Semi Automatic Transmission (How it Works and Pros/Cons)

Last Updated on May 6, 2020

Ever since the 1930s, semi-automatic transmissions have existed. But they slowly evolved over the decades and now we have something much different than what existed back then. That is common with every component of a car, though.

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What is a Semi-Automatic Transmission?

A semi-automatic transmission is basically a manual transmission that does not use a clutch. Instead, the gears shift as the driver gives a command that gets sent through electronic sensors and processors. These sensors are what replaces the clutch pedal, which would normally be depressed by the driver prior to shifting gears. Now the electronics tell the clutch what to do which helps great smooth shifts in the gears because the torque and timing are nearly perfect.

Automakers in Europe were responsible for developing the semi-automatic transmission because they felt it would enhance the experience of driving. This is especially the case in crowded places like cities where you must constantly stop at lights and go on green lights.

So, the main difference between manual transmission and semi-automatic transmission is that manual transmission uses pipes and cables while semi-automatic uses electronics and actuators. These computers take the pressure off the driver.

How It Works

The driver of a semi-automatic will still have to change gears using a manual gearbox. The only thing is the gearbox doesn’t need you to depress any clutch pedal because the electronics of the semi-automatic take care of the clutch themselves. Because of this, the gearbox can accurately calculate the right time for the gears to shift which enables them to shift fast and smooth.

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The only problem is that you may come across a gearbox which doesn’t perform its job as fast as you’d like it to. This would especially be the case if you’re driving and then must slam on your brakes to slow down quickly.


– Requires more money to maintain a semi-automatic than it does for manual.

– Repairing a semi-automatic is expensive. Replacement would actually be cheaper.

– Semi-automatic tends to malfunction and fail frequently. There are lots of reasons why this could happen and they may not even involve the transmission directly.


– The driving experience is very smooth when shifting gears.

– If the torque converters experience slippage, there won’t be any loss of energy. You won’t experience this loss during manual shifts either.


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