Flex Air drastically reduces chucking, absorbs road shock, and minimizes bounce. The internal air bag and built-in strut work with the rubberized pivoting head to achieve a dramatically smoother ride. Replaces Lippert 1621 pin boxes.
Features:
Specs:
Notes:
Getting there is half the fun, right? Not if you're being bumped, jerked, jammed, and pushed around from the chucking, road shock, and bounce that occurs as you tow your fifth-wheel trailer or RV. And imagine the costly wear and tear on your trailer as it endures that rocky ride.
Put the fun back into your trip and ease the stress on your trailer by replacing your factory pin box with the Curt Flex Air pin box. The internal air bag and built-in shock work together to cushion your ride, improve handling, and limit strain on both your truck and your trailer. But what sets the Flex Air apart from other air ride pin boxes is the addition of a pivoting head. This head, along with its built-in rubber compound, provides additional cushion, absorbs road shock, and reduces chucking for a significantly improved ride.
A heavy-duty rubber compound is built into the head assembly of the Flex Air pin box. This rubber is the first defense against road shock. It helps to absorb the bumps and vibrations experienced when towing a fifth-wheel trailer over rough roads. Standard pin boxes without any type of shock absorption transfer road shock to your trailer, resulting in potential damage to the trailer and an overall bumpy ride. The shock-absorbing rubber inside the Flex Air takes the beating so there's less wear and tear on your trailer or RV and you get a smoother ride.
Because the rubber may not be able to absorb all of the road shock that you experience, the Flex Air also implements air ride technology to virtually eliminate shock. When you encounter uneven terrain on your trip or hit a pothole on the highway, the Flex Air pin box compresses vertically, similar to how a pair of scissor blades closes in on each other. This compression transfers the road shock and vibrations to the internal air bag, saving your fifth-wheel hitch, trailer, and tow vehicle frame from enduring a rocky ride.
A built-in strut, or shock, controls the Flex Air's compression so that the internal air bag doesn't burst. The strut also causes the pin box to appropriately rebound without any bounce, and positions it to be ready for the next bump in the road.
The pivoting head on Flex Air allows for controlled back and forth movement of the king pin to reduce the uncomfortable jarring known as chucking. Unlike a rigid pin box that has little give at the point where the trailer and the hitch are connected, the Flex Air can pivot slightly to compensate for those times that your trailer suddenly pushes or pulls on your tow vehicle. Because the pin box head - not the king pin itself - is moving, the chucking that often occurs when the king pin jerks around inside the hitch is significantly reduced.
Simple Setup and Installation
First, simply remove your existing Lippert 1621 pin box from your trailer. The Flex Air uses the same bolts that held on your original pin box so no additional hardware is required for installation. Plus, the Flex Air pin box comes out of the box ready to be put on your trailer, so no assembly is needed. Because the Flex Air is quite heavy, you should put it on an elevated surface or have a friend help you support its weight during installation.
The internal air bag should be inflated after the Flex Air pin box has been mounted on your trailer. Using the air intake valve, inflate the air bag until the outer cylinder of the shock rises high enough to fully expose the yellow inflation indicator sticker.
Average Customer Rating: 4.6 out of 5 stars (104 Customer Reviews)
Flex Air drastically reduces chucking, absorbs road shock, and minimizes bounce. The internal air bag and built-in strut work with the rubberized pivoting head to achieve a dramatically smoother ride. Replaces Lippert 1621 pin boxes.This is the best money I have spent on my camper hands down. My hitch weight is a bit over 3200 lbs. I use a PullRite Super Lite hitch, photo attached. Once locked on the king pin, four bolts are set from the adapter plate against the king pin plate. The plate on the Flex Air is twice as thick as the original pin box and I have way more confidence in a solid set of these four bolts. I was blown away by how this hitch absorbed road shock. I will never have another 5th wheel without this set up.
Russ - 02/11/2021I bought the Flex Air to replace the standard Lippert pin box on our Cedar Creek fifth wheel that weighs 12K lbs. Just looking for something to smooth out the ride and the Flex Air seemed to have good reviews and recommendations. I went to the Lippert website to download the installation instructions because I couldn't get the link on the etrailer website to work. The instructions will give you the torque values required for installation and the air pressure for the inflatable airbag on the hitch. Installation was straight forward, but you better have a plan because this thing is heavy (300 lbs) and it will take some manpower to move around and install.
