Have you ever wondered what your clutch actually does? In its simplest form, your clutch allows engine power to be transferred and applied gradually to the wheels in any manual transmission vehicle.
What happens if the clutch in your car becomes worn, damaged or burnt out? This usually means that there is a problem with your car transmission and it doesn't shift gears properly due to internal problems. Most likely, your clutch could be facing problems, like clutch slipping, clutch burns, excessive heat, or excess wear.
What Is A Clutch?
A clutch is a mechanical device that is found in manual vehicles. The clutch controls the connection between the shaft coming from the engine and shafts that control the vehicle, including the drive shaft, so that a driver can change gears and speed. Essentially, this mechanism within the transmission transfers the rotational power from the engine to the wheels and can control this energy to ensure a car's momentum is not hindered or increased dramatically.
Within a car's clutch, there are a variety of moving parts that make up a manual transmission.
The Clutch Disc (Clutch Plate)
The clutch disc or clutch plate is a round, metal plate that connects the engine of a vehicle to the transmission input shaft that allows for temporary separation when shifting gears. It is located between the flywheel and pressure plate with a friction material that is similar to brake pads.
The clutch disc makes and breaks the flow of power and momentum from the engine to the transmission as it flows torque directly to the input shaft of the transmission. When a driver pushes their foot on the clutch pedal, the clutch disc will separate from the pressure plate and flywheel, allowing the driver to change gears. When a driver releases the clutch pedal, the clutch disc will make contact to constantly maintain the torque and energy being generated.
The Pressure Plate
A pressure plate is made up of a heavily spring-loaded diaphragm that is enclosed by an outer shell. This diaphragm provides the clamping force that is required to efficiently transmit the engine's torque to the transmission.
When the clutch is fully engaged, this clamping force is constant and is maintained by the spring-loaded diaphragm that is compressed by the driven plates and flywheel.
The flywheel is a component of a car's manual transmission that is attached to a vehicle's crankshaft and functions to assist in the start of an engine and maintain engine energy. The flywheel provides and maintains the engine's rotational mass with constant momentum for gear changes.
While driving, as the clutch pedal is pushed, the connecting clutch disc disengages from the flywheel which allows the car to idle to a stop while the gear shift is still in gear. When the pedal is released, the clutch disc then firmly presses into the flywheel's teeth and causes the transmission to rotate at the same speed as an engine's crankshaft as the flywheel maintains this power constantly.
How Does A Clutch Burn Out?
A burnt out clutch is caused by issues within a car's manual transmission system. This could include a worn or damaged clutch disc, a warped or glossy flywheel or general wear on the clutch disc or transmission.
Most often, a clutch burns out due to the excessive heat generated from a clutch slipping or clutch misuse which creates excessive heat and an acidic smell. Similarly, to a car's brake pads, a clutch's friction materials are designed to wear down slowly through normal use. While a clutch can wear down gradually, a burnt out clutch usually refers to a clutch that has worn very quickly. This can be due to a myriad of factors.
Using The Clutch Incorrectly And “Riding The Clutch”
Being unfamiliar with how to use a clutch properly is a common habit and occurrence among drivers learning to master a manual vehicle. However, it is something that anyone can do while driving a car.
When a driver 'rides the clutch' they are not fully disengaging the clutch when changing gears and instead change gears while still engaging the clutch pedal. This can also cause an uncomfortable, jerky ride for your passengers as the driver has failed to release the clutch pedal completely and can wear a clutch out fast.
Bad Driving Habits
There are some common driving habits that can damage your car clutch and cause clutch burn out. These habits don't usually occur in cars with an automatic transmission so it is important to pay attention to these habits when learning how to drive a manual vehicle.
Consistently driving in slow moving traffic (consistently going from a start to stopped position)
Changing gears slowly
Resting your hand on the stick shift while driving can put pressure on the gear forks of your gear box
Aggressive driving that can range from speeding to burnouts
Keeping your car in gear at a stoplight will continuously engage the clutch pedal
Clutch contamination is not an extremely common occurrence in a vehicle's clutch. This is when a fluid contaminates the clutch disc and shortens its lifespan. Any number of fluids can contaminate a clutch including engine oil, transmission fluid or fluid that powers the clutch cylinders.
