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  1. Vehicle Suspension
  2. Firestone
  3. Air Springs
  4. Towing/Load Leveling
  5. Rear Axle Suspension Enhancement
  6. Light Duty
THIS ITEM IS NOT A FIT FOR
2016 Ram 1500
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Firestone

Firestone Coil-Rite Air Helper Springs - Rear Axle

Part Number: F4138
In Stock
$158.89
Retail:$208.83
You Save: $49.94
Vehicle Suspension
Not Confirmed to Fit

2016 Ram 1500

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etrailer Installation
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For safety and stability, air springs are the perfect partner for your rear suspension when you are hauling heavy loads. Springs fit inside existing coil springs to help level your vehicle, improve braking and handling, and reduce tire wear. Great Prices for the best vehicle suspension from Firestone. Firestone Coil-Rite Air Helper Springs - Rear Axle part number F4138 can be ordered online at etrailer.com or call 1-800-940-8924 for expert service.
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  • Reviews (761)
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Firestone Vehicle Suspension - F4138

Highlights

  • Custom Fit for Your Vehicle: Mounts to existing attachment points
  • Levels Heavy Loads: Adds up to 1,000 lbs of support to stop rear sag and keep handling steady.
  • Improves Steering and Braking: Keeps your vehicle level so headlights aim right and braking stays consistent.
  • Custom Comfort Control: Adjusts 5–35 psi on each side to balance uneven loads for a smoother ride.
  • Prevents Bottoming Out: Cushions the suspension to reduce bounce and road shock under heavy weight.
  • Durable Polyurethane Design: Elastic air springs deliver long-term stability and even tire wear.
Made in USA

Features to know about

Stay Level and Confident Under Load: Up to 1,000 lbs of Rear Suspension Support

Heavy loads can make the rear of your vehicle sag and throw off steering and braking. Firestone Coil-Rite air helper springs fit inside your existing rear coil springs to provide up to 1,000 lbs of load-leveling support. They help keep your vehicle level when you’re hauling or towing, so braking stays even, steering stays responsive, and headlights stay aimed where they should.

Smooth Out Rough Roads and Prevent Bottoming Out: Adjustable Air Pressure from 5 psi to 35 psi

Road shock and uneven loads don’t have to beat up your suspension. These air springs let you fine-tune air pressure from 5 psi to 35 psi for the balance of comfort and control you need. Adjust each side manually through separate inflation valves to level off-center loads, soften harsh bumps, and stop the rear end from bottoming out when the weight gets heavy.

Built Tough for Long-Term Stability: Durable Polyurethane Construction

Made of elastic polyurethane, each Coil-Rite spring is built to handle years of heavy use without losing strength. The material flexes with the suspension to maintain stability over rough roads and helps reduce tire wear by keeping weight evenly distributed. It’s a durable setup that adds dependable support every time you load up.

Straightforward Installation with All Required Components Included

Each kit comes with the brackets, air springs, hardware, air line, and separate manual inflation valves needed for installation. The springs mount inside your existing coil springs using your vehicle’s spring seats. Once installed, they work quietly in the background to balance your load and keep your ride stable mile after mile.

Firestone Coil-Rite Air Helper Spring kit components including blue air springs, tubing, and installation hardware

Specs

Weight and Capacity

  • Load-leveling capacity: at least 500 lbs (at most 1,000 lbs)

Pressure

  • Adjustable air pressure: 5 psi to 35 psi

Firestone Coil-Rite airline installation showing routing of air tubing for manual inflation valves on rear suspension system

Warranty

  • Limited lifetime warranty: on air springs
  • 2-Year limited warranty: on hardware

Note

The construction material of the fittings may vary.

