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  1. 5th Wheel Pin Box
  2. CURT
  3. Lippert 1621
  4. 21000 lbs GTW
  5. Upgraded Pin Box
  6. Absorbs Road Shock and Reduces Chucking
Curt Rota-Flex 5th Wheel Pin Box - Lippert 1621 - 21,000 lbs
CURT

Curt Rota-Flex 5th Wheel Pin Box - Lippert 1621 - 21,000 lbs

Part Number: LC328329
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$719.00
Retail:$966.95
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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 pin boxes. 1-800-940-8924 to order CURT 5th wheel pin box part number LC328329 or order online at etrailer.com. Free expert support on all CURT products. Great prices and Fastest Shipping for Curt Rota-Flex 5th Wheel Pin Box - Lippert 1621 - 21,000 lbs. 5th Wheel Pin Box reviews from real customers.
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CURT 5th Wheel Pin Box - LC328329

  • Lippert 1621
  • 21000 lbs GTW
  • Upgraded Pin Box
  • Absorbs Road Shock and Reduces Chucking
  • CURT
  • Rubber Spring Suspension
  • 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 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 5th-wheel pin box
  • Weight capacity: 21,000 lbs
  • 1-Year limited warranty


Diagram of measurements for the Curt Rota-Flex pin box

Notes:

  • Do not use the Curt Rota-Flex pin box with any type of gooseneck adapter.
  • The Curt 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 checking and absorb road shock for a smoother ride as you tow your fifth-wheel trailer.


Pivoting Head Reduces Chucking

The Curt 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 Curt 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 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.



328329 Curt Rotaflex Fifth Wheel Kingpin Box for Lippert 1621

Replaces 328329 Lippert Components (LCI) Rotaflex by Trail Air Fifth Wheel Kingpin Box for Lippert 1621

Installation Details LC328329 Installation instructions


California residents: click here


Customer Satisfaction Score:

Ratings & Reviews

4.7

86 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 pin boxes.

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as Always one and done. keep it up



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Excellent service. Fast delivery and great price.



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arrived ahead of time in great shape. Have not put on yet.



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Super helpful, fast shipping, arrived earlier than expected, A+++ for Amy and her knowledge of the pin box I needed.



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Good Product will recommend to others



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Product arrived fast, although it was a little beaten by UPS item worked just fine



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Looks and works great. Easy install



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Shipment was on time as promised. The packing in the box was not well done and it had some scratches. Will be trying it out in a few weeks to see how it works.



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Works great



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It did what it was advertised to do.


