary.
Then, of course, you have to consider the labor costs of doing the replacement job. Since most auto mechanics charge about $90 to $110 per hour, you could be looking at paying close to $500 just for labor.
The reason for this is that the flywheel is attached to the crankshaft in an engine and it is harder for the mechanics to take out and replace. This requires more time which means you’ll be paying more money.
In total, you could be looking at anywhere between $550 and $1,000 on average.
If you’re an experienced mechanic who knows how to replace a flywheel or clutch or you have a friend who is, then it would be better to use this option rather than paying for the labor. It will save you a lot of money this way.
FAQs.
Q: What are the signs of a bad flywheel?
One of the things you wouldn’t want to give up without signs on your car is the flywheel. It may mean you are going to park your vehicle in a garage until you replace it. Luckily, some signs will pop up before the flywheel goes out. They’re as follows;
- Rattling noise when you depress or release the clutch pedal.
- Gear goes into neutral or slips out when shifting gears.
- Burning smell from the clutch.
- Regularly vibration when driving.
- Your car produces strange noise when turning the starter motor.
Q: Does Flywheel always spin?
We explained earlier that the flywheel keeps transferring power from the engine to the transmission once you start a car.
So, you might think the flywheel spins all the time. That’s not true. The flywheel does not spin when in neutral.
This is because the input shaft that connects to the clutch plate; then to the pressure plate which connects to the flywheel is designed to spin freely when the vehicle is in neutral.
Q: Can I drive with a bad flywheel?
Apparently, you can drive with a bad flywheel. It all lies in how severe the damage is. In some cases, a flywheel will keep you stranded in the middle of nowhere.
Before deciding to keep driving with a bad flywheel, you should note that when a flywheel goes out.
It can cause damage to other powertrain components in that area because the flywheel serves as a balancer between the engine and the transmission as the crankshaft rotates.
If it stops acting as a balancer, there will be vibrations as you drive. A rough idling will hinder the engine from producing peak performance.
Q: Why is flywheel so expensive?
There are two types of flywheels; fixed and dual flywheels. Fixed flywheels are considerably affordable to all car owners.
On the flip side, dual flywheels are more expensive than their variants because of the material used in production. However, a standard-style flywheel lasts much longer and hardly requires replacement.
Q: What happens if the flywheel breaks?
Since the main function of the flywheel is to transmit power from the engine to your tranny, if it suddenly breaks or fails, it will cause unexpected and severe damage.
It will also cause vibrations, rattling noise, gear slippage or hard shifting gear, or strange noise when turning the starter motor. In a worst-case scenario, it will cause your engine to underperform and lose torque and power altogether.
Q: How much does it cause to resurface a flywheel?
If there’s discoloration or glazing on the surface of the flywheel; it is a sign of wear, which can disrupt the smooth meeting of the flywheel with the clutch.
If this happens, you’ll need to resurface the flywheel. A resurface job should be between $20 to $50. This, however, does not include your mechanic’s service fee.
Q: Does the flywheel need to be replaced with a clutch?
If you notice gear slippage or any other symptoms of a bad clutch, and upon inspection, you find out you have a worn clutch disc, you don’t necessarily need to replace the flywheel.
However, it is recommended to resurface the flywheel in a high-mileage vehicle whenever you remove the clutch.
Q: How long does it take to machine a flywheel?
There are two methods of resurfacing a flywheel. The methods include grinding and cutting. Whichever method you chose to adopt, resurfacing a flywheel will take 3-5 minutes.
The purpose of resurfacing the flywheel is to remove the hard surface while leaving it with a homogeneous and smooth surface.
Q: How many times can you resurface a flywheel?
There’s no specified number of times to resurface a flywheel. However, I recommend resurfacing it once or twice, and nothing more than that.
In any case, Machine operators will be able to tell whether you need to resurface a flywheel or it’s long gone and needs a replacement by merely looking at it. This is their job, they do it often.
Final Word
At this juncture, you won’t be asking what is a flywheel, what it does, and the symptoms to watch out for when it goes bad.
Not only does this article provide a sufficient answer to the question ‘what does a flywheel do’ it also unveils the consequences of driving with a bad flywheel. Suppose you notice any of the symptoms above, consult your mechanic for professional inspection and fixes.