The function of the lower body of the car's rear bumper
The plastic plate located beneath the car's rear bumper (commonly referred to as the rear bumper under diffuser or rear lip) plays multiple important roles in vehicle design, mainly including the following points:
Enhancing driving stability: During high-speed driving, it effectively reduces the lift generated by the air flow and prevents the rear wheels from "floating", making the vehicle more grounded and providing better handling.
Optimizing aerodynamic performance: By guiding the airflow smoothly over the vehicle's underside, it reduces the drag coefficient and helps improve fuel economy.
Absorbing and dispersing impact forces: In low-speed collisions (such as rear-end collisions), it acts as a buffer structure, reducing damage to the vehicle's body structure, tail lights, trunk, etc.
Protecting the vehicle's underside: It prevents foreign objects such as road debris from directly impacting critical parts like the chassis lines, fuel tank, etc.
Safety protection: It provides some buffering effect during collisions, meeting the requirements of modern vehicle passive safety design.
Aesthetic enhancement: Through a streamlined design, it enhances the overall sportiness or technological appeal of the vehicle, improving visual recognition.
This component is typically made of plastic (such as PP material) and is fixed using screws or clasps, making it easy to disassemble and replace.
Common problems with the rear bumper assembly usually refer to issues such as looseness, lifting, cracks, paint peeling, deformation, or damaged clasps of the vehicle's rear bumper (also known as "rear bumper skin"). According to the latest publicly available information, the following are common causes and suggestions for handling:
Common causes
Worn or loose clasps: The bumper is fixed to the vehicle using plastic clasps. Long-term use or bumpy road conditions can cause the clasps to break or fall off, causing the lower part to lift or shift.
External impact or scratches: When reversing or parking, collisions with curb stones, trash cans, etc., may cause the bumper to develop dents, cracks, or frame fractures.
Chassis impact: When passing over speed bumps, potholes, or steep slopes, the rear bumper under guard or frame may be scratched by stones or other foreign objects.
Paint aging or spraying quality issues: Some new or refurbished vehicles may have bubble or peeling paint on the rear bumper bottom, which is a manufacturing or material defect.
Suggestions for handling
Initial inspection
Observe whether it is only a surface paint issue (such as paint peeling, scratches), or structural loosening, cracks.
Check if the clasps are missing or broken (need to check from the wheel arch or the inside of the trunk).
Minor fault handling
Loose clasps: Try to reinsert or replace the original factory clasps (costs approximately 5–20 yuan per piece).
Surface scratches: Use a touch-up paint pen or local spray painting to repair .
Minor cracks: If they do not affect the structure, use plastic welding to repair .
Severe fault handling
Clearly cracked, deformed frame or failed fixation: Do not continue driving, as it poses safety hazards. Immediately stop the vehicle and contact professional repair services .
Vehicle structure deformation (such as the lower beam): Requires the use of professional equipment (such as a beam correction instrument) for correction. Do not attempt to handle it yourself .
Insurance claim tips
If the vehicle is insured for vehicle damage, and the fault is caused by an accident (such as a collision or scratch), contact the insurance company for assessment, and some repair costs may be covered by the insurance .
Suggested operation process
Step 1: Take photos to record the faulty area and determine whether it is an appearance issue or a structural problem.
Step 2: Go to a reputable auto repair shop or 4S store for professional assessment.
Step 3: Based on the diagnosis results, decide whether to repair, replace, or continue observation.
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