3.31 Vs 3.55 Electronic Lock Rear Axle: Which One is Best?

A Ford F-150’s electronic locking differential is located at its rear axle, which allows all wheels on a particular axle to rotate simultaneously. A stuck vehicle can benefit from electronic locking differentials for additional traction.

In a vehicle, (ELD) electronic locking differential is only to be used off-road and should never be used on dry surfaces. On dry pavement, the electronic locking system can increase tire noise, wear, and vibration. The numbers 3.31 & 3.55 refer to axle ratios of Ford trucks. Since you own a Ford Super Duty, you forgot about the most useful and important axle ratio. 

3.31 Vs 3.55 Electronic Lock Rear Axle: which is really better? A 3.55 is considered a “standard selection,” with a 3.55 EL option being the most useful and popular. Would you like to know more? Continue reading for further information.

3.31 Vs 3.55 Electronic Lock Rear Axle: What is the Key Difference

3.31 Electronic Lock Rear Axle:3.55 Electronic Lock Rear Axle:
With 3.31, the rear wheel spins 3 1/3rd times before turning the driveshaft.In the electronic locking 3.55, you pull a 4×4 switch.
Best for gas V-8s & diesel tanks.3.55 is also best for gas V-8s & gallons of diesel.
3.31 good fit with 10-, 9-, or 8-speed automatic transmissions.Only 1 wheel is pulling, & there is no positive traction.
Towing mostly flat highways, you should be fine with the 3.31.Today, most trucks have a rear-end ratio of 3:55, roughly averaging power & fuel economy. 
You would normally get higher gas mileage with 3.31.You will get your trailer moving faster with the 3.55.
The price is lower than 3.55The price is quite higher than 3.31

In-depth Comparison Between 3.31 Vs 3.55 Electronic Lock Rear Axle

In the rear axle, there is an electronic locking differential. This device enables both wheels to run simultaneously. In case your car becomes stuck, the ELD provides extra traction.

Alternatively, electromagnets convert differentials into spools using E-lockers. 

When you open an E-locker, a magnet pulls apart 2 roller cams. In comparison with air lockers (which require both the compressor and 12-volt power), electronic lockers are operated by roller cams.

Features of 3.31 Electronic Lock Rear Axle:

  • When the axle ratio is 3.31, the rear wheel spins 3 1/3rd times before turning the driveshaft. Significantly greater gear ratios increase wheel torque & improve acceleration at low speeds.
  • With engines such as gas V-8s & gallons of diesel, those ratios provide excellent acceleration. In trucks with 10-, 9-, or 8-speed automatic transmissions, 3.31 ratios may be a good fit.
  • With the updated transmissions, the first and second gears are lower compared to the old 6, 5, and 4 speed transmissions, making up for the reduction in acceleration due to the axle ratio.
  • It will be easy to lift 1500 pounds with 3.31 gear ratios. For moderate loads, the 3.31 works just fine, but only with EcoBoost. Either way, don’t attempt it unless you’re certain the load capacity will exceed 8,000 pounds.

Features of 3.55 Electronic Lock Rear Axle:

  • In the electronic locking 3.55, you pull a switch (a 4×4 switch), and the axles are locked together so that positive traction is achieved (each rear wheel turns at equal speed).
  • If the rear axle is non-limited slip, only 1 wheel is pulling, & there is no positive traction. On average, most of the pickups built after 2010 have a towing axle ratio of 3.55 or 3.73. 
  • Technically, it can be calculated as a ratio, for instance, 3.55:1, which indicates the drive shaft rotates 3.55 times for every wheel turn. 
  • Gas V-8 engines and diesel can get good acceleration from these 3.55 electronic lock rear axle ratios.
  • With the E-locking 3.55, you pull a switch (that says 4×4), the rear axles are locked together, and positive traction is created (the wheels turn equally fast)

Fuel Economy

A lower axle ratio means increased fuel economy by reducing the engine’s rotational speed, but how much is it really different? As a general rule, trucks gain between 0.5 and 1.0 mpg for every 25 percent axle ratio reduction (for highway mileage only; axle ratios have little impact on city travel mpg).

With a 3.31 axle ratio and a 3.55 axle ratio, you wouldn’t significantly lose fuel economy for the 3.55 axle ratio. However, it’s worth noting that axle ratios as low as 3.31 are available; a 3.08 differential can also be found on some trucks.

In axle ratio, the wheels are measured by the number of revolutions of the driveshaft. As an example, a 3.31:1 electronic lock rear axle ratio means the driveshaft rotates 3.31 times each wheel turn and has a similar role with the 3.55 electronic lock rear axle ratio.

Pro Tips: Electronic lock rear axle differentials should not be used on dry and hard-surfaced roads. They can cause excessive noise, increased vibration, and more tire wear. If you encounter any problems disengaging your electronic locking differential, let off the accelerator while you are rolling and alternately turn the vehicle steering wheel.

Which is better: 3.31 Vs 3.55 Electronic Lock Rear Axle?

Are you confused about what to choose between 3.31 Vs 3.55 Electronic Lock Rear Axle in terms of axle ratios? Which one do you prefer, a 3.31 or a 3.55 ratio? On highways, you would normally get higher gas mileage with a 3.31 electronic lock rear axle. However, the 3.55 electronic lock rear axle will help you get your trailer moving faster. 

The 3.55 also helps you spend less time running your engine as you go uphill. Anyways, towing mostly flat highways, you should be fine with the 3.31. Basically, most trucks today have a rear-end ratio of 3:55, roughly averaging power & fuel economy. This ratio is suitable for those who occasionally tow or haul.

It’s time to pick up and worry-free drive since I have already answered all your questions.

3.31 Vs 3.55 Electronic Lock Rear Axle: Cost Comparison

The price of the 3.31 Electronic Lock Rear Axle is approximately $420.

The price of the 3.55 Electronic Lock Rear Axle is approximately $470.

The price range can vary depending on a number of factors, such as different seller’s websites, different state laws, truck and pickup models, electronic locking quality and more.

Frequently Asked Questions:

How does an electronic rear-axle work?

In the rear axle, there is an electronic locking differential. This device permits the pair of rear wheels to rotate simultaneously. Moreover, the electronic lock rear axle will offer additional traction when your vehicle becomes stuck. Both the front and rear axles can be equipped with these for those who plan to do some serious off-roading.

Is 3.31 a decent gear ratio?

Gas V-8s and diesel engines can accelerate very well with 3.31 ratios. 3.31 ratios may be suitable for trucks with 10, 9 and 8 speed automatic transmissions. With the brand-new transmissions, 1st & 2nd gears are lower than the previous 4, 5, and 6 speeds, thus improving acceleration.

How does a 3.55 axle ratio work?

In technical terms, it can be calculated as a ratio, for instance, 3.55:1, which indicates the drive shaft rotates 3.55 times for every wheel turn. This gear ratio is more commonly known as “3.55” or informally as “three fifty-five.”

The Bottom Line

In case your vehicle becomes stuck, your electronic locking system delivers additional traction. 3.31 Vs 3.55 Electronic Lock Rear Axle: Which is right for you?

Occasionally, the 3.31 axle has superior fuel economy, while the 3.55 axle ratio delivers slightly more torque. Most trucks today have rear-end ratios of 3:55, which is a good balance between fuel economy and towing power. The ratio is suitable for individuals who tow or haul from time to time.

However, when you look at the performance capabilities of these 2 axle ratios, they are rather comparable. In order to choose the right axle ratio on your truck, think about what it will mostly be used for. Take into consideration what the truck is equipped with first.

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