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  1. #1
    Site Sponsor jw^2 family's Avatar
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    Question Considering Air Springs / How to setup with Weight Distributing Hitch

    I brought home our brand new Imagine 2800BH last week. I'm towing with a 2014 F150 SuperCrew (with factory towing package; not heavy-duty payload package), and an Equal-i-zer 1,200/12,000 lb. hitch. I weighed the truck at a CAT scale down the road from the RV dealership before picking up the trailer, and then weighed again with the trailer hooked up, and was pleased to find that it's well within the truck's ratings for front GAWR, rear GAWR, GVWR, and GCWR.

    The dealer was very familiar with the Equal-i-zer hitch, and set it up per the manual, which is based on measurements of the truck's front axle (rise of front axle with weight distribution engaged should be no more than half of the rise without weight distribution engaged, etc.). With the trailer coupled to the truck and the weight distribution engaged, both the truck and trailer sit approximately level. The ticket from the CAT scale indicates that the hitch is probably pretty close to the right adjustment; front axle = 3,000-lbs. (front GAWR = 3,450-lbs.); rear axle = 3,460-lbs. (rear GAWR = 4,050-lbs.). The 25-mi. drive home with our new trailer went fine; neither the 10-mph wind nor passing semis were a problem.

    While the truck sits approximately level with an unloaded trailer, I expect that the rear of the truck may sit a bit lower once we get all of our gear loaded in the trailer. Some folks will advise to simply adjust the hitch to get the rear of the truck back to a desired height, but doing so would also shift more weight from the rear axle to the front axle of the truck. The truck's front axle is already closer to it's rated capacity than the rear axle, so I don't want to shift too much additional weight to the front axle, and I'm considering adding air helper springs (air bags) on the rear of the truck.

    Using air bags to raise the rear of the truck will obviously change the geometry of the weight distributing hitch, so the hitch setup would need to be adjusted after adding air bags. The Equal-i-zer manual advises "Suspension air bags should be inflated to their desired towing psi before hitch setup. Inflating rear axle air bags after setup will most likely decrease the amount of weight distribution provided by the hitch."

    For those who have successfully used air bags while towing a travel trailer, how did you determine what pressure to run in the air bags? I imagine a process of picking an arbitrary starting pressure for the air bags, adjusting the hitch based on the new geometry of the truck, hooking up the trailer and checking weights at the CAT scale, testing how it tows, and then deciding whether to change the psi of the air bags and start the adjustment process all over again. Is there a strategy to get closer to the right pressure in the air bags the first time, and thereby reduce the number of attempts required to get everything dialed-in?
    Joe & Joy + children
    2018 Imagine 2800BH
    2022 F250 Crew Cab 4x4 Tremor, 7.3L V8
    Equal-i-zer 1,200/12,000 lb. hitch


  2. #2
    Setting Up Camp
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    I found that you will need to fine tune the air pressure in the bags, I started at around 40psi in mine and have found that 20-25psi gives me the best ride. I also don't put air in the bags until after hooking up the trailer as your psi will change slightly with it hooked up vs unhooked. When I air the bags up my truck rises maybe 1" in the rear when hooked to the trailer. I tow a 308bhts with a 2500hd and have a blue ox wdh hitch so my setup is different but setup should be similar with your truck and trailer.

  3. #3
    Site Sponsor jw^2 family's Avatar
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    I installed some air springs (Hellwig #6115) today. The installation went fine, and the manufacturer's instructions specifically address how to coordinate installation of the air bag mounting brackets with a rear stabilizer bar (Hellwig #7705) which I had previously installed. I checked the air pressure 4 hours after initially airing them up, and they were still holding the same pressure - so far it looks like no leaks.

    I did not go with the on-board compressor at this time. It seems like that might be a more practical upgrade if pulling a fifth wheel rather than a travel trailer. For a travel trailer with a weight distributing hitch, it seems more important to get the weight distribution dialed in based on a fixed geometry (i.e. consistent pressure in air bags).

    Now to figure out what air pressure to run while towing... I believe that the Hellwig air bags are a little larger volume than the Firestone or Air Lifter bags, so they typically run at lower pressures. The label on the air bag says not to exceed 100-PSI but the manufacturer's instructions actually say not to run more than 50-PSI. So I may start off trying 20 or 25-PSI and see how that works.

