Learning how to adjust Fontaine fifth wheel settings is one of those tasks that sounds a lot more intimidating than it actually is. If you've been on the road for any length of time, you know the feeling: that annoying "clunk" or "slap" whenever you take off from a stop or slow down. That's usually the kingpin playing tag with your fifth wheel because there's just a little too much slack in the system. While Fontaine is famous for their "No-Slack" technology, even the best engineering needs a little human intervention every now and then to keep things running smoothly.
Getting this right isn't just about getting rid of a pesky noise, though that's definitely a perk. It's mostly about safety and extending the life of your equipment. A loose connection wears down the jaw and the kingpin much faster than a snug one. So, grab your gloves and maybe a rag, and let's walk through how to get that Fontaine fifth wheel dialed in perfectly.
Why You Might Need an Adjustment
Most modern Fontaine fifth wheels are designed to be self-adjusting. The "No-Slack" mechanism uses a spring-loaded wedge that moves in as the parts wear down, theoretically keeping the jaw tight against the kingpin at all times. But theory and the real world don't always shake hands.
Sometimes, grease buildup, cold weather, or just plain old wear and tear can cause the wedge to get a bit sluggish. If the wedge doesn't slide into place, you get slack. On the flip side, if someone messed with the adjustment bolt previously and tightened it too much, you might find it nearly impossible to uncouple your trailer. You're looking for that "Goldilocks" zone—not too tight, not too loose.
Before You Get Started
Don't just dive under the trailer. First, make sure you're parked on level ground. Set your tractor brakes, but do not set the trailer brakes just yet if you're trying to check for slack. You'll need to be able to move the tractor slightly to see how much play is in the connection.
You're going to need a few basic tools. Usually, a 15/16-inch wrench is the star of the show for the adjustment bolt. A good flashlight is also a lifesaver because it's dark under there, and you really need to see where the wedge is sitting. Also, keep a pry bar handy; it's the best way to check for movement without having to jump back in the cab and tug on the trailer.
Checking the Slack
Before you turn any bolts, you need to know if an adjustment is actually necessary. The easiest way to do this is the visual check. Look at the adjustment bolt—that's the big bolt sticking out of the side of the fifth wheel housing.
On a Fontaine No-Slack II, for example, there's usually about a 1/8-inch gap between the bolt head and the housing when the lock is closed and the kingpin is engaged. If that gap is significantly larger, or if the bolt is sucked all the way in flush against the frame, things are out of whack.
Another way to check is the "pry bar test." With the trailer coupled and the brakes set, try to jam a pry bar between the jaw and the kingpin. If you can wiggle it back and forth easily, you've got too much slack.
The Adjustment Process
Okay, let's get into the actual steps for how to adjust Fontaine fifth wheel locks. We'll focus on the manual adjustment of the No-Slack system since that's what most drivers encounter.
1. Close the Lock
You can't adjust the fifth wheel while it's open. You need to have a kingpin in there (or a test tool that mimics a kingpin) and the handle needs to be in the locked position. If you're doing this without a trailer attached, you'll need a dummy kingpin tool to trip the mechanism.
2. Locate the Adjustment Bolt
Look on the side of the fifth wheel. You'll see a long bolt with a heavy-duty spring. This bolt controls how far the wedge can travel. The wedge is what actually holds the jaw tight against the kingpin.
3. Turning the Bolt
If you have too much slack (the clunking issue), you want to turn the adjustment bolt clockwise. This moves the wedge further in. However, don't just crank it down. Usually, a turn or two is all it takes.
If the fifth wheel is too tight and you're struggling to pull the release handle, you'll want to turn the bolt counter-clockwise. This backs the wedge off and gives the jaw a little more breathing room.
4. The 1/8-Inch Rule
A good rule of thumb for Fontaine models is to adjust the bolt until there is roughly a 1/8-inch gap between the flat washer on the bolt and the side of the fifth wheel skirt. This isn't a "set it and forget it" number, but it's the factory-recommended starting point.
Testing Your Work
Once you think you've got it, it's time to verify. If you're hooked to a trailer, jump in the cab and perform a standard tug test. Then, get out and look at the handle. Does it look fully seated?
The real test comes when you try to uncouple. If the handle pulls out with a firm, steady pressure, you're golden. If you have to put your whole body weight into it and use a pull-bar just to get it to budge, you've probably adjusted it too tight. Back that bolt off a half-turn and try again.
Pro tip: Always make sure the trailer is pushing slightly against the fifth wheel when you try to uncouple. If the trailer is pulling away (even slightly), it puts tension on the lock and makes it feel like it's adjusted too tight when it's actually just physics working against you.
The Importance of Grease
You can spend all day learning how to adjust Fontaine fifth wheel parts, but if the thing is bone dry, it'll never work right. The No-Slack wedge relies on being able to slide easily. If there's old, crusty grease or rusted metal-on-metal contact, that wedge is going to get stuck.
Make sure you're hitting the grease zerks regularly. But don't just add new grease on top of the old stuff. Every once in a while, it's a good idea to clean out the gunk. Use a degreaser or a pressure washer to get the old, grit-filled grease out of the jaw and wedge area, then pack it with fresh, high-quality lithium-based grease. A well-lubricated fifth wheel often "adjusts itself" just like it was designed to do.
When to Call a Professional
Sometimes, no amount of turning the bolt is going to fix the problem. If you notice that the jaw itself looks thin or if there are visible cracks in the casting, stop right there. Fifth wheels are tough, but they aren't immortal. If the internal springs are snapped or the wedge is chipped, you might be looking at a rebuild kit or a full replacement.
Also, if you've adjusted the bolt all the way in and you still have slack, that's a clear sign that the components are worn beyond their service limits. At that point, you aren't adjusting anymore; you're just masking a mechanical failure. Safety first—if it doesn't feel right, get it into the shop.
Final Thoughts
Knowing how to adjust Fontaine fifth wheel tension is a great way to make your daily drive a lot more comfortable. No one likes feeling their load jerk around behind them. It's a simple process of checking the gap, turning a bolt, and making sure everything is greased up.
Keep an eye on that 1/8-inch gap and listen to what your truck is telling you. If you take care of your Fontaine fifth wheel, it'll take care of you for hundreds of thousands of miles. Just remember to stay safe, use the right tools, and never skip the tug test. Happy trucking!