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  1. 5th Wheel Pin Box
  2. CURT
  3. Lippert 1621
  4. Lippert 1621HD
  5. 18000 lbs GTW
  6. Upgraded Pin Box
Trailair Rota-Flex 5th Wheel Pin Box - Lippert 1621 or 1621HD - 18,000 lbs
CURT

Trailair Rota-Flex 5th Wheel Pin Box - Lippert 1621 or 1621HD - 18,000 lbs

Part Number: LC328330
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$736.15
Retail:$876.95
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5th Wheel Pin Box
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This Rota-Flex pin box has a pivoting head with a built-in rubber compound that works to reduce chucking and absorb road shock, resulting in a smoother ride and less wear and tear on your trailer. Replaces Lippert 1621 or 1621HD pin boxes. 1-800-940-8924 to order CURT 5th wheel pin box part number LC328330 or order online at etrailer.com. Free expert support on all CURT products. Great prices and Fastest Shipping for Trailair Rota-Flex 5th Wheel Pin Box - Lippert 1621 or 1621HD - 18,000 lbs. 5th Wheel Pin Box reviews from real customers.
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  • Reviews (83)
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CURT 5th Wheel Pin Box - LC328330

  • Lippert 1621
  • Lippert 1621HD
  • 18000 lbs GTW
  • Upgraded Pin Box
  • Absorbs Road Shock and Reduces Chucking
  • CURT
  • Fixed Turret

This Rota-Flex pin box has a pivoting head with a built-in rubber compound that works to reduce chucking and absorb road shock, resulting in a smoother ride and less wear and tear on your trailer. Replaces Lippert 1621 or 1621HD pin boxes.


Features:

  • Pivoting pin box replaces standard pin box on your 5th-wheel trailer to improve handling and limit strain on the truck and trailer
    • Minimizes chucking by allowing controlled movement of 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 or 1621HD 5th-wheel pin boxes
  • Weight capacity: 18,000 lbs
  • 1-Year limited warranty


Diagram of measurements for the Lippert Rota-Flex pin box

Notes:

  • Do not use the Trailair Rota-Flex pin box with any type of gooseneck adapter.
  • The Trailair Rota-Flex is not compatible with Curt E-Series or Q-Series 5th wheel hitches.

The Rota-Flex pin box has a pivoting head and built-in rubber compound that help to reduce chucking and absorb road shock for a smoother ride as you tow your fifth-wheel trailer.


Pivoting Head Reduces Chucking

The Lippert Rota-Flex pin box has a pivoting head to help reduce chucking

The pivoting head on the Rota-Flex 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 Rota-Flex 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.


Rubber Compound Absorbs Road Shock

The Lippert Rota-Flex pin box has a built-in rubber compound to help absorb road shock

A heavy-duty rubber compound is built into the head assembly of the Rota-Flex pin box. This rubber absorbs the bumps and vibrations, or road shock, 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 Rota-Flex takes the beating so there's less wear and tear on your trailer or RV and you get a smoother ride.


Easy, Bolt-On Installation

The Rota-Flex is easy to install. Simply remove your existing Lippert 1621 or 1621HD pin box and install the Rota-Flex on your trailer or RV. The Rota-Flex uses the same bolts that held on your original pin box so no additional hardware is required. Plus, it comes out of the box ready to be put on your trailer, so no assembly is needed. Because the Rota-Flex is quite heavy, you should put it on an elevated surface or have a friend help you support its weight during installation.



328330 Lippert Components (LCI) Rotaflex by Trail Air Fifth Wheel Kingpin Box for Lippert 1621 or 1621HD

Replaces UF35-946202 Ultra-Fab Rubber Ride Kingpin Box by Rota-Flex

Installation Details LC328330 Installation instructions


California residents: click here


Customer Satisfaction Score:

Ratings & Reviews

4.7

83 reviews
This Rota-Flex pin box has a pivoting head with a built-in rubber compound that works to reduce chucking and absorb road shock, resulting in a smoother ride and less wear and tear on your trailer. Replaces Lippert 1621 or 1621HD pin boxes.

