1. Fifth Wheel King Pin
  2. Lippert Components
  3. 1621
  4. Lippert
  5. Reduces Bounce and Jarring
  6. 18000 lbs GTW
Trailair Flex Air 5th Wheel Pin Box - Lippert 1621 - 18,000 lbs

Trailair Flex Air 5th Wheel Pin Box - Lippert 1621 - 18,000 lbs

Item # LC328492
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Fifth Wheel King Pin
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LC328492 - Reduces Bounce and Jarring Lippert Components Fifth Wheel King Pin
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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. Call 800-298-8924 to order Lippert Components fifth wheel king pin part number LC328492 or order online at etrailer.com. Free expert support on all Lippert Components products. Guaranteed Lowest Price and Fastest Shipping for Trailair Flex Air 5th Wheel Pin Box - Lippert 1621 - 18,000 lbs. Fifth Wheel King Pin reviews from real customers.
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Lippert Components Fifth Wheel King Pin - LC328492

  • 1621
  • Lippert
  • Reduces Bounce and Jarring
  • Lippert Components
  • 18000 lbs GTW
  • Cushioned
  • Pin Box Upgrade
  • Fixed Turret

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:

  • Air ride pin box with a pivoting head replaces standard pin box on your 5th-wheel trailer to cushion your ride, improve handling, and limit strain on truck and trailer
    • Drastically reduces chucking
    • Virtually eliminates bounce and jarring
  • Internal air bag absorbs road shock
    • Scissor-like motion allows pin box to compress, compensating for jarring and bounce
    • Built-in shock ensures that pin box rebounds - keeps air bag from breaking down
  • Pivoting head limits chucking by allowing controlled movement of the king pin within your hitch
  • Rubber compound built into the head absorbs road shock
    • Reduces wear and tear on trailer
  • Black powder coat provides rust resistance
  • Sturdy steel construction
  • King pin connects to any 5th-wheel trailer hitch
  • Bolt-on installation with no assembly required
  • Made in the USA


Specs:

  • Designed to replace Lippert 1621 5th-wheel pin box
  • Weight capacity: 18,000 lbs
  • 1-Year limited warranty


Notes:

  • Do not use the Trailair Flex Air pin box with any type of gooseneck adapter.
  • Because of the size of this item, it ships via truck freight.

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 Trailair 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.


Rubber Compound and Internal Air Bag Absorb Road Shock

Lippert Flex Air pin box has a rubberized pivoting head

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.


Lippert Flex Air pin box has a shock and air bag

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.


Pivoting Head Reduces Chucking

Lippert Flex Air pin box has a pivoting head that reduces chucking

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.



328492 Lippert Components (LCI) Flexair by Trail Air Fifth Wheel Kingpin Box for Lippert 1621

Installation Details LC328492 Installation instructions




Customer Reviews

Trailair Flex Air 5th Wheel Pin Box - Lippert 1621 - 18,000 lbs - LC328492

Average Customer Rating:  4.5 out of 5 stars   (50 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.

- LC328492
by:

Very happy with the hitch. Makes the towing easier and less stressful. 427818



- LC328492
by:

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. 375017



- LC328492
by:

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. 333916



- LC328492
by:

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. 637982



- LC328492
by:

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!!! 602475


Comments
I cannot believe it has been a year....and a trip to Perdido Key, FL and Breckenrigde CO. In addition to taking care of us, I have to tell you, it will take care of your trailer too! Improved our towing experience old pin box was an upgrade Rotoflex greatly. Worth every penny! If you did not see my earlier post, my friend and I installed it ourselves. Motorcycle jack in the back of a pick up bed. :
James J - 02/05/2020

65292

- LC328492
by:

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. 318083



- LC328492
by:

Great product and eTrailer shipped this heavy, large item very fast. Ordered on a Monday and delivered at the door on Friday!. Installed on my Grand Design but haven’t hooked up for a run yet. This is a very heavy unit (232 lbs) so get a team together to get it installed. 796232



- LC328492
by:

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. 769619



- LC328492
by:

Increased a smooth ride by 100%. No more jolting when you drive over bumps in the road. I used to dread crossing state maintained bridges because of the enter and exits bumps, but not any more. Thanks e-trailer! 767467



- LC328492
by:

Since changing to the Flex Air, there is no comparison to the ride. Nothing out of place inside the RV after being on the road. Highly recommend this pin box, well worth the money to me. 766726



