There are a number of car parts whose location many drivers are not aware of and the transmission, commonly known as the gearbox, is one of them. Many drivers, as long as they can start their car in the morning and drive off, never worry about such things until the car stops in a jam or even fails to change gears.
That is when they understand the importance of knowing the location and function of such parts as the gearbox.
Types of gearboxes
Eric Amadi, a mechanic at Dallas Auto Garage, explains that a gearbox is a mechanical method of transferring energy from one device to another and is used to increase torque while reducing speed. Wisegeek describes torque as the power generated through the bending or twisting of a solid material. The gearbox is located at the junction point of a power shaft.
Amadi explains that there are four types of gearboxes. These include automatic, semi-automatic, manual and tiptronic gearboxes. He says many drivers prefer manual shifting due to better handling and ability to control the vehicle as opposed to auto transmission. With auto, the engine control unit of the car picks gears at any given time. When it comes to semi-automatic, the driver has the option of shifting to manual gear and switching back to automatic mode when they are tired.
Drivers who enjoy the thrill of racing in manual cars can as well enjoy the same comfort in tiptronic cars.
Autobyetel.com describes a tiptronic transmission as one that works in an opposite style, adopting manual characteristics to an automatic gearbox by allowing the driver to select gears manually, overriding the computer that controls normal shifting and using a torque (rotation)onverter instead of a clutch.
Repairs on the gearboxes
Check the automatic transmission fluid level to determine if it is low. If it requires replacement, you should buy the fluid from a fuel station and top up. “If the car is stuck in one gear, especially in reverse mode, it could indicate a faulty gearbox switch. The best you can do in such a situation is to park and call a mechanic to avoid further damage. You should also ensure to stick to the regular service timetable,” Amadi notes.
Mike Lukyamuzi, a mechanic at Micky Auto Garage in Namuwongo, a Kampala suburb explains that unlike some Japanese manufactured cars, German made cars such as BMW, Mercedes Benz, VolksWagon and Audi, mainly have two types of gearboxes manual and automatic.
He says for such cars, when the gearbox has a mechanical problem, which Lukyamuzi notes usually occur when the car has been driven beyond its mileage duration for service, the car will stop.
“When it stops, the only way you can move it is by using a car carrier or a tow truck to take it upto the garage,” Lukyamuzi explains.
He adds that when it gets there, the mechanic removes the gearbox clunk and strainer to find out if the hydraulic fluid is still functional and at the right level to keep the gearbox running.
He says the amount of hydraulic fluid that goes into a gearbox depends on the size of the gearbox and car but they usually take six litres and above.
Changing hydraulic fluid
He points out that when a German-made car fails to start, even if it has enough fuel, in most cases, the problem could be with the gearbox. In such a case, a diagnosis machine has to be used to detect the mechanical problem with the car.
Lukyamuzi adds “not every type of hydraulic fluid can work in a German made car. Each type of car has a different type of hydraulic fluid it uses that the driver should always know.”
He is, however, quick to explain that unlike Toyota cars that use between four to six litres of hydraulic fluid in the gearbox, most, if not all German made cars, use approximately six to eight litres.
And depending on the type and class of hydraulic fluid a driver chooses to use, in a German made car gearbox, Lukyamuzi says it costs between Shs70,000 and Shs200,000 per litre.
“A driver should always be on the lookout for the right hydraulic fluid because some shops sell second hand hydraulic fluid at Shs20,000 yet it will not last long,” he aises, adding that when a car owner uses hydraulic fluid that is of poor quality, they end up spending a lot more money than if they used something better.
Maintain clean transmission fluids
Eric Amadi, a mechanic, aises drivers to always ensure that their transmission fluid is always kept clean to prevent damage to the gearbox strainer.
Some cars such as Subarus come with superior gearboxes. These gearboxes are meant for high performance cars and should be handled by highly skilled drivers since their gear engagement is different from that of an ordinary manual car.
Need for consultation before gearbox change
“If a driver is to go for a complete gearbox change, they should consult a professional mechanic because it is hard to buy a brand new gearbox from the manufacturer.
Most people buy reconditioned gearboxes that are not reliable because the owner can’t determine how long they have been used,” Amadi cautions.
Common gearbox problems
Amadi explains, “Most people spoil their gearboxes by not following proper service regulations and timelines.
It may include failure to change the automatic transmission fluid in time, which makes it dirty thus choking the gearbox filter and causing transmission problems,” Amadi explains,
He says another common problem is ignorance about gearboxes because most of them start to leak when they are getting worn out.
You know there is a leak when you notice oil drops after parking a car. He recommends that this should be addressed by a mechanic as soon as possible to avoid further damage.
Reckless driving and hitting potholes lead to the development of dents on gearboxes and this puts pressure on the gearbox strainer hence causing transmission problems.
Amadi aises that drivers who don’t know how to engage gears or have not mastered the art of driving manual cars should also be cautious on how they handle the clutch because they may easily cause the clutch to burn which leads to stalling of the vehicle.
SIGNS OF A FAULTY GEARBOX
Delayed change of gears
Just like any part of the car, the gearbox can also fail but it will always show warning signs. Amadi therefore says you should lookout for gear changes that happen later or take longer than usual to engage or are not as smooth as they should be. “If the engine revs between gears, that’s a sign that something is wrong with the automatic kind of gearbox. If the revs are high, but the vehicle moves slowly or not at all, it’s a sign of another problem that requires a mechanic,” Amadi notes.
The check engine light
Additionally, the “check engine” red icon that lights up on the dashboard is an early indicator that something is wrong with the gearbox or transmission. And in rare cases with modern cars, the traction control system could alert a driver to visit a technician to run a diagnosis on the vehicle and assess the exact mechanical issue.
In a well-functioning car of any gearbox type, Amadi says the gear should stay in the mode the driver chooses, or what the computer designates for a given period, until the driver or the computer initiates a gear shift. But for a gearbox or transmission in which the gears slip, the car can slip out of the gear when in motion. This, he says, is a clear indicator of transmission malfunction and should be corrected by a mechanic.
Grinding sound and shaking of the car
In manual, a common sign of gearbox failure is a grinding sound when a driver engages another gear. “If you fully engage the gear and hear a grinding sound, you may have a worn out clutch or there is a need to have it adjusted,” Amadi points out, “Also, that with most automatic gearbox problems, a driver could feel the car shake into each gear, or even the gearbox make a jerking sound into the next gear. Both are signs that a gearbox needs attention.
“If you notice anything other than a smooth transition between gears, then you might need to have your automatic transmission looked at by your mechanic,” Amadi aises.
Most drivers have experienced oil leaks, especially when they park the car in one place. This, Amadi says, is an indicator of a problem with automatic transmission fluid circulation in the vehicle, and that it should be checked by a mechanic early enough to avoid complex mechanical issues.