How to Rebuild a Transmission: Step by step (2022)

A failing transmission system can spell doom to any user of a vehicle at any time. It is an experience that you would not love to go through.

But what do you do when this vital component in your car starts to fail?

Do you buy a new one or you repair it?

Some people will go for a new one, while others will decide to rebuild the transmission system. It all depends on the ability of one’s pocket.

If you decide to rebuild it, how do you do it?


Come with me as I show you a step by step guide, on how you can rebuild your Transmission.

But before that, we have to understand what entails the transmission system.


What is Transmission?


Transmission is a mechanism contained in the engine of a vehicle. The responsibility to change the gears of the vehicle solely falls on it.

This engine energy is, in turn, transferred to the wheels to enable the car to move.

In simple terms,

It is the mechanism that converts the engine power into a force. When that force reaches the wheels, it enables the vehicle to move forward.

There are two types of Transmission.

  1. The Automatic Transmission. It is where the vehicle shifts the gears on its own without the input of the driver. It means the driver does not change the gears of the car.
  2. The manual Transmission. It is where the driver shifts the gears of the vehicle. It happens with the help of a transmission stick and the clutch pedal.

The vehicle cannot move from point A to point B without the Transmission. So, it is a vital component in any type of automobile


What is the importance of a transmission to a vehicle?

The Transmission system is an essential part of your vehicle. Therefore, it plays a crucial role in your car.


The transmission system is a combination of parts that play essential functions. These parts include the following,

1. Transmission fluid

Hand pouring transmission fluid through funnel

Hand pouring transmission fluid through funnel as for the good car maintenance

Transmission fluid plays the role of lubricating the engine parts. The fluid ensures the proper functioning of the transmission system.

Also, it helps to lower the engine’s heating, which ensures the engine stays cool. The luid is also viscous. It is a medium through which power flows from the engine to the transmission system

2. Planetary gear set 

Planetary gear set 

It is a set of gears that help to transfer the most significant revolution force compactly to make the car move.

3. Transmission Sensors

Transmission Sensors

There are two types of sensors, the speed sensor, and the pressure sensor.

The speed sensors identify the input and output speed of the Transmission. It, in turn, transfers the same information to the transmission control unit (TCU).

The information helps to regulate pressure and decide which gear to engage.

The pressure sensors determine the hydraulic pressure on the transmission components.

4. Torque converter

Torque converter

It is essential to the car because it helps the vehicle to come to a stop without an abrupt stoppage of the engine.

It also helps when starting your vehicle by giving it that extra force to move

Other components found in the transmission system are

  • Clutch pack and bands.
  • Output shaft and axle.

All the above parts play an essential role in the transmission system.

Let us get back to what I was saying about the importance of the Transmission.

It is important because it converts the engine force into power that enables the vehicle to move. Without Transmission, engine power cannot reach the wheels of your car.

Simply put, the transmission system is a link between the engine and the wheels.

Another aspect that you should understand is the RPM. The engine operates at a higher RPM (revolutions per minute). It usually is 700-7000 RPM than the wheels, which is 700-1600 RPM.

So, it means the wheels cannot keep up with the engine speed. Why? Because the wheels RPM is much slower than that of the engine.

The transmission system ensures harmony between the engine and the RPM of the wheels.

The work of the Transmission is to convert both momentum and speed into power. In the same way, it enables the car to use the power to make it move.

When you fail to maintain the Transmission with proper care, it is likely to malfunction. It is a crucial point to remember at all times.

Unfortunately, it can cost you a fortune to repair or rebuild when it malfunctions.


How do you know that your Transmission Needs a Rebuild?

rebuild transmission

Certain things can state to you that your transmission system needs an overhaul.

  1. When you step on the accelerating pedal, the engine makes loud and unpleasant noise. There and then, you will know that the Transmission has a problem and needs a rebuild.
  2. While in motion, you will notice a burning smell or odd smell emanating from the engine.
  3. Another visible sign is the leaking transmission fluid.

When you park your vehicle at one point for some time, you notice colored fluids on the ground. It is an indicator of a faulty transmission system. Remember, the transmission fluid comes in different colors. It helps to distinguish it from other oils.

  1. Another indicating factor is the grinding of gears, making it hard when shifting. It may be as a result of heating or dirty transmission fluid, thus causing the gears to grind.
  2. When engaging the gear, it stays in one gear, or it won’t engage at all. It should tell you that your transmission system needs a rebuilt
  3. Despite the vehicle engine running normally, the car has little or no power at all. The vehicle appears to be struggling to move. It should tell you there is a problem with the Transmission.
  4. Most vehicles have the transmission light signals. When this light pops up, then it is time for you to check the Transmission

Once you note the above signs, you must check your transmission system. That is when you can determine if you need to perform a rebuild or replace the entire system.

