ZF5 Transmission Guide: ZF S5-42 and S5-47 Specs and Compare

The ZF5 Transmission: A Comprehensive Guide to the ZF S5-42 and ZF S5-47

You can also view the contents of this page as a video on YouTube.

Introduction

The ZF5 transmission, known for its strength and reliability, is a 5-speed manual gearbox used in many Ford trucks from the late 1980s through the late 1990s. Manufactured by ZF Friedrichshafen AG, this transmission came in two main variants: the ZF S5-42 and the ZF S5-47. Both versions were designed to handle the demands of heavy-duty trucks, making them popular choices for Ford F-Series trucks and Broncos. This guide covers the ZF5 transmission’s history, specifications, differences between the S5-42 and S5-47, compatibility, common issues, and maintenance tips.

History and Development

Introduction of the Transmission
ZF introduced the ZF S5-42 transmission in the late 1980s as a heavy-duty 5-speed manual option for Ford trucks. The S5-42 was designed to replace older 4-speed transmissions, providing an extra gear for better fuel efficiency and improved highway driving. In the mid-1990s, the S5-47 was introduced as an upgrade to the S5-42, offering increased torque capacity and enhanced durability.

Design Purpose
The ZF5 transmission was built to handle the demands of heavy-duty trucks, including towing and off-roading. It was designed with durability and reliability in mind, offering a 5-speed configuration that provided a good balance between low-end torque for towing and higher gears for efficient highway cruising. The S5-47 variant, in particular, was designed to handle more powerful engines and heavier loads, making it a popular choice for later model trucks.

Production and Usage
The ZF S5-42 was produced from 1987 to 1994 and was commonly found in Ford F-250, F-350, and F-450 trucks, as well as full-size Broncos. In 1995, the S5-47 replaced the S5-42, continuing production until 1998. The S5-47 was used in similar vehicle models but was designed to handle the increased torque of newer, more powerful engines. Both versions of the ZF5 transmission have remained popular among truck enthusiasts, particularly those involved in heavy-duty work or off-roading.

Vehicle Model	Years	Bellhousing Pattern
F-250 (Gas Engines)	1987-1997	Small Block (S5-42), Big Block (S5-47)
F-250 (Diesel)	1987-1997	Diesel Pattern
F-350 (Gas Engines)	1987-1998	Small Block (S5-42), Big Block (S5-47)
F-350 (Diesel)	1987-1998	Diesel Pattern
F-450 (Gas Engines)	1988-1997	Big Block Pattern (S5-47)
F-450 (Diesel)	1988-1997	Diesel Pattern
F-150 (5.0L / 5.8L)	1987-1996	Small Block Pattern (Limited Availability, mostly fleet)
E-Series Vans (E-250/E-350)	1988-1996	Small Block Pattern (Gas), Diesel Pattern

Popularity
The ZF5 transmission gained widespread popularity for its robustness and ability to handle heavy loads. The addition of a fifth gear was a significant improvement over the older 4-speed transmissions, offering better fuel efficiency and more versatility. Both the S5-42 and S5-47 are highly regarded in the Ford truck community, with many drivers seeking them out for their reliability and performance in demanding conditions.

Transmission Specifications

Number of Gears
The ZF5 transmission is a 5-speed manual gearbox. This configuration provides a balance of performance and efficiency, making it suitable for a variety of driving conditions. The fifth gear offers improved fuel efficiency during highway driving, which is especially beneficial for trucks used in long-distance travel or towing.

Synchronized Gears
All five forward gears in the ZF5 transmission are synchronized, which helps ensure smooth shifting and reduces wear on the gear components. This feature is particularly beneficial for drivers who frequently shift under load, as it helps prevent gear grinding and extends the life of the transmission.

Gear Ratios
The gear ratios in the ZF5 transmission are identical between the S5-42 and S5-47 models. Both variants share the following gear ratios:

1st Gear: 5.72:1
2nd Gear: 2.94:1
3rd Gear: 1.61:1
4th Gear: 1.00:1
5th Gear: 0.76:1
Reverse: 5.24:1

While the gear ratios are the same, the S5-47 features stronger internal components to handle higher torque loads compared to the S5-42. The low first gear in both versions is ideal for towing and heavy hauling, while the overdrive fifth gear helps reduce engine RPM at highway speeds, improving fuel economy.

Case Material
Both the ZF S5-42 and S5-47 transmissions feature an aluminum case, which provides strength while keeping the overall weight of the transmission relatively low. The use of aluminum helps dissipate heat, which is crucial for maintaining safe operating temperatures during heavy use.

