Media post: What Every DIY Mechanic Should Know Before Tackling a Clutch Job
To remove the gearbox so that you can install a new clutch is a task that often provides a sense of accomplishment to people who work on vehicles with manual transmissions. Before you begin to loosen the bolts, it helps to understand how the flywheel functions. If you make sure that this component is in good shape, it is as important to the result as the clutch assembly is.
The Clutch System Works Harder Than Most People Realize
The flywheel is attached to the crankshaft with bolts and it performs three functions simultaneously. It reduces the vibrations that occur during combustion plus it provides a flat surface for the clutch disc to contact. In addition it supports the gear that the starter motor engages. There is a pressure plate which forces the disc against the surface of the flywheel. When the pedal is up, the engine and the gearbox are connected. If the pedal is down, the connection between the engine and gearbox is removed. According to Haynes, the parts that apply force are the central part of every clutch system.
In older vehicles, a solid single mass flywheel (SMF) is the standard component. As many modern engines operate, they use a dual mass flywheel (DMF). There are two separate masses in this part and internal springs connect them to one another. With this design, the component absorbs the pulses of torque before they can reach the gearbox. For the driver the result is that the vehicle moves from a stopped position with less vibration. And it is because of this process that the drivetrain produces less sound during regular use.
How to Tell When Something Inside Is Starting to Go Wrong
Components do not usually fail suddenly – if the car vibrates when you begin to drive, the friction surface of the flywheel is likely glazed or marked by high temperatures. It is also possible that the internal parts of the dual mass flywheel (DMF) are losing their ability to absorb shocks. When you hear a metallic sound from the bellhousing while the engine idles, the springs inside the DMF are probably worn – but this noise is less noticeable if you press the clutch pedal down. To find the cause, you must check if the components are in good working order.
When a clutch slips, the engine rotations per minute increase but the vehicle does not move faster – this condition often begins because the friction disc is thin from use. It becomes more severe if the flywheel has dark spots caused by high temperatures. Sometimes there is an odor similar to materials that are burning. To prepare for a repair, check your car’s spec to check the original equipment specifications. By doing this you can identify if the car has a single mass flywheel or a dual mass flywheel. For the buyer this information matters because the two types of parts are not interchangeable.
Tracking Down the Right Replacement Part Without Overpaying
By ensuring that parts fit correctly, you avoid future technical problems. If you want to identify the correct components, you must obtain the full vehicle identification number and the engine code. To achieve a successful installation, you should verify that the bolt pattern, the number of teeth on the ring gear and the type of the flywheel are identical to the specifications of the vehicle. In this process rough measurements are insufficient. When you buy a used or refurbished part, you need to examine images that show the two friction surfaces clearly. For a thorough inspection, you must see the identification numbers that are printed on the parts. It is also important that the seller provides the identity and the mileage of the vehicle from which the part was removed.
If you browse listings on flywheel for sale from a supplier that has a good reputation, you have a solid base for a purchase. On a used single mass flywheel, you need to examine the surface so you can ensure that no cracks or deep marks are present. On a dual mass flywheel, the person inspecting the part should confirm that the two masses move against each other only a small amount. In addition there must be no grease that leaks from the seam. When a person chooses a reconditioned flywheel carefully, the component functions consistently and costs less than a new part.
A Few Final Thoughts Before You Start Wrenching
You should have a clutch alignment tool, a high quality torque wrench and the service manual for your vehicle available before you begin. It is important to follow the specifications for torque and angle – you must not guess those values. While the gearbox is out, check the rear main seal to see if any oil is leaking. By fixing the seal now, you ensure that your new clutch is protected from damage. And you should drive the vehicle at moderate speeds for the first few hundred miles. For this duration, you allow the components to adjust to each other until they function together as intended.
