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A Guide to Changing a Gear Box

MG, an Air- Warrior is a lover of Automobiles and has a fair amount of knowledge on cars and maintenance



I have always been fond of cars and my repertoire of them includes a BMW, Ford Mustang, and not forgetting the Mahindra XUV 500 and Toyota Prado. Many years back while driving in the mountains of Ladakh, my gearbox began to give some problems and that is the time when my driver told me that we would have to remove the gearbox and then somebody would have to take it to get it repaired. We removed the gearbox and I realized the importance of knowing all things mechanical about my cars.

A gearbox is a mechanical way to transfer energy from one device to another. It is an essential ingredient of a car. It has a system of metal gears that enmesh with each other and directly increase torque and reduce or increase speed in a motorcar. Generally, gearboxes work with special gear oil, which cuts down the friction between the metal gears for longer life. Modern gearboxes last many years, but depending on the type of driving a gearbox may last longer or wear out. All gearboxes have a clutch which is a plate that is synchronized with the gears to facilitate easy shifting of gears.

This plate or clutch can either be operated manually or automatically. In automatic gearboxes, the gear changes are synchronized with the speed of the car and change automatically. But a special slot is a requirement for a reverse gear or an uphill climb.


When to Change a Gear Box

Gearboxes last a lifetime, but depending upon the type of driving, a gearbox may require repairs. In case a gearbox wears out or its gears break, the only option is to either change the gearbox or repair it. Changing a gearbox is a costly proposition; as such it’s always better to get it repaired.

In both cases, a gearbox will have to be first removed. It can be fitted back after it is repaired. Gearboxes are mostly at the bottom of the car where they are located. Mostly they will be at the rear of the engine. To remove a gearbox is not easy and one will have to bend down under the car to remove a gearbox. You will also require special tools with you and in the case, I have mentioned above as we were going to travel in barren and mountainous areas, with no population a set of tools was carried in the car

Tools Required for Change of a Gear Box

Before starting to remove a gearbox, it is imperative that the proper set of tools is available. These tools should be so placed that the person removing the gearbox has easy access to them. It is preferable to keep them on an oilcloth close to the car within easy reach. The following tools will be required; a hammer, Torx set, sets of spanners, a Socket set, a Chisel to ping hub nut loose, Pliers, and a girlfriend to serve you tea. The last may not be available in case you are driving in a desolate place like Ladakh.

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Steps to change a Gearbox

The first step is to drain the gearbox oil. This can be done by getting under the car and loosening the drain plug of the gearbox. This is at the bottom of the gearbox. A metal trough should be placed under the drain plug to collect the gear oil; otherwise, the entire oil will spill and spoil the floor.

The next step is to remove the front wheels. This is essential so that the mechanic can have free and unfettered access to the gearbox.

The third step is to try and down the gearbox. This is done by unloosening the driveshaft hub nuts. These will require some effort and it is important that the correct size wrench be used. Follow up by removing the wishbone pinch bolt. By using a hammer, the wishbone next to the ball joints is removed.

The gearbox is normally kept synchronized with the engine with a set of bolts in a housing. These bolts will now have to be loosened and removed. Once the driveshaft is disconnected from the gearbox, the mechanic would have finished almost 60% of the job. Ensure that you have a jack for the engine; otherwise, it may fall to the floor.

Follow up by removing all linkages and pull the gearbox away from the engine. The task is now complete and the gearbox can be sent for repairs, which is a specialized task. The gearbox cannot be repaired in your garage or on the road and must be sent toa specialized workshop. In our case, the driver took a lift in an Army vehicle and went for repair to the army workshop.

Fixing Back

Fixing the gearbox is a greater pain than removing it. The gearbox will have to be held firmly, to position it in the housing, and immediately the bolts must be tightened. Once the gearbox is in position the other linkages can be re-connected.

Last Word

Generally removing a gearbox of a small car is about an hour’s job. By small car, I mean cars of about 1000 cc like Suzuki. But removing the gearbox from larger cars is best left to a professional. Don't attempt it also and I will not advise it. You have a problem on the road just ask for a tow vehicle.


MG Singh emge (author) from Singapore on December 09, 2020:

Thank you Lt Col for commenting. Yes, one can easily do it in a Suzuki 800 or similar cars but not in the bigger cars.

Lt Col Parduman Singh on December 09, 2020:

Nice article, yes, I agree you can do this for a small car. I was once stranded in the jungle in Chattisgarh in my Suzuki, an 800 cc car, and could remove the gear box. I dare say not possible in larger cars like a Fortuner.

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