Like muscles in the body

A vehicle’s transmission works hard and can take a beating from inexperienced drivers, often resulting in the need for reconditioning or a rebuild. William George looks into the factors that vehicle operators should bear in mind when taking a transmission to an aftermarket workshop.

The primary function of a transmission, or gearbox, is to transmit power from the engine to the driving wheels – much like muscles in a body transmit energy to the limbs. Another function is to reduce high engine speed to the slower wheel speed, while multiplying torque in the process. 

Common transmission failures 

Transmissions wear down over time, mainly because of the friction and heat around the moving parts. Abnormal problems such as oil leaks, overheating, noise levels, and no response or taking longer than usual to shift gears are all clear signs that a transmission may need to be checked. 

Regular scheduled maintenance 

Sticking to a strict maintenance schedule helps to maximise the chance that a fault will be recognised and rectified before damage is caused. It is always advisable to adhere to scheduled maintenance and servicing, or to consult an expert or the original equipment manufacturer (OEM) in the case of symptoms of failure. 

Keeping a transmission in good shape 

One industry recommendation is to use the information stored in the transmission’s control unit. A one-size-fits-all kit does not exist for transmissions. Failure of one subsystem in the drivetrain can result in consequential damage to another system, of which the transmission can be one.

There are many ways to look after a transmission, some of which involve taking care of components such as the engine, clutch, and others parts of the vehicle. 

“A transmission repair is usually a major repair and not a simple quick fix,” says Boeta Kotze, director at BT Transmissions. “A complete assessment has to be made when repairing the transmission.” This means evaluating the parts individually and understanding the interdependence of different subsystems on each other. By doing this, the root cause can usually be determined. 

The following are some tips for transmission care: 

• Each transmission type has a list of recommended service intervals based on the lubricant used.

• Ensuring that the transmission is serviced as per the schedule will fully extend the life of the transmission. 

• Through the electronic integration of mechanical transmissions, some functionality is constantly measured. Once a fault code is logged related to the transmission (or any other subsystem for that matter), it is important to have the fault investigated to ensure that consequential damage is limited. 

Servicing vehicle transmissions 

General servicing of the transmission entails cleaning up the oil pan and removing the filter and replacing it with a new one. This also involves draining the oil and refilling it with the specific transmission fluid.

Automatic transmission valve body machines test transmission valve bodies before they are installed into the vehicles. Kotze says that it is beneficial for this diagnostic equipment to be used by skilled technicians who have undergone training at different OEMs, both in South Africa and overseas.

“It is essential that the transmission oil gets changed in accordance with the OEM service intervals. Furthermore, it is imperative that the correct specification (viscosity) oil is used that conforms to the OEM specifications,” he expands. 

It is important to remember that most failures are maintenance related and can be avoided by adhering to the service schedule of the OEM. The correct oil levels should be maintained through regular checks. A daily trip inspection can help operators to ensure any abnormality around the transmission is reported and dealt with before it causes a failure.