- LC328492
by:

In 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. 761863



- LC328492
by:

Arrived in Excellent Shape!...having the new pin box installed today. 760592



- LC328492
by:

This new Pin Box was the Best Investment I have made since owning my 5th Wheel RV !!!! It has almost completely eliminated the "Chucking" of the RV/Truck combo while traveling over less than perfect roadways, and we all know how many there are in the South ! The Installation went exactly as the Instructions spelled out ! You will need a strong helper ! I built a wooden box to put on top of my Hydraulic Jack to make the lifting a much easier process ! I would recommend this product to anyone owning a 5th Wheel RV !!! 757537



- LC328492
by:

I 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. 749960



- LC328492
by:

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. 749458



- LC328492
by:

Pin box was just as I ordered. It does improve the ride. Won't make your truck ride like a Cadillac but does help. I was also surprised that it was shipped in a card board box that was coming apart when it got to me. A wooden crate I think would be better. 725583



- LC328492
by:

This is our second Flex Air. It really smooths out the ride for the 5th wheel on wavy or bumpy roads. 722990



- LC328492
by:

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. 722359



- LC328492
by:

Great product! Took 80% of the bucking out of the ride.It was an easy install and very happy with the results. Just came back from a 4,000 mile test drive and all is good. 706049



- LC328492
by:

Have 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. 694438



- LC328492
by:

I wasn’t expecting a big difference in the ride of my F350 and my 5er and boy was I surprised! The chucking was reduced significantly and the RV was floating on air. Figuratively and literally. It could not compensate for crappy roads and pot holes but it sure made a difference in the ride overall. 668004



- LC328492
by:

helps with eliminating bounce and push 660290



- LC328492
by:

Love this product 625338



- LC328492
by:

After getting past the shipping companies mess ups, finally installed the new pin box with the help of a few friends. Had to bring toyhauler to dealer yesterday and the difference in the ride was amazing. We are not known for exceptionally smooth transitions on bridges but this hitch took the jarring out of the ride. 582788



- LC328492
by:

Having owned a previous version of this king pin I know and understand how it works and is why I replaced it with a similar product. The previous version was the tri-glide model that was know for going bad, which mine did. I’ve been happy with this newer version other than it seems to loose air over time. 577488


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Ask the Experts about this Lippert Components Fifth Wheel King Pin