W237604138 Firestone Coil Rite Air Bags - Suspension Kit - Rear Axle

4138

Installation Details F4138 Installation instructions

This Product Fits The Following Vehicles




Customer Satisfaction Score:

Ratings & Reviews

4.4

761 reviews
Review sort icon
For safety and stability, air springs are the perfect partner for your rear suspension when you are hauling heavy loads. Springs fit inside existing coil springs to help level your vehicle, improve braking and handling, and reduce tire wear.

by:

I initially ordered the wrong airbags. I called eTrailer and Jeremy H. was very understanding. He got the right ones immediately shipped out and sent me a return label and info while I was on the phone with him. The bags seem good quality comparable to my previous Airlift bags. Instructions were well written and all hardware was accounted for in the shipment.



by:

Easy install on lc200, it’s only been a couple days but test run with a trailer was great. Recommend getting getting inflation bracket (Firestone WR17607560) to reduce the need for any drilling if you don’t go with onboard compressor.



by:

The airbags were difficult to install on a 2021 Sienna. It required removing the rubber stopper from inside the coil spring. Once that was out, install was easy. However, these need to be installed with the valve down as the plastic spacers fall out when the van is lifted for service when installed right side up as recommended. Upside down the air hose is routed thru the center of the plastic donut spacer which holds it in place when the van is lifted. However, once installed "upside down" the valves tend to pinch on the suspension as they move around. The pinching lets the air out and requires the bags to be frequently repositioned especially after the van is lifted for service. It is a good product, just unreliable and requires much inspection and maintenance to work properly. Will be loading up again for a summer trip and will need to reposition them so they work as I just had the oil changed.



by:

These bags along with minor adjustments to my load leveling hitch made towing my 19.4 No Bo trailer so much more relaxing!I am running 20 PSI and 3/4 of an inch higher than stock ride hight. Easy peasy



by:

I bought this set because I was having problems with one of the airbags I previously had gotten. It was on the right side of my forerunner. It had a slow leak. When I replaced the airbag this time it had a very fast leak. I finally found That if I used NAPA Sil-Glyde to insert tube it seems to be holding air. And I squeezed air bag into the spring. Use soap for sliding it in.



by:

Phone service was excellent. Air bags helped a lot with stability. I found it easier to remove the spring from the Avalanche than to fight with it in chassis. Removing the spring also gave me a chance to clean the dirt and rocks out of the hose routing area. It was a little more work to drop the axle down but it really wasn't that bad. I was able to do it all without a hoist. Just used two floor jacks. I just let one side down at a time. Remove your swaybar link and shock and let one side down. Pull the spring and do the work in a vise. Its much easier than fighting with it on your back. Also put the air hose in really hot water and it will relax its memory.



by:

Well I did not expect to have a one year follow up from ETrailer! I’m a 5 Star happy with these airbags over the AirLift 1000’s I had that blew out just after the warranty was up! These bags are more than twice the product, as you can inflate to >60 psi and that makes for a way more steady ride with weight! I typically run mine at around 45 psi now, the AirLift are limited to 28 psi. The construction is far superior and quality is excellent!!!



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All went well I was informed when there was a delay.



by:

Have not installed it yet but I will follow up when it is installed. Great ordering experience and all was as described on website.



by:

So far so good, It's been installed for a month, carries the wheel chair with little or no
dropping of the rear end.



by:

Idk how well they work they haven't been right since first hooked them up. Was in contact with customer service and my busy schedule i didn't get to reply quickly. But I was told it was something I messed up so I've never had these working. One side would hold air for a day at most other never did.

Jenny N. profile picture

Jenny N.

12/28/2021

I will have our customer service team reach out to you. I recommend using the soapy water technique to see where it may be leaking. If you spray the air lines with soapy water typically you can see where the air is bubbling and what is causing the leak. Most of the time leaks are at where the air line s into a fitting. If the air line was not cut perfectly square it will end up leaking. I would check there first.



by:

The gabs arrived with a leak in one and it took over 12 months to get a replacement from Firestone .. which also leaked. eTrailer was no help in resolving the problem - they just redirected me to Firestone and the unmotivated and poorly organized staff there. If yo buy these, get them at [online]- that company stands behind the product they sell.

Jenny N. profile picture

Jenny N.

