The Ford S550 Mustang utilizes a Trac-Lok limited-slip differential to enhance traction. This system employs clutch packs to manage power distribution. Tuning can optimize performance for different driving styles, and power levels. Upgrades offer improved power delivery.
Understanding the S550 Mustang Differential
The S550 Mustang’s differential is a crucial component in its drivetrain, responsible for transmitting power from the engine to the rear wheels. Ford utilizes the “Super 8.8” differential in the S550 platform, which is an independent rear suspension design. This design differs from earlier Mustang models, offering enhanced handling and refinement. The differential’s primary function is to allow the rear wheels to rotate at different speeds, which is essential for cornering. Without a differential, the inside wheel would need to travel the same distance as the outside wheel during a turn, causing binding and loss of traction. The S550 Mustangs come equipped with either an open differential, a Trac-Lok limited-slip differential (LSD) or a Torsen differential, depending on the model and options selected. Understanding how these differentials operate and their impact on performance is key to effective tuning. The Trac-Lok is a clutch-based system, while the Torsen is a gear-based design. Knowing these differences is essential for selecting the right upgrades.
Types of Differentials in S550 Mustangs
S550 Mustangs feature three main differential types⁚ open, Trac-Lok limited-slip, and Torsen. Each type offers different performance characteristics and impacts traction and handling. Understanding their differences is crucial for tuning.
Trac-Lok Limited Slip Differential
The Trac-Lok differential, a standard feature in many S550 Mustangs, is a clutch-based limited-slip system. It enhances traction by transferring torque to the wheel with more grip when one wheel begins to slip. Unlike an open differential, which allows one wheel to spin freely, the Trac-Lok uses clutch packs to engage and distribute power. This design helps maintain stability during acceleration and cornering. The amount of slip allowed by the Trac-Lok is limited by the compression of the clutch packs. This system is designed to prevent excessive wheel spin and enhance the overall performance of the vehicle. While not as sophisticated as some high-performance options, it offers a good balance of performance and cost. It is important to note that the Trac-Lok may require friction modifiers for optimal operation, depending on the fluid used. Upgrades are available for those seeking more aggressive performance.
Torsen Differential
The Torsen differential, often found in Performance Pack S550 Mustangs, is a helical gear-based limited-slip system. Unlike the clutch-based Trac-Lok, the Torsen uses gears to distribute torque between the rear wheels. This design is known for its smooth and progressive engagement. The Torsen differential directs torque to the wheel with the most traction based on a bias ratio. However, if one wheel loses all traction, the Torsen will function like an open differential. This means no torque will be transferred to the wheel with grip. The Torsen is typically considered a higher-performance option compared to the Trac-Lok, offering better handling and power delivery. It doesn’t have clutches that wear and is therefore not tuneable in the same way as a clutch pack. It is also typically paired with specific gear ratios such as 3.55-4.10.
Open Differential Functionality
An open differential, unlike the Trac-Lok or Torsen, provides equal torque to both rear wheels regardless of traction. This means that if one wheel loses traction, it will spin freely, and no power will be transferred to the other wheel. This design is simple and cost-effective but not ideal for performance applications. In situations where one wheel has significantly less grip, such as on loose surfaces or during hard cornering, an open differential will struggle to deliver power effectively. The lack of limited-slip action leads to wheel spin and reduced acceleration, hindering overall performance. An open differential is the least desirable option for performance driving, as it does not optimize power delivery or traction. The open differential does not offer any form of torque bias.
Performance Implications of Differential Choice
The choice of differential greatly affects a Mustang’s performance. Limited-slip differentials like Trac-Lok improve traction and power delivery. This enhances acceleration and cornering capability, unlike an open differential, which provides no traction benefits.
Traction and Power Delivery
Traction and power delivery are crucial aspects of performance, especially in high-powered vehicles like the S550 Mustang. The differential’s role is paramount in managing how engine torque is distributed to the rear wheels. A standard open differential allows one wheel to spin freely when traction is lost, resulting in wasted power and reduced acceleration. In contrast, limited-slip differentials, such as the Trac-Lok, work to mitigate wheel spin by transferring power to the wheel with more grip. This improves acceleration, particularly when launching or exiting corners. The efficiency of this power transfer is directly related to the differential’s design and its ability to respond to varying traction conditions. The Trac-Lok uses clutch packs to achieve this; its performance can be further enhanced through tuning and upgrades, ensuring that the S550 Mustang maximizes its power potential. Proper tuning can significantly improve how the car translates engine power into forward motion, delivering a more engaging and effective driving experience.
Cornering and Handling Characteristics
The differential plays a significant role in the cornering and handling characteristics of the S550 Mustang. During cornering, the inside wheel travels a shorter distance than the outside wheel. An open differential allows these wheels to rotate at different speeds, but it can also lead to inside wheel spin when accelerating out of a corner, causing understeer. A limited-slip differential, like the Trac-Lok, helps to mitigate this by transferring power to the outside wheel, which has more traction. This leads to improved stability and more neutral handling. A well-tuned differential can allow the driver to apply power earlier when exiting corners without experiencing excessive wheel spin. The result is a more predictable and controlled driving experience. The Trac-Lok’s ability to manage power distribution during cornering, is key to maximizing the S550’s handling capabilities. Upgrades and adjustments to the differential can further enhance these characteristics, enabling sharper and more precise cornering.
Tuning and Upgrading the S550 Trac-Lok
The S550 Trac-Lok differential can be tuned through clutch pack adjustments and gear ratio changes. Aftermarket limited-slip differentials offer enhanced performance. These modifications improve traction, handling, and power delivery.
