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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 0719 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 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.
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 0719 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.
Ratings & Reviews
Product is great but I found out it was not compatible with my Anderson hitch so I had to return it
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.
The reason I purchased the pin box is I needed some extra distance between my truck bed and 5th wheel. It did the trick, I got an extra 5" (had 4"). But the ride is amazing! Very pleased with towing, I almost can't tell I'm pulling a 44' toy hauler cause it's so smooth. My ordering experience was top notch, I will definitely purchase again from etrailer.com
Believe the hype! This kingpin is the “kingpin of kingpins”. I went from my straight 1621 to this. The difference was astounding. It was like going from being on the SS Minnow on rough seas to the USS Nimitz on a calm bay. Very little chucking. True night and day difference. Yes, it is a little pricey, but if you consider the potential outlay of cash to the incurred maintenance of wear and tear from travel to BOTH the tow vehicle and trailer-I felt it was worth the investment. If you’re looking into upgrading-do it. It’s worth it!
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.
Top notch pin box. I received it earlier than expected, by 1 day. I received great info as to which pin box I needed. Thanks for all the good info. I followed the directions as given on the etrailer website. Yes, a guy reading directions..lol! It went on extremely easy. My wife and I installed it, with the aid of a borroed forklift, it is extremely heavy. Bolted on and filled directions to make sure it was level. It went very good, without any problems. Took fifth wheel rv for a test drive and could tell in the first block, it made the difference. Thanks etrailer!
Installed on my 2019 Grand Design Momentum 351 and it fit perfect. Shipper came on time and helped me slide it on to my tailgate, it came on a small pallet. I backed it up to the camper and used a car jack to lift up the aft end. Once I got the lower holes on either side aligned I installed bolts loosely. Then I jacked up the forward side and installed bolts once they lined up. Installed very easy by myself. I did purchase grade 8 replacement bolts from [farm store]. Original bolts were 1 1/2" I put in 2" because the metal is thicker on the new pin box and I wanted threads to come through the nuts. I installed the new bolts with the nut on the outside to make it easier to torque the bolts to the required xxx lbs. I haven't got to try out how it helps out for chucking yet. I will add to this review later to tell how it went.
Replaced Rhino with this unit on my Cedar Creek 311RL. It was straight forward and simple, but not easy for this old man to do it solo. Used the tailgate as my shop. Stuck the back up in the air and drove back to insert into the bracket. I then used the levelor on the trailer to line up 2 of the holes to insert the first bolts. I used a car jack near the pin to raise the 230 pound box into line up position to insert the other 8 bolts. Torqued it down and aired it up, then test drove it. Rides like a dream. Much softer on those in the tow vehicle and I assume on the fifth wheel itself.
Service from etrailer was good. The advice and recommendations for my specific rig was a little off. But I was able to do research myself. Shipping was timely. Over all another successful etrailer transaction. Thanks to everyone.
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.
Much was learned installing the Curt Air Pin Box. For context this was installed on a 2022 Grand Design 337RLS hitched to a B&W Slider on a 1 Ton SRW GMC.
1) Don't even think about installing this unless you have a forklift. If you are installing this yourself, rent one. United Rentals delivered one to me next day. One day rental, delivery and pickup was ~$723. Five of us using various options including truck tailgate, muscle, engine hoist, and engine stand failed until we used the forklift. The forklift method is also much safer. The Curt Flex Air plus the pallet it is delivered on weighs 290 lbs. Also consider that the Pin Box is intentionally a very tight fit into the RV frame. With a forklift and one person to guide the effort it's very doable.
2) Some of America's road are just not smooth (especially in some sections of I95 in South Carolina). This is arguably one of the best Pin Boxes. It is still not going to take all the chucking and jarring out of the ride. It will improve it.
3) On balance, the Curt Air Pin Box did reduce the harshness of the chucking and jarring. Small jarring is removed. Harsh conditions are softened--which frankly is good for both the RV and the truck. When the road is harsh the truck (even if not towing anything) is jarred, but some of that is no longer carried to the RV frame. You will still feel it in the truck however.
Likewise, road harshness under the RV axles are not passed to the truck as harshly.
5) Finding the sweet spot for air inflation will take some trial and error. I had it a little too high originally and incurred additional "bouncing".
6) Put 303 Aerospace Protectant (or similar) on the rubber ring when you apply the same to the rubber seals on your slides.
7) I used the same bolts and washers, but not the same holes in the frame or Pin Box. You will need to measure and assess which you should use based on height requirements and ability to engage the back end of the Curt Air into the frame.
I think this is a great product but gave it four stars because:
1) Cost of the Pin Box + Forklift Rental;
2) My expectations on improvement given that cost were unrealistically too high.
First, 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.