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Drove well



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Great product, unfortunately I was very displeased with how it was delivered. The product was unwrapped and had the potential to be scratched up and chipped.



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Nice pin box



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Looks and works great. Easy install



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It did what it was advertised to do.



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Helps take the bumps out of our wonderful roads.



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Haven't installed pin box yet but it was delivered uncrated, and it looked like it was a used pin box.



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Great product, Installed and what difference the ride. Thanks SJ McDonnell



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> haven taken trip yet but i know there be a huge difference in the ride



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Great quality, great customer service - I’ll use E-trailer for everything I can now!



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Switched from a ball. Glad I did. Very well pleased.



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Works great eliminated the jaring. Also shorter so I can make a hard turn without touching the sides of my box



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Great service and fast shipping!! Great King pin . But wouldn’t fix my 5 wheel pin box.



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I received the pin box in good condition. Preparing to install. Much anticipation to get rid of present air ride hitch which is woefully inadequate.



by:

Product was as ordered. Hat's off to etrailer. After UPS lost the first one, etrailer expedited its replacement



by:

The pin box made the 5th wheel handle better, with less chucking and very stable.



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The hitch arrived poorly packaged in a cardboard box. The hitch is very heavy. It was scratched and required repainting.

The hitch itself looks well made and strong.



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Have not installed yet, paint has been scraped off in several locations especially on top and on the rounded corners from shipping. Will have to do some touch up painting. Excited to get installed and pull trailer next weekend



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Definitely dampened the chucking and my wife is much happier with the ride. Also it seems to be much quieter. Noticed at the camper show many units come with the Roto flex from the factory.



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I installed this by myself (it is heavy!) by putting it in the bed of my pickup & strapping it to a floor jack but not a job I’d recommend doing it by yourself.
I already have airbags on the rear axle of my pickup is why I chose this king pin . Only a 200 mile trip and the bucking on the 5th wheel was gone. But the real test will be on a rough highway...