Joel - 02/13/2021 Joel - 02/13/2021Product arrived in a timely fashion in an un damage condition. Quality was better than expected. Installation for me took about two hrs, with my wife helping. I placed the pin box in the bed of my truck with the help of a frontend loader and let it down on a floor jack. From there install was fairly easy. Pros: Good quality Heavy Duty Cons: You will need 3 or 4 strong friends to handle it No instructions included I did find a pdf on the bottom of the page however that listed the torque for 1/2" bolts
Paul` - 08/28/2021
4 stars as I have just recently installed this although I received it over a year ago. I just put 750 miles on it and experienced almost every PAVED road condition imaginable and it worked great. I can't imagine what that would have been like with the stock pin box. 4 stars because I still need to see how it performs off road and I am just a few days into using it on a trip covering OR, ID, MT and WY so I still have my personal evaluation to complete and need more drive time to see if anything fails on it. Installation was a breeze but it's a heavy hitch so caution is advised.
Arman K - 10/08/2019First, about etrailer. As always, their service was outstanding. They honored their low price guarantee without question and shipping was fast. I upgraded from a Trailair Air Ride pin box with a fixed turret. That pin box helped with bouncing and jarring, but I still got a lot of "chucking". This FlexAir pin box solved that problem as well. Installation was a breeze, although you must make sure you have enough adjustment on your trailer to mount this pin box higher up than your existing pin box. I had to mount it at the very highest set of holes on my trailer. Lipperts web site has specs on this pin box and installation instructions, including measurements and torque specs. With the help of a friend and using the bed of my pickup truck, we unbolted the old one and bolted the new one in. Took about an hour and that was not hurrying. I took the trailer out this past weekend with the new pin box and hit some pretty bad roads. Wow! What a difference this pin box makes. I can only describe the ride one way. Smooooooth. I am very pleased with both etrailer and this product. It's pricey, but to me, pulling a large fifth wheel trailer, it's worth every penny. Highly recommended.
Reflection 320MKS Dealing with etrailer was very easy. Starting with getting the correct information on which pin box would be suitable for our trailer. The unit arrived in 10 days from ordering it. Which was less than the estimated timeframe when placing the order. The only down side, on inspection when arrived, the air bag valve was damaged in transit. A quick email with photos, a call to etrailer & they have a replacement part ready to dispatch. Great customer service & i would definitely recommend them.
Install went pretty smooth. Did it from the bed of the truck, using a motorcycle jack in front and a small hydraulic in back. Make sure your torque wrench can dial to 160 ftlbs. I will update after I tow it!!!
James J - 02/05/2020Have not had a chance to take it for a road test yet. But it fit well, was easy to mount, the issue I ran into was getting the pin height. As my truck is 4x4, and the B&W hitch is as low as it can go, I still needed another 2 inches to get the pin box high enough, could not raise pin box any higher, and with the 5th wheel already at 13'4" did not want to lift the trailer, so ended up lowering the truck 2 inches to get everything back level again. But will find out next week how it works as we start out on a close to 12,000 mile trip to the west coast and back across through canada and back to florida.
Awesome price! Being installed on a Grand Design 375RES. Shipment went great this is a heavy unit, arrived banded on pallets in excellent condition. Installation was simple and as instructions stated. Waiting for the next road trip to be able to test effectiveness. Always been a pleasure dealing with E-Trailer.
I will be on the third flexair pin box when it gets here on the 21st of November 2016. The problem iIm having is with the lower roto flex portion. The rubber block shifts and I have talked to others with the same problem. Lippert has been great about the replacement, But the the hassle of replacing this three times in one year is not worth it.
I have used my Flex Air for over one year and put around 3000 miles on it. I purchased this for one reason to reduce bucking when I it bumps in the road. I can safely say that it has virtually eliminated the bucking. It has also made the ride a lot smoother. I would highly recommend the Flex air. I did my own install of this product by my self. My rig 2018 Toyota Tundra with a Husky 16 KW Hitch 2017 KZ Durango 30 ft.
The FlexAir pin box has been great. The ride while pulling our Laredo 5th wheel is much smoother. Traveling is much more pleasurable. I especially appreciate the follow up from etrailer.