When a clutch has been installed incorrectly, grease can also appear on a clutch's surface.
Carrying Heavy Loads
If a vehicle is carrying loads heavier than what is recommended, the clutch is bound to wear out quicker than expected as it takes on more torque, weight and energy from the engine. When towing a heavy load, it is important to carry these loads slowly and smoothly as possible with your shifts being as controlled as possible.
Burnt Clutch Symptoms
The main symptoms of a burnt out clutch could range from loud noises to putrid smells of burning rubber. However, a clutch pedal continuously slipping, erratic acceleration and difficulty changing gears are also problems you may experience with a burnt out clutch.
Burnt Clutch Smell
A burnt out clutch will usually result in a burning smell that is very similar to burning brakes or burning rubber. The reason for this smell is due to the materials that make up a clutch. A clutch disc includes fibreglass strands, metallic powder, rubber compounds and rings, along with phenolic resin and Kevlar creating a very chemically burnt rubber smell.
When these clutch materials begin overheating, as the flywheel and clutch disc rub against each other, the materials begin to wear away which causes the foul smell. These burnt clutch smells are usually noticeable after a driver changes gears as the spinning clutch disc becomes fully disengaged and re-engaged.
Clutch chatter is a common symptom that may indicate a worn clutch. Clutch chatter is when a driver tries to make gear changes with a damaged or worn clutch which causes their gear changes to be rough and noisy with strange clunking, chattering or banging noises and vibration across the car.
However, clutch chatter can be a symptom of oil leaking from the engine onto the clutch assembly, poor flywheel surfaces or clutch facings, damaged pressure plates, sprung clutch disc hubs or improper alignment between the engine and transmission. It is important to get these issues diagnosed by an automotive mechanic or professional to ensure they are resolved quickly.
Clutch slipping is the most common cause of a burnt smell coming from a clutch. It happens when a worn down clutch has less friction material to grip to the flywheel and pressure plate. This makes it difficult to transfer torque and power to the transmission smoothly causing a slipping feeling in the clutch.
A problem like clutch slipping can be caused by a variety of factors including damaged pressure plates, incorrect clutch components, misadjusted linkage or regular wear.
Difficulty Changing Gears With The Clutch Pedal
A side effect of clutch slipping is difficulty changing or engaging gears. When a clutch becomes burnt out, the clutch plate has difficulty disengaging from a flywheel entirely when the clutch pedal is pressed. This causes the clutch plate to slip and burn more as it partially engages with the flywheel and can further compound the problem.
Erratic Acceleration And Engine Revving
If a clutch is severely burnt it may increase the acceleration and engine revving of a car while the car only increases in speed slightly. When a scorched clutch plate becomes unable to grip the surface of a flywheel, unnecessary strain is put on it causing slipping and surges at a higher than normal torque causing an engine to feel like it is accelerating more than it should.
When changing gears, if a flywheel is not gripping as quickly and smoothly as it should, it can cause an engine to jerk and surge because the engine power is not being transferred to the wheels efficiently. This happens as a clutch pedal is released and the accelerator is pushed in where a car attempts to maintain speed.
Can You Fix A Burnt Clutch In A Manual Transmission?
In short, no. If your clutch is burnt out it will require a complete clutch disc replacement.
A professional automatic transmission mechanic or technician will need to remove and inspect the manual transmission to inspect its components. During this, the pressure plate is inspected for any damage and the flywheel is checked for any hot spots or warpage. It is very important to replace all parts that have been affected by the burn out as it could lead to more costly clutch repairs.
What Does It Cost To Repair A Burnt-Out Clutch?
Clutch replacements and repairs will vary in cost depending on the make, model and components that are required for the repair.
The average cost of a clutch disc is between $450 and $700 when including labor. A complete, new clutch kit plus a flywheel can cost between $750 and $2000. In a clutch repair, most mechanics use a complete kit that includes a replacement clutch disc, a new pressure plate, pilot bearing, and a thrust bearing. If you are worried about any of your clutch components or are concerned about a burnt out clutch in your manual transmission vehicle, Enji can put you in contact with a local mechanic in your area who can help you.