Welded Differential: In The World Of Differentials

The welded differential, is the modification of any budget drift car. If you are looking to start drifting or off-roading you may have heard people talk to you about welding your differential.

In this article, we will not only cover why they a so popular but how a welded differential truly compares against other store-bought differentials and every other important details you need to know about welding differentials.

welded differential

What is a welded differential

A welded differential is as the name implies, a differential someone welded together.

Welding your differential is the easiest and cheapest way to turn your boring rear-wheel drive car into an absolute drift missile. This modification is also often used for off-roading allowing better traction and power control in slippery and uneven terrain.

A welded differential locks and forces the wheel on both sides of your car to rotate at the same speed. This will drastically change how your car behaves around corners, and it is not ideal for everyday street driving.

Therefore, to properly understand why people do this backyard modification to their car, let’s look at what a normal or “open” differential is.

What is a differential

When taking a corner the wheels on the outside of that corner need to rotate much faster and travel a greater distance to keep up with the ones on the inside.

This effect is easily achieved when it comes to the non-drive wheels of your car. They can simply be on two different axles and spin independently.

However, the drive wheels need to be connected to both receive the power from the engine. Despite the fact that they are powered by the same source and share the same axle, they must be able to move freely from one another.

This is where engineers came up with the “Differential”. A differential is a simple mechanism composed of gears allowing this effect to occur.

Axle ratio or Final drive ratio

Since the differential is made up of gear there is ultimately a gear ratio that goes with it. This gear ratio is called the axle ratio or the final drive ratio. It can be modified according to the simple principles of gear ratio and allow for better acceleration or better top speed. (1)

Acceleration: A higher final drive ratio like 4:1 will give better acceleration but lower top speed.

Top speed: A lower final drive ratio like 3:1 will give better top speed but slower acceleration.

How does a standard differential work

The functioning of a differential is a very simple concept to understand. However, it is easier explained over video than images and text.

Therefore, if after our explanation you’re still unsure about the functioning we recommend you do a quick search on YouTube to fully grasp the concept.

Differential Gears
Differential Gears

Drive shaft and pinion gear

The drive shaft is what connects and transfers the power from your transmission to the rear wheels of your car. It is connected to the pinion gear which is the first gear inside your differential.

The pinion gear is also the motor gear of the assembly and rotates with the drive shaft.

Ring gear

As the pinion gear rotates it turns the ring gear with it. The ring gear is connected to the gray assembly in the image above. Both the ring gear and gray assembly rotate together as one big piece.

For better visualization: The ring gear rotates the same way as the car wheels.

Spider gears

The spider gear is attached to the ring gear assembly and therefore rotates with it. However, the spider gear can also rotate freely on its own axis.

There can be up to 4 spider gears one on each side (front, back, top, bottom) for durability.

side gears

The side gears are connected to your axles, one on both sides of the car. The axle and its corresponding side gear move together.

This is where the tricky part comes in.

The side gears are being rotated by the spider gears and the spider gears rotate the side gears by moving with the ring gear assembly.

When the car is going straight both axles can move as one solid unit. But when you take a turn the spider gears rotate on their own axis allowing the side gears to move at different rpm.

This also implies that power is always sent to the wheel with less resistance.

How does a welded Differential work

A welded differential as we said earlier is the modification of a standard open differential.

It consists of welding the spider gears to the side gears. Therefore, the ring gear, the spider gears, and the side gear all become one big moving part. A welded differential is simply the transfer of the drive shaft rotation through the ring gear and directly to the wheels.

This ensures that both wheels spin at the same rpm by welding and locking them together.

The reason for a welded differential

As you may be thinking, differentials were added to cars for better handling and drivability so why weld them? The simple answer is drifting.

Drifting is the primary reason people weld their differential, yet another reason like off-roading is also pretty common.

When drifting you want maximum power delivered to both of your rear wheels. With an open differential as we said earlier the power is always sent to the wheel with less resistance.

As a result, you will find yourself burning rubber on only one tire or you will have a hard time oversteering and sending that rear end sideways. A welded differential ensures that no matter what both wheels will receive the same amount of power and rotate together at all times.

A welded differential is also great for off-roading. Because when driving on uneven terrain, one wheel will occasionally be in the air, and you do not want that wheel to receive all the power from your drive shaft.

The pros and cons of a welded differential


  • Quick modification to do
  • Budget friendly
  • Easy modification to do
  • Good durability if done properly
  • Better drifting performance 
  • Better off-roading performance


  • Decent welding experience is needed
  • Harder to park your car
  • Harder to back up your car
  • Slow and tight turns on pavement will cause your tire to skip (bounce) and squeal
  •  Uneven or quicker tire wear
  • Bad traction in snow and rain (dangerous)
  • Higher risk of breaking an axle when offroading
  • Overall not amazing for daily driving

How to weld a differential

Step 1: Locate and remove the differential

The differential is not hard to find. It is the box attached to your rear axle and driveshaft.

