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Fifth Wheel King Pin > Air-Ride > Fixed > Lippert > 1621 > 21000 lbs GTW > Ultra-Fab Products


Ultra-Fab TrailAir Air Ride 5th Wheel King Pin - Lippert 1621 - 21,000 lbs

Ultra-Fab Products Fifth Wheel King Pin

Code:   UF35-946203

Retail:$1,245.00

Price:$886.95


Shipping Special

Shipping Weight: 184 pounds

Quantity: 







Ultra-Fab Products Fifth Wheel King Pin - UF35-946203

Experience smooth, stable towing with your fifth-wheel trailer by replacing your ordinary pin box with an air-ride-equipped model. The scissoring action of the coupler allows the interior air bag to absorb road shock so that you won't feel it.

Features:

  • Air ride pin box replaces standard pin box on your 5th-wheel trailer to enhance performance
    • Cushions and absorbs road shock
    • Improves handling and overall ride
    • Limits strain on truck and trailer frames
  • Scissor action allows pin box to compress, compensating for jarring and bounce
    • Internal air bag absorbs the road shock
    • Built-in spring ensures that pin box rebounds - keeps air bag from breaking down
  • Direct replacement for OEM pin box
  • King pin connects to any 5th-wheel trailer hitch
  • Sturdy steel construction


Specs:

  • Designed to replace the following pin boxes:
    • Lippert 1621
  • Weight capacity: 21,000 lbs
  • 1-Year warranty


Notes:

  • Not for use with any type of gooseneck adapter
  • Because of the size of this item, it ships via truck freight

Eliminate the bounce from your ride with the Trailair air ride coupler. The unique scissoring action of the pin box ensures that road shock is absorbed, preventing the harsh, rigid ride that you typically encounter while towing your fifth-wheel trailer. Not only does this improve your overall towing experience, but it also helps maintain a sound, well-functioning system. Less bounce and jarring means less stress on your truck, trailer and hitch.


Trailair Air Ride Coupler

How the Trailair Air Ride Works

When you encounter uneven terrain on your trip or hit a pothole on the highway, the Trailair pin box compresses, transferring the road shock to its internal air bag. A built-in air spring ensures that this compression occurs in a controlled fashion so that the air bag doesn't burst. It also causes the pin box to appropriately rebound, positioning it so that it's ready for the next bump in the road.



35-946203 UltraFab Trail Air Kingpin Box - L05









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Ask the Experts about this Ultra-Fab Products Fifth Wheel King Pin
Expert Answers about Ultra-Fab TrailAir Air Ride 5th Wheel King Pin - Lippert 1621 - 21,000 lbs - UF35-946203Do you have a question about this Fifth Wheel King Pin?


  • Deciding Between UltraFab TrailAir and Reese 5th Airborne Pin Boxes for 5th Wheel Trailer
  • If your trailer gross weight is under 18,000 lbs you might consider the TrailAir Tri-Glide, part # UF35-946229. A photo is attached. This product includes the air bag and shock features of the TrailAir # UF35-946203, but also adds three steel roller rods that allow the bottom jaw to glide back and forth while towing, which reduces chucking effects. (Note the TrailAir is not for use with gooseneck adapters.) Overall the TriGlide will deliver the best overall performance provided that its...
    view full answer...

  • Difference Between Ultra-Fab TrailAir King Pin and Ultra-Fab TrailAir Tri-Glide King Pin
  • The Ultra-Fab TrailAir Air Ride King Pin, part # UF35-946203, is the original Air Ride King Pin that has an internal air bag that helps absorb road shock and uses the scissoring action to prevent a harsh, rigid ride. The Ultra-Fab TrailAir Tri-Glide Air Ride King Pin, part # UF35-946229, is the newer king pin that has a redesigned lower jaw. The lower jaw has 3 steel rods that act as rollers and will let the jaw glide forward and back during towing. This will help reduce the chucking...
    view full answer...

  • Best Fifth Wheel Pin Box Replacement to Reduce Chucking
  • Your correct set-up would depend on the length of your truck bed. If you have a 6-1/2 foot bed and a sliding hitch, the Ultra-Fab Trailair you referenced, part # UF35-946206 would dramatically improve your ride quality. This pin box is a direct replacement for the Lippert 0179. If you had the Lippert 1621 king pin, you would need part # UF35-946203. If you have the 5-1/2 foot bed, you would need to use a 5th Airborne Air Ride with Sidewinder to provide additional clearance between...
    view full answer...

