Clutch and Clutch Parts

What is an automotive clutch and where is it located?

The clutch on a vehicle engages and disengages the mechanical connection between the engine and the rest of the drivetrain. When the automobile’s clutch is engaged, the clutch disc is clamped to the flywheel by a pressure plate, transmitting power from the crankshaft to the transmission. In order to change gears, though, you need to disengage the clutch.

A typical automotive clutch is made up of a few major components that are located between the engine and transmission that are prone to wear. First, there is the flywheel, which is a large thick round metal plate attached to the rear of the engines’ crankshaft and rotates at the same speed as the engine. Next in line is the clutch disc, which is a metal disc with friction material mounted to both sides. The center of the clutch disc is splined for the transmissions input shaft. The pressure plate assembly—sometimes called a clutch cover—bolts to the flywheel over the clutch disc and consists of a round metal disc with many fingers that extend to its center. The outer shell of the pressure plate houses the springs or sprung steel disc that maintains pressure against the disc. Contrary to how it looks, the pressure plate works with a cantilever type action, applying force to the center fingers counteracting the pressure plates own force to the disc. And finally the clutch fork and throw out bearing, which are attached to the transmission housing.

In a vehicle with a manual transmission, there must be some way for the driver to disengage the clutch from the engine flywheel in order to shift gears. In some vehicles, this is accomplished via a cable, rod, or lever connected to the clutch pedal. 

On vehicles with a hydraulic system that includes a clutch master cylinder and a clutch slave cylinder, when the driver presses on the clutch pedal, it pushes forward a piston inside the clutch master cylinder. This pushes out fluid, essentially the same as brake fluid, which creates hydraulic pressure. Fluid hoses carry that pressure to the slave cylinder, which in turn moves the clutch fork, which in turn disengages the clutch from the flywheel. The clutch fork and bearing push against the finger at the center of the pressure plate, which releases the clutch disc from the flywheel. The throwout bearing allows contact with the continuous rotating of the pressure plate fingers.

The clutch master cylinder can be found inside the engine compartment, attached to the firewall, opposite the clutch pedal. It is usually next to the brake master cylinder, further to the driver’s side of the vehicle.

The clutch slave cylinder is located by the transmission. Its exact position varies from one model to another.  It may be mounted to the outside of the transmission, or it may be inside the transmission bell housing. If it is outside the transmission, it may be on top, and more easily accessed through the engine compartment, or it may be underneath and more easily accessed from below the vehicle.

How do I know if my clutch assembly needs to be replaced?

As you can imagine, the friction between the flywheel, clutch disc and pressure plate can take its toll over time. Some automotive clutches may last the life of the vehicle; it all depends on how it’s used. If you do a lot of towing, the extra strain on the transmission can wear down the clutch faster. Frequent use of the clutch, like in city driving, will also wear out the clutch faster. If you are in the habit of riding the clutch, driving with the clutch pedal partially depressed due to resting your foot on the pedal, or downshifting to slow down, the partial slipping between the flywheel and clutch disc will wear out those parts over time. 

If the automobile’s clutch is worn, it might begin to slip. That means the flywheel isn’t engaging fully to the clutch disc. That can make it hard to accelerate. You might find that when you press on the gas pedal, the engine revs up, but the car or truck doesn’t go much faster. A worn clutch may also skip or chatter when you use the clutch pedal. 

Problems with other parts of the clutch system can cause wear on the clutch. A worn out clutch fork can’t fully disengage the clutch, which causes grinding during gear shifts. Leaking clutch cylinders or hydraulic lines can also keep the clutch from disengaging fully. 

Over time, the seals inside the master cylinder can break down from use and can cause fluid to leak out of the system. Without proper fluid levels in the system, the clutch pedal can feel soft and not allow for proper movement of the clutch. A soft pedal is the first sign that something is wrong with the clutch master cylinder. If the pedal feels “spongy” when you press it, this can indicate that there is air in the hydraulic system, which you may be able to solve by bleeding the system. If the pedal sinks to the floor and stays there when you take your foot off, then there is definitely a leak in the clutch system. 

