After you have modified your vehicle, whether it be an engine modification, auto-to-manual transfer, tyre size change, or other modification, your car’s differential ratio may alter and no longer suit your needs. 

As part of our car differential services, the highly skilled and experienced team at Automatic Transmissions R Us can provide a number of solutions to deliver more get-up-and-go on take-off, or for pulling loads.




What is a Differential Ratio?

A differential ratio is a number that shows how many times a vehicle’s driveshaft turns compared to its wheels. It affects a vehicle’s performance, like acceleration and fuel efficiency.

A lower ratio gives better fuel economy but slower acceleration, while a higher ratio provides quicker acceleration but lower fuel economy. This number helps you understand a vehicle’s performance and choose the best option for your driving needs.


Low Differential Gear Ratio

A lower differential ratio (e.g. 2.5:1) offers certain advantages and disadvantages for vehicle performance. Here are some pros and cons:



  1. Fuel efficiency: A lower differential ratio requires fewer engine revolutions to achieve a given wheel speed. This means the engine works less and consumes less fuel, resulting in better fuel economy.
  2. Higher top speed: With fewer driveshaft rotations needed for each wheel rotation, the vehicle can achieve a higher top speed, as the engine doesn’t reach its maximum RPM as quickly.
  3. Less engine wear: Since the engine runs at lower RPMs for a given speed, there is less wear and tear on the engine components, potentially increasing the engine’s lifespan.



  1. Slower acceleration: A lower differential ratio means the engine’s torque is spread over a wider range of wheel speeds, which results in slower acceleration and reduced responsiveness.
  2. Reduced towing capacity: Vehicles with lower differential ratios have less torque available at low speeds, making it harder to tow heavy loads or drive up steep inclines.
  3. Poor off-road performance: Lower differential ratios don’t provide as much torque at low speeds, making it more challenging to navigate rough or slippery terrain where maximum traction is required.


High Differential Gear Ratio

A higher differential ratio (e.g. 4.0:1) also has its own set of advantages and disadvantages for vehicle performance. Here are some pros and cons:



  1. Quicker acceleration: A higher differential ratio provides more torque to the wheels at lower speeds, resulting in faster acceleration and improved responsiveness.
  2. Improved towing capacity: With more torque available at low speeds, vehicles with higher differential ratios can tow heavier loads and better handle steep inclines.
  3. Better off-road performance: Higher differential ratios deliver more torque at low speeds, making it easier to navigate challenging off-road conditions, such as rocky or muddy terrain, where maximum traction is needed.



  1. Lower fuel efficiency: A higher differential ratio requires more engine revolutions for a given wheel speed, causing the engine to work harder and consume more fuel, resulting in reduced fuel economy.
  2. Lower top speed: With more driveshaft rotations needed for each wheel rotation, the vehicle reaches its maximum engine RPM more quickly, limiting the top speed.
  3. Increased engine wear: Since the engine runs at higher RPMs for a given speed, there is more wear and tear on the engine components, which may potentially decrease the engine’s lifespan.


How to Find Your Differential Gear Ratio?

If you have modified your vehicle or are considering modifications, it’s important to know the differential gear ratio to ensure optimal performance. Here are some common methods to determine the differential ratio:

  1. Check the documentation: First, look for the differential ratio in your vehicle’s owner’s manual or on the manufacturer’s website. This will give you the stock differential ratio, which might have been changed if modifications were made.
  2. Investigate modifications: If you have documentation or receipts from the modifications, check if any changes were made to the differential. This could include installing a different ring and pinion set or a complete differential replacement.
  3. Consult a professional: If you’re unsure whether modifications have been made to your vehicle or if you don’t have the necessary documentation, consult a professional mechanic for assistance. You can contact the team at Automatic Transmissions R Us to inspect your vehicle and determine the current differential gear ratio.


What Are the Signs You Might Need Your Differential Gear Ratio Changed?

Changing the differential gear ratio itself is not typically considered a maintenance item or something that wears out. However, there are situations where you might want to change the gear ratio to better suit your driving needs or preferences.

Here are some signs that you might consider changing your differential gear ratio:

  1. Performance issues: If you find your vehicle is lacking in acceleration, you might want to consider a higher differential gear ratio to improve responsiveness and low-end torque.
  2. Towing or hauling capacity: If you regularly tow heavy loads or haul heavy cargo, a higher gear ratio can provide better towing capacity and help your vehicle handle the added weight more effectively.
  3. Fuel efficiency concerns: If you primarily drive on highways and are looking to maximize fuel efficiency, a lower differential gear ratio may help reduce engine RPMs at cruising speeds, leading to improved fuel economy.
  4. Off-road capability: For off-road enthusiasts who frequently encounter rough terrain or steep inclines, a higher gear ratio can provide better low-speed torque and control, making it easier to navigate challenging conditions.
  5. Modified vehicles: If you have made significant modifications to your vehicle, such as adding larger tires, increasing engine power, or altering the transmission, the original differential gear ratio may no longer be optimal for your vehicle’s performance. In such cases, you might need to change the gear ratio to match your vehicle’s new characteristics.

If you’re considering changing your differential gear ratio, consult our team at Automatic Transmissions R Us to discuss your specific needs and preferences. We can help you determine the best gear ratio for your vehicle and perform the necessary work to ensure optimal performance and reliability.


Make An Enquiry with Automatic Transmissions R Us

To find your differential gear ratio with the help of Automatic Transmissions R Us, schedule an appointment with us and explain your concerns about the differential and any modifications. Their skilled technicians will inspect the differential, assess any modifications, and provide you with the current gear ratio, along with any recommendations for further modifications or maintenance.

For example, our technicians can fit another crown wheel and pinion to your vehicle, which will alter your speed/revs to your required rate. 

To find out more about our ratio change services, contact Automatic Transmissions R Us at or phone (08) 9240 5449.

Contact Auto Trans R Us Today!