Installation of air suspension systems, such as DIRTY AIR's "STEALTH" and "El Grande" series, is a complex task that requires precise procedures to ensure both performance and safety. The following guide addresses the specifics of installing a DIRTY AIR fast-up system for Harley-Davidson (HD) touring models, including considerations for model variations, component differences, and technical best practices.
Overview of the DIRTY AIR Systems
DIRTY AIR provides two primary air suspension upgrade packages designed for HD touring models: the STEALTH and the El Grande. Both systems offer a "fast-up" design, meaning they provide an instant height adjustment through an integrated air system. Despite their functional similarities, the systems differ in components, installation options, and compatibility with specific model years.
STEALTH System: Includes premium aluminum rear air shocks, stainless steel tank with a high-pressure solenoid valve manifold, and a 40Cal air compressor. Designed for a plug-and-play installation, with all necessary wiring components included. It is always equipped with premium aluminum shocks and includes necessary front fork bump stops or caps where required.
El Grande System: Offers steel shocks (upgradable to aluminum) and allows for additional tank and compressor mounting options. The El Grande supports larger components ideal for bikes with side dump exhausts and extended saddlebags. It includes all wiring components but requires manual connection during installation.
Both systems require careful attention to mounting location, component alignment, and wiring pathways to avoid interference with audio and other electrical systems, especially in models with internal components like the Rockford Fosgate or Boom stereo systems found in Harley-Davidson saddlebags (‘14-‘20 and ‘21-later).
Mounting and Clearance Considerations
Correct mounting of the air tank and compressor is crucial to avoid physical or electrical interference. In the STEALTH system, the tank mounts to the right side fender or saddlebag support, while the compressor attaches to the left side fender or saddlebag support. This layout helps maintain balance and reduces the likelihood of parts being damaged by road debris or movement.
However, models equipped with internal audio components (e.g., Boom or Rockford Fosgate systems) may face fitment or clearance issues. On these models, the location of saddlebag-mounted wire connectors could conflict with the mounting of the air system’s electrical components. This situation may necessitate rerouting of audio wires and the installation of spacers or mounting plates specifically designed to resolve interference issues.
It is important to select the correct year and model-specific options during purchase, as many system parts will vary depending on the model year and other options selected. The documentation emphasizes that some parts may not be included or may not exactly match images in the product description due to these variations.
Compatibility and Model-Specific Restrictions
DIRTY AIR explicitly states that its front components will not work on "inverted front ends" found in newer CVO models. Specifically, 2023.5 and newer CVO or CVO ST models are incompatible with the standard front assembly. This is due to differences in fork geometry that prevent the bump stops from functioning properly and could compromise the structural integrity of the system.
The documentation also notes that the system includes installation instructions, and while professional installation is recommended, it is not mandatory. However, users selecting the El Grande package will need to manually connect wiring components, which requires additional skill and attention to detail during assembly.
Air System Installation Best Practices from Monroe
Monroe highlights several key principles for air suspension installations that are broadly applicable and essential for ensuring system durability and performance.
Correct Fitting Installation
Monroe advises using proper torque techniques during the air line fitting installation. Over-tightening a plastic nut on the dust shield fitting can damage the air line, pinching it and preventing air from entering the shock. The recommended practice is to tighten the fitting by hand, ensuring a secure but not excessive connection.
O-Ring and Nut Placement
The O-ring on an air line fitting is critical for maintaining an airtight seal. Monroe recommends the following procedure for insertion:
- Slide the nut and O-ring onto the air line before inserting it into the shock.
- This prevents the O-ring from being damaged or misaligned during installation.
- If the nut and O-ring are accidentally installed on the shock first, the fitting may leak unless properly reassembled.
T-Fitting Mounting Location
Mounting the T-fitting in an accessible location, such as the trunk or under the vehicle, is advised for easy maintenance and inflation checks. The placement should ensure that the fitting is away from potential storage obstructions, such as heavy cargo, tools, or spare parts, to prevent accidental damage.
Air Line Protection and Routing
Air lines on air ride systems are vulnerable to wear and tear from road debris, heat exposure, and contact with other vehicle components. Monroe recommends the following:
- Mounting lines close to the vehicle frame or body to shield them from external damage.
- Using zip ties to secure air lines to the frame or dust shield, preventing them from vibrating against the tire or exhaust system.
Failure to follow these practices can lead to air line deterioration, pinching, or rubbing, which can result in compressed air leaks or system failure.