Once you have located it, remove all surrounding parts that could interfere with the removal of your differential case. Afterward, proceed to unbolt the case from your axle and drive shaft.

Removing the differential from your car is recommended but may not be necessary in all cases. For example, if you are working on a lifted truck you will more than likely have enough room to work comfortably underneath the truck.

Furthermore, not removing the differential can make your life easier especially if you are working outside on the ground. However, If you leave the differential case installed on the car it is very important to take necessary precautions for any hazards.

*The gas tank is often located right above the differential*

Step 2: Drain oil and open the differential

Whether you chose to leave the differential installed or not, your next step will be to drain the oil from the differential case by removing the drain plug.

The plug will usually be located at the back of the differential on the case lid (there might not be one). Once you have drained the oil you can proceed to remove the differential case lid. If you haven’t drained the oil by the plug be sure to have a catch pan underneath when removing the case lid.

step 3: Clean the differential

Now that your differential is open it is very important to thoroughly clean it. It is not ideal to weld dirty and oily metal. This step is very important for your welds to be strong and durable. (2)

Step 4: weld the differential

Now that the gears in your differential are clean you can start the process of welding them together.

You want to weld the spider gears to your side gears. (see image #1 and #2 above) It is very important to make good and well-penetrated welds to ensure a strong final product.

There are two main ways people usually go to weld their differential. You can either weld the gears together directly (see image #3) or cut a square metal plate and weld the gears to that plate. (see image #4)

If you choose the first option, doing a weld as shown in image #3 is perfectly fine. However, a personal recommendation is to weld inside the first gear slot beside your weld on both gears to make it even stronger.

Step 5: Clean and close the welded differential

It is important to give your welded differential a good clean and inspection before closing it back up. You want to remove anything that may have fallen in the case during this whole process.

You can also check and make sure there isn’t any small drop of metal from your welding that could come loose in the case. After making a last check you can reinstall the differential case lid.

step 6: fill up with oil and install welded differential

You now have a welded differential. You can fill the differential up with oil and install it back on your car.

Welded differential alternatives

As we said above, welding your differential is a backyard, cheap and easy alternative to lock your rear wheels together. However, If you’re prepared to invest the money, there are other differential options you can purchase instead of welding your differential.

Common welded differential alternatives includes the following:

Limited slip differential (LSD)

Mechanical limited slip differentials are arguably the most common type of differential due to their wide range of applications.  They are a great differential to reduce loss of traction.

They are used to limit the amount of independence each axle has from one another.

Like an open differential, it allows the wheels to rotate at different speeds. However, it limits the amount of power sent to the wheel with less traction while effectively offering constant power to the tire with higher traction when needed. 

This allows the wheel with traction to receive more torque in order to continue to move the vehicle. 

The most common type among drifters is the 2-way clutch LSD.

Locking differential

These differentials are basically an on-and-off welded differential. As the name suggests this differential locks the axles together. But it can also be unlocked.

This mechanism can be either automatic like the Detroit system where the differential remains locked unless something forces the wheels to spin at different speeds. Or it can be driver controlled by either an air system, an electronic system, or even a cable system.

These types of differential are usually great for off-roading.

welded differential FAQ

Daily driving with a welded differential

Many people do it every day and it is totally fine to do so. However, it comes with disadvantages as listed above in the pros and cons section.

Track a welded differential

A welded diff is great for drifting on the track. However, when it comes to normal racing it could cause understeer which isn’t ideal.


It all depends on the quality of your welds. A welded diff can last for a very long time if the welds are strong and well-made.

What happens when a welded differential breaks

You will lose all power and have a differential case full of metal pieces.

Is a welded differential a good idea

If you are looking to get into drifting or off-roading and you are on a tight budget welding your differential is the cheapest and best way to go.

This allows you to save some money for extra performance mods for your car. However, if you do have the money to buy a differential it is definitely recommended to do so.


In conclusion, a welded differential is a modification that involves welding the spider gears to the side gears of a standard open differential. This transforms the differential into a solid unit, ensuring both rear wheels rotate at the same speed.

While primarily used for drifting, a welded differential also enhances off-roading performance by providing better traction and power control on uneven terrain.

The modification is quick and budget-friendly, but it is not ideal for everyday street driving due to challenges in maneuverability and tire wear. Alternatives to welding, such as limited slip differentials or locking differentials, offer more flexibility and better handling characteristics for specific applications.

Ultimately, the decision to weld a differential depends on personal preferences, budget constraints, and intended usage.