Space Needed Between Upper & Lower Fifth Wheel

This article may contain affiliate links where we earn a commission from qualifying purchases.

When hauling a fifth-wheel trailer, it is critical to couple the kingpin correctly. How much of a gap should be between the upper and lower fifth wheel?

There should be no space between the upper and lower sections of the fifth wheel. The kingpin should be clamped into the hitch jaws appropriately. With fifth wheels, the hitches often move side to side and front to back to give the trailer enough room to negotiate turns and road imperfections.

There is no question that fifth-wheel travel trailers are becoming the RV of choice for millions. Whether hauling a trailer to the lake for a fun weekend or exploring the wonder of the American landscape with a cross-country trip, fifth wheels provide families with many of their home’s amenities. They provide functionality and convenience as owners can haul many of their home’s amenities wherever they go. Hauling a fifth-wheel trailer means that you need to know a few things. There is so much more to a safe tow than just backing a truck up to the kingpin box, snapping your fingers, and pulling on down the road. If you are new to RV ownership, or this is your first time hooking a kingpin to a fifth-wheel plate, this article is for you. How much space should be between the various portions of the fifth wheel? How snug does the kingpin have to be? How can you tell if a kingpin is hooked up correctly? Let’s examine the ins and outs of fifth-wheel hitches.

Table of Contents


How Does A Fifth Wheel Hitch Work?

A fifth-wheel hitch comes in two parts with a hitch assembly with a U-shaped mounting plate bolted to the tow vehicle's frame. The hitch’s mounting plate accepts a downward-extending kingpin installed on the trailer's front overhang. When the kingpin comes in contact with the u-shaped locking plate, two powerful jaws lock onto the kingpin, ensuring the connection between the truck and the trailer.

The hitch plate may be able to slide back and forth or from side to side slightly, which helps increase the distance between the trailer and the tow vehicle. (It also keeps the camper’s front from ramming through the rear cab window).

When you align the truck to the fifth wheel’s kingpin, the locking jaws should be open. As the u-shaped hitch contacts the trailer’s kingpin, the locking jaws should close, holding the trailer's pin box in place. There should be no space between the upper part of the kingpin and the lower hitch plate.

What Is The Procedure For Hooking A Fifth Wheel?

Hooking up a fifth-wheel camper to a truck is relatively easy if you have some experience with it. (These instructions assume that you have already installed a fifth wheel hitch to the cargo bed of your truck with mounting rails bolted to the truck frame). Follow these instructions to ensure that you hook up the fifth wheel correctly.

Park On A Level Surface

The trailer and truck need to be on level ground to ensure a viable connection between the truck and the trailer. To keep the trailer from moving, chock the trailer wheels. Ensure the trailer is the correct height (use the crank handle to adjust the camper’s legs and move the kingpin up or down). Do not attempt to connect the camper with any electrical lines stretching over the trailer.

Install a lube plate onto the kingpin (this plate is a small plastic disc that slips over the kingpin and sits flush with the top of the kingpin - where it connects to the pinbox).

Open the Lock Jaws To Receive The Kingpin

You must open the locking jaws on the fifth wheel hitch to receive the kingpin. Most units have a release handle on the side that retracts the jaws. Pull the sidebar and set it into the open position.

Back Your Truck Up To The Kingpin

Lower the tailgate of your truck and slowly back the truck up to the kingpin. (Make sure that your truck and the trailer are lined up in a straight line). Safety is paramount here, so keep kids and other family members from the kingpin area.

It is a good idea to have friends, or family members act as a signal guide to help you as you back toward the kingpin. When the kingpin is about five inches from the plate, stop the truck, put it in park, and get out to inspect the work.

Make Any Adjustments To Trailer Height That Are Needed

This is a great time to adjust the height of the trailer’s kingpin down to about half an inch difference between the hitch plate and the top of the kingpin and the lube wheel of the pinbox. (The hitch plate should be higher than the kingpin box)

Back The Truck Up To Engage the Fifth Wheel Hitch Plate.

As you back up the truck, the hitch plate should receive the kingpin and become fully integrated. Inspect the hitch plate to ensure the locking jaws have latched onto the kingpin. Some fifth-wheel hitches require owners to manually engage the locking bar, while others do so automatically with light bars to help owners know when the hitch is secure.

Once the jaws have engaged, insert the safety pin to keep the jaws in the locked position.

Test The Connection

Once the safety pin is inserted and the jaws are locked onto the kingpin, you need to test the connection. Put your foot on the brake pedal, disengage the parking brake, and engage your manual trailer brake controller. Let off the brake, and allow the truck to move forward slowly. If you feel resistance, you are good to go (the connection is secure). If the truck moves forward without any trailer resistance, double-check the connection. Remember that there should be no space between the kingpin box and the hitch plate once the connection is made.

Perform a Final Inspection. Plug The Wiring Harness and Attach Safety Chains

At this point, you need to close the tailgate, remove the trailer wheel chocks, finish plugging in the wiring harness, and hang the safety chains from the trailer’s overhang and the truck bed. Test the trailer brakes, if you haven’t already. Have someone inspect whether the brake lights, turn signals, and tail lights are working correctly. Raise the landing gear to cruising heights.

Many states require safety chains for fifth-wheel campers. Knowing what your state requires is always good. Use safety chains that are adequate for the trailer's size and weight. (You should never try to tow a camper that is more than your GVWR).

Do a Final WalkAround

You want to make sure that everything on the trailer is secure. Ensure that all air and electrical lines are stored properly and are not dragging on the ground. Air lines can come loose if not stored properly.