Transmission technology continues to move forward at a rapid rate particularly in the area of automated gearboxes, however manual gearboxes haven’t been drastically altered since the idea of having multiple speeds for a rotating machine surfaced in the early 1900s. Modern cars are equipped with synchromesh, and some also have rev-matching facilities However, they all require a clutch of some description and it’s a serviceable item and it’s best to know when it’s in need of attention.
What’s a clutch’s job?
In simple way, the clutch sends electricity from your engine back to the transmission, but it’s able to separate an engine’s power from the gearbox to allow the shifting of gears within the gearbox. The clutch plate is made up of metal trimmed in the form of a material that is friction on both faces. It has a splined middle section, which allows it to slide along input shaft of the gearbox. In its default position (i.e. with no clutch pedal pressing) the clutch is held against the flywheel using the clutch pressure plate. The clutch pressure plate is in a position that does not slip.
When you press the clutch pedal it disconnects the clutch so that power is cut off. Certain cars employ the clutch cable to pull a lever inside the gearbox (called the fork that releases bearings), which in turn pushes the release bearing into between the plates. A diaphragm spring allows the clamping pressure to be released, meaning the clutch plate will no longer be held against the flywheel and allows it to move at a different speed based on the selected gear. The clutch can be ‘slipped depending on how hard the pedal for the clutch is pressed. Although the basic principle is the same, various cars use hydraulic operation instead of a clutch cable in which the pedal’s motion is controlled by a master cylinder which alters hydraulic pressure to a slave cylinder. The slave cylinder then controls the movement of the fork bearing release.
What are the signs that the clutch in your vehicle needs to be replaced?
Clutch Slip:
With time, the friction material on your clutch will wear away and, when it does, the clutch will start to slide. It should be quite obvious when the clutch of your car is slipping when it shouldn’t be. If the clutch pedal is completely removed (i.e. that it is not being pressed at all) it should show zero slip. Slip can be identified by an abrupt increase in engine speed without accompanying acceleration when your car is in gear the clutch pedal isn’t pressed and you push the throttle pedal. It is also evident when you attempt to accelerate your car up a steep hill. Although the degeneration of the clutch happens slowly over time (depending on the type of driving you do and the conditions – stop-start traffic can wear down clutches more quickly than, say motorway drivers), if it is slipping in this manner then it really is an ideal time for van clutch replacement. There are other signs to watch out for like strong odors emanating from the engine compartment in the event of a sudden departure from the stop or an increased “bite” point on the clutch pedal than it was before.
The latter can also signify something is up with the hydraulics of the clutch (if your vehicle has an automatic clutch that is hydraulically operated). The first thing to do is examine the master cylinder reservoir (in the engine bay, which it looks like the reservoir of brake fluid) is filled with fluid for the clutch. If it’s in good condition, it’s time for you to bring your vehicle to a garage in order to identify if the slave cylinder is in need of replacement. For cars that utilize the clutch cable rather than hydraulic actuation, the cable itself can stretch and isn’t an expensive or difficult component to replace.
Clutch Judder:
The most obvious sign of juddering is when starting from a halt. It manifests itself as a intense sound
from the transmission or engine when you let the clutch go in order to make the car move. It’s usually hydraulic fluid or oil that somehow has found its way on to it’s surface itself and is causing it to not grip properly or smoothly when it is engaged, creating a frictional effect of gripping partially, it slips and then grabs the same place and then again. It can also result from misalignment or misalignment the clutch or the flywheel having a slight warp or being plain worn out or coated to the point it’s not gaining consistent grip. Clutch judder can actually be extremely severe, so much that it could make the car difficult to navigate, especially in rush hour. It’s also very unpleasant to bear! The only solution for clutch judder is to get it replaced.
Worn Release Bearings & Two Mass Flywheels:
I’ve put these two components together since, although they’re quite different, when they begin to fail, they could sound similar. If you hear an eerie sound from the gearbox, which goes away when you press the clutch pedal then it’s possible you’re experiencing a problem with either the release bearing, or the dual-mass flywheel (if you have one in your vehicle).)
Other Issues Other Issues: There are several clutch-related problems that may not be the fault of the clutch itself. Sometimes, the issue isn’t related to slippage, but sticking. If your clutch doesn’t release properly it will continue to spin the input shaft. This could cause grinding or completely stop the car from entering gear. The most common reasons why for a clutch to stick are:
A stretched or broken clutch cable The cable must have the right degree of tension in order to push and pull effectively.
Leaky or defective slave and/or master clutch cylinders. Leaks stop the cylinders from building enough pressure to meet the requirements.
In the line of hydraulics, air – Air influences the hydraulics through taking up space the fluid requires to increase pressure.
Incorrectly adjusted linkage – when your foot hits the pedal, the linkage transmits the wrong magnitude of force.
If you’re experiencing any of these symptoms , you could be lucky and not need to replace your clutch, in fact, it might be something much more straightforward and affordable to repair!
Replacing the clutch on your vehicle.
It’s required in almost all cars (there are some exceptions) to take the gearbox off the vehicle to change the clutch. This is the reason it’s an expensive and time-consuming piece of work to complete irrespective of the cost of the parts themselves. Thus while it’s typically just the clutch plate that’s in need of replacing, it’s worth buying the entire kit, which includes the pressure plate as well as the release bearing. If you’re going to undertake to replace the clutch yourself, ensure you know the process, consult a workshop manual if necessary and stay safe.
A note on dual-mass flywheels.
A lot is said concerning dual-mass drive wheels. They effectively dampen out vibration in cars that produce massive torque at lower speeds, but can cause issues for all models based on the kind of driving it is most often utilized for. The mechanism is weakening and breaking down over time, which can lead to poor performance when starting and running. If you’re replacing the dual mass flywheel, make sure you replace the other parts of the clutch, as the gearbox is taken out in any event. And a word of warning that it’s quite popular in certain cars to switch from dual mass flywheels to a single flywheel. Most often, it’s because they’re cheaper, however, often due to the fact that dual mass flywheels are subject to lots of negative press on reliability. However, they’re there for a reason and changing yours to a proper conversion can cause a significant increase in the amount of vibration that is felt through the clutch pedal and into the cabin as a whole.
© Jenson Racing Archives
- January 19, 2025 5:34 pm