Are all Ford 8.8-31 spline?

No, not all Ford 8.8-31 spline axles are the same. The 8.8-inch rear axle is a common component found in many Ford vehicles, but the specific spline count and other details can vary depending on the model year and application.

Understanding Ford 8.8-31 Spline Axles

The Ford 8.8-inch rear axle is a popular and durable component used in a variety of Ford trucks, SUVs, and performance vehicles. The "8.8" refers to the diameter of the axle housing, while the "31" indicates the number of splines on the axle shaft.

While the 8.8-31 spline configuration is common, there are several variations that Ford has used over the years. Some key differences include:

• Model Year: Ford has used the 8.8-31 spline axle in vehicles ranging from the 1980s to the present day. The specific design and components can vary between older and newer models.


• Vehicle Application: The 8.8-31 axle may be found in different Ford models, from light-duty trucks to high-performance sports cars. The axle specifications can differ to match the vehicle's intended use and power output.


• Differential Type: Ford has used both open and limited-slip differentials with the 8.8-31 axle, depending on the vehicle's intended use and performance requirements.

It's important to note that while the 8.8-31 spline configuration is common, there are also other Ford axle designs, such as the 8.8-28 spline, that may require different components and modifications.

Verifying Axle Compatibility

When working on a Ford vehicle with an 8.8-31 spline axle, it's crucial to verify the specific model year, vehicle application, and differential type to ensure compatibility with any replacement parts or modifications. Consulting a trusted mechanic or referring to the vehicle's service manual can help ensure the correct components are used.

In summary, while the Ford 8.8-31 spline axle is a widely used component, there are variations that must be considered when performing maintenance or upgrades. Proper identification and verification of the specific axle configuration is essential for ensuring a successful and safe repair or modification.

What is the difference between Ford 8.8 28 and 31 spline?

The keys to building the 8.8 Ford are pretty simple. If you plan to make at least 400 Horsepower through the 8.8 Rear, the first step is better axles. 31 spline axles which are about 30% stronger than the 28 spline axles making them a popular aftermarket upgrade for Fox, SN95, and New Edge Mustang owners.

How much horsepower can 31 spline axles handle?

31-spline axles can handle a wide range of horsepower, with many common setups holding between 500 and 800 horsepower, though some high-end aftermarket 31-spline axles can handle even more. However, the axle's ability to handle horsepower is highly dependent on factors such as the material quality, the vehicle's setup, and driving style. 
Factors that influence an axle's strength

• Material and manufacturing: A high-quality, forged 31-spline aftermarket axle will be significantly stronger than a stock one. 
• Vehicle setup: Other components in the drivetrain, such as the differential and housing, must also be robust enough to handle the power. A strong axle in a weak housing will be a point of failure. 
• Driving style: Consistent launches at high RPMs put more stress on the axle than typical street driving. 
• Traction: A slick tire with a lot of grip on a launch is more likely to break an axle than a tire that spins and releases some of the torque. 

Approximate limits

• Stock components: Under aggressive driving, a stock 31-spline setup can start to fail at around 400 horsepower. 
• Aftermarket components: With a properly built aftermarket setup, 31-spline axles are often reliable up to 800 horsepower, and sometimes more, especially with the right differential and housing combination. 

How many splines does a Ford 8.8 have?

The Ford 8.8 axle most commonly has either a 28-spline or a 31-spline axle count, which varies by application. Early models and some V6 Mustangs typically use 28-spline axles, while later models like most V8 Mustangs and many Explorers come with stronger 31-spline axles. 
28-spline

• Common in: Early models, some V6 Mustangs, and many light-duty trucks and SUVs.
• Characteristics: A less robust setup compared to the 31-spline version. 

This video demonstrates how to identify the spline count by removing the axle and counting the splines: 1mMo's TubeYouTube · Mar 26, 2020
31-spline

• Common in: Later-model V8 Mustangs, Explorers, Expeditions, and F-150s. 
• Characteristics: Offers increased strength over the 28-spline version and is a common upgrade for many applications. 

How to identify your axle's spline count

• Check the vehicle's documentation: The owner's manual or a build sheet might have the axle's specifications. 
• Visually inspect the axle: The easiest way is to pull the rear differential cover and visually count the splines on the axle shafts that go into the differential. 
• Consult a parts catalog: Use your vehicle's year, make, and model to look up compatible axle parts, which will list the spline count. 

How do you tell if you have 28 or 31 spline axles?

Measure the axle housing if it's a 2.5 inch diameter it's a 28 spline axle if it's a 31 spline it a 3.25 inch diameter.