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Fifth Wheel hitches

Used primarily for RVs, fifth-wheel setups have been around for about as long as goosenecks, have always been more expensive and used mostly on roads, because until the 1990s they had no side tilt. Modern fifth-wheels now tilt to the sides and are easier to hook up than goosenecks because the coupler in the bed is “funneled” to capture the king pin on the trailer, which helps guide it into place.

Neither the fifth wheel nor gooseneck setup is inherently better or more stable. Although differences in fore and aft loads are more discernible with fifth-wheels, vertical loads on the pickup’s bed are the same. In general, your towing needs determine which system you will use. Also, because fifth-wheel hitches are anywhere from 14 to 18 inches above the bed, they can be susceptible to chucking, a looseness where the coupler jaws grab the king pin. This is especially true with cheaper setups. So the adage is true. You really do get what you pay for. If you spend a bit more on a better fifth-wheel coupler that adjusts to keep a tight grip on the king pin, you won’t have to listen to all that clunking.

One thing that is crucial when selecting fifth-wheel couplers is cab-to-axle ratio, which is really just a fancy way to express the measurement from the rearward-most portion of the cab to the center point of the hitch ball or coupler, which is located directly above or slightly forward of the rear axle. Standard requirements for a full-size bed are a minimum of 48 inches behind the cab. When using a short-bed pickup (less than or equal to 6 feet) to pull a fifth-wheel, the measurement can be as little as 38 inches if you also use a pin-box extension (12-18 inches) and slide rails for the coupler. Some automakers expressly advise against using shortbed pickups for fifth-wheel applications.

A pin-box extension is part of the trailer. Simply put, it extends the pivot point, which normally would be the king pin, farther forward. The effect is that the vertical load of the trailer still rests above the axle (or slightly forward of it) but the leading edge of the trailer’s cabin is farther rearward to mitigate interference with the truck’s cab when turning. However, even with a pin-box extension, some short-bed, crew-cab style trucks need a coupler that slides fore and aft for tight, slow-speed maneuvering, such as backing into a space in a campground. It’s actually a pretty simple system. Unlock the coupler from the slide rails in the bed, lock the trailer brakes and pull forward a bit. Then you lock the coupler in place and you have all the clearance you need for backing and tight maneuvering. Bear in mind that before you leave the campground, you’ll have to unlock the coupler, slide it forward again, then lock it in place for highway driving. It might sound like a lot of work, but hitch manufacturers have made the process as easy as possible—and it also keeps the trailer from smashing through the back window of your truck. And that’s a good thing.

Because they have no cargo bed, SUVs won’t do fifth wheels. Also, because the fifth wheel hitch sits in the pickup’s bed, it takes up much of space you might otherwise use for carrying cargo. You must also remove the factory tailgate to use a fifth wheel. You need a reasonably flat surface to hook them up correctly, and you also must be willing to let the shop drill holes in the bed of your truck.

When hooking up a fifth wheel trailer, be sure you back up far enough so that the king pin is all the way in and touching the forward surface of the coupler. Once you have the king pin into place, pull the hand lever to lock it into position. Then lift the trailer stands to their upper most positions. In many cases, towing a fifth wheel requires an extension harness, which is available where you have the hitch installed or from your truck’s manufacturer. Some fifth wheels require a harness with fuses and relays all their own, but in most cases, the extension is just a length of cable and two seven-blade connectors. Now check your lights, turn signals and brakes.

 

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