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Enhance your FAW truck’s undercarriage protection and aerodynamic profile with the genuine Lower Left Deflector, OEM part number 5704221-B90/H. This essential panel is mounted below the cab on the driver’s side, designed to shield critical chassis components, manage airflow under the vehicle, and reduce road spray. As a fundamental part of durable Faw truck parts, the 5704221-B90/H deflector safeguards the fuel tank, battery box, and air lines from stones, mud, and corrosive road salts.
Its carefully engineered shape also improves fuel efficiency by smoothing turbulent air beneath the cab and chassis. Replacing a missing or damaged 5704221-B90/H unit restores vital protection for expensive components, reduces wind resistance, and helps maintain a cleaner undercarriage. This direct-fit, left-side specific part is crucial for long-term durability and operational cost savings in demanding trucking environments.
Lower Left Deflector
Нижний левый дефлектор
The primary role of the Lower Left Deflector 5704221-B90/H is to act as a physical barrier between the road and vital under-cab components. Positioned on the driver’s side, it intercepts rocks, debris, and slush thrown up by the front tires. This direct protection is essential for preventing damage to the fuel tank, which is vulnerable to punctures and corrosion.
It also shields electrical wiring harnesses, air brake lines, and other sensitive parts mounted along the chassis rail. By deflecting these hazards, the 5704221-B90/H significantly reduces the risk of costly leaks, shorts, and component failures, enhancing vehicle reliability and safety.
Beyond physical protection, the 5704221-B90/H plays a key aerodynamic role. It helps streamline airflow underneath the cab and chassis, reducing turbulent drag that increases fuel consumption. A smooth underbody airflow contributes to better highway stability and fuel economy.
Additionally, the deflector’s shape is designed to control road spray. It minimizes the amount of water and mud thrown onto the chassis and the rear of the tractor, keeping components cleaner and reducing the accumulation of corrosive salts and dirt that accelerate rust.
| Parameter | Specification |
|---|---|
| OEM Part Number | 5704221-B90/H |
| Component Name | Lower Left Cab Deflector / Splash Guard |
| Position | Left Side, Below Cab (Driver’s Side) |
| Primary Material | High-Density Polyethylene (HDPE) or Reinforced Plastic |
| Finish | Molded Color (Typically Black) or Paintable |
| Mounting | Bolts to Cab Floor and Chassis Brackets |
The 5704221-B90/H deflector is constructed from tough, flexible plastics like High-Density Polyethylene (HDPE). This material is chosen for its exceptional impact resistance, allowing it to absorb blows from road debris without cracking. HDPE is also impervious to corrosion, chemicals, and moisture, making it ideal for under-vehicle use.
Its design often includes molded-in ribs or contours for added stiffness and to guide airflow effectively. The mounting brackets are typically made of coated steel for strength, ensuring the deflector remains securely attached despite constant vibration and exposure to harsh conditions.
Replacing the 5704221-B90/H involves safely jacking and supporting the truck for undercarriage access. The old deflector is unbolted from its mounting points on the cab floor and chassis brackets. Any accumulated debris in the area should be cleaned before installing the new part.
The new OEM 5704221-B90/H deflector is positioned, aligning all holes with the corresponding brackets. It’s critical to use the correct hardware and torque specifications to ensure a tight, rattle-free fit that can withstand high-speed wind pressure and road vibrations.
The deflector’s location makes it the first line of defense for the fuel tank, a safety-critical component. A stone impact on an unprotected tank can be catastrophic. The 5704221-B90/H absorbs and deflects such impacts, directly preventing fuel leaks and fire hazards.
It also protects expensive air system components, battery boxes, and hydraulic lines from abrasion and impact damage. This protection extends the service life of these parts and reduces unscheduled downtime for repairs.
By blocking road spray, the 5704221-B90/H significantly reduces the amount of water, salt, and mud that contacts the chassis frame and components. This is a major factor in preventing rust and corrosion, which weakens structural integrity.
A cleaner undercarriage is also easier and faster to inspect during maintenance checks. Mechanics can spot leaks, cracks, or wear more easily when components are not covered in a thick layer of grime, improving maintenance quality.
