When restoring a Buick Grand National, one of the most impactful yet often overlooked upgrades is replacing the plastic bumper filler panels. Over time, these fillers become cracked, warped, or completely disintegrated due to age, heat exposure, and general wear. At Kirban Performance, we’ve spent decades helping G-body owners bring their vehicles back to showroom condition, starting with essential exterior components like bumper fillers and extending to key parts of car interior restoration.
In this post, we’ll cover bumper filler restoration best practices, sharing our proven tips on fitment, avoiding sag and droop, and how to choose the right parts for the job.
Why Bumper Fillers Matter
The plastic filler bumper panels fill the gap between the body and bumper, giving your Grand National a seamless, finished look. Originally made from polyurethane, many OEM fillers have now deteriorated beyond repair. Replacing them not only improves the car's aesthetic but also helps prevent moisture intrusion and further body damage.
Whether you’re performing a complete frame-off restoration or freshening up your daily driver, restoring the bumper fillers is a high-impact, low-effort upgrade.
Choosing the Right Plastic Bumper Filler
Not all fillers are created equal. At Kirban Performance, we offer reproduction plastic bumper filler panels molded from tough, heat-resistant materials like TPO (thermoplastic olefin) or ABS. These replacements are designed for long-term durability and factory-correct fit.
For example, our Hard Plastic Front Bumper Filler Panels (Part #KPP8671) are a popular choice for Grand National owners who want a precise fit and clean finish. These panels require light sanding and an adhesion promoter before painting, ensuring a strong, lasting bond.
Installation Tips for a Seamless Finish
To get that “from worn to wow” result, here are our top installation tips:
1. Test Fit Before Painting
Place the bumper fillers loosely on the car before you paint them. This helps identify any slight alignment adjustments needed for a flush finish.
2. Use Quality Adhesion Promoter
Modern plastic fillers like TPO don’t hold paint well without a proper primer. Use an adhesion promoter designed for automotive plastics to avoid chipping or peeling over time.
3. Avoid Sag with Proper Bracing
One of the most common issues we see is sagging filler over time. Make sure your mounting points are intact, use washers if necessary to support the filler’s weight, and don’t overtighten screws, which can crack the panel.
4. Match Paint Carefully
Although it might be tempting to use off-the-shelf black paint, we recommend getting your paint mixed to match your car’s exact color code. Even black can vary by shade between years or exposure.
Before and After: The Visual Payoff
Restoring your bumper fillers dramatically sharpens your vehicle’s lines. Whether you’re showing your GN or just enjoying a cleaner look on your weekend cruiser, the result is always worth the effort. Our customers often tell us that the new fillers make the car look “10 years younger”, especially when paired with refreshed trim and interior parts of a car like dash overlays and pillar moldings.
Don’t Forget the Interior
While restoring the exterior, it’s a great time to refresh worn-out parts of the car interior as well. We carry a wide range of interior restoration parts at Kirban Performance, everything from A-pillar moldings and headliner clips to seatbelt sleeves and power window switches. These small details add up to a complete and cohesive restoration that feels just as good inside as it looks outside.
Shop Trusted Bumper Fillers and Interior Parts at Kirban Performance
Whether you're after a full restoration or a quick facelift, upgrading your plastic filler bumper panels is a high-impact project you can tackle with confidence. At Kirban Performance, we’re proud to supply top-quality restoration parts for Buick Grand Nationals and other G-body vehicles.
Explore our full range of exterior and interior parts of a car restoration components at Kirban Performance.