Dealing with you guys and your suppliers ment all kinds of information going in different directions and nothing ever jiving. Worst experience I've ever had with your delivery companies. Making promises never fulfilling them never calling ahead of time me having to chase them down when you chase him down you talk to somebody that is in the orient. They say will have someone call you in 1 hour. Never did they ever call back. I'll just stop is here because I don't want to get angry it's too upsetting. Finally got delivery 5 days after it was supposed to be here 3 days waiting all day long as promised and nobody showed up when you call back they say will have someone call you in an hour. They still have not called driver showed up here finally 5 days late said he didn't have my number you're the reason I know that it would be was here cuz he had a 40 ft tractor trailer
Love it! Makes the ride so much better and safer especially when you cross those roller-coaster bridges that will nearly bounce the rear tires off the ground without this hitch. Only complaint is that I have to add air if it sets for a couple weeks.
Reduced chucking and has made towing my fifth wheel much less stressful, would buy again.
This 250 lb item was shipped in a cardboard box that was just sitting on a pallet. When I opened the box I found the Flex Air was sitting upside down with the foam pad on top. I have no idea how the air filling nozzle wasn't damaged. Luck I guess. There were no "UP" markings on the box. No instructions were included. Installation went smooth, it's just heavy so be careful. Instructions and videos can be found on-line. The Flex Air is at least 4" taller than the OEM box that came with our Grand Design Reflection. I mounted the Flex Air as high as I could and lowered the receiver on the truck. The trailer is still nose high but seems to tow fine. My test ride was noticeably smoother. You can see a lot of motion on the Flex Air that would have otherwise been transferred to the truck.
Steve t - 11/04/2020great customer service and shipping wow hitch made it from Missouri to Ca. in under a week.
Excellent product although we haven;t yet installed it due to the manufacturer torquing the mounting bolts on our original pin box so tightly that I can't get them off. That is no knock on this product. I will be taking it to a dealer for mounting. I will followup for more comments when it's mounted next week. Looking forward to the promised smoother ride. The product arrived quickly and in good condition.
Eric - 03/23/2021My pin box arrived in excellent condition!! Installation was easy with good help. Thanks E-trailer
Smooth ride and no chucking at all. Great pin box!
Really helped take away most of the jerky ride we used to get from our solid king pin. The air bag helps to smooths out rough roads. As per the advice of Lippert customer service I made 5 pound adjustments until I found the best ride. I keep a portable battery operated air pump along for adjustments. My airbag had a small air leak at the valve threads when new. After resealing the threads all is good.
Wesley - 05/28/2019This is our second Flex Air. It really smooths out the ride for the 5th wheel on wavy or bumpy roads.
Alfred R - 11/07/2020In a word, my experience with the Flex Air has been so-so. I bought this product to eliminate a pretty severe chucking problem with my 5th wheel. While this has been a nice improvement, it did not eliminate as much of the chucking as I has hoped. Certainly not to the extent that you see on the e-trailer video for this product, where the bobble head on the dashboard shows almost zero chucking after FlexAir is installed. And yes, I do have a level ride, good weight distribution, and the hitch installed directly over the rear axle. So the typical causes of chucking have been addressed. The shocks do control the up and down motion pretty well, but the FlexAir doesn't do as good a job on the front to rear motion as advertised. Not sure this is really worth the expensive price that is charged for the unit.
Having not pulled a fifth wheel with a traditional pin box setup I have nothing to compare it to. Watching the suspension action over various road conditions I would have to assume that it is doing a very good job of stopping the transfer to the trailer. We have found that we have to keep an eye on the air pressure because it seems to lose air over time (months). We keep a portable air pump in the trailer to cover this situation. The only other observation I have is that the design does seem to carry the nose of the trailer a bit higher. My truck has had no suspension adjustments made to it and the hitch-head is set at it's lowest setting. I can't blame the pinbox alone because there are many contributing factors, but an element of consideration none-the-less. All in all it's a sturdy, well built, piece of hardware that adds a third layer of suspension to the traveling experience. The health of the trailer will definitely benefit from its use. I have had multiple comments made by other campers.
The Flex Air does exactly what I wanted it to do. It absorbs the shock of bumps and transfers that energy to the hitch, not the truck or the fifth wheel. Installation was straight forward with a little bit of planning. It did require I adjust the fifth wheel hitch in my truck as this is a little longer than the original and extends downward more. I was able to modify the settings on my hitch to accommodate. Overall, I've happy I added this to my RV.
Do you have a question about this Fifth Wheel King Pin?
Info for this part was:
At etrailer.com we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.
Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.
Error submitting comment. Please try again momentarily.