When should a manual clutch be replaced?
October 09, 2021
Any car with a manual transmission has a clutch. It's needed so that the transmission could be disengaged from the engine while shifting gears or while the car is stopped at the red light.
Pressing the clutch pedal mechanically disconnects the transmission from the engine. Releasing the clutch pedal re-engages the transmission to the engine.
How long does the clutch last?
This depends on many factors including parts quality, driving style and traffic. If the car is mostly used for long highway trips, the clutch wear is minimal. Driving daily in stop and go traffic will cause the clutch to wear out sooner. On average, the clutch lasts for 100K-150K miles. However, we have seen many cars with over 200K miles that still have an original clutch.
How do you know if your manual clutch is going out?
One of the early symptoms of a worn clutch is when it's adjusted properly, but engages the transmission closer to the top of the clutch pedal travel. Normally, when releasing the clutch pedal, the transmission starts engaging somewhere at the mid-point of pedal travel.
Worn-out clutch disc and pressure plate.
Another symptom is occasional slipping while driving, when the engine RPMs rise, but the speed doesn't increase, or increases with a delay.
Often it's more noticeable when accelerating in 2-nd or 3-rd gear, especially with a heavy load or driving uphill. When the clutch slips, it overheats and wears faster. A burnt clutch smell coming from under the hood is another sign. Typically, once the clutch starts slipping, it will not last long. The slipping occurs because a worn-out clutch disc becomes thinner and slips between the flywheel and the pressure plate. Read more how the clutch system works below.
How much does it cost to replace a clutch?
Clutch pressure plate, disc and release bearing.
To inspect or replace the clutch, the transmission has to be removed and reinstalled after.
This is not an easy job and it takes from 5 to 10 hours of labor depending on the car, plus the cost of parts.
What parts are required for clutch replacement?
Typically a clutch replacement includes replacing the pressure plate ($200-400), the clutch disc ($70-180) and the release bearing ($50-130). In some cases, the flywheel will also need to be resurfaced ($50-$100) or replaced. The crankshaft pilot bearing (bushing) may also need to be replaced. In some cars, the clutch slave cylinder is installed inside the transmission housing and may also need to be replaced as part of the clutch job.
Resurfaced (machined) flywheel.
If there are any oil or transmission fluid leaks (e.g. leaking input shaft seal) in the clutch area, they must be repaired before the new clutch is installed.
Considering high labor costs, it's recommended to use OEM or high-quality aftermarket parts, so the clutch and related parts will last longer.
In most modern cars with a hydraulic clutch system, the clutch is self-adjusting and doesn't need any adjustment. in some older cars and trucks, the clutch may need to be properly adjusted after the replacement or as it's wearing down. The clutch adjustment is typically done so that the clutch pedal has some specified amount of free play between the top most position and the point where the clutch starts to engage. In technical terms, it means to the point when the release bearing contacts the springs of the pressure plate. See the diagram below.
How to make your clutch last longer?
The clutch mostly wears from excessive friction. In normal driving, most friction happens when releasing the clutch while accelerating from a stop. The longer the clutch release and the harder the acceleration while releasing, the more friction the clutch has to bear. Drivers that want to extend their clutch life, first take off gently from a stop and then accelerate more when the clutch pedal is fully released.
What can cause difficulty shifting into low gears with the engine running? If it's easy to shift into any gear with the engine off, but difficult when the engine is running, most likely it's because of a "clutch drag." This problem could be caused by air trapped in the clutch hydraulic system or the clutch being out of adjustment. If the adjustment is correct and bleeding the hydraulic system makes no difference, the clutch needs to be disassembled and all components inspected.
What can cause a whirring noise that happens when the engine is running and the clutch pedal is depressed that goes away when the pedal is fully released? There are several possibilities, but the most common cause is a bad clutch release bearing. The release bearing only operates when the clutch pedal is depressed and the engine running. However, to inspect the release bearing, the transmission needs to be removed and it makes sense to replace all worn out clutch parts along with the bearing.
How does the clutch system work?
Modern cars have a hydraulically operated clutch system. When a driver presses the clutch pedal, the clutch master cylinder creates hydraulic pressure that pushes the fluid through the clutch line and hose to the clutch slave cylinder.
The pressure inside the clutch slave cylinder pushes out the piston that in turn pushes the release fork. The opposite end of the release fork slides the release bearing towards the clutch pressure plate (see the diagram). The release bearing presses the spring diaphragm that moves the pressure plate away from the clutch disc, releasing it free.
The pressure plate and the flywheel are bolted to the engine crankshaft, while the clutch disc is connected to the transmission input shaft. As the pressure plate moves away from the flywheel, the clutch disc can rotate freely, disengaging the transmission.