240sx Rear Lower Control Arm: Upgrading Your Suspension

The Nissan 240SX, a darling of the drift and tuning communities, offers a fantastic platform for suspension modifications. One of the most impactful upgrades you can make is replacing the factory rear lower control arms (RLCAs). While seemingly a simple component, the RLCA plays a critical role in suspension geometry and overall handling. This guide will delve into the function of RLCAs, the benefits of upgrading, and the technical considerations involved in choosing the right aftermarket option.

Understanding the Rear Lower Control Arm

The RLCA, also known as the rear lateral link, is a key component of the 240SX's multi-link rear suspension. It connects the vehicle's chassis to the rear hub assembly. Its primary function is to control the lateral movement of the wheel during suspension travel. Think of it as the horizontal arm that keeps the wheel from moving too far inward or outward relative to the car's body as it goes over bumps or leans into a turn.

More specifically, the RLCA contributes significantly to several important aspects of suspension geometry:

Camber Control: Camber, the angle of the wheel relative to the vertical axis, is crucial for optimal tire contact. The RLCA's position and length influence how camber changes as the suspension compresses and extends.
Wheelbase Variation: As the suspension moves, the distance between the front and rear wheels (wheelbase) can slightly change. The RLCA, in conjunction with other suspension links, influences this wheelbase variation. Excessive variation can lead to unpredictable handling.
Roll Center Height: The roll center is an imaginary point around which the vehicle rolls during cornering. The position of the RLCA significantly affects the roll center height. A lower roll center generally reduces body roll.

The stock 240SX RLCA is typically constructed from stamped steel with rubber bushings. While adequate for everyday driving, these components have limitations when pushed to their performance limits.

Why Upgrade Your RLCAs?

There are several compelling reasons to consider upgrading your 240SX's RLCAs:

Improved Handling and Stability

Aftermarket RLCAs often feature:

Adjustability: The primary benefit is adjustability. Most aftermarket RLCAs offer adjustable length. This allows fine-tuning of the rear suspension geometry to achieve desired camber settings, particularly after lowering the vehicle. Lowering a 240SX significantly alters suspension geometry, often leading to excessive negative camber in the rear. Adjustable RLCAs allow you to correct this, restoring optimal tire contact and improving grip.
Increased Strength and Durability: Aftermarket RLCAs are typically constructed from stronger materials like high-strength steel or aluminum. This increased strength resists bending and deflection under high loads, leading to more predictable handling and improved durability, especially important for drifting or track use.
Improved Bushings: Stock rubber bushings are designed to absorb vibrations and provide a comfortable ride. However, they also allow for significant deflection under load, which can negatively impact handling precision. Upgraded RLCAs often use polyurethane or spherical bearings (heim joints) instead. Polyurethane bushings offer a good balance of stiffness and compliance, while spherical bearings provide virtually no deflection for the most direct and precise handling feel.

Correcting Geometry After Lowering

Lowering a 240SX dramatically alters its suspension geometry. The stock RLCAs are not designed to compensate for this change. As mentioned earlier, excessive negative camber is a common issue. This leads to:

Uneven Tire Wear: The inner edge of the tire wears much faster than the outer edge.
Reduced Grip: The tire is not making full contact with the road, reducing overall grip, especially during acceleration and braking.
Unpredictable Handling: The car may feel twitchy and unstable, particularly at higher speeds.

Adjustable RLCAs allow you to correct the camber angle back to a more optimal range, restoring proper tire contact and improving handling and tire life.

Enhancing Performance for Drifting and Track Use

For drifting and track applications, the benefits of upgraded RLCAs are even more pronounced. The increased strength and reduced deflection allow for more aggressive driving styles and improved control. The ability to fine-tune camber allows drivers to optimize their setup for specific track conditions or drifting techniques. Some RLCAs also offer additional features such as:

Relocated Mounting Points: Some RLCAs feature relocated mounting points to further optimize suspension geometry and improve anti-squat characteristics.
Reinforced Construction: Reinforced designs are available for extreme applications, such as competitive drifting, where the suspension is subjected to immense stress.

Technical Considerations When Choosing RLCAs

Selecting the right RLCAs for your 240SX requires careful consideration of several factors:

Material

Steel: Steel RLCAs are generally more affordable and offer excellent strength. They are a good choice for street cars and those who prioritize durability over weight savings. Look for high-strength alloys like chromoly steel for maximum strength.
Aluminum: Aluminum RLCAs are lighter than steel, which can improve handling and reduce unsprung weight. However, they are typically more expensive and may not be as durable as steel in extreme conditions. Ensure the aluminum is a high-grade alloy, such as 7075-T6, for optimal strength and corrosion resistance.

Bushings/Bearings

Rubber: Avoid rubber bushings in aftermarket RLCAs intended for performance use. They offer too much deflection.
Polyurethane: Polyurethane bushings offer a good balance of stiffness and compliance, making them a popular choice for street cars and those who want improved handling without sacrificing too much ride comfort. Pay attention to the durometer (hardness) of the polyurethane. A higher durometer bushing will be stiffer and offer less compliance.
Spherical Bearings (Heim Joints): Spherical bearings provide virtually no deflection, resulting in the most direct and precise handling feel. However, they can transmit more noise and vibration into the cabin and may require more frequent maintenance. Look for sealed or Teflon-lined spherical bearings for improved durability and reduced noise.

Adjustability

Ensure the RLCAs offer sufficient adjustability to achieve your desired camber settings. Consider the range of adjustment offered and whether it is suitable for your vehicle's ride height and intended use. A good rule of thumb is to choose RLCAs with a wider range of adjustability than you think you need, as you may need to adjust them further in the future as you modify other suspension components.

Construction Quality

Pay close attention to the construction quality of the RLCAs. Look for well-welded seams, durable finishes, and high-quality hardware. A poorly constructed RLCA can fail under stress, leading to dangerous handling situations.

Brand Reputation

Stick to reputable brands with a proven track record of producing high-quality suspension components. Read reviews and do your research before making a purchase. A well-known brand is more likely to offer better customer support and warranty coverage.

Installation Considerations

Installing RLCAs is a relatively straightforward process, but it's essential to follow proper procedures and take necessary precautions.

Safety First: Always use jack stands when working under a vehicle. Disconnect the battery to prevent accidental electrical shorts.
Torque Specifications: Use a torque wrench and tighten all bolts to the manufacturer's specifications. Over-tightening can damage the components or cause premature failure.
Alignment: After installing new RLCAs, it's crucial to get a professional wheel alignment. This ensures that the suspension geometry is properly set and that the vehicle handles correctly.
Loctite: Use threadlocker (Loctite) on all bolts to prevent them from loosening over time.
Adjustable End Links: Consider upgrading to adjustable sway bar end links to fine-tune the sway bar preload and optimize handling.

Conclusion

Upgrading your 240SX's rear lower control arms is a highly effective way to improve handling, correct suspension geometry after lowering, and enhance performance for drifting and track use. By carefully considering the material, bushings, adjustability, and construction quality, you can choose the right RLCAs for your needs and transform your 240SX into a more capable and enjoyable driving machine. Remember to prioritize safety during installation and always get a professional wheel alignment after making suspension modifications. Properly chosen and installed RLCAs will significantly enhance your driving experience. Investing in quality components and proper installation will pay dividends in terms of performance, handling, and overall driving enjoyment.