12/6/2022

It is very unusual to have two air bags that would be defective from Firestone. Typically what can happen is the air line hose is not cleanly cut or is cut at an angle which can cause leaks over time. I recommend checking the hose and using a hose cutter like part # AL10530 to ensure clean cuts. I also advise using the soapy water method to locate any leaks. You can just spray soapy water on the air hose lines and see see if any bubbles form. If they do then you will know where the leak is coming from.



by:

Firestone Coil-Rite still doing great.



by:

Great product for Kia Sedona 2012
Towing
my boat was heavy on car’s rear suspention. These airhelpers are great
Easy to install



by:

Easy installation, has worked as advertised on my Kia Sedona van. I carry heavy equipment and inventory for my mobile embroidery business and it definitely helps with leveling and stabilizing the load.



by:

Installed easily on my 2016 Sedona. I am pulling a pop up camper and this helped keep it level without adding stiffness to the van suspension. I only wish the tube didn't hang down below the suspension,



by:

Maybe excellent after I try to fix it. Seems the driver side wont hold air too long. I just need it when I pull my Casita camper with my KIA Sedona and I just add air before I start out. Not too annoying really. Fixing it may be a little more difficult then living with it. But I think it was a good idea to buy and install.

Mike L. profile picture
Etrailer Expert

Mike L.

4/13/2019

The vast majority of the time, leaks will occur where the tubing enters the spring. If the tubing is not cut at a perfect 90° angle, its going to leak. You can test this by pressuring up the system and painting a solution of dishwashing liquid and water at the point where the tubing enters the fitting. If theres bubbles, theres your leak.



by:

Love the product! Holds my Sedona level, even with all the kids plus a load in the rear. Evens out the ride driving over bumps. Great for towing a trailer. Only down side was installation. I had the product installed by the Kia dealer as I figured it would be easy for them; it took the professionals 4 hrs to install. Outside of the cost for installation, great value for the money. Highly recommend!



by:

Kit has made the ride in my Honda Odyssey overall better. Also keeps the back end from sagging to far when I've got the trailer on.

Quality parts (stainless steel valves and valve caps) easy instructions and it fits perfect.

Only drawback was that I had to have my mechanic install it, but after talking with him he said that it would have been a challenge without a lift.



by:

The kit works but unfortunately the bags leak out within 15-20 minutes. I had to route the lines inside the cabin and have my son maintain pressure during the long road trip

Gwendolyn Y. profile picture
Etrailer Expert

Gwendolyn Y.

10/10/2024

That doesn't sound like a fun start to a trip. If both bags are leaking, I would start by putting some soapy water around the fittings to see if the leak is there. If there is bubbling at the connection from the airline to the fitting, the cut on the airlines may not be a clean cut causing the leak, you can recut using part # AL10530. This is the most common case. If the bubbling happens at the fitting itself or on the bag, that would be more of a warranty issue. If that is the case, please let me know.



by:

Most challenging to install. Not snap fit. Removal of several components and careful routing of delicate air line also had to purchase grommets for holes where chaffing of air line would occur. Don't expect longevity. Suggest development of a single support spring assembly to be better engineered and increase longevity, reliability, and ride stabilization as well as load capacity. Rusted parts don't disassemble with out heat and air tools. New bolts washers and nuts should be included. Thank you



by:

I have a 2003 Acura MDX with 197k miles on it. I have used it for towing a 6x12 trailer for 3 quads. I have also towed many loads of dirt, mulch you name it. The rear sags allot and I just bought a 19' boat. I found this kit on etrailer and ordered it. The box came and it said it was for a Honda Odyssey. I double checked online with various sites and confirmed that all Acura MDX, Honda Pilot, Honda Odyssey, & Honda Ridgeline all have the same coil spring suspension with bumper stops inside the coil. I found a great forum which included pics of someone else that installed similar kit. I used those as references to install mine. Here are the steps to install which took about 2 hours:
1) Jackup car, and suppored with good jack stands
2) Removed tires
3) Using a 7/8" hole saw and made a hole in the middle of the lower control arm.
4) Filed the burrs
5) Installed a 7/8" grommet (not included in kit, I got this a local ACE hardware store)
6) Removed bolt from lower control arm knuckle to lower the arm.
7) The bolt for the bumper stop is not accessible, so I used a hand saw and cut about 2" of the rubber stop out.
8) Compressed the air bag and installed the plug (supplied) to keep it compressed, inserted the airbag thru the coil.
9) I deviated from the instructions which says to use the included plate at the top of the airbag which requires removing the bumperstop. Instead I placed this at the bottom of the airbag, which nicely has a grove in the middle which allows the connection for the airtube to sit in and keep it protected.
10) I routed the airline thru the factory openings in the lower control arm & rear end and up thru the trailer harness opening into the rear compartment in the trunk where the head rests go for the third row.
11) Reattached the lower control arm
12) Install tires
13) Lowered car
14) Inflated the bags to 15 psi which returned the truck to just a little above the stock height.