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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.
    view full answer...
    Image 1 for
  • Troubleshooting Roto-Flex Pin Box Screeching/Scratching Noise
    The noise you described would be from the pivot point of the Rota-Flex. I spoke with my contact at Lippert and he said that typically when the noise you described is heard it is because there is a gooseneck adapter on the pin box which isn't recommended. To lube the pivot point my contact said to take the bolts out of the lower piece, pull the pin out, and then put lube in where the pin rotates.
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  • Is The Curt Rota-Flex Pin Box Compatible With The Curt CrossWing 5th Wheel Trailer Hitch
    Yes, the Curt CrossWing Lightweight 5th Wheel Trailer Hitch - 20K # C86JR can be used with the Curt Rota-Flex 5th Wheel Pin Box # LC328329. If you look at Curt's website there's reviews from customers who say they use the two together, with one stating that the combination virtually eliminated all of the chucking he was feeling in his Ford.
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  • Can Gooseneck Adapter Be Used With Trailair Rota-Flex 5th Wheel Pin Box?
    A gooseneck adapter cannot be used with the Trailair Rota-Flex 5th Wheel Pin Box - Lippert 1621 - 21,000 lbs # LC328329 because of the excess play and movement that would be present at the connection point. You would instead need to swap out your setup for a gooseneck setup.
    view full answer...
  • 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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  • Why Can't Furniture Switch # 37213925 be Used with Slide Out
    It's an amperage problem. The # 37213925 can only support 40 amps peak and 20 continuous whereas the switches for slide outs like the part # 37212075 can handle 40 amps continuous.
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  • Is Taller Pin Box Available for a 2022 Vanleigh 41FLB 5th Wheel Trailer?
    Hey Steve, thanks for reaching out! What's your reasoning for not wanting to adjust your ET Senior hitch? I looked it up out of curiosity and it has 2" of upwards travel so that would solve your issue right away and would be completely free as well. Most pin box boxes have the same basic dimensions so that stresses are placed in the same locations on the trailer frame so I can't promise we'll be able to find something taller, but if you can let me know your pin box model number I'll be...
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  • Compatible Replacements For A Lippert Rhino Box Pin Box On A 2021 Cedar Creek 37MBH
    The Trailair Rota-Flex 5th Wheel Pin Box # LC328329 you linked to is a fit for the 1621 bolt pattern pin boxes so it will not fit your Lippert Rhino Box, but you have three other options that will. The first option is the MORryde Cushioned 5th Wheel Pin Box for 14K to 18K Trailers w/ Lippert Rhino # MR83QR. This cushioned model will dampen road shock and reduce back-and-forth chucking for a more relaxed towing experience. Unlike air bags, the internal rubber spring requires no maintenance. The...
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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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  • How To Fix a Misaligned Pad On the Trailair Rota-Flex 5th Wheel Pin Box
    Yes, the rubber cushion inside the Trailair Rota-Flex 5th Wheel Pin Box like part # LC328329 is essential to its functionality so if this is out of place or misaligned then that is certainly a cause for concern. That said, this is actually covered under warranty as it is a known issue. If you have proof of purchase then Lippert with send you an entire replacement pin box but if you do not have proof of purchase then you would need to replace the pin box on your own. If that is the case...
    view full answer...
    Image 1 for
  • Capture Plate for Lippert Trailair Rota-Flex Pin Box and Demco Hijacker Autoslide 5th Wheel Hitch
    I believe that you are referring to the Lippert Trailair Rota-Flex 5th Wheel Pin Box like part # LC328329 which has the pivoting head. If this is the case then yes, the Demco Hijacker Autoslide Capture Plates # DM6171 are what you need to use so that you can use the Demco Hijacker Autoslide like part # DM8550034. Attached is a picture and review video of these 3 products installed together for you to reference.
    view full answer...
    Image 1 for
  • Is the Rubber for the Trailair Rota-Flex Pin Box Replaceable?
    The Trailair Rota-Flex 5th Wheel Pin Box - Lippert 1621 - 21,000 lbs # LC328329 does not have that rubber compound as a replaceable part option from the manufacturer. I called to confirm that was the case and they said the rubber compound is built into the head. That rubber compound is designed to reduce wear and tear on the trailer by reducing road shock. It is extremely durable and I've never heard of anyone needing it replaced but older models had a different jounce style bumper that...
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    Image 1 for
  • Determining Hitch Height Needed For Proper Bedrail Clearance
    The Curt Rota-Flex 5th Wheel Pin Box # LC328329 is not compatible with a Curt E-Series or Q-Series fifth wheel hitch like your # C16265. The design of the Rota Flex will actually wear down the head of these hitches and end up breaking them. You'll want to immediately stop using the two together to avoid any chance of damage going forward and swap out either the hitch or pin box. To solve your bedrail issue we'll need to see how you trailer sit and the height of your bed to determine the...
    view full answer...
    Image 1 for
  • Will a B&W Companion Hitch Work w/ a Curt Rota-Flex Pin Box?
    Yes, you can use the Curt Rota-Flex 5th Wheel Pin Box item # LC328329 with the Sliding B&W Companion 5th Wheel Trailer Hitch # BWRVK3400 or the Fixed item # BWRVK3500. Both of these hitches will work with your F-250's Turnover ball system. Since you have the shorter bed length I recommend using the slider. The Curt Rota-Flex 5th Wheel Pin Box item # LC328329 will replace a Lippert 1621 pin box and has a 21,000 lbs capacity. To make towing with a 5th wheel easier, I recommend adding the...
