Differential/axle breather serves the important purpose on a 4WD vehicle of venting the air pressure in your drivetrain assemblies such as differentials, gearbox, and transfer case.

  • when these assemblies heat up under normal operation the air inside expands increasing the pressure and needs to be vented to the atmosphere
  • when the drivetrain assembly cools down the air inside contracts and creates a vacuum


Many drivetrain assemblies are fitted with a breather from the factory. The factory breather is usually a one-way valve mounted directly to the axle housing or remotely on a short tube. The shortfall with the factory breathers arises particularly when driving through water crossings where the drivetrain assembly will cool rapidly creating a vacuum.


This vacuum will close the one-way valve tightly shut causing air to be instantly drawn into the assembly through the axle/shaft seals. However, because the seals are probably still submersed below water the water will be drawn into the drivetrain contaminating the oil and possibly damaging drivetrain components or your Air Locker. The contaminated oil will then need to be changed.


The Differential Breather is designed to eliminate these shortcomings by providing a high flow, zero backpressure, and zero vacuum breather system.


This is achieved with a central high-flow air filter and manifold that will allow up to four drivetrain assemblies to be vented to one central location on the vehicle that will be above the water level at all times. This kit is intended to replace your factory breathers and contains enough fittings and tubing to connect at least two drivetrain assemblies. More tubing and fittings can be purchased separately to connect up to four assemblies to the central manifold.


What does a differential breather do?

A differential breather, also known as an axle or gearbox breather, serves as a vent for the differential. As the differential heats up during operation, the air inside expands. Without a way to escape, this expanding air can create pressure inside the differential. The breather allows this excess pressure to be released, preventing seals from being pushed out or damaged. Additionally, it prevents water, dirt, and other contaminants from entering the differential when it cools down and creates a vacuum.


Is a differential breather necessary?

Absolutely. A differential breather is essential for maintaining the health and longevity of the differential. Without it, the increased pressure from the expanding air can lead to seal failures, resulting in oil leaks. These leaks not only lead to a loss of lubrication inside the differential but can also cause environmental harm. Moreover, without a breather, contaminants can enter the differential, leading to premature wear and potential damage to the gears and bearings.


Do all diffs have breathers?

Most differentials come equipped with some form of breather, as manufacturers recognize the importance of this component. However, the design and location of the breather can vary. Some vehicles may have a simple vent, while others might have a more intricate breather system with hoses leading to a higher point in the vehicle. This is especially common in off-road vehicles, where the risk of water ingress is higher.


What is the importance of rear axle breather?

The rear axle breather performs the same function as the differential breather but is specifically for the rear axle. Given that the rear axle is often subjected to harsher conditions, especially in rear-wheel-drive or four-wheel-drive vehicles, its breather is of utmost importance. It ensures that the rear differential remains free from contaminants, operates at optimal pressure levels, and retains its lubrication. For vehicles that frequently traverse waterlogged terrains, an extended rear axle breather can be crucial to prevent water from entering the differential.


Conclusion

In conclusion, differential breathers, whether for the front or rear axle, play a pivotal role in the health and performance of a vehicle's differential. They ensure optimal pressure levels, prevent contaminants from entering, and safeguard the differential's lubrication. For those who use their vehicles in challenging terrains, ensuring the proper function of the differential breather is a small step that can prevent costly repairs in the future.