If you find that you must frequently refill the fluid reservoir for the clutch master cylinder or that the master cylinder has oily fluid on it, then it likely has a leak. You may also ask an assistant to press the clutch pedal and watch if the fluid level lowers and rises as expected. 

If the clutch master cylinder cannot produce enough pressure, then the slave cylinder might not be able to disengage the clutch completely. This may lead to loud noises from the engine compartment while you are stopped and idling. Eventually, if the problem is allowed to get worse, you may be completely unable to shift the vehicle into gear, leaving you immobile and in need of a clutch master cylinder replacement.

Many of these symptoms can also apply to the clutch slave cylinder, so you should pinpoint the exact cause of the problem before attempting a repair, or consider replacing both clutch hydraulic cylinders.

Can I replace the clutch and other components myself?

Replacing a clutch is a very involved procedure and is probably best left to very experienced do-it-yourselfers or professional mechanics. Replacing a clutch requires removing the engine or the transmission depending on application, so if you are not comfortable removing your engine or transmission we recommend the work be done by a professional.

If you do decide to tackle the job yourself, an assistant can be helpful in many parts of the repair. You will also need a clutch alignment tool. Many automotive clutch kits come with this tool. You should also be willing to put aside a full day (or more) for the repair, since the job takes so many steps. A shop manual or a detailed set of instructions specific to your car or truck will also be a big help. 

You will need to raise and secure the vehicle. You may have to remove the driveshaft, exhaust pipes, the engine speed sensor, the clutch slave cylinder or other nearby parts. Then, you can unbolt the transmission from the engine and remove the mounts. Then, carefully separate the two components. Then you will be able to remove the clutch parts. Once the flywheel is visible, you must determine its condition. In many cases it is best to remove it and replace it or have it turned by a local machine shop. Thoroughly clean the area around the crankshaft and check both the rear main seal on the engine and the input shaft on the transmission. This is your best opportunity to replace these seals.

Use the clutch alignment tool to line up the clutch parts as you put them in place. When you are installing the new clutch, be sure not to get any grease or oil, whether it’s from the engine or your skin, onto the clutch parts. Tighten all bolts to the manufacturer’s recommended torque specifications.  When you are installing the bolts for the clutch parts, you will have to tighten the bolts in stages. Tighten each bolt partially, then go through and tighten each one some more, and so on until they are fully tightened. This prevents warping the clutch. An assistant can be very helpful when you are lining up the clutch parts, and when you are maneuvering the engine or transmission back into place. Once back in place, you can reinstall all the parts you removed earlier, in the reverse order. 

These general tips should help make the job easier, but we certainly recommend getting a set of directions specific to your car or truck as clutch jobs can differ. 

Need replacement clutch parts?

Are you having trouble getting your manual transmission in and out of gear? Are you finding it hard to accelerate? If the answer to these questions is yes, you may need a new clutch assembly. You can't expect to drive your car or truck without a properly functioning clutch assembly, from both a performance and safety perspective. So if you are having problems with your clutch assembly it is vital to address it immediately. Luckily, 1A Auto carries all of the aftermarket clutch parts you need for your vehicle, and at great prices. You’ll find clutch kits and sets that contain the replacement parts you need to get your vehicle up and running again! We also carry other replacement clutch parts such as clutch master and slave cylinders, forks, cables, hoses, lines and more, and all at great prices. If you need to repair your clutch, 1A Auto is your source for aftermarket parts.

At 1A Auto, we make shopping for aftermarket clutch kits and other replacement clutch parts for your car, truck, SUV or van easy - we're here to help you select the right parts for your vehicle! Call our customer service toll free at 888-844-3393 if you have any questions about our aftermarket clutch parts, warranty, compatibility or to purchase, or you can buy online.