What is the diff ratio for a Model T?
The Ford Model T, an iconic vehicle that revolutionized the automotive industry, has a unique design that includes its differential gear ratio. Understanding the diff ratio is essential for enthusiasts and restorers who want to maintain or modify this classic car. In this article, we’ll explore what the diff ratio is, why it matters, and the specific ratio used in the Model T.
What is a Differential Ratio?
The differential ratio, often referred to as the "diff ratio," is the ratio between the number of teeth on the ring gear and the number of teeth on the pinion gear in a vehicle's differential. This ratio determines how many times the driveshaft rotates for each rotation of the wheels. It plays a critical role in balancing speed and torque, affecting the vehicle's performance and efficiency.
The Standard Diff Ratio for the Model T
The Ford Model T, produced between 1908 and 1927, typically came with a standard differential gear ratio of 3.63:1. This means that the driveshaft rotates 3.63 times for every single rotation of the rear wheels. This ratio was chosen to provide a balance between power and speed, making the Model T suitable for the unpaved roads of its time.
Why the Diff Ratio Matters
The differential ratio impacts several aspects of a vehicle's performance. Here are some key reasons why it matters:
- Acceleration: A lower diff ratio (numerically higher) provides more torque to the wheels, improving acceleration but reducing top speed.
- Fuel Efficiency: A higher diff ratio (numerically lower) can improve fuel efficiency by reducing engine RPM at cruising speeds.
- Terrain Adaptability: The Model T's 3.63:1 ratio was ideal for the rough and uneven terrain of the early 20th century.
Modifications and Variations
While the standard diff ratio for the Model T was 3.63:1, some owners and restorers have modified their vehicles to use alternative ratios. For example, a 4:1 ratio might be used for better hill-climbing ability, while a 3:1 ratio could be chosen for improved speed on modern roads. These modifications depend on the intended use of the vehicle and the preferences of the owner.
Conclusion
The differential ratio of the Ford Model T is a fascinating aspect of its engineering that contributed to its versatility and success. Whether you're restoring a Model T or simply curious about its mechanics, understanding the diff ratio provides valuable insight into this legendary vehicle. If you have any questions about maintaining or modifying your classic car, feel free to reach out to us at Kevin's Autos for expert advice and service!
Frequently Asked Questions
What is the diff ratio of the Model T?
The Model T rear axle's differential contained a pinion wheel with 11 teeth and a crown wheel with 40 teeth, thus giving a final drive ratio of 40/11 = 3.6363:1.
Which is better, 3.73 or 4.10 axle ratio?
Performance Relative to Use
That 3.73 vs. a 4.10 has a huge impact on engine rpm because you are selecting second gear with a 3.73 to pull the grade, but you can hit third gear with a 4.10. Your engine speed is about 1,000 rpm lower, so temperatures under hood are going to be significantly lower.
What is Tesla's gear ratio?
Transmission
| Type | Specifications |
|---|---|
| Type | Single speed fixed gear |
| Overall Final Drive Ratio | Small motor: 9.0:1 Large motor: 9.7:1 |
| Reverse Gear | Reverse direction of motor, limited to 24 km/h |
What gear ratios were used in the Ford 8.8 factory?
Traction-Lok differentials have a big S-shaped spring in the center of the differential gears. There's no way to identify this feature from the outside other than reading the tag. The 8.8 was built with the following ratios: 2.26, 2.47, 2.73, 3.08, 3.27, 3.45, 3.55, 3.73 and 4.10:1.
What is the gear ratio of the Model T Ford?
The figures below show calculations for a stock Model T with various gear ratios: 3.64:1 (standard), 4:1 (10 tooth pinion), 3:1 and 5.6:1 (3.64 in Ruckstell low). The graphs show that top speed increases just a bit more than one mph with 3:1 gears, i.e. not much. However, performance in the hills suffers dramatically.
What gets better gas mileage, 3.73 or 4.10 gears?
To keep it simple, if you want a daily driver and want to save a little on fuel and you care about performance but don't want screaming RPM, then taller gears like the 3.73 ring and pinion are the way to go.
What is the best rear end ratio?
The most popular rear end ratio in trucks today is the 3:55, which sort of averages towing power and fuel economy. This is a good ratio for the occasional towing or hauling individual. For a person who tows more often, and heavier loads, the 3:73 or 4:10 may be more appropriate.
What is the gear ratio in a Tesla?
Transmission
| Type | Specifications |
|---|---|
| Type | Single speed fixed gear |
| Overall Final Drive Ratio | Small motor: 9.0:1 Large motor: 9.7:1 |
| Reverse Gear | Reverse direction of motor, limited to 24 km/h |
Did the Ford Model T have a differential?
The heavy-duty Model TT truck chassis came with a special worm gear rear differential with lower gearing than the normal car and truck, giving more pulling power but a lower top speed (the frame is also stronger; the cab and engine are the same).
Did the Model T have a differential?
Power reaches the differential through a single universal joint attached to a torque tube which drives the rear axle; some models (typically trucks, but available for cars, as well) could be equipped with an optional two-speed rear Ruckstell axle, shifted by a floor-mounted lever which provides an underdrive gear for ...
