We'll connect you with nearby partnered installers who know this exact setup.

Firestone

Firestone Coil-Rite Air Helper Springs - Rear Axle

Part Number: F4138

780 Reviews | 13 Questions

In Stock

$158.89

Not Confirmed to Fit

2015 Ford F-150

Will this fit?

To see if this custom-fit item will work for you please tell us what vehicle you'll use it with.

Add to cart

Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.

Error submitting comment. Please try again momentarily.

Product Images

firestone vehicle suspension rear axle enhancement coil-rite air helper springs -

firestone vehicle suspension air springs

firestone vehicle suspension air springs f4138

firestone vehicle suspension towing/load leveling rear axle enhancement coil-rite air helper springs -

firestone vehicle suspension towing/load leveling coil-rite air helper springs - rear axle

Show All (6) Product Images

Show Fewer Product Images

In Use/Installed

2009 kia sedona vehicle suspension firestone air springs rear axle enhancement f4138

2009 kia sedona vehicle suspension firestone towing/load leveling f4138

2009 kia sedona vehicle suspension firestone towing/load leveling rear axle enhancement on a

2009 kia sedona vehicle suspension firestone towing/load leveling rear axle enhancement coil-rite air helper springs -

2009 kia sedona vehicle suspension firestone air springs on a

2009 kia sedona vehicle suspension firestone rear axle enhancement f4138

2009 kia sedona vehicle suspension firestone air springs f4138

2009 kia sedona vehicle suspension firestone towing/load leveling coil-rite air helper springs - rear axle

Show All (8) In Use/Installed

Show Fewer In Use/Installed

Customer Photos

Firestone Coil-Rite Air Helper Springs - Rear Axle customer photo

Show All (9) Customer Images

Show Fewer Customer Images

Videos

Checking Out the Firestone Coil-Rite Air Helper Springs

Firestone Coil-Rite Air Helper Springs Road Test

Install: Firestone Coil-Rite Air Helper Springs on a 2009 Kia Sedona

Setting up the Firestone Coil-Rite Air Helper Springs on your 2012 Kia Sedona

Show All (4) Videos

Show Fewer Videos

We'll connect you with nearby partnered installers who know this exact setup.

SCHEDULE AN INSTALLATION

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.

All Info
Reviews (780)
Q & A (0)
Related Parts
Photos

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.

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

2007 - 2008 Hyundai Entourage
1999 - 2004 Honda Odyssey
2003 - 2004 Honda Pilot
2006 - 2016 Kia Sedona

Customer Satisfaction Score:

96% were satisfied with this product

4% of customers were not satisfied

Wrong item was ordered
Defective

4% of customers were not satisfied

Wrong item was ordered
Defective

4.4

780 reviews

5 Stars		(521)
4 Stars		(141)
3 Stars		(50)
2 Stars		(26)
1 Star		(42)

by: Martin B 07/06/2019 One Year Later

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.

Click to Enlarge

by: David Bordne 08/12/2014

2015 Honda Odyssey

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!

Click to Enlarge

by: Carl L 06/25/2016 One Year Later

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: Jeff I. 07/22/2013

2004 Honda Odyssey

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: R Johnson 05/31/2018

2016 Kia Sedona

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: joe rice 04/12/2019 One Year Later

2014 Kia Sedona

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.

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: Scott 04/02/2019 One Year Later

2016 Kia Sedona

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: S.luke 02/02/2020 One Year Later

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: Mikhail 10/01/2024

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.

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: Marcel 10/13/2018 One Year Later

Kia Sedona

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

by: Walt A 03/30/2017 One Year Later

Firestone Coil-Rite still doing great.

by: Graham G 12/04/2022 One Year Later

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.

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: Shawn 12/27/2021 One Year Later

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.

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: Steve 10/04/2017 One Year Later

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: Michael D. 07/17/2014

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: Walt 08/19/2022

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

by: Lyle 06/06/2024

by: Randy 06/05/2021

by: Stanley 07/03/2025 One Year Later

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!!!

Click to Enlarge

Gwendolyn Y.

