Automatic transmission

By Leamas, 9 November, 2022
Some modern transmissions do not require oil maintenance because they are filled with lifetime fluid that supposedly last the lifetime of the transmission.

Technically, there is more to the meaning of lifetime transmission fluid. When people say they last the lifetime of the transmission, they may be right or not right. Theoretically yes, but practically maybe no.

There have been many other definitions. Some attribute it to warranty period. Others attribute it to 100 miles, 120 miles or 150 miles of vehicle usage.

By Leamas, 6 November, 2022
The eCVT in hybrid cars have electric motor/generator sets in it which the engine and regenerative brake system uses to charge the hybrid battery. A wrong transmission fluid in it will cause short circuit, malfunction and damage.

There are different types of automatic transmissions and different specifications of automatic transmission fluids, depending on the car. Most hybrid cars use eCVT (electronic Continous Variable Transmission) which uses planetary gear sets and electrical motor/generator sets.

The electrical machine in the transmission acts as a motor when it is being used to drive the wheels and acts as a generator when it is being used to charge the battery.

By Leamas, 27 June, 2022
Transmission fluids expand as they heat up. This changes the volume and the fill level. This makes the temperature st which fluid level is checked important.

As a car is being used, it is good preventive maintenance practice to check the quality and quantity of the transmission fluid at intervals.

The quantity check is done by monitoring the fill level of the transmission oil.

Also, transmission fluids degrade over time. At a point, it becomes necessary to remove old fluid and put in fresh fluid. The process of filling requires transmission level check.

By Leamas, 26 April, 2022
Coolant can gain access to transmission through the transmission oil cooler. The oil cooler can leak internally causing the coolant and oil chambers to be linked.

Transmissions are one system of cars that work hard and generate lots of heat. As the transmission runs, the cluches, bands and gears generate a lot of frictional force and heat.

This makes external cooling of the transmission to be necessary, though not all transmissions are externally cooled. Water getting into the transmission can damage it in no time.

When this happens, the transmission will need a rebuild or a replacement unless the issue is identified and fixed before the damage begins.

By Leamas, 12 March, 2022
If a transmission was previously not properly maintained by not carrying out regular oil change, changing the oil later might cause it to slip or not shift at all.

When a transmission has poor maintenance history, it's good to know and apply an approach that will not cause it to start slipping or not engaging at all after fresh fluid is introduced into it.


What is an automatic transmission fluid?

An automatic transmission fluid commonly called ATF which is an abbreviation is a special fluid formulated for torque converter operation, valves operation, transmission clutches and brakes operation, heat transfer and for lubrication of gears.

By Leamas, 9 December, 2020
Transmission fluid leak can degenerate to serious transmission faults or total damage if the leak is not fixed immediately.

Have you noticed a transmission fluid leakage and you don't know whether you can manage the car to your next destination or simply park the car to fix it first?

Transmission oil leakage can be minor or major but not fixing it will eventually lead to destruction of the transmission.

Even if the leakage is minor, it should be fixed immediately.



1. Leak in oil pan due to impact with rocks, curbs and so on..

By Leamas, 27 November, 2020
Transmission especially the automatics can overheat. The causes range from bad clutch, wrong fluid, overfilled or underfilled transmission and bad oil cooler.

Overheating is a major killer of automatic transmissions especially when the overheating is not caught on time.



Fluid leak - When the automatic transmission fluid is low due to leakage, there won't be enough fluid to circulate and dissipate the heat thereby causing transmission overheat.

Low fluid - Low transmission fluid level can be as a result of fluid leakage or incorrect fill level when the transmission was filled.

By Leamas, 23 November, 2020
Modern transmissions are not as simple as they used to be. We can say that transmissions have become smart with the introduction of AI machine learning algorithms.

Through artificial intelligence and machine learning, transmissions can learn and make adjustments to stored values without those values being explicitly programmed into the transmission's computer (TCU or ECU).


Two important parameters in the operation of an automatic transmission

1. Shift pressure

2. Shift timing


This shift pressure and timing in the valve body of the automatic transmission controls the application of the clutches.

By Leamas, 6 November, 2020
Replacing old tranny fluid at the right time is crucial to performance & lifespan of transmissions. Transmission fluid quality should be checked periodically.

Automatic transmission of a car is very delicate and should be taken care of.

It is very important to carry out oil change preventive maintenance on a car's transmission to ensure its longevity.

By Leamas, 14 October, 2020
Fitting the checkball in Aisin transmissions when it is mounted in the car can be a nightmare. This is a simple technique to use to fit the checkball.


The check ball can sometimes be a pain to fit back into its normal position when the transmission valve body is removed.

During valve body removal of Aisin transmissions, the check ball could easily fall off and where it falls from is sometimes a challenge to technicians. The picture attached serves as an example since the check ball position looks identical in many Aisin transmissions.