I must say this is exactly what I was looking for. I towed the boat this weekend and didn't sag at all, the ride was much smoother then ever. Even with nothing attached to the truck, the ride is much better. My opinion is that this should be installed for anyone that uses the third row seat, or tows anything at all Acura MDX, Honda Pilot, Honda Odyssey, & Honda Ridgeline as it eliminates the typical rear sag!



by:

The instruction video showed exactly how to install these. Just disconnected rear lower suspension arms and drilled holes for the air lines. Swapped in the top plates for the air bags and put everything back together. They work great. We top them off every couple weeks, but really only necessary to top them off when we are going on trip or towing something. Hitch doesn’t scrape any more and body roll is reduced. Great investment. Highly recommend.


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See what our Experts say about this Firestone Vehicle Suspension

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  • Parts Needed to Safely Tow a Pop Up Camper with a 2016 Kia Sedona
    1. Normally I'd say that your 2016 Kia Sedona would be just fine as long as the pop up has brakes, but since your towing capacity without brakes is only 1,000 lbs it would be a good idea to install one. As far as the warranty is concerned you are protected by the Federal Magnuson-Moss Warranty Act. The Act states that if something breaks on your vehicle and you take it in for warranty repair, the dealer must honor your warranty unless whatever modifications you have added to your vehicle...
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  • Rear Air Bag Suspension Setup For 2015 Kia Sedona To Reduce Vehicle Sag
    The only rear suspension enhancement system that is confirmed to fit your 2015 Kia Sedona is the Firestone Coil-Rite Air Helper Springs - Rear Axle # F4138. This air bag setup has a weight capacity of 1000lbs which should be more than enough for your vehicle. It will drastically reduce rear-end sag on your Sedona as well as improve handling and reduce body roll on turns. While this kit includes everything necessary for installation and use, you may find it useful to add a compressor kit...
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  • Will The Firestone Coil-Rite Air Helper Springs # F4138 Fit a 2017 Kia Sedona
    Doing a parts search I do see the same rear coil springs were used on the 2015-2018 Kia Sedona. Unless there is something added inside your coil springs that would prevent the Firestone Coil-Rite Air Helper Springs # F4138 I do not see why they wouldn't fit. I have also linked an installation video near the bottom of the page you can reference to determine if there are any other differences with your rear suspension. Firestone would not tell me the dimensions of the bag itself. If there...
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  • Can a 2015 Kia Sedona Safely Tow a 3,700 Pound Jayco Travel Trailer
    What I recommend is a trailer that has a gross trailer weight that meets or is under the towing capacity of your 2015 Kia Sedona which is 3,500 pounds as long as the trailer has brakes. You can tow a trailer rated higher provided that the actual weight of the trailer does not exceed that 3,500 pound tow vehicle capacity. So they aren't lying about that but you do run the risk of overloading the tow vehicle by going with a heavier trailer. You will likely need suspension enhancement when...
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  • Suspension Enhancement for 2016 Kia Sedona
    eTrailer.com does not manufacture air bags, but we do offer suspension enhancement air springs for your 2016 Kia Sedona. Firestone's Coil-Rite Airs Helper Springs, # F4138, are the only enhancement we currently offer that is a fit for your vehicle, but they are a custom fit. This system utilizes compressed air to partner with your vehicle's rear suspension. The air springs fit inside the metal coil springs already on your 2016 Kia Sedona to help with a number of issues, like sagging,...
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  • Comparing the Reese Light Duty Weight Distribution System to the Pro Series RB2 for a 2700lb trailer