    I'm planning to stop by the RV dealership later this week to get the hitch adjusted to accommodate the new geometry, and then test out how it rides and take it down the road to the CAT scale to find out exactly how the weight is distributed.
    Joe & Joy + children
    2018 Imagine 2800BH
    2022 F250 Crew Cab 4x4 Tremor, 7.3L V8
    Equal-i-zer 1,200/12,000 lb. hitch


  4. #4
    Fireside Member rbrown597's Avatar
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    Quote Originally Posted by jw^2 family View Post
    I installed some air springs (Hellwig #6115 ) today. The installation went fine, and the manufacturer's instructions specifically address how to coordinate installation of the air bag mounting brackets with a rear stabilizer bar (Hellwig #7705 ) which I had previously installed. I checked the air pressure 4 hours after initially airing them up, and they were still holding the same pressure - so far it looks like no leaks.

    I did not go with the on-board compressor at this time. It seems like that might be a more practical upgrade if pulling a fifth wheel rather than a travel trailer. For a travel trailer with a weight distributing hitch, it seems more important to get the weight distribution dialed in based on a fixed geometry (i.e. consistent pressure in air bags).

    Now to figure out what air pressure to run while towing... I believe that the Hellwig air bags are a little larger volume than the Firestone or Air Lifter bags, so they typically run at lower pressures. The label on the air bag says not to exceed 100-PSI but the manufacturer's instructions actually say not to run more than 50-PSI. So I may start off trying 20 or 25-PSI and see how that works.

    I'm planning to stop by the RV dealership later this week to get the hitch adjusted to accommodate the new geometry, and then test out how it rides and take it down the road to the CAT scale to find out exactly how the weight is distributed.
    Thanks for posting your air bag set up. I just had Firestone Air Bags installed on my 2018 F150 XLT 5.0 SCREW. I DO NOT have the max tow package. I am using a propride with 1400# bars on my 2800BH. I added the air bags to stiffen up the rear a little under load. Now comes the fun part of retuning the WDH and air pressure to fine the "sweet spot". I'll post all my weights and settings after I find them all. Thanks again for a starting point.
    Bob and Betty
    Lilly, our Old English Sheepdog
    Penny, our Shitz Tzu/Maltese mix
    New Owners 2019 Imagine 2800BH
    2018 F150 CREW 5.0 V8

  5. #5
    Site Sponsor jw^2 family's Avatar
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    Quote Originally Posted by rbrown597 View Post
    Thanks for posting your air bag set up. I just had Firestone Air Bags installed on my 2018 F150 XLT 5.0 SCREW. I DO NOT have the max tow package. I am using a propride with 1400# bars on my 2800BH. I added the air bags to stiffen up the rear a little under load. Now comes the fun part of retuning the WDH and air pressure to fine the "sweet spot". I'll post all my weights and settings after I find them all. Thanks again for a starting point.
    I settled on just 15 psi in the Hellwig air springs while towing. More air pressure than that makes the rear of our F150 sit higher than I'd like. As it's set up now, our Equal-i-zer hitch transfers enough weight to return the truck's front axle to its unloaded weight, and there's 1,000-lbs. added to the truck's rear axle when towing. That seems to put enough pressure on the hitch's spring bars to achieve decent sway control.
    Joe & Joy + children
    2018 Imagine 2800BH
    2022 F250 Crew Cab 4x4 Tremor, 7.3L V8
    Equal-i-zer 1,200/12,000 lb. hitch


  6. #6
    Fireside Member Bill Davey's Avatar
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    My method is not scientific, but it works for me. Hitch the truck and trailer and install the Equil-I-zer bars THEN add just enough air to the bags to raise the rear of the truck less than one inch. YMMV.
    2017 Grand Design Reflection 313RLTS, purchased April 2018. 2014 Ram 1500 Ecodiesel (I need a bigger truck!). Oswego NY in the summer, Ft. Myers Beach, Fl in the winter. GD is my summer home. Previously owned: 2015 Rockwood 2604WS; 2012 KZ Stoneridge 43' toy hauler; 2005 Titanium 39' toy hauler.

  7. #7
    Long Hauler
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    Sometimes you have to live by the tape measure.

    Measure your truck bumpers before and after and make adjustments based on the squat. If your rear end is riding where it originally was after you cranked up the bars, it doesn't need much air.

    The whole thing with air bags is to remove the squat and get it back level.

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