Easy install. Took 2 people due to the weight of the Flex Air pin box. The Lippert 1621 is pretty light comparatively. We placed the pallets the flex air was shipped on (Estes Freight) in the back of the Dually, then labored the Flex Air on top of the pallets. Backed the truck under the 5th wheel and were able to start getting bolts through with small adjustments. Too heavy to lift and put bolts through. Tools used: 1/2 in High Torque Dewalt Impact, 15/16 impact socket, 15/16 wrench, 50-250 torque wrench, impact driver to get the breakaway removed and remount. The grade 5 bolts I have required xxx ft lbs torque. Completed install in 45 minutes.
I'm sorry I can't give a 5 star rating for this order. As always etrailer service was 5 star. But, unfortunately the pin box was received with some damage. Originally I thought the damage was limited to cosmetic only. There were some gashes in the metal and deep scratches in the paint. However, after about 5 months of use I noticed a bolt on the jaw that appeared to be misaligned. Upon inspection it was obvious that the bold was striped. It must have taken a direct hit when dropped during shipping.
The good news is LCI did replace the pin box for me under warranty. However, I had to pay for the installation which was understandable.
In retrospect I should not have accepted the shipment. I'm not sure where the packaging was done but this would have been avoided if this 230 lb product was packaged appropriately.
The order was delayed while etrailer waited for it to be built after I ordered it. Shipping was slow and the product sat on the truck dock in Denver for at least one day before being transferred to the freight company for delivery to Casper. The local freight company was good to deal with once it finally got Casper and I picked it up on their dock. Removal of the old pin box went smoothly, but there were absolutely no installation instructions for the Curt Flex Air pin box and there were none on the internet. The online video was no help, either. Finally got it installed after too many hours. I DO NOT understand why the new pin box has raised the nose of my 5th wheel by over 2 inches, so now I have to work on the hitch and lower it 2 inches. Will be glad when this is DONE tomorrow.
My wife and I are very pleased with our purchase of this product. We have taken numerous trips with our rig since installing it and what a difference it has made from the standard basic pin box. We no longer feel any chucking from starting off and stopping when towing our trailer. I figured it would definitely reduce it but it eliminated it completely. We tow with a one ton F350 long bed SRW and a B&W hitch. In my opinion It is not a DIY installation because of the sheer weight of the product otherwise I think that it would be. It is not a complicated item to install its just super heavy. In addition to my praise of this product, I would like to recommend the addition of grade eight hardware to be included with the product for installation. I think a few dollars more for the price should more than cover that cost. When it comes down to it the grade five hardware is sub standard for such a massive object in my opinion. It is supporting not only the weight of the pin box but the torque under load as well so for the purpose of safety, which is why we purchased it in the first place the hardware has to come off anyway to take off the old pin box. So why not replace it at the same time. My two cents worth anyway. I would definitely recommend this product to others who are looking to eliminate the chucking felt under a standard fifth wheel pin box.
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.
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.
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.
Having just installed the pinbox, it's really too early to review the functionality or performance; however, I did want to document a problem I observed.
The shock absorber was installed backwards so the "Inflate to here" markings stamped into the metal face backwards and are difficult to see. Also, your website shows a white line to highlight the location of the "Inflate to here" marking, but on mine, the white line was missing. I will turn around the shock and paint a white line on it myself.
I just opened the box last night on my Curt Flex Air 5th Wheel Pin Box. I could not believe the amount of steel in this setup. The quality of construction is impressive. If it preforms as well as it looks, I will be thoroughly satisfied and impressed. Another quality product that I have purchased from ETrailer.
Changed out my old pin box for a Curt Flex Air pin box. This one seems to be very heavily built and should last for years to come. Haven’t had a chance to pull it yesterday but am sure it will pull and perform great. Thank you etrailer for another great shopping experience.
This pin box is a beast! I am glad I had a tractor with a front end loader and pallet forks! Shipping was pretty fast and item was received in great condition. I haven't hooked it up on to the truck yet, but I expect it do deliver as advertised. I will know more after our trip at the end of August to Jellystone RV park in Elberta, AL. It certainly looks very nice on our 2017 Sandpiper Select 329RE!
This item arrived much faster than etrailer said it would. It came by truck, and the freight company driver was very nice and made sure I opened the box before he left.
I installed it myself with some help from my 15 year old son. We used our forklift tractor attachment to put it in place. The Curt Flex Air totally changed the experience of pulling our 5er. It eliminates most of the chucking, and acts like shocks on a car, so ride returns to normal immediately after a bump in the road...which the Flex Air absorbs most of.
I haven't tested it out yet, but I can't wait! I have friends that just marvel about this pin box.
I have been very happy with the ride of the pin box. It was a little tough to get it mounted high enough to get the right box clearance, but it can be done.
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Richard R.
3/20/2023
No problems, I dont know if the chucking is improved as I have nothing to compare to. I went off a recommendation of a friend.