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Show More Reviews

See what our Experts say about this CURT 5th Wheel Pin Box

  • Dimensions of the Rota-Flex 5th Wheel Pin Box # 328330
    The Trailair Rota-Flex 5th Wheel Pin Box - Lippert 1621 or 1621HD - 18,000 lbs # LC328330 does require capture plates for the Demco Hijacker autoslide that is similar to the Pull Rite Autoslide you have. The measurement from the front of the plate to the king pin is 4-1/2 inches. The overall plate is 11.387 inches by 12.655 inches.
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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...
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  • Reese Goose Box Replacement for 1621 Pin Box
    KZ does not specify in their online manual which pin box they install but since you know you have the Rota-Flex # LC328330, which is compatible as a replacement for a 1621 or 1621HD pin box, you can be assured of the fit of the Reese Goose Box # RP85FR, which comes with new mounting hardware. You can read what customers had to say after installing the Goose Box by referring the reviews which I linked for you. Goose Box # RP85FR has a high overall satisfaction rating. You can see more product...
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  • How Many Bolts Get Used to Install a RotaFlex Pin Box on a Trailer
    When you attach a RotoFlex pin box like the part # LC328330 you will need to use the same amount of bolts per side of the pin box like that the original pin box used to secure to the trailer frame. Some setups will require only 4 bolts and some may require 5 or 6. It really depends on the trailer and what was originally on the trailer.
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  • Adjusting Lippert Components Rota-Flex 5th Wheel Pin Box
    In order to resist the chucking (fore and aft jarring movement) experienced, the swiveling skid plate is pretty stiff by design. The relatively gentle jarring experienced during hitching will not move the plate much at all but any chucking experienced during travel will be dampened by the pin box. The bolts that hold the skid or pin plate to the pin box are properly torqued during the assembly process, and for safety reasons should not be loosened. Once the pin box is installed and the...
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  • Lippert Solid Step Manual RV Steps for 24-Inch Wide Doorway
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  • Recommended Capture Plates for Trailair Rota-Flex Pin Box with Demco Hijacker Autoslide
    It looks like you might have a Trailair Roto-Flex 5th Wheel Pin Box like # LC328330. I do recommend confirming this by locating the model name of your existing pin box. If this is the case, then to use the Demco Hijacker Autoslide 5th Wheel Trailer Hitch # DM8550034 referenced in your question, you will just need to add the Demco Hijacker Capture Plates # DM6171. These capture plates are designed specifically for the Trailair Rota-Flex pin boxes and will prevent the king pin from pivoting...
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  • Trailair Rota Flex Cushioned Pin Box that Fits as Replacement for Fabex 665
    The cushioned Trailair Rota-Flex 5th Wheel Pin Box # LC328330 does fit the Fabex 665 that you have now and would work great as a cushioned replacement. While this pin box states it's designed to fit as a replacement for the Lippert 1621 or 1621HD we've found that in general the 1621 and the Fabex 665 are identical.
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    You definitely have the right setup in mind. Since the Ram Box on your 2018 Ram 2500 with a short bed limits the inside width of your truck bed a Sidewinder is the only viable solution. I called my contact at Lippert who said that your Trailair Rota-Flex has the pin box number 1621 according to the serial number, making it part # LC328330 on our site. For a Sidewinder that is a compatible replacement you can use part # RP34FR. We also have the 5th Airborne Premium # RP61422 which adds...
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  • Replacing Rota Flex Pin Box On 2019 Grand Design Solitude Fifth Wheel.
    Great question and information. Based on your information I recommend the Trailair Rota-Flex 5th Wheel Pin Box - Lippert 1621 or 1621HD - 18,000 lbs # LC328330. Since your trailer is at 16,800 GVWR you really do not need to go up to 21,000 unless you just want to. The 18k capacity of this pin box will be enough. If you do want the larger capacity you can get it here. Curt Rota-Flex 5th Wheel Pin Box - Lippert 1621 - 21,000 lbs Item # LC328329. From the center of the king pin to the center...
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  • Best Cushioned Pin Box Replacements for Lippert 1621HD with 18k Capacity
    The correct Rota-Flex pin box you need to replace the Lippert 1621HD you have on your trailer that has an 18k weight rating is the part # LC328330. This provides front to back cushioning with the cushioned pin box plate. If instead you wanted vertical cushioning in addition to that we have the Flex Air part # LC328492 which I recommend highly. This is the most effective cushioned pin box solution available for your trailer.
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  • Is The Rubber Cushion In The Lippert Trailair Rota-Flex Pin Box Replaceable
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  • Is MORryde or Rota-Flex a Better 1621 Pin Box Replacement?
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  • Replacing Lippert Rota-Flex with Reese Goose Box on 2018 Grand Design Solitude
    To replace your existing Rota-Flex 5th wheel pin box with the Reese Goose Box 5th-Wheel-to-Gooseneck Air Ride Coupler Adapter # RP85FR, you'll need to confirm its model number and weight rating. This information is typically displayed on a sticker or plate on the pin box itself. Lippert makes three models of the Rota-Flex, so the weight rating on the label is enough to identify which of these three you have: -Model 1621/1621HD Trailair Rota-Flex 5th Wheel Pin Box 18,000 lbs # LC328330 -Model...
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  • Rota-Flex or MORryde to Reduce Chucking to Replace Lippert 1621 Pin Box
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  • Is Lippert 1621 Pin Box Different Height from Rota Flex that Fits 1621
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  • Torque Value of Hardware for Trailair Rota-Flex 5th Wheel Pin Box
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  • Will the Demco Recon Work w/ a Rota Flex Pin Box?
    Yes, you can use the Demco Recon Gooseneck-to-5th Wheel Trailer Hitch Adapter for Recessed Ball item # DM8550046 with a Curt Rota Flex pin box like item # LC328330. The Recon is not compatible with rotating pin boxes but will work great with the Rota Flex.
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  • Will The Curt Q20 5th Wheel Trailer Hitch Work With The Trailair Rota-Flex 5th Wheel Pin Box
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