    When choosing a weight distribution system, the most important factor to consider is the fully loaded and ready to tow tongue weight of your trailer plus the weight of any cargo behind the rear axle of your 2004 Honda Odyssey. Tongue weight of a trailer is typically calculated to be 10 to 15 percent of the gross trailer weight. If your Scamp trailer weighs 2,700 lbs, then the tongue weight may be around 270 lbs to 405 lbs. You must then add the weight of the cargo that you load in the back...
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  • Suspension Enhancement Options for Towing With 2004 Acura MDX
    The Firestone # F4138 and # W237604138 are the same part. 4138 is the part number, and W237604138 is the SKU number that Firestone uses internally. Both the # F4138 and the Timbren # THROD2 are compatible with MDX models that have the coil spring rear suspensions only. It will not work on models equipped with the Coil-Over-Strut suspension. The Timbren springs will suspend up to 2000 lbs loaded in your MDX, while the Firestone Air Suspension is good for up to 1000 lbs. Neither system...
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  • How to Get the Rear Spring off the Spring Perch on a 2010 Kia Sedona
    A long screw driver or pry bar should do that trick. I had a similar situation with my car and was able to pry the last bit of the spring off the perch by using a pry bar in one hand and a long slot screwdriver in the other. I pried up with the pry bar and then to the side with the screwdriver to help slide it off the perch. Be careful and take your time. To get it back on you will just need to reverse the process. Leverage is your friend, use the pry bar to compress the spring and the...
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  • Installing Firestone Coil-Rite Air helper Springs On 2000 Honda Odyssey
    Per the installation instructions for the Firestone Coil-Rite Air Helper Springs, part # F4138, the overload bumper inside the coil spring will need to be unbolted and removed. You will also need to drill a hole in the lower control arm when installing this system. I have attached the installation instructions for this system you can check out. Installing a system like the Firestone Air Springs will not increase the vehicle weight carrying capacity.
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  • How to Check for Air Leaks on a Firestone Coil-Rite System with Inaccessible Inflation Valve
    That is an excellent point. Firestone was recently here for training and they did address the issues installers have had with the instructions. Basically they are going to be redesigning all the instructions. But for you, you can check for leaks at every other place that you can (without disassembling the vehicle). Assuming everywhere else checks out then if there is a leak the only remaining place it could be would be the one place you can't get to unless you pull that control arm back down.
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  • Installation of Firestone Coil-Rite Air Helper Springs Part # F4138 on 2007 Hyundai Entourage
    According to our friends at Firestone, drilling the hole in the control arm will not weaken or otherwise damage the vehicle. The hole is absolutely necessary to provide access for the air line to connect to the bottom of the Coil Rite air spring.
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  • Installing Firestone Coil Rite Air Helper Springs # F4138 on 2010 Kia Sedona
    The Firestone Coil-Rite Air Helper Springs, part # F4138 will install so that they sit inside the coil springs of your suspension on your Sedona. To install the springs, the lower control arm will be unbolted from the knuckle, allowing it to drop free and the coil spring to be removed so that the air spring can be inserted. You can see the full installation instructions by clicking on the link I provided. When installing the springs, cutting the air line perfectly square is crucial for...
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Info for this part was:

Employee Leah B
Updated by:
Leah B
Employee Mary K
Updated by:
Mary K
Employee Wilson B
Updated by:
Wilson B
Employee Daron K
Updated by:
Daron K
Employee Alex H
Updated by:
Alex H
Employee Mike L
Expert Research:
Mike L
Employee Jeffrey L
Expert Research:
Jeffrey L
Employee Tyler C
Written by:
Tyler C
Employee Joshua S
Video Edited:
Joshua S
Employee Jacob T
Video Edited:
Jacob T
Employee Chris R
Video Edited:
Chris R
Employee Nicholas E
Test Fit:
Nicholas E
Employee Alan C
Video by:
Alan C
Employee Jonathan Y
Video by:
Jonathan Y
Employee Robert C
Installed by:
Robert C

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