  • Benefit of Using 5th Wheel Pin Box Rated for More Than Trailer Actual Weight
    The Lippert TrailAir Flex Air 5th Wheel Pin Boxes # LC328492 and # LC369535 are both bolt-on replacements for the model 1621 OEM pin box. Their difference, as you noted, is in their rated weight capacities; 18K for # LC328492 and 21K for # LC369535. Either one will be fine for use with a compatible trailer with a GVWR of 16,500-lbs. But yes, safety margin in the form of extra capacity is a good thing. The relatively low incremental cost for the 21K pin box over the 18K makes a pretty...
    view full answer...
  • How to Determine Fifth Wheel Pin Box Model
    If you are unable to contact your trailer's manufacturer with your VIN to find the factory pin box model number there are some steps you can take which will allow you to determine what pin box model you have so you can purchase a new FlexAir. To do this you will need to follow the steps in the linked help article, which I will go over with you. Start by selecting your pin box style like in the accompanying photo (which you will also find in the help article). You will then need to use...
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  • Replacement Pin Box for a 2012 Jayco Eagle 5th Wheel Trailer
    I spoke to my contact at Lippert and they informed that they did not start keeping a record of pin boxes until 2013. Therefore, the only way you are going to be able to identify what bolt pattern you have is by measuring the mounting holes using the attached photo. The most common bolt pattern is a 1621 which measures as follows: 2a: 7-7/8" 2b: 2" 2c: N/A 2d: 5/8" 2e: 15/16" 2f: 6 3a: 17-3/4" 3b: 25-5/8" 3c: 12" If your measurements match these then the correct Trailair Flex...
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  • Replacement Trailair Flex Air 5th Wheel Pin Box for Lippert 1621
    No, the Lippert 1621 will not have any issues with an 8' truck bed. The trailer will just sit a little further back. I spoke to my contact at Lippert and they stated that the general rule of thumb for a truck with an 8' bed would be to use a short/medium pin box. However, this could in turn create an interference issue with the tailgate as you mentioned. It will also put more stress on the trailer's chassis. Therefore, I recommend replacing the Lippert 1621 pin box that came on your trailer...
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  • Replacement Trailair Pin Box for MOR/ryde RPB72-1716 Pin Box on Trailer
    Based on my research, your MOR/ryde RPB72-1716 pin box would have replaced the factory Lippert 1716 pin box on your trailer. The Trailair Flex Air 5th Wheel Pin Box # LC328492 that you referenced is designed to replace the Lippert 1621 pin box, so it will not work on your Arctic Fox trailer. The closest pin box upgrade we have available to the Trailair Flex Air that will work on your trailer is the Trailair Air Ride # LC158777, which is designed to replace the Lippert 1716 pin box. This...
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  • Should Pin Box or Suspension be Upgraded to Reduce Jarring and Bouncing While Towing
    A cushioned pin box, like the Trailair Flex Air 5th Wheel Pin Box # LC328492 for a Lippert 1621 replacement that you referenced, will greatly improve the ride between your 2016 Ram 3500 and your Forest River Chaparral 37FL whereas upgraded suspension parts on your trailer are geared more towards the ride quality of your trailer. If the jarring that you are getting is from the trailer bouncing around then I recommend starting with suspension enhancement. From the info you gave it sounds...
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  • Can Trailair Flex Air # LC328492 Replace Lippert 1621HD Pin Box on a 2017 Jayco Seismic Wave 355W
    You are on the right track of choosing an upgrade for the Lippert pin box on your 2017 Jayco Seismic Wave 355W. Since the pin box is a 1621HD instead of a regular 1621 you need to go with a different pin box as the Trailair Flex Air # LC328492 is only compatible as a 1621 replacement. If you like the Trailair line then you can use the Trailair Air Ride # LC158778. This is rated for 21,000 lbs and the only difference between this and the Flex Air is that the Flex Air has a pivoting head...
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  • Recommended Replacement Pin Box for Lippert 182209 1621 on 2010 KZ Durango LX
    I reached out to my contact at Lippert and you do have the 1621 pin box on your 2010 KZ Durango LX. If you are looking for a cushioned pin box, I recommend the Trailair Flex Air 5th Wheel Pin Box - Lippert 1621 - 18,000 lbs # LC328492 or the 21,000 lb # LC369535. Either of these will work well and they not only have the air ride but also have a rubber compound and moving head to be the fist defense against road shock and chucking. If you desire greater turning clearance, then the 5th...
    view full answer...
  • Will Lippert Trail Air LC158777 Pin Box Provide More Clearance than Existing Trail Air Rota-Flex
    According to Lippert, the Rota-Flex was never available as a replacement for the 1716 pin box, are you sure you don't have one that's a replacement for a 1116? The Lippert 1716 and 1116 share the same bolt pattern, but the 1716 is 6-1/2 inches longer and would provide more clearance. If you'll look at the diagram I provided, you can see the bolt spacing that the 1716 uses. You can compare that to your existing Rota-Flex, and if they're identical you could certainly use the # LC158777...
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  • Sidewinder Pin Box Recommendation for 2018 Grand Design Momentum 351M For Short Bed Turn Clearance