Identifying and Fixing Air Leaks
The importance of maintaining an airtight system cannot be overstated. According to AccuAir, air lines are the most common source of leaks in air ride suspension systems. These leaks often occur due to exposure to the elements and physical strain from vehicle movement. Over time, air lines may develop holes, tears, or degraded seals, especially at connection points with the air tank, compressor, and solenoid manifold.
Testing for Leaks
A widely used method for detecting air leaks is the soapy water test, which involves applying a soap solution to all connection points and watching for bubbles, indicating air escape. This test is particularly effective for identifying slow leaks that may not be noticeable during regular operation.
Fixing Leaks
- Air Line Damage: Replace damaged sections of air lines with replacement tubing for a secure solution.
- Leaky Fittings: If a leak is traced to the thread connections on the air tank, solenoid manifold, or compressor, the fitting should be unthreaded, cleaned, sealed with thread sealant, and reinstalled.
- Damaged Valve Manifold or Compressor: If the leak is internal to these components (not at a fitting), inspection and replacement of the unit are recommended to restore system integrity.
Air Pressure Management and Ride Height Adjustments
Monroe and DIRTY AIR recommend maintaining the original manufacturer intended ride height by adjusting air pressure accordingly. While air shocks allow for ride height variation, increasing it beyond the original setting can alter suspension geometry, leading to excessive tire wear, handling instability, and part damage.
Pressure Guidelines
- Manual Systems: A minimum of 20 PSI should be maintained in the air shocks to ensure structural support.
- Loaded Conditions: Additional air may be added to maintain ride height under load, but over-pressurization should be avoided due to its potential to affect suspension performance and comfort.
It is important to understand that while air shocks can improve ride quality, they are not designed to support the total weight of the vehicle. Their role is to provide additional support under load, not to replace the mechanical aspects of the original suspension system.
Vehicle-Specific Application Notes
Monroe and DIRTY AIR both note that air shocks are typically best suited for ½-ton and light-duty ¾-ton trucks, not for heavy-duty ¾- or 1-ton models. The suspension systems in heavy-duty trucks are designed to handle heavier loads without additional modification, unlike ½-ton trucks that may benefit from added support to prevent sagging when under heavier loads.
The documentation further cautions against improper use cases, such as:
- Installing front air shocks for snowplow support: Doing so alters alignment angles and can damage suspension geometry.
- Using air shocks to support a dune buggy or off-road vehicle entirely: Air shocks are not designed to bear the full dynamic weight of a vehicle in these conditions and can fail prematurely under stress.
- Exceeding manufacturer GVWR: Installing air shocks does not increase the Gross Vehicle Weight Rating (GVWR) of the vehicle. Users should respect the original weight capacity, as exceeding it can compromise safety and performance.
Component Differences and System Integration
DIRTY AIR system components are tailored to the model year and available configurations, and users must ensure correct part selection to avoid misfit. The STEALTH system includes wiring, making it a more streamlined installation. The El Grande system, while less integrated in terms of wiring, offers larger air tanks and compressors that may be required for bikes with extended saddlebags or side dump exhausts.
In addition, both systems include a fixed alignment for the upper and lower shock mounts due to the bellows structure. Monroe advises that air shocks should not be twisted during installation, as misalignment can lead to improper function and potential component failure.
Final Installation Steps and Safety
Before testing the fully installed air system, several final checks should be performed:
- Verify all mounting points are secure and components are aligned.
- Check for air leaks using the soapy water method at all joints and fittings.
- Ensure the wiring has been correctly routed, especially in models with internal audio systems.
- Visually inspect the air lines for damage or possible pinching under tension.
- Test the system under low load, slowly increasing pressure to ensure a smooth and stable response.
A final warning from Monroe highlights that air shocks are not a substitute for proper vehicle maintenance or engineering improvements. They should be viewed as additional support under load, not as replacements for the original suspension system or vehicle weight ratings.
Conclusion
DIRTY AIR's fast-up suspension systems offer a versatile and upgraded air ride experience for Harley-Davidson touring models. Proper installation, however, requires attention to model-specific compatibility, mounting instructions, air line routing, and wiring integration. By following the detailed guidance from both DIRTY AIR and Monroe, users can ensure that their installation is both functionally sound and safe.
The systems are particularly suited for newer HD models with specific year-based hardware and mounting constraints. Adhering to pressure guidelines, avoiding over-pressurization, and understanding the role of air shocks in supporting rather than replacing the original suspension system are all critical for long-term performance and safety.