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  • Solution for Hitch Noise of Roto-Flex Pin Box Trailer Towed with Curt Q20 Hitch
    The thing that causes the noise you are experiencing is actually the hitch you have and not the Roto Flex. The biggest factor in how much noise you'll experience when towing a fifth wheel trailer is the hitch itself since it has moving parts and it's responsible for grabbing onto the trailer. The Q20 hitch you have is not known to be super quiet so I'm not totally surprised you are having issues with noise. If you wanted to quiet down your towing setup a quieter hitch would be the best...
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  • How To Lubricate the Pivot Points On A Curt Rota-Flex Pin Box
    To lubricate the Curt Rota-Flex 5th Wheel Pin Box # LC328329 pivot points you'll just need a can of dry grease like part # RM-747 to grease the points without attracting dirt and debris that could gunk up the brackets. You'll just spray it on the points I have pictured below and try to work the king pin plate back and forth to let it fully sink in.
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    Image 1 for
  • Is Trailair Rota-Flex Compatible With B&W Companion 5th Wheel Hitch
    Yes, you can use a Trailair Rota-Flex 5th Wheel Pin Box like # LC176440 (which replaces Lippert 1116) or # LC328329 (which replaces Lippert 1621) with the B&W Companion 5th Wheel Trailer Hitch # BWRVK3500. I have linked video reviews below for you to check out of both the Rota-Flex and the Companion.
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  • Recommended Sidewinder Pin Box to Replace a Curt Rota Flex 1621
    Yes, you can replace a Curt Rota-Flex 1621 Pin Box item # LC328329 with a rotating turret. Since you have a 2021 Ram 3500 w/ Ramboxes this is the only way you will be able to tow a 5th wheel trailer. To add a rotating pin box to your 2022 CrossRoads Aire CR32BH, I recommend the Reese Sidewinder 5th Wheel King Pin with Rotating Turret item # RP34FR. The Reese Sidewinder fits both the Lippert 1621 an 1621HD pin box. Not all 5th wheel hitches are compatible with a rotating pin box. If your...
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  • Replacement Pin Box For Gooseneck Connection On a Dutchmen Voltage 4225 Toy Hauler
    Yes, the Gen-Y Hitch Shock Absorbing 5th Wheel to Gooseneck Pin Box # GY66FR is the correct weight capacity and bolt pattern for your 2021 Dutchmen Voltage 4225 5th Wheel Toy Hauler. It uses the same 1621HD bolt pattern as the Lippert Trailair Rota-Flex Pin Box # LC328329 that comes on your Voltage. The Gen-Y is rated for a tongue weight of 3,500-5,500lbs and your dry tongue weight is 3,685lbs. The maximum trailer weight is 25,000lbs and your Voltage is rated to 20,000lbs. You might...
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  • Torque Spec Rating for Curt Rota-Flex Skit Plate Bolts
    Oh wow, that's definitely not a good experience but I'm glad you made it home safely! The bolts that hold the rotating skid plate to the Rota-Flex pin box, like part # LC328329, are definitely Grade 5 bolts and although I'm unsure which exact size they are, Curt/Lippert does give us a torque spec guide in the Rota-Flex instructions so you just have to confirm the size of the bolt and make sure the torque spec matches: 1/2"-13 is 65 ft-lbs 5/8"-11 is 135 ft-lbs 3/4"-10 is 220 ft-lbs Please...
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  • Correct Capture Plate Needed to Use PullRite 4100 SuperGlide with Rota-Flex 5th Wheel Pin Box
    According to PullRite you will need to measure from the front edge of your king pin to the leading edge of the king pin plate to verify which capture plate to use with your Rota-Flex 5th Wheel Pin Box, like part # LC328329. If that measures 5-3/8" then you need capture plate 331707 but if it is just 5" then you need capture plate 331760. You can acquire either of these from PullRite.
    view full answer...
    Image 1 for
  • Replacement Pin Box For Fifth Wheel Trailer With Lippert 1621 Pin Box
    I called my contact at Lippert and they told me the 119115 number you referenced is actually the Lippert 1621 pin box. We do not offer a Flex Air pin box that has a weight capacity of 21,000-lbs. The highest capacity Flex Air unit we offer is part # LC328492. it has a capacity of 18,000-lbs. We do offer the Rota-Flex pin box, part # LC328329, that can replace your 1621, and has a 21,000-lb capacity. This system has a pivoting head and built-in rubber compound that absorbs road shock...
    view full answer...
  • Replacement Upgraded Pin Boxes for a Lippert 1621 Pin Box
    Trailair Flex Air 5th Wheel Pin Box # LC328484 is actually not the correct model to replace the Lippert 1621 pin box. Instead it fits the Lippert 0719 pin box so it will not work with your trailer. For your 1621 pin box there are more options: # LC328492 rated for 18,000 pounds # 5AB-E1621-610 rated for 21,000 pounds # 5AB-E1621-16K rated for 16,000 pounds # LC158778 rated for 21,000 pounds # LC328330 rated for 18,000 pounds # LC328329 rated for 21,000 pounds The TrailAir and Tri-Glide...
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  • Install Video Guide to Use When Installing Rota-Flex Pin Box in Place of Lippert 1621
    While we don't have an install video for the exact pin box model you referenced part # LC328329 we do have install videos for similar cushioned pin boxes that fit the same application (Lippert 1621) which would work great as an install guide. I attached a video link to this page for the similar 5th Airborne part # 5AB-E1621-610 for you to check out. This will walk you through the important steps that are the same like the removal of the old box and the install of the new one. For the...
    view full answer...


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