Weight and Dimensions
The ZF5 transmission weighs approximately 175 pounds without fluid, making it manageable for installation and removal in most truck setups. The dimensions are consistent between the S5-42 and S5-47, with typical measurements as follows:

Length: 26.5 inches
Width: 16.5 inches
Height: 17 inches

These compact dimensions allow the ZF5 to fit comfortably in a variety of Ford truck models, offering versatility in both 2WD and 4WD configurations.

Engine Compatibility
The ZF5 transmission was designed to be compatible with a range of Ford engines, particularly those found in heavy-duty trucks. Common engine pairings include:

Ford 5.8L (351 Windsor) V8: A popular engine for both the S5-42 and S5-47, providing a balance of power and durability.
Ford 7.5L (460) V8: The S5-47 variant, in particular, was often paired with this engine, handling its high torque output with ease.
Ford 7.3L IDI Diesel: Both versions were commonly used with the 7.3L IDI diesel engine, though the S5-47 was preferred for the later, more powerful turbocharged versions.

The S5-42 and S5-47 transmissions share broad engine compatibility, but the S5-47 was specifically designed to handle the increased torque of newer engines introduced in the mid-1990s.

Recommended Fluid Type and Capacity
The ZF5 transmission requires high-quality manual transmission fluid (MTF), with Mercon ATF being the recommended fluid for both the S5-42 and S5-47. This fluid ensures proper lubrication and helps maintain smooth shifting.

Fluid Capacity: The transmission holds approximately 5 quarts of MTF, though this may vary slightly depending on the specific vehicle setup.
Service Interval: It’s recommended to change the transmission fluid every 30,000 to 50,000 miles under normal driving conditions. For trucks used in heavy-duty applications, such as towing or off-roading, more frequent changes (every 20,000 to 30,000 miles) are advisable to maintain optimal performance.

Shift Pattern

The ZF5 transmission, which includes the ZF S5-42 and ZF S5-47 variants, has a typical 5-speed manual shift pattern. Here’s how the shift pattern is laid out:

1st Gear: Top left
2nd Gear: Bottom left
3rd Gear: Top middle
4th Gear: Bottom middle
5th Gear (Overdrive): Top right
Reverse: Bottom right

To engage reverse, you typically need to move the shifter to the far right and then down. Some versions of the transmission may require you to push down on the shifter or pull up on a collar to engage reverse, depending on the vehicle and the specific shifter setup.

Transmission Compatibility: Clutches and Transfer Cases

Manual Transmission Clutch Compatibility

Clutch Types: The ZF5 transmission is compatible with a range of clutches, depending on the engine and vehicle application. Standard diaphragm-style clutches are typically used, with clutch sizes varying from 11 inches to 12.25 inches. The S5-47, given its higher torque capacity, may require a more robust clutch, particularly in performance or heavy-duty applications.
Hydraulic Clutch System: The ZF5 often uses a hydraulic clutch actuation system, which offers smoother and more consistent engagement compared to cable-operated systems. This setup is standard in both the S5-42 and S5-47, providing ease of use and reducing the need for frequent adjustments.

Transfer Case Compatibility

4WD Integration: The ZF5 transmission is compatible with several transfer cases, making it suitable for 4WD vehicles. The Borg-Warner BW1356 and the New Process NP205 are common pairings. The transfer case compatibility remains consistent between the S5-42 and S5-47, though the increased torque handling of the S5-47 may make it a better match for heavier-duty transfer cases.
Direct Bolt-On Transfer Cases: Both versions of the ZF5 transmission bolt directly to compatible transfer cases, simplifying installation and ensuring proper alignment. This direct compatibility is advantageous for those looking to maintain or upgrade their 4WD Ford trucks.
Performance and Durability: In off-road and towing applications, the ZF5 transmission performs reliably, especially when paired with a strong transfer case. The S5-47, with its enhanced durability, is particularly well-suited for more demanding conditions where higher torque is a factor.

Cooling System

Standard Cooling
The ZF5 transmission relies on its aluminum case for heat dissipation. This design is generally sufficient for most driving conditions, as the aluminum helps to dissipate heat quickly. However, vehicles used in heavy-duty applications or in hot climates may benefit from additional cooling measures.

Additional Cooling Options
For trucks frequently involved in towing or off-roading, additional cooling may be necessary. Installing an external transmission cooler can help manage heat more effectively, especially for the S5-47, which may generate more heat due to its handling of higher torque. An external cooler reduces the risk of overheating and extends the life of the transmission fluid and internal components. While the standard cooling setup works well for typical use, a supplementary cooler offers extra protection in more demanding conditions.

