How to Install a Fifth Wheel Hitch

by Don Bowman

When installing a fifth wheel hitch on a truck, the trailer should never match or exceed the load bearing capacity of the truck itself. There should always be a 20 percent fudge factor so the suspension does not stress out. The hitch must always be forward of the rear axle. Long bed trucks are preferred, although shortbed trucks can be used with a slider king pin. This allows the king pin to slide toward the rear to allow tight turns at slow speed when parking. Without the slider, the trailer contacts the cab in a tight turn.

Measure 56 inches back from the cab on a long bed or 36 inches for a short bed. Make a mark close as possible to the middle of the bed with these distances.

Measure 28-5/16 inches from the tailgate and make a mark in the center of the bed for a long bed, 26-5/16 inches for a short bed. This is where the rear rail for the fifth wheel is to be located. The mark should be the bolt hole in the center rear of the rail.

Install the rear rail using the existing bolt in the bed if possible. Most domestic trucks from 1999 forward should accept the rails without drilling. If the holes are not present, drill the two holes on either side of the rail. Insert the bolts and nuts and tighten with the ½-inch drive socket and ratchet. This tool is used for all bolts and nuts in this installation.

Lay the fifth wheel on the rear rail and line up the bolt holes. Install just the bolts to hold it in place. Install the front rail under the fifth wheel. Line up the holes and insert the bolts only.

Install the end bolts in the front rail or drill the holes and install the bolts and tighten. Install the nuts on the front and rear bolts, securing the fifth wheel and tighten securely.

Install the sidewinder fifth-wheel extension for short-bed trucks. It attaches right to the fifth-wheel king pin. It is a 20-inch extension from the truck king pin to the pin box on the trailer. In normal use the entire extension is locked solid. When parking, the front part in the truck king pin gets locked and the rear portion gets unlocked so it will swivel giving the truck cab more clearance in a turn.

Items you will need

About the Author

Don Bowman has been writing for various websites and several online magazines since 2008. He has owned an auto service facility since 1982 and has over 45 years of technical experience as a master ASE tech. Bowman has a business degree from Pennsylvania State University and was an officer in the U.S. Army (aircraft maintenance officer, pilot, six Air Medal awards, two tours Vietnam).