The transmission assembly is a group of parts that regulates the amount of power and torque transferred from the engine to the wheels and ensures that the transfer of energy is efficient. While the exact process depends on the transmission type, e.g., whether it's a manual or automatic, the overall intended outcome is to allow the gear ratio between the engine and the wheels to adjust when the vehicle decelerates or accelerates.

What Transmission Assemblies Do

The transmission assembly makes use of a variable set of gear ratios in order to alter the torque output to the wheels from the engine's rotation. This is coordinated by a transmission computer in automatic transmissions and by the driver's input when they operate the clutch pedal and stick shift in manual transmissions.

Transmission Assembly Components

Gearbox (The Transmission)

The gearbox, also known as the transmission, is a part that contains various gears that adjust the engine's output.

Clutch (For Manuals)

In manual transmission assemblies, the clutch serves as the bridge to allow transfer between the engine and the transmission. By disengaging the clutch momentarily, the driver is able to change gears without grinding.

Torque Converter (For Automatics)

Found in automatic transmissions, the torque converter is a type of fluid coupling that transfers power from the engine to the transmission and is analogous to the mechanical clutch found in manuals.

Drive Shaft or Propeller Shaft

The drive or propeller shaft transfers power from the transmission to the differential and connects the transmission to the rear wheels.

Universal Joints

Universal joints are X-shaped parts that allow the vehicle's driveshaft to connect to the transmission and rotate freely.

Rear Axle

The rear axle is found in RWD vehicles and transfers power from the transmission to the rear wheels.

Wheel & Tires

Wheels rotate about the axle while tires provide them with traction to grip the road surface, allowing the vehicle to move.

Types of Transmission Assemblies

Automatic

Most automatic transmissions use a torque converter (while some use a mechanical clutch) that is controlled automatically through electronics, pneumatics, or hydraulics instead of manually through a clutch pedal to change gears.

Manual

In manual transmissions, gear shifting is performed manually with a gear stick and clutch. With proper operation, manual transmissions allow vehicles to achieve better fuel efficiency and performance. Manuals come with a learning curve, however.

Automated Manual Transmission (AMT)

The Automatic Manual Transmission is a semi-automatic gearbox system where the driver can choose between manual and fully automatic shifting.

Continuously Variable Transmission (CVT)

The CVT, or continuously variable transmission, can change through a never-ending range of gear ratios as opposed to other transmissions that only offer a limited number of gear ratios in fixed steps. This allows it to achieve better fuel efficiency and acceleration.

Maintenance

Proper care and maintenance are needed for your vehicle's transmission to last. Make sure to send your vehicle for scheduled maintenance, including transmission fluid checks. When driving, ensure that you're in the correct gear (that means not leaving your manual transmission in a low gear for too long) and that you warm up your vehicle before driving so that oils flow correctly. Make sure that your tires are not overly low, as driving on them can put unnecessary strain on your transmission. Finally, your vehicle's cooling system is also responsible for cooling the transmission fluid to an appropriate temperature, so make sure it is running in good order.

When to Replace Your Failing Transmission Assembly

Transmission Fluid Leak

A fluid leak can lead to low levels of oil running in the system and cause transmission overheating and inefficiency. Leaks can occur anywhere in the transmission, so you should have them repaired as soon as possible. In some cases, and if the transmission has incurred sufficient damage, replacement might be necessary.

Slipping Gears

Gears might slip if they are worn down and not meshing properly, resulting in lurching or unexpected speed changes. This is a safety issue and should be addressed as soon as it is identified.

Trouble Shifting Gears

If the gears are feeling clunky, making grinding or whining noises, or are delayed in shifting, there might be an issue with the transmission.

Burning Smell

Burning smells indicate that the transmission fluid is overheating. This usually happens when the transmission fluid hasn't been replaced in a long time. Old transmission fluid loses its lubricating and cooling ability and can make the transmission more susceptible to damage. This can be prevented by regularly replacing the fluid.

Check Engine Light

The check engine light might illuminate if the computer detects a problem with the transmission assembly. Get your vehicle checked to see if the transmission is at fault and if it needs to be replaced.

How to Choose the Right Transmission Assembly

Aftermarket or OEM

Original Equipment Manufacturer (OEM) transmission assemblies are those made by either the car brand itself or its authorized manufacturers, whereas aftermarket units are made by third-party manufacturers.

We recommend investing in OEM transmission assemblies to return your vehicle to its original level of performance. Because of the more stringent levels of manufacturing, you'll likely get more use out of an OEM replacement. Not to mention, aftermarket units may void your vehicle's warranty.

Vehicle Compatibility

When getting a replacement transmission assembly, you should choose one that matches your vehicle to ensure an accurate fit and original level of performance. Wherever you are purchasing yours from, select one with the same make, model, and model year.

Installation Considerations

If you're facing significant transmission issues, you'll have to opt for a rebuild or replacement. Rebuilding involves swapping out faulty parts and is the more economical option. Replacement, on the other hand, consists of replacing the existing one with a new or refurbished unit and is recommended when the current transmission assembly has suffered severe damage. Although it's more expensive, you'll likely get more use out of a replacement transmission.

Where to Buy Quality New & Used Transmission Assemblies

For brand-new, genuine transmission assemblies, head to your OEM part retailers in your country. Looking for a more affordable alternative? Purchase a transmission assembly in good condition and at great prices from a trusted dealer like BE FORWARD Auto Parts.