Maximum Torque and Durability

Torque Capacity

Stated Torque Rating: The ZF S5-42 transmission is rated to handle up to 420 lb-ft of torque, while the S5-47 can handle up to 470 lb-ft. This increase in torque capacity makes the S5-47 better suited for more powerful engines and heavier-duty applications.
Impact of Overloading: Exceeding the transmission’s torque rating, particularly with the S5-42, can lead to premature wear or failure. It’s essential to match the transmission to the engine’s output, especially in performance builds or heavy-duty scenarios.

Durability

General Reliability: Both the ZF S5-42 and S5-47 are known for their durability, especially in stock configurations. The S5-47, with its stronger internal components, offers enhanced durability, making it a preferred choice for more demanding applications.
Service Life Expectations: Under normal driving conditions, both versions of the ZF5 transmission typically require minimal maintenance beyond regular fluid changes. However, trucks used for heavy-duty tasks or performance driving may require more frequent inspections and service to ensure continued reliability.

Common Issues

Transmission-Specific Issues: While the ZF5 transmission is generally reliable, a few common issues may arise over time, with some differences between the S5-42 and S5-47:
- Synchro Wear: Over time, the synchronized gears can wear out, leading to difficulty shifting, especially under load. This issue may be more common in the S5-42, given its lower torque rating.
- Input Shaft Bearing Wear: The input shaft bearing can wear out, causing noise or vibration. This issue can affect both the S5-42 and S5-47, though the S5-47’s stronger bearings may offer slightly better longevity.
- Fluid Leaks: Both versions may develop leaks over time, particularly around the seals and gaskets. Regular inspection can help catch and address these leaks before they lead to more serious issues.
Causes and Solutions:
- Synchro Wear: Regular maintenance and using high-quality transmission fluid can help extend the life of the synchros. If wear becomes significant, a rebuild may be necessary.
- Input Shaft Bearing Wear: Replacing the input shaft bearing and ensuring the transmission is properly installed can prevent further issues.
- Fluid Leaks: Regularly checking for leaks and replacing worn seals can prevent fluid loss and potential transmission damage.

Driving Dynamics and Typical Usage

Shifting Characteristics

Shift Feel: The ZF5 transmission is known for its solid and precise shift feel. While it may require more effort than lighter-duty transmissions, its positive engagement is appreciated by drivers who value control. The S5-47 may feel slightly more robust due to its enhanced components, but both versions provide a reliable and predictable shifting experience.
Shift Timing: The transmission allows for quick, deliberate shifts, particularly in lower gears. Proper maintenance ensures that shifts remain smooth and timely over time. Adjustments to the clutch system can also help fine-tune shift timing to match driving preferences.

Typical Usage

Daily Driving: Both the ZF S5-42 and S5-47 perform well in daily driving scenarios, offering reliable and predictable shifts. The 5-speed configuration suits a variety of driving conditions, providing strong low-end torque for city driving and efficient cruising on the highway.
Towing: The ZF5 transmission excels in towing applications, with the S5-47 particularly well-suited for heavy loads due to its higher torque capacity. The gear ratios offer excellent low-end torque for pulling heavy loads, while the overdrive fifth gear helps maintain efficiency at highway speeds.
Off-Roading: When paired with a compatible 4WD transfer case, the ZF5 performs admirably in off-road conditions. The low first gear and durable construction make it capable of handling rough terrain, while the S5-47’s enhanced durability makes it a better choice for more extreme off-roading.

Why I’m Considering a ZF S5-42 for My 1985 F150 Build

So, I’ve got this 1985 Ford F150, and it’s been a solid truck with the 300 inline-six and NP435 transmission combo. It’s a setup that’s built for toughness, no doubt, but my plan is to change things up. I’m swapping in a 351 Windsor and maybe even stroking it to a 408 monster. And with that, I’m also considering swapping out the old NP435 for a ZF S5-42 5-speed. Here’s why I think this could be the right move for my build.

The 351 Windsor: More Power, More Fun

The 300 inline-six is a great engine, especially for torque and reliability, but let’s be honest—it’s not exactly a powerhouse. I’ve been wanting something with more kick, and the 351 Windsor is a great choice. It’s a versatile V8 with a lot of potential, and if I decide to go all-in and stroke it to 408 cubic inches, I could be looking at around 400 horsepower.

That’s a lot more muscle under the hood, and it would definitely wake up the truck. But whether I stick with the 351 or go for the 408, one thing’s clear: the NP435, while tough, might not be the best match for what I want. It’s a 4-speed with pretty wide ratios, and it lacks overdrive, which isn’t great for highway cruising.