Clutch Pack Adjustments
The Trac-Lok’s performance is heavily influenced by its clutch pack configuration. Adjusting the clutch pack involves modifying the number and arrangement of friction and steel plates within the differential. Increasing the number of friction plates typically leads to a higher locking force, which results in improved traction during acceleration. This change can be beneficial for high-horsepower applications where wheel slip is a concern. Conversely, reducing the number or changing the arrangement can decrease the locking force, which is sometimes preferred for improved cornering performance by allowing some degree of slip. Careful adjustment is crucial as excessive locking can cause wheel hop and reduced handling. The condition of the clutch material is also critical. Worn clutches can lead to slipping and inconsistent performance. Some performance enthusiasts opt for upgraded clutch materials, which provide enhanced durability and more consistent locking. These clutch pack adjustments are a key part of fine-tuning the Trac-Lok for specific performance requirements.
Gear Ratio Considerations
Gear ratios in the S550 Mustang’s differential significantly impact the vehicle’s acceleration and top speed. A lower gear ratio, such as 3.73 or 4.10, enhances acceleration by providing more torque to the wheels but may reduce top speed. Conversely, a higher gear ratio, such as 3.15, will improve fuel economy and highway cruising speeds. The choice of gear ratio must align with your driving needs and the vehicle’s power output. For track use, lower gears are often preferable, enabling quicker acceleration out of corners. However, they can result in higher engine RPMs at cruising speed. It’s essential to note that some differentials, like the Torsen, are designed to work with specific gear ratios, typically ranging from 3.55 to 4.10; Changes in the gear ratio must be carefully considered to ensure compatibility and optimal performance. Swapping gears requires recalibration of the vehicle’s computer to maintain accurate speed and shift points, especially for automatic models. Gear ratio modifications are a key aspect when tuning and upgrading S550’s differential.
Aftermarket Limited Slip Differentials
For S550 Mustang owners seeking enhanced performance, aftermarket limited-slip differentials (LSDs) offer a significant upgrade over the stock Trac-Lok system. These differentials, such as those from OS Giken and Kaaz, provide improved power delivery and handling. OS Giken’s Super Lock LSD is designed to help the car rotate in all phases of a corner and is recommended for extensively modified vehicles. Typically, these units offer a more aggressive lock-up and are often adjustable, allowing drivers to fine-tune performance. Kaaz LSDs come in 1.5-way and 2-way configurations, catering to different driving styles, with the 2-way being more suitable for track use. Upgrading to an aftermarket LSD can drastically improve traction, especially in high-horsepower applications, and reduce wheel spin. These units can feature clutch-type designs with adjustable lock-up settings. Choosing the right aftermarket differential is crucial, requiring consideration of the vehicle’s use, power levels, and desired handling characteristics. Installation typically involves professional work to ensure proper setup and function.
Common Issues and Solutions
S550 Mustang Trac-Lok differentials can experience vibrations or slipping, especially with high power. Overheating is another concern, often linked to track use. Upgrades and proper maintenance can address these issues.
Vibrations and Slipping
Vibrations and slipping in the S550 Mustang’s Trac-Lok differential are common issues, particularly in high-performance scenarios or with modified vehicles. These symptoms often manifest when the differential struggles to manage the torque being applied to the rear wheels. The feeling of slipping can occur when the clutch packs within the Trac-Lok fail to engage fully, allowing one wheel to spin excessively while the other lags behind. This can result in a loss of traction and control, especially during hard acceleration or cornering. Vibrations may stem from worn clutch packs, uneven wear, or improper fluid levels. High horsepower applications can exacerbate these problems, pushing the differential beyond its design limits. Furthermore, incorrect gear ratios can also contribute to these issues. Addressing these concerns often requires a combination of careful inspection, proper maintenance, and potentially, upgrades to the differential’s internal components. Early detection and resolution are key to maintaining optimal performance and avoiding more severe damage.
Overheating Concerns
Overheating is a significant concern with the S550 Mustang’s Trac-Lok differential, particularly during demanding driving conditions such as track days or aggressive street use. The friction generated within the differential, specifically within the clutch packs, can cause temperatures to rise rapidly. Prolonged high temperatures can lead to fluid breakdown, diminishing its lubricating properties and accelerating wear on internal components. Overheated fluid can also lose its ability to effectively transfer heat, creating a vicious cycle. This can result in reduced differential performance, increased slippage, and, ultimately, damage to the clutch packs and other parts. The lack of dedicated cooling for the differential in the S550 exacerbates this issue. While some drivers may not experience overheating in typical driving, those pushing their Mustangs to the limit should monitor differential temperatures. Addressing overheating may require fluid changes, upgraded cooling systems, or even aftermarket differential options designed to handle higher thermal loads. Regular maintenance and preventative measures can prevent damage.
The S550 Mustang’s differential, whether the Trac-Lok or Torsen, plays a crucial role in its performance, affecting traction, handling, and overall driving experience. Understanding the nuances of these differentials is key to optimizing your S550. While the Trac-Lok offers a solid foundation for everyday driving and some performance applications, its limitations become apparent at higher power levels or during intense track use. Tuning the Trac-Lok with clutch pack adjustments and gear ratio modifications can improve performance but may not be sufficient for all scenarios. Upgrading to an aftermarket limited-slip differential can address limitations of the stock units, offering enhanced traction and handling, and is often a necessary step for those seeking maximum performance. Additionally, addressing common issues such as vibrations, slippage, and overheating is paramount in maintaining the longevity and effectiveness of the differential system. Ultimately, choosing the correct differential solution and proper maintenance is critical for maximizing your S550’s performance and enjoyment.