  • Replacement Pin Boxes for a 5th Wheel Trailer with an RBW 7016-2P Pin Box
  • If your pin box ends up being an RBW 7016-2P then there are 2 options. First we have the 5th Airborne, # 5AB-T7016. These units have a rear mounted shock, an enclosed air spring, and a pivot point that allows the king pin to move up and down. It is rated for 21,000 pounds. I have included a link to the installation details for you. The other option, Ultra-Fab Trailair Air Ride 5th Wheel King Pin, # UF35-946221, works in much the same way, it just has a different configuration. It also...
    view full answer...

  • How Difficult to Install is the Ultra-Fab TrailAir Replacement Pin Box # UF35-946203
  • The Ultra-Fab TrailAir 5th Wheel Pin Box is a bolt-on application. The torque specifications are included with the instructions. The pin box is HEAVY, but with few helpers you should be able to lift the pin box into place and get the bolts secured. Keep in mind that these units are pin box specific. You would need to get the manufacturer name and model number of the OE pin box, and choose a replacement that is compatible. The Ultra-Fab model you referenced is a replacement for a...
    view full answer...

  • Air Ride Pin Box Recommendation for a 2007 Keystone Copper Canyon 5th Wheel to Reduce Chucking
  • The Trailair pin box that I would recommend for your 2007 Keystone Copper Canyon fifth wheel trailer is the Ultra-Fab Trailair Tri-Glide Pin Box, # UF35-946229. This is a direct OEM replacement pin box and will fit the same bolt pattern as your Lippert 1621. It has an 18,000 lb weight capacity and includes three integrated steel rollers that allows the bottom jaw to glide, reducing fore and aft movement, or chucking, when towing your trailer. The Trailair pin box, # UF35-946203, that...
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  • What is the Capacity of the Air Spring in the Ultra-Fab TrailAir King Pin
  • I spoke to my contact at Ultra-Fab and she informed me that the Ultra-Fab TrailAir Air Ride 5th Wheel King Pin # UF35-946203 that you referenced has a 21,000 lb capacity air spring.
    view full answer...

  • Which Air Ride Pin Box Fits a 2012 Heartland Elkridge 29RKS 5th Wheel Trailer
  • I spoke with Lippert and determined that you have a 1621 pin box, very common, and for a Trailair, which is what Lippert sometimes puts on their chassis, you can use the 18K model # UF35-946229, which is a Tri-Glide. For a 21K air ride model use # UF35-946203.
    view full answer...

  • Which TrailAir Replacement Pin Box for 18K Toy Hauler with Lippert 1621 OEM Pin Box
  • There are two Ultra Fab L05 replacement pin boxes, as you have found. The # UF35-946203 is the standard air ride pin box that uses an airbag to reduce bouncing and jarring. The TrailAir Tri-Glide, part # UF35-946229 has the same air bag, but also adds the Tri-Glide system, which is three steel rods that act like rollers and help reduce chucking (see photo). If the fully loaded weight of your Toy Hauler does not exceed its 18K capacity, you can use either pin box. If you are right at...
    view full answer...

  • Which Sliding 5th Wheel Hitch or Sidewinder to Tow 36-Foot Cougar Trailer with Short Bed Silverado
  • To select the correct cushioned pin box for your 2010 Cougar 36-foot Fifth Wheel trailer you will need to know which pin box model you have on your trailer. Most king pins will have the pinbox number listed on a sticker or it will be stamped on the king pin itself. If it is not there or worn off, call the trailer manufacturer with the vin number of your trailer so they can provide you with the pin box number. The Ultra-Fab King Pin you reviewed, part # UF35-946203, is a direct replacement...
    view full answer...

  • Which Air-Suspension Pin Box to Replace Lippert 1621HD on 18,000 Lb 5th Wheel Trailer
  • The HD designation on your Lippert 1621HD pin box does indicate that it is a heavy duty model. Based on your estimated 18,000 lb gross trailer weight you can use the Ultra-Fab TrailAir # UF35-946203. I did confirm with my contact at Ultra-Fab that the UF35-946203 will work in your application. Or you can use one of the other replacement pin boxes listed below. The 5th Airborne # RP61423 is a sidewinder-equipped Air-Ride model rated at 19,500 lbs. The Reese # RP61421 is a sidewinder...
    view full answer...

  • Measurements of Ultra-Fab TrailAir 5th Wheel King Pin Box Rated for 21,000 Pounds # UF35-946203
  • I went out to our warehouse and measured the Ultra-Fab TrailAir Ride 5th Wheel King Pin box # UF35-946203, and the distance from the center of the kingpin to the outer most portion of the box is 32 inches. The distance from the center of the king pin to the center of the first hole is 23-3/16 inches and the holes are 8 inches apart, center to center. I have confirmed with my technical contact at TrailAir and you will be using the existing hardware that is already on your Lippert 1621...
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  • What is the Air Pressure Setting On an Ultra-Fab TrailAir Air Ride 5th Wheel King Pin # UF35-946203
  • According to Ultra Fab there are many factors that can effect air pressure such as the size of the air spring in diameter and height, the pin weight of the trailer, the mechanics of each individual hitch, altitude and air temperature. Ultra Fab has stated that usable air pressures can range from 20 to 120 psi. Therefore a specific air pressure is not recommended. Instead it is recommended to inflate the air bag to maintain a ride height. To determine the ride height Ultra Fab has indicated...
    view full answer...