7/10/2025

Really cool to hear how well the airbags have been working out for you, especially hearing your experience in the past. How's the ride day-to-day when you're not hauling that awesome camper?

Stanley One Year Later

7/4/2026

Other than a slight leak in the driver’s side that is not any fault of the product, this set up has worked extremely well! I’m very happy with these air bags and would highly recommend them over the AirLift1000 bags as there’s no comparison in quality! These Ride Rite bags are worth every penny!!!

by: Dustin 07/29/2026

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.

Click to Enlarge

Heather A.

7/30/2026

Thank you so much for taking the time to leave a review and for sharing those awesome photos! I'm really glad Jeremy was able to get everything straightened out quickly and make the exchange process easy. How are the bags working for you so far?

by: Joel 01/19/2026

Chevrolet Avalanche

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.

Click to Enlarge

Lazer S.

1/20/2026

Good idea taking the springs off, Joel! These can definitely be a bit of a pain in the butt with all the stuff impeding an easy install. Being able to clean the area is also nice! What are you towing with your Avalanche? Or did you want these more for regular driving?

by: Randall 08/26/2026

2022 Ram 1500

Great Idea - but they won’t hold air, which makes them useless! I knew they would be difficult to install, so I had an experienced auto mechanic who has installed these before to help me. They went in nicely, there were no leaks at the fittings-but they just refuse to hold air. Very disappointing.

Mike L.

8/26/2026

Have you tried putting a dishwashing liquid/water combo on the area where the air line joins with the bag? This will make any leaks stand out like a sore thumb. It's extremely important that the air lines are cut precisely at a 90° angle. You can't use angle cutters, because it will crush the air line and it'll always leak....

Randall

9/4/2026

@MikeL Yes we did the soap/water thing with no obvious leaks and we were very careful about how we cut the air line. I got underneath the truck again and redid the soap/water spray without any obvious signs of a leak! I tightened all the fittings a little more and topped off the air — waited overnight and checked again —— still leaking, but maybe not as bad. In any case, to keep the minimum pressure I’ll have to ad air every morning before I can go anywhere! Not very convenient.

by: Tom 07/13/2026 One Year Later

Installer couldn't get them to hold air for more than a day.
And if pressure falls below 5 psi, there's a risk of damaging them.
Installation was difficult.
But they do fix the ride height issue when towing.
If I had it to do over, I'd get Sumo springs.

Mike L.

7/14/2026

I'd make sure that the tubing that goes into the air spring's fittings are cut so they're perfectly square. That is the main culprit when it comes to leaks....

by: Ethan 06/23/2025

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.

Ethan One Year Later

6/25/2026

I had to take the right rear airbag and deflated it. I took a piece of mudflap about a quarter inch thick and put it on top of the airbag with a hole in the middle of the mudflap piece that gave more clearance between the car and the airbag valve. Now I have had no leaks for a year. With the least 9000 miles of towing and rough terrain.

by: Jeffery 07/16/2025

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

Click to Enlarge

Gwendolyn Y.

7/25/2025

That's an awesome shot, Jefferey! Where were you camping at?

780

true

Show More Reviews

See what our Experts say about this Firestone Vehicle Suspension

Do you have a question about this Vehicle Suspension?

What can I do to Level My 2008 Kia Sedona when Towing a Trailer
What year is your Kia Sedona?
view full answer...
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...
view full answer...
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...
view full answer...
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...
view full answer...
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...
view full answer...
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...
view full answer...
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,...
view full answer...
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...
view full answer...
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...
view full answer...
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.
view full answer...
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.
view full answer...
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.
view full answer...
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...
view full answer...

Do you have a question about this Vehicle Suspension?

Info for this part was:

Updated by:

Leah B

Updated by:

Mary K

Updated by:

Wilson B

Updated by:

Daron K

Updated by:

Alex H

Expert Research:

Mike L

Expert Research:

Jeffrey L

Written by:

Tyler C

Video Edited:

Joshua S

Video Edited:

Jacob T

Video Edited:

Chris R

Test Fit:

Nicholas E

Video by:

Alan C

Video by:

Jonathan Y

Installed by:

Robert C

At etrailer we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.