    Since your 2018 Grand Design Momentum has a Lippert 1621 pin box the Trailair Flexair part # LC328492 will fit and give you a much smoother ride but will not make a noticeable difference in clearance between truck cab and trailer. A better option for that would be the 5th Airborne Sidewinder part # RP61422 which fits the Lippert 1621, is also cushioned, but moves the pivot point back 22.5 inches so that you can tow your trailer with your short bed truck and fixed hitch. Only other way...
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  • Are Replacement Parts Available for the Trailair Air Ride 5th Wheel Pin Boxes
    The reason that you cannot find the replacement shaft is because Lippert does not offer this separately. If the shaft is worn or damaged then it is time to replace the pin box. There are only very minimal replacement parts for these pin boxes (valve part # LC156740, shock part # LC177223, airbag part # LC432404) and this is intentional to discourage home repairs on such a critical component. That said, this might be a good to time to upgrade from the Trailair Air Ride 5th Wheel Pin...
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  • Is There an 18K Trailair Air Ride Pin Box for the Lippert 1621HD on a Forest River Vengeance 295A18
    The Lippert 1621 and Lippert 1621HD Pin Boxes are very similar and can be used in place of one another if you drill out the lower front hole on each side of the trailer wings which is very easy to do. The difference between the two has to do with the mounting holes and weigh ratings. Therefore, if you do the above you can use the Trailair Flex Air 5th Wheel Pin Box part # LC328492 which is rated for 18,000 lbs or you can just use the Trailair Air Ride 5th Wheel Pin Box part # LC158778 as...
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  • Will Husky Lube Plate Fit King Pin on Trailair Flex Air 5th Wheel Pin Box
    The Trailair Flex Air 5th Wheel Pin Box # LC328492, which replaces a Lippert 1621 pin box, has a standard 2" king pin. The Husky Lube Plate # HT34914 will still fit though as the 2-7/8" diameter referenced is talking about the upper "lip" area right under the pin box (see attached). These 2 pieces will work great with a Curt 20K 5th wheel hitch.
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  • How To Choose Pin Box Replacement Without a Sticker On Pin Box
    Since trailer manufacturers do not make information like pin box models readily available to the public, you will need to contact the dealership with the serial number and they should be able to tell you what pin box is on it. Otherwise, the only other way besides a sticker is taking a few measurements. I have attached an article explaining how to measure your pin box to figure out which replacement is suitable.
    view full answer...
  • Will the Flex Air Pin Box be at the Same Height as the Factory Pin Box on a 5th Wheel Trailer
    Yes, the positioning of the Trailair Flex Air pin box # LC328492 will be approximately the same as the factory hitch on the trailer. It may be a little different once you add or remove air from the air bag as needed. To lower the front of the trailer as much as you can you can mount the pin box as high up as it will go. And most 5th wheel hitches are also height adjustable so if you can lower yours it will help too. The other option is to raise the back of the trailer to compensate for...
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  • Replacement Cushioned Pin Box for Lippert 1621 That Can be Used With Andersen Ultimate Hitch
    We do have a solution for you to use a cushioned pin box with your Andersen Ultimate Connection 5th Wheel Trailer Hitch # AM3200, though the Trailair Flex Air 5th Wheel Pin Box # LC328492 you referenced is not compatible with the Andersen or other type of adapters. Instead, you can use the 5th Airborne Premium Fifth Wheel Air Ride Coupler # 5AB-E1621-610 which is designed to replace a Lippert 1621 pin box and is compatible with your Andersen hitch. The 5th Airborne will provide you with...
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  • Correct Trailair Flex Air 5th Wheel Pin Box for a Heartland Bighorn 3010RE
    The Trailair Flex Air 5th Wheel Pin Box part # LC328492 is compatible with a Heartland Bighorn 3010RE and will work with a PullRite SuperGlide 5th Wheel Trailer Hitch. However, you will need to obtain a Quick Connect Capture Plate from PullRite. This capture plate is to ensure the Flex Air does not pivot inside the jaws on the SuperGlide.
    view full answer...
  • Which is Better Cushioned Pin Box for Lippert 1621 Replacement Sidewinder 5th Airborne or Flex Air
    The FlexAir pin box part # LC328492 that is a replacement for your Lippert 1621 is the most cushioned option out there and will not add height to your trailer. Now that said the ultimate fifth wheel pin box replacement is the 5th Airborne/Sidewinder you also mentioned part # RP61422. The cushioning on this is one of the best options around and gives you the better turning clearances as well. Since it costs more and not a standard style of pin box we don't normally recommend it for people...
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  • Replacement Pin Box Recommendation for 2009 Cardinal 34QRL with Trailair 181445
    I sent this info to Trailair to help identify what you have and they informed me that you have a Rota Flex pin box that was designed to fit as a Lippert 1621 replacement. Replacement parts are not available for this style of pin box since it's now discontinued but we do have the upgraded version of what you have with the Trailair Flex Air part # LC328492. This has a similar front to back cushioning as your Rota Flex but also has a vertical cushioning setup with an air bag and shock which...