  • What Trail-Air Pin Box Will Fit a 2009 Holiday Rambler Presidential 5th Wheel Trailer
  • Trail Air pin boxes are designed to replace specific OEM pin boxes on trailers. To ensure we recommend the correct Trail Air pin box for your 2009 Holiday Rambler Presidential, we need the manufacturer and model number of the pin box that is currently on the trailer. This information can be found on the pin box on the trailer. Trailer manufacturers can use different pin boxes on the same models of trailers and unfortunately there is no cross reference for pin boxes and trailers available. The...
    view full answer...

  • How to Pick Out The Correct Cushioned Pin Box
  • In order to pick out the correct cushioned pin box for your 2006 Alfa 30 foot Fifth Wheel trailer you will need to know which pin box model you have on your trailer. Most king pins will have the pinbox number listed on a sticker or it will be stamped on the king pin itself. If it's not there or worn out you will need to call the trailer manufacturer with the vin number of your trailer so they can provide you with that information. Check out the FAQ article I attached on cushioned pin...
    view full answer...

  • Compatibility of TrailAir Air-Ride Replacement Pin Box with Pullrite Superglide 5th Wheel Hitch
  • According to the folks at Pullrite, their Superglide 5th wheel hitches are compatible with the Ultra-Fabe TrailAir Air Ride Pin boxes. The person I spoke with at Pullrite tells me that you will need a capture plate that is specific to the TrailAir Pin Box, which would be available from Pullrite. In order to bolt up properly, you will need to choose the correct replacement pin box. The TrailAir you mentioned is a compatible replacement for a Lippert 1621 pin box. If the manufacturer and...
    view full answer...

  • Fifth Wheel to Gooseneck Adapter Recommendation for a Lippert 1621 Pin Box
  • I have a great solution for you. Check out the Reese Goose Box part # RP94622. This product is designed specifically to work on Lippert 1621 Pin Boxes to adapt from a fifth wheel trailer to a gooseneck hitch and also has air ride to cushion the towing experience. Check out the review video I attached as well. The Ultra-Fab TrailAir Air Ride 5th Wheel King Pin # UF35-946203 that you referenced is not designed for use with gooseneck adapters so I would not recommend it for you.
    view full answer...

  • How to Find a Trailair Tri-Glide Pin Box to Replace a Trailair Rota-Flex Pin Box on a 2014 Solitude
  • To determine which Trailair Tri-Glide pin box will replace your Rota-Flex pin box, we will need to know the part number of your Rota-Flex pin box. The part number is usually located on a sticker on the pin box. There are several different Rota-Flex pin boxes out there because they replace specific OEM pin boxes. We want to make sure we choose a Tri-Glide pin box that will have the same mounting dimensions and bolt pattern. If you cannot locate the part number of the pin pox, your trailer...
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  • How Often Should Air be Added to the Ultra-Fab Trail Air Ride 5th Wheel King Pin
  • You should only need to add or remove air from the TrailAir pin box # UF35-946203 to get the lower portion of the upper collar on the shock lined up with the arrows on the lower part of the shock when under load. Take a look at the picture I provided to get a visual of what I mean. Like any system that holds air (like tires for example) environmental factors can change the air pressure in the air bag. Be sure to that the shock is lined up properly as described above before towing. If...
    view full answer...

  • Replacing an Ultra-Fab Rota-Flex 5th Wheel Trailer Pin Box with a Trailair Tri-Glide Pin Box
  • You likely have Rota-Flex pin box, # UF35-946202, so that narrows it down quite a bit. It fits the Lippert 1621 pin box. For a Trailair Tri-Glide that fits the same Lippert pin box you can use # UF35-946203. There is usually a model number on the pin box and you would need that to identify which Rota-Flex you have for sure. Or you could call the trailer manufacturer with the VIN and they can tell you what pin box came on it originally. You can also take some measurements, see link,...
    view full answer...

  • Can an Air Bag be Added to Ultra-Fab Rota-Flex 5th Wheel Pin Box, Part # UF35-946202?
  • The Ultra-Fab Rota-Flex 5th Wheel Pin Box with Rubber Bushings, part # UF35-946202, is designed to reduce shock with its rubber bushings. Its internal construction differs substantially from the # UF35-946203, which is an air bag-equipped pin box. My contact at Ultra-Fab confirms that your unit cannot be retro-fitted with an air bag. You will need to replace your unit with the Ultra-Fab TrailAir Air Ride 5th Wheel King Pin, part # UF35-946203.
    view full answer...

