How do I know if I have 8.8 or 9.75 rear end?
To know whether you have an 8.8 or 9.75 rear end, you'll need to inspect the rear differential cover or consult your vehicle's documentation. The rear axle ratio is an important specification that affects your vehicle's performance and fuel efficiency, so it's important to be aware of which ratio your car or truck has.
Identifying the Rear Axle Ratio
The rear axle ratio is typically stamped on the rear differential cover or housing. You can also find this information in your owner's manual or by contacting the manufacturer. Some common rear axle ratios include:
- 8.8 - This is a common ratio found in many Ford vehicles.
- 9.75 - This is a larger, heavier-duty ratio often used in trucks and SUVs.
- Other ratios like 3.55, 3.73, 4.10, and 4.30 are also common.
The rear axle ratio determines the relationship between the rotation of the driveshaft and the rotation of the rear wheels. A higher ratio, like 9.75, means the rear wheels turn fewer times for each rotation of the driveshaft, providing more torque but lower top speed. A lower ratio, like 8.8, results in more revolutions of the rear wheels per driveshaft rotation, sacrificing some torque for higher top speed.
Checking the Rear Differential Cover
The easiest way to determine your rear axle ratio is to inspect the rear differential cover. This cover is usually located on the rear axle housing and may have the ratio stamped on it, such as "8.8" or "9.75". You can also try to find a tag or sticker on the differential cover that lists the ratio.
If you can't find the ratio on the differential cover, you may need to consult your owner's manual or contact the vehicle manufacturer for the specific details on your model.
How do I know what size rear differential I have?
Without an ID tag, differentials are 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.
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.
What vehicles have a Ford 9.75 rear end?
Popular Applications:
| Ford F-150 | 1997 to Current | Rear |
|---|---|---|
| Ford F-150 Raptor | 2010 to Current | Rear |
| Ford Transit | 2015 to Current | Rear |
| Ford E Series Vans | 1999 - 2014 | Rear |
| Ford Expedition | 1997 - 2014 | Rear |
How do you tell what size differential you have?
Ring gear diameter can be a helpful way to identify which differential you have. The ring gear diameter is measured across the face of the gear. To obtain the ring gear diameter, simply place a tape measurer across the gear. This can be tricky if the ring gear & carrier are still in the housing.
What Ford has a 8.8 rear end?
8.8 Solid Axle
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.
How do I identify my Ford 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.
How can I tell what gear ratio I have without pulling cover?
I have my buddy holding the other Tire. I start spinning this and I'm watching the other. One. That's one full rotation right there.
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.
How can you tell what type of rear end you 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.
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.
