How do I tell if I have a 8.8 or 9.75 rear end?
If you're unsure whether your vehicle has an 8.8-inch or 9.75-inch rear axle, there are a few ways to determine the correct size. Knowing the rear axle type is important for selecting the right parts and accessories for your car or truck.
Measuring the Rear Axle
The easiest way to identify your rear axle type is to measure the diameter of the axle housing. An 8.8-inch rear axle will have a housing diameter of approximately 8.8 inches, while a 9.75-inch rear axle will measure around 9.75 inches. You can use a tape measure or caliper to take this measurement.
Checking the Rear Differential Cover
Another way to determine the rear axle size is to look at the rear differential cover. Many manufacturers stamp the axle size directly on the cover. If you can't find this information, you may need to consult your vehicle's service manual or contact the manufacturer.
Identifying by Vehicle Model
The rear axle type is also often tied to the specific make, model, and year of a vehicle. For example, Ford Mustangs from 1979-2004 typically came equipped with an 8.8-inch rear axle, while later models often have the larger 9.75-inch version. Knowing your vehicle's details can help you narrow down the rear axle size.
Consulting Online Resources
If you're still unsure, there are many online resources and forums where you can research your vehicle's specifications and get advice from other owners. Websites like 4WheelParts.com and RockAuto.com often have detailed information on rear axle sizes for different makes and models.
Accurately identifying your rear axle type is an important first step in ensuring you purchase the right parts and accessories for your vehicle. By measuring the axle, checking the differential cover, or researching your specific model, you can confidently determine whether you have an 8.8-inch or 9.75-inch rear end.
What cars have 8.8 rear ends?
Applications
- 1988-1997 Ford Thunderbird.
- 1999-2004 Ford Mustang Cobra.
- 2003-2010 Ford Explorer.
- 2003-2010 Mercury Mountaineer.
- 2003-2005 Lincoln Aviator.
- 2003-2006 Ford Expedition.
- 2003-2006 Lincoln Navigator.
What Ford trucks have the 8.8 rear end?
Ford first used the 8.8 axle in 1983 model year trucks and is still in production for the Ford Ranger and Ford F-Series. It was also used in the Ford SUVs until Independent suspension replaced the solid axle.
What is my rear end ratio?
Rotate the marked tire one revolution while counting how many times the driveshaft rotates. eg, If your driveshaft made 3 3/4 revolutions, that would determine a 3.73 gear ratio. If you get approximately 2 3/4 revolutions, you have a 2.76 gear ratio.
How do I know my rear end ratio?
If you are not sure about your results when using the wheel rotation method, the number of teeth is stamped on the ring gear. The small number is the pinion-gear tooth count. The large number is the ring-gear tooth count. To find the gear ratio, divide the big number by the little number.
What did the Ford 8.8 come in?
Ford first used the 8.8 axle in 1983 model year trucks and is still in production for the Ford Ranger and Ford F-Series. It was also used in the Ford SUVs until Independent suspension replaced the solid axle. Ring, pinion and carrier all remained between the solid axle and independent rear suspension.
How to tell the difference between 8.8 and 9.75 rear end?
On the passenger's side upper and lower corners, there's two semi-circular divots that can easily be seen when looking at the cover from straight on. While the Super 8.8's cover has a bulge for the ring gear, it's not anywhere near as pronounced as the 9.75's.
How to identify an 8.8 rear end?
Almost all 8.8s—and all post-1986 Ford rearends—have letters and numbers. The first number refers to the plant where it was built, and the next three refer to the ratio and type.
What is a 9.75 rear end?
The 9.75 is a new kid on the Ford axle block. It debuted in 1997 and found a place in Ford's uprated-capacity 1/2-tons. Its primary home is in the new-generation F-150s with the higher GVW package or 5.4L V-8, but it can also be found under the '98-'02 Ford Expeditions and Lincoln Navigators.
How to tell rear end ratio?
If you are not sure about your results when using the wheel rotation method, the number of teeth is stamped on the ring gear. The small number is the pinion-gear tooth count. The large number is the ring-gear tooth count. To find the gear ratio, divide the big number by the little number.
How do I tell what size rear differential I have?
If the ID tag or stamp is missing or unreadable, differentials can be identified by the number of cover bolts, the distinctive shape of the cover, the number of ring gear bolts, and ring gear diameter. They can also be identified by whether the center section is an integral or dropout design.
