Identifying the Rear Pillar Glass on Your Optima
When searching for replacement side glass, many drivers search for a vent window, but this vehicle actually carries a fixed C-pillar rear quarter window. Unlike the mechanically related Hyundai Sonata, which incorporates its rear quarter pane directly into the roll-down rear door frame, this car mounts the glass statically into the unibody pillar sheet metal. Every factory pane comes standard as a solar-control green tempered unit with an integrated black and chrome perimeter moulding pre-bonded to the edge.
To confirm exactly what you need, check your vehicle's market origin and the side of the car requiring replacement. North American models use dealer baseline assembly numbers 87810-D5000 for the left side and 87820-D5000 for the right, whereas European or global market sedans correspond to the D4000 series. When sourcing high-quality aftermarket replacements from manufacturers like PGW, FYG, XYG, or Pilkington, I cross-reference these against standardized NAGS catalog numbers to ensure the encapsulated studs and edge trim seat flush with the quarter panel.
| Side | NAGS Number | North American OEM | Global / Euro OEM |
|---|---|---|---|
| Driver Side (Left) | FQ26877 | 87810-D5000 | 87810-D4000 |
| Passenger Side (Right) | FQ26876 | 87820-D5000 | 87820-D4000 |
Mechanical Fasteners and Surrounding Pillar Trim
You will not find defroster wires, antenna grids, or wiper hardware on this glass. However, the encapsulated moulding relies on integrated threaded retaining studs that pass entirely through the body aperture. From inside the cabin, these studs are fastened using factory retention nuts under part numbers 13271-05001 and 87818-3N000.
Because of this mechanical anchoring, I have to dismantle the interior upper C-pillar trim panels and release the interior garnish clips (OEM 85818-37000) to reach the sheet metal mounting points. Removing the interior panels also allows me to vacuum out all the broken tempered pebbles that inevitably slip down behind the rear seat side bolsters during a break-in.
On the exterior, the window aligns against two critical decorative pieces:
- C-Pillar Center Moulding Garnish: Sits directly adjacent to the glass assembly (Left: 87850-D4000, Right: 87860-D4000).
- Roof Arch Beltline Moulding: The continuous chrome trim running along the roofline that meets the encapsulated top border of the window.
Preventing Post-Replacement Cabin Whistling and Leaks
A frequent complaint on the JF platform after a break-in replacement is a high-pitched highway whistle or water seeping past the headliner. These issues almost always trace back to an incomplete seal around the complex curves of the pillar recess or misaligned studs that tilt the encapsulated outer trim away from the body.
Because the outer chrome trim is permanently bonded to the replacement glass assembly at the factory, the entire unit must seat flush against the exterior sheet metal. If the retaining nuts are torqued unevenly against the inner unibody, the exterior garnish creates wind turbulence against the rear door glass edge. Ensuring the mechanical studs sit centered in their factory holes keeps the side profile seamless and stops water from entering the inner quarter cavity.
