WHAT IS THE GEARBOX?

A gearbox is a contained gear train that is composed of a number of mechanical gears designed for controlling the torque and the speed of a vehicle. In manual transmissions a gearbox, technically a ‘constant-mesh gearbox,’ is the second stage of the transmission system after the clutch. There can be as many as four or five forward speeds, one reverse, and one neutral position in the gearbox.

Gearbox Housing

WHAT DOES THE GEARBOX DO?

The gearbox is designed to increase or decrease speed in a vehicle using different gears or gear ratios. This is executed by the gearbox’s ability to alter torque and speed between the motor and a load. In other words, because gears move at a higher speed than the wheels of your vehicle, multiple gears are required to reduce the speeds. A gearbox has a variety of gears for either standing, climbing, or cruising – and the lower the gear, the slower the wheels turn compared to the engine’s speed.

WHAT DOES A GEARBOX LOOK LIKE?

A gearbox is a single housing unit that contains a number of gears and is part of the transmission (a transmission refers to the whole drivetrain, including clutch, gearbox, differential, driveshafts, etc.). The gearbox is usually bolted to the rear of the engine, with the clutch in between them.

WHERE IS THE GEARBOX TYPICALLY LOCATED ON THE VEHICLE?

The gearbox is the second stage of the transmission that is located after the clutch. This part is bolted to the rear of the engine.

WHAT DO YOU LOOK FOR IN A USED GEARBOX?

When shopping for a used gearbox, be sure to check the gears themselves to make sure that they are not worn. Also, you want to make sure that the housing itself is in top shape and that there are no cracks in the gearbox casing. Also, check to make sure that the gearbox itself is free of any rust of corrosion.

WHAT ELSE SHOULD I KNOW ABOUT A GEARBOX BEFORE I PURCHASE ONE?

The typical gearbox will last about 100,000 miles. However, if a gearbox has been well maintained, then it may last for up to 300,000 miles. If you are pulling a gearbox out of an existing vehicle, be sure to check the vehicle’s mileage. Also, it’s a good idea to check the maintenance record of the vehicle if it is available.

WHAT OTHER PARTS ARE CONNECTED TO THE GEARBOX THAT I MAY NEED?

The gearbox is part of the transmission and it is connected to the clutch. Therefore, you may want to consider getting a clutch shaft along with the gearbox.

WHEN SHOULD THE PART BE REPLACED?

The gearbox should be replaced if you notice the following performance issues of a vehicle:

• Dashboard warning lights - check to see if your transmission temperature is running at a high level.
• Leaking fluids - A failing gearbox can lead to leaking transmission fluids.
• Audible noises - If you begin to hear noises coming from the transmission, then you may be having issues with the gearbox.

FREQUENTLY ASKED QUESTIONS ABOUT A GEARBOX

WHAT ARE THE THREE TYPES OF TRANSMISSIONS?

When selecting a gearbox, it is important that you select a model that works with the transmission of your vehicle. The three types of transmissions are manual, automatic and CVT. Make sure that you get a gearbox that is compatible with the right transmission.

HOW MUCH CAN IT COST TO HAVE A GEARBOX INSTALLED?

If you are looking to have your gearbox professionally installed, then you can expect to pay anywhere between $400 to $800 depending on the model of the vehicle. Note that this cost does not include the price of the gearbox part itself. The gearbox may not be sold as a separate item at your local salvage yard and may be considered part of the transmission.

You can purchase a transmission at a salvage yard like Pull-A-Part for about $100. You can also search pricing for transmissions and any related parts in the used auto parts pricing section of our website. Prices are consistent for each part type regardless of vehicle year, make and model.

HOW DO YOU REMOVE A GEARBOX?

Removing a gearbox may vary from vehicle to vehicle. You should search YouTube for a video on how to remove a gearbox from your particular year, make and model vehicle to provide you with more specific information and directions before heading out to the salvage yard.

In general, to remove a gearbox from a vehicle, you’ll follow these steps:

1. Remove the gear shifter, handle, and/or knob
2. Remove the trim plate or console
3. Remove any wires or cables that may be attached (you may want to label the wires with tape if you also need the wires or related connectors for your repair)
4. Remove the transfer case by loosening the bolts attaching it to the transmission – the driveshaft (for rear wheel drive) or axle shafts (for front wheel drive)
5. Remove shifter or shifter lever – if you have a shifter or shifter lever attached, you’ll want to remove it
6. Remove transmission mount – remove the bolts holding the main transmission in place and the mount
7. Remove the crossmember from the frame
8. Support the rest of the transmission before removing the gearbox – you do not want the transmission to fall onto you or the ground. Please don’t work from underneath the transmission itself.
9. Remove the gearbox using the bolts that attach it to the transmission – be sure the transmission is supported before removing it.

WHAT TOOLS WILL I NEED TO REMOVE A GEARBOX?

If not obvious from the steps above, removing a gearbox does require a fair amount of work on your part. We recommend searching YouTube for a video on how to remove a gearbox from your specific year, make and model vehicle, as you will learn the tools you will need and time required to remove a gearbox for your vehicle.

In general, to remove a gearbox from most vehicles, you should have a variety of wrenches, sockets and ratchet, a breaker bar for leverage, and penetrating lubricant to loosen nuts.