When the king pin on your B&W Gooseneck Coupler wears out or gets damaged, you do not have to replace the entire coupler assembly. The GNXA4000 is the factory-spec replacement king pin for B&W's 4000 series gooseneck coupler, machined to the same tolerances as the original. Keep your towing system performing at full capacity with a genuine B&W replacement part instead of a universal substitute that may not fit or meet the original load ratings.
The king pin is the single pivoting connection point between your gooseneck ball and the coupler jaw. Over time, road vibration, heavy loads, and exposure to the elements can wear the pin surface, introduce slop into the connection, or cause visible scoring. A worn or damaged king pin is not a cosmetic issue -- it directly affects trailer tracking, brake response, and overall tow vehicle control.
The B&W GNXA4000 restores that connection to factory specification. At 19.8 lbs and sized at 12.25 x 12.25 x 9.5 inches, this is a substantial, precision-machined component built to the same standards as the original pin that shipped with your 4000 series coupler. If you already own a B&W 4000 series gooseneck coupler, this is the correct replacement king pin -- no adapters, no guesswork.
Machined to the same dimensions and tolerances as the original B&W 4000 series king pin. Drop-in fit with no modifications required.
Heavy-duty steel construction at 19.8 lbs provides the strength and wear resistance expected of a genuine B&W component.
Eliminates slop, rattle, and wear-induced play in the coupler jaw connection -- restoring tight, secure gooseneck engagement.
Sourced directly from B&W Hitches -- the same manufacturer that built your original coupler. Not a generic substitute.
B&W's 4000 series gooseneck coupler (commonly sold under the Turnoverball and companion coupler systems) is one of the most widely used gooseneck towing platforms in the North American RV and trailer market. The system is designed to work with B&W's underbed gooseneck ball and provides a positive-locking jaw mechanism that engages around the king pin. The GNXA4000 is the service replacement for the king pin component of that jaw assembly.
If you are unsure whether your coupler is a 4000 series unit, look for the B&W logo and model designation stamped or labeled on the coupler housing. B&W also offers higher-capacity coupler series (such as the 20K and 25K platforms), so confirming your coupler model before ordering is important.
The GNXA4000 king pin is designed specifically for the B&W Gooseneck Coupler 4000 series platform. It is not a universal king pin and is not interchangeable with fifth-wheel king pins, conventional trailer coupler pins, or B&W coupler assemblies outside the 4000 series designation.