Why the ZF S5-42?

Enter the ZF S5-42. It’s a 5-speed manual that’s also known for its durability, but it brings a lot more to the table in terms of everyday drivability. First off, it has an overdrive gear, which is a game-changer. With overdrive, I could hit the highway without the engine screaming at high RPMs, making for a quieter, more fuel-efficient ride.

The ZF5 is also just a better match for a more powerful engine. It’s rated to handle up to 420 lb-ft of torque, which should cover me whether I stick with the 351 or decide to go for that 408 stroker. The gear ratios are more refined too—better for getting off the line, hauling, and just making the truck more fun to drive.

Thinking About the Driving Experience

One of the big reasons I’m leaning toward the ZF S5-42 is the driving experience. The NP435 is a workhorse, but it’s not exactly smooth or quick to shift. The ZF5, on the other hand, offers smoother shifts and a more precise feel. Plus, all five gears are synchronized, which means no more double-clutching or grinding gears—just a more modern, enjoyable driving experience.

With the ZF5, I’d also have that fifth gear for cruising, which is something I really like. It’s not just about power—it’s about making the truck more versatile, whether I’m towing, off-roading, or just driving around town. The ZF5 would make the F150 feel more responsive and easier to live with day-to-day.

The Swap Process

As for the swap, it’s not a simple bolt-in, but it’s definitely doable. The ZF S5-42 will bolt up to the 351 Windsor, which is a big plus. I’ll need to sort out the clutch, driveshaft length, and maybe tweak the transmission crossmember and floorpan, but those are manageable challenges.

Once everything’s in place, I’m expecting a big difference in how the truck drives. It’s going to feel like a whole new vehicle, with the power and gearing to match whatever I end up doing with the engine.

Wrapping It Up

So, that’s where I’m at. Swapping to the ZF S5-42 seems like a solid move, especially with the 351 Windsor (or possibly 408) in mind. It’s about making the truck more versatile, more powerful, and just more fun to drive. I’m not 100% set on all the details yet, but I’m excited about where this build is heading. If everything goes as planned, the F150 is going to be an absolute blast on the road.

Serviceability and Rebuild Costs

Ease of Service
The ZF5 transmission is relatively easy to service, especially for those familiar with manual transmissions. Routine maintenance tasks, such as fluid changes and clutch replacements, are straightforward and can be performed with basic tools. More complex repairs, like replacing synchros or bearings, may require more expertise but are still manageable for experienced mechanics.

Rebuild Costs
The cost to rebuild a ZF5 transmission varies depending on the extent of wear and the specific components that need replacement. On average, a professional rebuild can range from $1,000 to $1,500, including parts and labor. DIY rebuild kits are available for around $400 to $600, though rebuilding a transmission requires a solid understanding of its internal workings. The S5-47, due to its stronger components, may have slightly higher rebuild costs.

Aftermarket Support and Modifications

Available Upgrades
Both the ZF S5-42 and S5-47 are robust in their stock forms, but several aftermarket options are available to enhance performance or longevity:

Heavy-Duty Clutches: Upgrading to a heavy-duty clutch can improve the transmission’s ability to handle higher torque levels, particularly in the S5-47, which may be used in more demanding applications.
Short-Throw Shifters: Installing a short-throw shifter can reduce shift time and effort, making the transmission more responsive and enjoyable to drive.
Additional Cooling Systems: Adding an external transmission cooler can help manage heat in demanding situations, extending the life of the transmission.

Limitations
Despite its strengths, the ZF5 transmission has some limitations, particularly in high-performance applications. Its 5-speed configuration and moderate torque capacity in the S5-42 may limit its use in extreme builds. Enthusiasts seeking more gears or greater efficiency may need to consider alternative transmissions or significant modifications to the ZF5.

Conclusion

Summary
The ZF5 transmission, available in both the S5-42 and S5-47 variants, is a durable, reliable, and versatile gearbox that has served countless drivers over the decades. Its 5-speed configuration, combined with its robust construction, makes it an enduring choice for Ford trucks and other vehicles. While the S5-42 is well-suited for moderate applications, the S5-47 offers enhanced durability and torque capacity, making it ideal for more demanding conditions.

Final Thoughts
Whether you’re maintaining a stock truck, building a high-performance vehicle, or planning upgrades, the ZF5 transmission offers a solid foundation. With extensive aftermarket support and the ability to handle a wide range of driving conditions, it remains a reliable choice among Ford enthusiasts. Proper maintenance and thoughtful modifications can keep both the S5-42 and S5-47 running smoothly for years, ensuring your vehicle stays both functional and true to its original design.