  • Should the Air Bag in a TrailAir Pin Box Be Deflated When it is in Storage
  • You would not really damage the air bag if you left air in the bag, but just for good practice, I would deflate the bag. This would keep any pressure off of the bag and fittings while it is in storage. Since you plan on storing the trailer, I also recommend either covering the pin box to protect it and the bag from the sun or applying something like Armor All to the air bag to protect the rubber.
    view full answer...

  • Reese Goose Box for a Fabex 663 5th Wheel Trailer Pin Box
  • Reese Goose Box # RP94622 should fit all of the Fabex 600 series pin boxes. The 600 series pin boxes have most of the same important measurements. The only thing that seems to differ is the amount of bolts per side and the overall length of the pin box. Other replacement pin boxes that are a fit for the 600 series do fit the 663 so you should be good to go. I have included a link to a video review of the Goose Box for you.
    view full answer...

  • How to Determine Which Replacement Air Ride Pin Boxes will Fit a 5th Wheel Trailer
  • Replacement pin boxes like # UF35-946203 fit specific trailer pin box models so the truck and 5th wheel hitch do not matter. You will need to look at the pin box currently on the trailer and get the manufacturer and model number off of it. Then you can look through the replacement fixed pin boxes we carry, see link, to determine if there is one that fits.
    view full answer...

  • Availability of Replacement Air Ride Pin Box for 2010 Kaddy Kruizer 5th Wheel
  • The length of your original pin box would not necessarily impact whether a given air ride pin box will fit. The bolt hole pattern of the turret where the pin box bolts to the 5th wheel is what determines if the replacement pin box will fit. If the bolt patterns match, the fully loaded and ready to tow weight of the 5th wheel needs to be within the weight capacity of the air ride pin box. In order to determine if there is a compatible replacement air ride pin box, I would need to know...
    view full answer...

  • Replacement Drop Leg Pin for Ultra-Fab Electric Landing Gear
  • It sounds like you are talking about landing gear like # UF17-943010. There are a couple of pins used in the drop legs on these landing gear jacks. I spoke with Ultra-Fab and found that the pin used is a 1/2 inch diameter. You can use a pin like # 12h.
    view full answer...

  • Determining Which Trail-Air Replacement Pin Box is Needed for a 2010 Montana Mountaineer 3214RLQ
  • To determine the correct Trail-Air Pin Box you will need to know what pin box is currently installed on your 2010 Montana Mountaineer. There is usually a sticker or stamping on the pin box it that indicates the model number of the pin box on your trailer. If you can not find any markings that indicate this, then you can call your trailer manufacturer with the vin number of your trailer and they can provide this information for you. It is crucial to make sure that you have the correct...
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  • Reducing Chucking When Towing 5th Wheel w/ 2007 Tundra Equipped w/ SuperGlide 5th Wheel Hitch
  • Chucking is usually caused by a loose fit between the jaws of the fifth wheel and the king pin. The jaws can be tight enough to secure the king pin, but loose enough to allow a bit of movement. Even if this 'slop' is only an 1/8 of an inch, it gets pretty amplified when its caused by a 10K fifth wheel. It can certainly make for an unpleasant ride. In some cases this loose fit is just the nature of the beast, and in some cases it's caused by worn parts. I'd recommend giving the jaw assembly...
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  • Replacement Pin Box for 5th Wheel Trailer
  • If your truck if a long-bed you should be fine using the original pin box supplied on your 5th wheel trailer. Short-bed trucks can sometimes need a replacement Sidewinder pin box to provide enough turning clearance but this concern does not usually affect long beds. When needed a replacement pin box for a 5th wheel trailer can be selected based on the existing pin box brand and number. This information can be found on the safety sticker on your existing pin box. For reference an article...
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  • Can an 18K Rated TrailAir Replacement Pin Box be Used on a 19K 5th Wheel Trailer
  • It is not recommended to use a replacement pin box such as # UF35-946229 if its 18k rating is lower than the gross trailer weight. If you do have a Lippert 1621 pin box, which is what the TrailAir fits, then you would want part # UF35-946203 which has a 21,000 pound capacity. If you have a different pin box, let me know what it is and I can make a recommendation for you. The pin box should have a sticker or plate on it with the manufacturer and model number of the pin box.
    view full answer...


Info for this part was:


Photos by:
Theodore B

Expert Research:
Michael L

Written by:
Lindsey S

Expert Research:
Michael H

Expert Research:
Jeff D

Expert Research:
Jameson C

Expert Research:
John H

Expert Research:
Adam R

Updated by:
Laura H

Expert Research:
Lori W

Expert Research:
Rachael H

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