Large cracks or holes in the deflector render it ineffective. Severe deformation or sagging changes its aerodynamic profile and reduces ground clearance. Missing or broken mounting brackets cause the 5704221-B90/H to hang loosely or rub against tires.
Excessive wear or brittleness from UV exposure and age can compromise its strength. Any of these conditions mean the deflector is no longer providing adequate protection and should be replaced promptly with a genuine 5704221-B90/H unit.
The 5704221-B90/H is engineered exclusively for the LEFT lower side of the cab. Its shape accounts for the asymmetric placement of components like the fuel tank, battery box, and exhaust system on the driver’s side. A right-side deflector has a different part number and contour.
Fitment is also specific to the FAW truck model and cab configuration. The genuine part ensures perfect alignment with all factory mounting points and proper clearance with the fuel tank, steering linkage, and other adjacent parts.
While often overlooked, underbody aerodynamics play a role in overall fuel efficiency. The 5704221-B90/H helps create a smoother path for air flowing under the truck, reducing drag-inducing turbulence. This can contribute to a small but measurable improvement in miles per gallon.
For fleet operators, this slight gain, multiplied across many trucks and millions of miles, translates into significant fuel cost savings. Maintaining all aerodynamic components, including lower deflectors, is part of a holistic fuel management strategy.
Regularly inspect the 5704221-B90/H during oil changes or tire rotations. Look for cracks, especially around mounting holes and edges. Check that all bolts are tight, as vibration is intense in this area. Ensure the deflector is not bent inward and rubbing on tires or components.
Clean off caked-on mud or ice that adds weight and can distort the panel. In winter regions, pay extra attention to ensure road salt buildup is washed off to prevent accelerated corrosion of the metal brackets behind the plastic shield.
The genuine 5704221-B90/H deflector is designed and tested to meet FAW’s exacting standards for material strength, aerodynamic effect, and impact resistance. It guarantees a perfect fit with no modification required, saving installation time and frustration.
Aftermarket alternatives may use thinner, weaker plastics that crack easily or have imprecise mounting holes leading to poor alignment. The OEM part provides reliable performance and longevity, ensuring your investment in protection is sound.
A secure 5704221-B90/H deflector prevents it from becoming a detached road hazard. It also ensures that spray is controlled, improving visibility for following drivers—a key safety consideration. Protecting fuel and air lines directly prevents failures that could lead to accidents.
In some jurisdictions, having intact underbody panels and spray suppression devices is part of roadworthiness inspections. Maintaining your 5704221-B90/H helps ensure your truck passes these checks and remains legally operational.
The Lower Left Deflector 5704221-B90/H is one part of a complete underbody aerodynamic system. It works in tandem with right-side deflectors, front air dams, and side skirts. For maximum efficiency and protection, all these components should be present and in good condition.
When replacing one side, it is wise to inspect the condition of the corresponding deflector on the other side and related panels. A cohesive, undamaged underbody system provides the best results in both fuel savings and component protection.
The cost of a new 5704221-B90/H deflector is minor compared to the potential repair bills it prevents. A damaged fuel tank, ruptured air line, or corroded electrical system can cost thousands to repair and cause days of downtime.
Proactively replacing a worn deflector is a classic example of preventative maintenance. It safeguards much more expensive components, ensuring continuous operation and protecting your bottom line from unexpected major repairs.
The FAW Lower Left Deflector, OEM number 5704221-B90/H, is a vital component that offers multifaceted benefits. It provides robust physical protection for expensive chassis parts, contributes to aerodynamic efficiency, and helps control road spray.
Its durable construction is built to endure the harsh under-vehicle environment. Choosing the genuine, side-specific part ensures optimal fit and performance. Regular inspection and timely replacement of the 5704221-B90/H is a smart, cost-effective practice for any FAW truck operator.
This component plays a silent but crucial role in reducing operating costs, enhancing safety, and prolonging the service life of your vehicle. Protect your investment and ensure your truck’s reliability by maintaining its lower deflector in excellent condition.
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