    view full answer...
  • Flex Air Replacement Shock Availability
    It's hard to see the dent in the picture you submitted so it's harder to say but it looks like it's probably fine. I'd probably take it on a short trip around the block keeping and eye on it and see if it works like it should. If you find you need a replacement you'd want the part # LC177223.
    view full answer...
  • Fifth Wheel Pin Box Upgrade Recommendations for a Trailer with a Lippert 1621 Pin Box
    If your 2014 345 Open Range Fifth Wheel Trailer has a Lippert 1621 pin box the Trailair Flex Air 5th Wheel Pin Box # LC328492 that you referenced would be an excellent option. The only option I would recommend over this would be for if you have a short bed truck. Then I would recommend the cushioned Sidewinder part # RP61422 that will give you the turning clearance your trailer would need to make tight turns without having to use a slider hitch. To determine what pin box you have...
    view full answer...
  • Will a Capture Plate for a PullRite SuperGlide Fit the Flex Air Pin Boxes
    We do not sell the capture plate you need but it is 331761. That is the model indicated by PullRite that fits the Flex Air pin boxes such as # LC328492.
    view full answer...
  • Can a Pullrite Slider Hitch be Used with a Trailair Flexair
    PullRite Slider Hitches can be used with the Trailair Flex Air 5th Wheel Pin Box # LC328492 that you referenced. All you need is the correct capture plate but you can get that from Pullrite. It should be part number PR_331756 or PR_331760.
    view full answer...
  • Trailair Flex Air 5th wheel Pin Box Additional Bed Rail Clearance Replacing Lippert 1621
    In general the aftermarket pin boxes do achieve a better clearance than the stock pin boxes simply because they offer more adjustability. The Trailair Flex Air 5th Wheel Pin Box # LC328492 will give you an additional 3-3/4 inches in length and the height from the bottom the kingpin to the top of the mounting bracket is 19-9/16 inches, so you will need to measure to see how much additional clearance you will gain based on your current pin box.
    view full answer...
  • Trailair Flex Air Pin Box Compatibility With Demco Hijacker Autoslide 5th Wheel Hitch
    The Trailair Flex Air 5th Wheel Pin Box - Lippert 1621 - 18,000 lbs # LC328492 is compatible with the Demco 18K Hijacker Autoslide 5th wheel hitch like # DM8550034 when you use the Demco Hijacker Autoslide Capture Plates for Trailair Rota-Flex Pin Boxes # DM6171. I've attached a video to assist. If you have the factory prep package, you will also want to use the rail adapter # DM6194. That combination will give you a really nice ride and driving experience with your short bed truck....
    view full answer...
  • How to Measure to Determine Correct Replacement 5th Wheel Pin Box
    A replacement pin box can be confirmed by cross-referencing the brand and part number that appear on its safety sticker (usually on its left side) or by taking measurements of its dimensions and mounting holes. The Lippert Trailair pin box # LC328492 that you referenced matches up to and directly bolts on in place of a Lippert 1621 pin box. Part # LC155943 fits in place of a Lippert 1116 pin box. The linked articles show both how to cross-reference a new pin box based on your OEM...
    view full answer...
  • How Many Bolts are Required to Install the Trailair FlexAir Pin Box on a Trailer
    When installed the Trailair Flex Air 5th Wheel Pin Box # LC328492 only requires 4 bolts to be ran through the pin box and the trailer frame. I attached a picture that shows this pin box installed on a similar trailer and that it only uses 4 bolts. So if you can secure the pin box at the height you need with 4 bolts you would be just fine.
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  • Distance From Front Bolt Holes to King Pin on Trailair Flex Air # LC328492
    The Trailair Air Ride 5th Wheel Pin Box # LC328492 that you referenced, which is confirmed to work with the Lippert 1621 pin box on your trailer, features a distance of 21-1/2 inches from the center of the front row of bolts to the center of the king pin. I have attached an image to assist. This replacement pin box will do a great job of reducing chucking and absorbing road shock with its internal air bag and built-in strut. I have attached a short video demonstration on this product...
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  • Air Ride Pin Box for an 18,000 Pound 5th Wheel Trailer with Lippert 1621HD Pin Box
    For an air ride pin box that will fit in place of your 18K rated Lippert 1621HD pin box you have a couple of options. You can use the 5th Airborne unit # 5AB-E1621-610. I have linked a video showing an example installation for you. You could also use the 21K rated FlexAir pin box, # LC328492. Both of the above pin boxes feature both an air bag and a shock to reduce chucking and provide an overall better towing experience. But if I was choosing one I would go with the new FlexAir....
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Info for this part was:

Expert Research:
Mike L
Expert Research:
Michael H
Expert Research:
Jameson C
Expert Research:
John H
Expert Research:
Adam R
Expert Research:
Jeffrey L
Written by:
Chelsea B
Updated by:
Shelly K
Updated by:
Sarah W
Updated by:
Hannah L
Updated by:
Isabelle B
Updated by:
Noah M
Installed by:
Michael B

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