How to Buy Gearboxes and Gearbox Parts

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How to Buy Gearboxes and Gearbox Parts

There are a lot of details that go into owning and personally maintaining one's own car. Knowledge is key whether one must change a tyre or fix an engine. A transmission is another important element, and whether the goal is to fix a broken transmission or to completely rebuild a car from the ground up, knowing how to buy gearboxes and gearbox parts is essential. This important element of a car's internal system must be solid if a car is to work at an optimal level. However, this means that buyers must be informed before they buy.

Understanding how a gearbox functions within one's transmission is the first step. Next, buyers should be familiar with common gearbox parts that they may need to buy. Finally, before moving on to the shopping step, buyers should also be aware of strategies they can use to successfully locate and save money on gearboxes and gearbox parts. Chief among these strategies is online buying techniques including the proper utilisation of eBay.

Understand the Function of a Gearbox

Before moving on in the buying process, it is essential that buyers familiarise themselves with the basic functions of a gearbox within a car's internal system. And, although the term gearbox is used interchangeably with 'transmission', in reality, the gearbox is simply the largest component of an entire system, which is collectively called the 'transmission'. The job of a car's transmission system is to allow the car to drive both forward and backward, and the gears within the gearbox determine the speed and direction in which the car moves. There are two major types of transmissions: manual and automatic. The gearbox functions differently in each of these types.

The Gearbox of a Manual Transmission

A manual transmission, sometimes called a standard transmission, requires the driver to select the gear within the gearbox that is needed in order to achieve the desired speed. This is completed using a gear shift which is located inside of the vehicle to the left of the driver's seat along with a clutch, which is operated through a third foot pedal located next to the gas and the brake. A manual transmission uses what is known as a simple gearbox which requires outside input in order to function.

Benefits of a Manual Transmission

The manual transmission is far more hands-on as compared to an automatic transmission, requiring a more active role on the part of the driver. There are several benefits to this including the fact that manually operating the gearbox gives the driver more control over the dynamics of the car in terms of both stopping and speeding up the vehicle. This control over the car's relative speed can lead to fuel savings as well as prolong the life of a car's brakes.

The Gearbox of an Automatic Transmission

An automatic transmission operates in a quite different fashion. Rather than requiring the driver to manually switch the gears within the gearbox, as the name indicates, an automatic transmission does this on its own. An automatic transmission has a gearbox which operates under a closed system. The driver needs not add much input in order for the system to work and for gears to change. Instead, the driver merely depresses the gas pedal as needed. The only control that a driver exhibits on the gearbox in an automatic transmission car is to put the car into forward or reverse.

Benefits of an Automatic Transmission

Although automatic transmissions allow for a lesser degree of control, they are the prefered transmissions of many drivers today. This is because these cars are considered more user-friendly and require a less active role in the process of speeding up and slowing down the vehicles.

Learn About Common Gearbox Parts

If one has a completely broken transmission or is trying to rebuild a car, the easiest thing to do is to replace the entire gearbox without worry to the component parts within it. All he or she needs to do is determine whether he or she needs a manual transmission gearbox or an automatic transmission gearbox.

However, if the damage done to a gearbox can be fixed, it becomes necessary to find individual parts for the gearbox in question. Like buying the complete gearbox, the parts needed vary depending on the type of transmission within the car.

Common Manual Transmission Gearbox Parts

Because of the complexity of operating a manual transmission, there are several component parts that can commonly malfunction. Remember, a manual transmission depends on driver input to function, so therefore the driver and driving conditions are more likely to directly affect the operation of the transmission and gearbox. The table below briefly describes each of the most common parts of a manual transmission gearbox and their relative function.

Gearbox Part


Mainshaft Gears

All modern manual transmissions are of a constant-mesh type in which all main shaft gears constantly mesh with the cluster gears, and therefore each must be functional at all times

Cluster Gears

Same as above


Used to prevent the above gears from clashing or grinding during their constant engagement

'Synchros' consist of several other parts including an outer sleeve, shifter plates, an inner-splined hub, blocking rings, and lock rings (or springs)

The table above outlines the most common basic parts of a manual transmission gearbox. It is important to note, however, that these are very broad terms. This is because the complexity of the gearbox makes it more efficient to replace the entire unit unless the problem is small, such as a single gear or gear set.

Common Automatic Transmission Gearbox Parts

An automatic transmission consists of two, separate systems: mechanical and hydraulic. These systems must work together in order to automatically adjust speed and gears of the car. There are parts within each category. In the table below, each of these parts are outlined, along with their system and function.

Gearbox Part




Mechanical and Hydraulic

Outermost part of the transmission which contains all mechanical and hydraulic systems

Gear Set


Known as 'planetary' gears; attached to planetary carriers via shafts to keep gears evenly spaced

Torque Converter


Fluid coupler system that allows an engine to idle without engaging transmission

Valve Body


Chamber containing one-way check valves, labyrinthine fluid channels, and solenoids; considered the 'brain' of an automatic transmission

Like a manual transmission gearbox, the gearbox within an automatic transmission is complex and difficult to fix in pieces. However, the closed system operates in a different way than the open, user-input system of the manual transmission, and therefore leads to a different list of gearbox parts which are worth reviewing.

Buying Gearboxes and Gearbox Parts on eBay

Once buyers are familiar with the function of the gearboxes within their cars and the parts that they need to get in order to fix or build them, it is time to begin the shopping process. Although car parts are common items in many physical stores, shopping online allows buyers the ability to quickly sort through all of the options there are as well as find the best price for gearbox and gearbox parts they need all from the comfort of home. eBay is a great place to complete this process.

Searching eBay for Gearboxes and Gearbox Parts

Like many car parts, gearboxes and gearbox parts are tailored to the type of car you drive. Therefore, the searching process should focus not only on the part or type of gearbox needed, but also the type of car for which it is needed.

Therefore, buyers can begin by conducting a general search using the main search bar at the top of every eBay page. However, success here depends on using the proper keywords. Therefore, "Honda torque converter" is good, but "Honda Civic torque converter" is better.

Alternately, buyers can start with a more generalised search and then narrow down the results according to their particular needs. This way, buyers begin by searching for "torque converter" and then use the limiters provided by eBay to narrow options by make and model of car.


For amateur and professional mechanics alike, the knowledge of vehicle systems is the more important aspect of proper maintenance. This includes everything from the simplest tyre change to the complex inner workings of a car's transmission and gearbox. Therefore, learning how to buy gearboxes and gearbox parts is an exercise in overall knowledge as well as purchasing skill.

Though the terms gearbox and transmission are often used interchangeably, technically speaking the gearbox is merely the largest component part of a car's transmission system. It varies in its functions and parts according to whether the transmission is manual or automatic. Common parts needed for a manual transmission include mainshaft gears, cluster gears, and synchronisers, whereas common parts in an automatic transmission include the case, gear set, torque converter, and valve body.

Once buyers know what they need to fix their gearboxes, or even if they decide to replace the gearboxes, the buying process is best conducted online. This gives buyers an easy way to compare available items and prices. eBay, for example, if searched properly, can offer buyers targeted options and easy cost comparison leading them to saving time and getting their cars fixed or built faster.

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