Clutches
At Ihanzu Auto we do clutches for all vehicle types.
Common clutch problems
The most common problem with clutches is that the friction material on the disc wears out. The friction material on a clutch disc is very similar to the friction material on the pads of a disc brake or the shoes of a drum brake — after a while, it wears away. When most or all of the friction material is gone, the clutch will start to slip, and eventually it won’t transmit any power from the engine to the wheels.
The clutch only wears while the clutch disc and the flywheel are spinning at different speeds. When they are locked together, the friction material is held tightly against the flywheel, and they spin in sync. It’s only when the clutch disc is slipping against the flywheel that wearing occurs. So, if you are the type of driver who slips the clutch a lot, you’ll wear out your clutch a lot faster.
Sometimes the problem is not with slipping, but with sticking. If your clutch won’t release properly, it will continue to turn the input shaft. This can cause grinding, or completely prevent your car from going into gear. Some common reasons a clutch may stick are:
- Broken or stretched clutch cable – The cable needs the right amount of tension to push and pull effectively.
- Leaky or defective slave and/or master clutch cylinders – Leaks keep the cylinders from building the necessary amount of pressure.
- Air in the hydraulic line – Air affects the hydraulics by taking up space the fluid needs to build pressure.
- Misadjusted linkage – When your foot hits the pedal, the linkage transmits the wrong amount of force.
- Mismatched clutch components – Not all aftermarket parts work with your clutch.
A “hard” clutch is also a common problem. All clutches require some amount of force to depress fully. If you have to press hard on the pedal, there may be something wrong. Sticking or binding in the pedal linkage, cable, cross shaft, or pivot ball are common causes. Sometimes a blockage or worn seals in the hydraulic system can also cause a hard clutch.
Another problem associated with clutches is a worn throw-out bearing, sometimes called a clutch release bearing. This bearing applies force to the fingers of the spinning pressure plate to release the clutch. If you hear a rumbling sound when the clutch engages, you might have a problem with the throw-out.
In the next section, we’ll examine some different types of clutches and how they are used.
Types of Clutches
Here are many other types of clutches in your car and in your garage.
An automatic transmission contains several clutches. These clutches engage and disengage various sets of planetary gears. Each clutch is put into motion using pressurized hydraulic fluid. When the pressure drops, springs cause the clutch to release. Evenly spaced ridges, called splines, line the inside and outside of the clutch to lock into the gears and the clutch housing.
An air conditioning compressor in a car has an electromagnetic clutch. This allows the compressor to shut off even while the engine is running. When current flows through a magnetic coil in the clutch, the clutch engages. As soon as the current stops, such as when you turn off your air conditioning, the clutch disengages.
Most cars that have an engine-driven cooling fan have a thermostatically controlled viscous clutch — the temperature of the fluid actually drives the clutch. This clutch is positioned at the hub of the fan, in the airflow coming through the radiator. This type of clutch is a lot like the viscous coupling sometimes found in all-wheel drive cars. The fluid in the clutch gets thicker as it heats up, causing the fan to spin faster to catch up with the engine rotation. When the car is cold, the fluid in the clutch remains cold and the fan spins slowly, allowing the engine to quickly warm up to its proper operating temperature.
Many cars have limited slip differentials or viscous couplings, both of which use clutches to help increase traction. When your car turns, one wheel spins faster than the other, which makes the car hard to handle. The slip differential makes up for that with the help of its clutch. When one wheel spins faster than the others, the clutch engages to slow it down and match the other three. Driving over puddles of water or patches of ice can also spin your wheels.
Gas-powered chain saws and weed eaters have centrifugal clutches, so that the chains or strings can stop spinning without you having to turn off the engine. These clutches work automatically through the use of centrifugal force. The input is connected to the engine crankshaft. The output can drive a chain, belt or shaft. As the rotations per minute increase, weighted arms swing out and force the clutch to engage. Centrifugal clutches are also often found in lawn mowers, go-karts, mopeds and mini-bikes.