You may wonder why some people use the terms rebuild and others overhaul. The words mean the same.

More about that later


How do you Rebuild the Transmission?

rebuild transmission 2

As mentioned early, the Transmission is a complex component than any other part in a vehicle.

Rebuilding the Transmission is not an easy task like replacing your car tire. You must have some basic mechanical or automotive knowledge and skill.

The knowledge and skill make it easier for you to carry out the Transmission rebuild.

Come with me as I explain step by step on how to rebuild your Transmission.

  1. You must have the right transmission rebuild kit before you start a rebuild. You can buy the package or borrow it. The type of kit will depend on the type of vehicle that you have.

What is essential is that the package of the transmission kit must have all the tools. If you are buying from a dealer, go for the one that comes with a full instruction manual.

Also, it is worth mentioning that an ideal transmission kit should come with a warranty.

  1. The second step is to remove the Transmission from your vehicle. Accessing the Transmission will involve removing the entire engine block. Also, you will have to remove the torque converter, followed by the oil pan.

Why is this second part important?

Well, it is easy to access the Transmission if it is not attached to the vehicle.

The Transmission has many almost identical parts. Therefore the last thing you can do is remove it without paying attention to these parts.

If need be, then the labeling of these parts is crucial.

After you have removed the Transmission, you can now disassemble the Transmission. But before that, ensure you drain all the transmission fluid.

  1. The third step is the cleaning and inspecting the transmission parts. After you have done the second step above, the most crucial part follows.

You inspect and identify the faulty part. How do you do it? It involves cleaning these parts in a specially formulated chemical.

By doing all this, you identify any worn out and wonky parts that need replacement with new ones. Likewise, the ones still in good condition, you clean, and replace them in the Transmission.

Remember, it is essential to replace all the oil seals and gaskets with new ones.

It is essential because it helps you to cut or avoid any leakage that the old ones might cause.

  1. Reassembling of the Transmission. It is the part that will require you to pay attention to every piece. You must ensure that each part fits precisely in its rightful spot.

Any little mistake will make you start over again. Of course, this is why where labeling of these parts while removing them comes in handy.

You have to verify that every part has fitted precisely in its right place. Then, you perform the pressure test, which comes last.

The pressure test helps you to determine whether the pressure is too low or too high, is it leaking or not. Don’t forget the role of pressure in the Transmission.

Therefore you must carry out pressure tests and checks.

  1. The final step that follows is to mount back the rebuild transmission to the vehicle. It should not be a problem with the right tools in place.

After understanding what to do when you are rebuilding your Transmission,

How Long Should it Take you to Rebuild a Transmission?

As I mentioned early, transmission rebuild is not your usual standard service procedure. A procedure, such as changing engine oil, or replacing your car tire, is a simple task that any novice can do.

But, it takes more than that when it comes to a Transmission rebuild.

It is a complicated undertaking that requires a lot of proper knowledge. The person doing it has to know how to do it.


The duration of the transmission rebuild depends on the complexity of the problem.

Also, it will depend on the person doing the rebuild. If the person is a novice, then it is likely to take longer than it should be.

But, if the person is an experienced mechanic, it should not take longer than expected.

Usually, a transmission rebuild takes 3 to 4 days. It will depend on where you have taken the Transmission for a rebuild.

It is wise that you take care of your transmission problem early. It not only brings down the time taken to rebuild the Transmission but also saves you the cost to incur.

So, failing to address these small issues will take you long to rebuild your Transmission. Do not forget the strain and pressure it will be putting on your pocket.

The above procedure involves rebuilding a transmission. But here is a question you should ask yourself.

How Much Will it Cost me to Rebuild a Transmission?

The answer to this will solely depend on some factors. One is the type and the model of the vehicle you are using.

If the car you are using is much expensive, then expect the cost of rebuilding the Transmission to be higher.

In the same way, a cheaper car will require low cash input to reconstruct the Transmission.

What is the size of the damages? To what extend is the damage to the transmission parts? Therefore, the more the injury to the transmission parts, the higher the cost of a rebuild.

So, if I rebuild it at the garage or any type of shop, it will cost me close to 3000 US Dollars. It is so when you factor in labor costs and other things that technicians will carry out.

But if I decide to do it myself, I will cut the cost to half. That is 1000 -2000 US Dollars. It means it will cost me more at the garage than when I do it myself.


To sum up, rebuilding a transmission should not be a pain in the neck. It is a procedure that requires one to have the right knowledge, skill, and tools to carry it out.

It will take you a shorter time with a little cost if you know what to do. Trust me. You’ll be glad you did.


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