Preparing to buy – Understanding car transmissions

November 6, 2018 11:46 am | macarthurautomotive.com.au, macarthurrenault.com.au

Cars generally come with two different types of transmissions, though there are more varieties available. However, if you know nothing about cars, even the word 'transmissions' is likely to leave you bewildered, despite how important it is to the running of a car.

Put in context the term is much more recognisable, for example, when being told that the Renault Captur Zen has a 5-speed manual transmission. 

If you're looking to buy a new car, what do you need to know about transmissions, and which type best suits your needs?

What is a car transmission?

Simply put, a transmission is the part of the drive train which takes an engine's power and transmits it to the car's drive wheels.

When it comes to car engines, power and torque are at their maximum within a narrow RPM range. To keep the performance of a vehicle at its best it needs to stay within this band. If it sits below, your car won't be getting enough torque to move. However, if it goes above this, the sound produced by the engine isn't a pleasant one, and you don't even get any more torque to work with to compensate for it. Anyone that's revved their engine too hard will be aware of this problem, and probably all too eager to avoid that noise ever again. 

A transmission helps keep the engine running within the right RPM range while ensuring that the wheels receive the amount of power they need for moving and stopping the car. It does this by sending the torque through a variety of gears, relying on gear ratios, to convert it accurately. 

It's possible to break transmission types down into a range of varieties. However, you'll largely only need to know about the two main ones. Often which one works best for you depends on the type of driving you do.

The pros and cons of a manual transmission

Pros:

  • Generally, manual transmissions have better fuel economy.
  • Due to fewer parts involved, less maintenance is needed.
  • A manual gives you more control. You can use your gears to monitor vehicle speed or shift down when an extra boost of power is needed.
  • More involved driving experience.

Negatives:

  • It's more difficult to learn to drive a manual. 
  • Less convenient, especially for city driving.

The pros and cons of an automatic transmission

Pros: 

  • They're convenient and easy to drive.
  • Good for city driving where sitting in traffic is common. 
  • Automatics are more popular and prevalent, meaning they're easier to buy. 
  • Parts are simpler to find. 

Cons:

  • Repairs tend to be more expensive. 
  • More maintenance is needed.
  • Issues develop more regularly than for manual transmissions.

Do electric cars dream of transmissions? 

Unlike figuring out whether androids dream of electric sheep, it's much easier to work out whether electric cars require a transmission. Blade Runner references aside, the simple answer is no. An electric motor produces its best power output over a much larger RPM range than petrol cars, meaning that gears aren't required to keep the vehicle performing at its best.

However, this doesn't mean that a transmission couldn't add something to an electric car, which is why well-known transmission makers like ZF are working to create them. Currently one of the issues found in electric vehicles is that the overall top speed is reduced to allow an evenly spaced amount of power.

So as electric cars develop, keep an eye out for ones boasting a multi-gear transmission, and test out the difference it makes yourself. 

If you want to get more advice on which transmission type works best for you, head down to the Macarthur Renault dealership and talk to the friendly team there.