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1984 Mercedes-Benz 240
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Firestone Coil-Rite Air Helper Springs - Rear Axle
Part Number: F4173
$146.45
1984 Mercedes-Benz 240
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- Reviews (780)
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Firestone Vehicle Suspension - F4173
Highlights
- Custom Fit for Your Vehicle: Mounts to existing attachment points
- Keeps Your Vehicle Level: Adds 500–1,000 lb of support to stop rear sag when hauling heavy loads.
- Improves Steering and Braking: Levels suspension so handling and headlight aim stay consistent.
- Smoother, More Stable Ride: Absorbs road shock and prevents bottoming out under rough or uneven loads.
- Balances Uneven Cargo: Adjust 5–35 psi side to side to level off-center loads and reduce body roll.
- Durable, Long-Term Support: Elastic polyurethane air springs stay reliable through years of use.
Features to know about
Stay Level When the Load Gets Heavy: Up to 1,000 lbs of Rear Support
When you’re hauling a heavy load or towing, rear-end sag can throw off your balance and steering. These Firestone Coil-Rite air helper springs fit inside your existing rear coil springs to add up to 1,000 lbs of load-leveling support. By keeping your vehicle level, they help maintain even load distribution and steadier braking and handling under heavy conditions. You get better control and more confident driving without bottoming out or squatting when the weight piles on.
Fine-Tune the Ride with Adjustable Air Pressure: 5 psi to 35 psi
Every load is different, and these air springs let you dial in the pressure to match. With a manual inflation range from 5 psi to 35 psi, you can balance off-center loads or soften the ride when running light. The separate inflation valves for each side let you compensate for uneven weight so the vehicle stays steady through turns and rough spots. The result is a smoother ride that absorbs road shock and helps prevent harsh contact between axle and frame.
Built Tough to Handle Real-World Hauling: Durable Polyurethane Construction
Long drives, rough roads, and heavy weight demand strong parts. The Coil-Rite springs are made from durable, elastic polyurethane built to maintain comfort and stability over years of use. They’re engineered to work under heavy loading and adverse road conditions without giving up their shape or support. Each kit comes with brackets, hardware, air line, and separate valves for manual inflation so you have everything needed for installation.
Keep Control and Stability Under Load: Balanced Suspension Performance
A loaded rear end can lift the front end and reduce tire contact with the road. By adding these air springs inside your coil suspension, you help restore proper balance for improved braking, steering control, and traction. They also help level your headlight beams for safer nighttime driving while reducing tire wear from uneven weight distribution. It’s dependable suspension support designed to keep your setup stable when it matters most.
Specs
Weight and Capacity
- Load-leveling capacity: at least 500 lbs (at most 1,000 lbs)
Adjustability
- Adjustable air pressure: 5 psi to 35 psi
Warranty
- Limited lifetime warranty: on air springs
- 2-Year limited warranty: on hardware
Note
The construction material of the fittings may vary.
W237604173 Firestone Coil Rite Air Bags - Suspension Kit - Rear Axle
4173
This Product Fits The Following Vehicles
- 2018 - 2018 Jeep JK Wrangler
- 2018 - 2018 Jeep JK Wrangler Unlimited
- 2007 - 2017 Jeep Wrangler
- 2007 - 2017 Jeep Wrangler Unlimited
Video of Firestone Coil-Rite Air Helper Springs - Rear Axle
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Video Transcript for Checking Out the Firestone Coil-Rite Air Helper Springs
Today we're going to be taking a look at the Firestone coil rite line of air helper springs. Be sure to see eTrailer's fit guide for your application.Our springs are designed for a wide variety of vehicles. They're going to fit most passenger vehicles, vans, some light duty pickup trucks and motor homes. Whenever you haul a heavy load, have a lot of equipment in your vehicle or have a heavy trailer hooked up to it, it's going to cause the back end to sag down which is putting a lot of strain on your rear suspension, not to mention you're taking the contact off the front tires and misalignment your headlights. Our coil rite springs are going to take a lot of that effect out and help the sag in the rear end.Your air springs may look a little bit different than we have here, so you want to make sure you check each other's fit guide for your specific application, but these are going to provide us a smoother ride for vehicles that have coil springs in the back. They're designed to fit inside the spring, which is going to create a variable spring rate and help prevent the sag when we're loaded down and take stress off the rear suspension.
Our springs are going to be made out of a polyurethane, so they're going to be durable and last a long time. They are rated for working in temperatures from negative 40 degrees Fahrenheit all the way up to 180 degrees Fahrenheit. Each set is designed to support 500 to 1000 pounds and having an operating range of five PSI all the way up to 35 PSI.One thing I do want to mention is that our coil rite springs are not going to increase the payload of our vehicle. They're just there to help support the extra weight. So you always want to double check your vehicle's owner's manual and never exceed the manufacturer's recommended weight.Compared to other style of EHRs springs these are specifically made for the coil spring suspension, opposed to the leaf spring where that would sit on top.
These are gonna help out a lot with the SAG and prevent bottoming out and give us a smoother ride even when we're unloaded.Our kit's gonna come with two manual inflation valves. That way the bags can work independently from each other so we can inflate each one to our desired amount. That's going to help a lot with those off center loads, or if we take an evasive maneuver, it's going to take out some of that body roll. Our helper spring kits is going to come with everything you need to get it installed. Both springs, any brackets necessary, the lines, and the inflation valves.Ryan wrote in saying the install was easy on his 2014 FJ cruiser.
A year later he wrote back in and saying after a year of regular use, the bags had been great. They keep as FJ level where he's towing, and as a result, the steering while towing is vastly better.If you've had the back end of your vehicle sag down, rough ride, uneven tire wear, or even misaligned headlights our coil rite springs are going to help out a lot. All while giving us a smoother ride.
Ratings & Reviews
4.4
780 reviews
by:
Ron
09/26/2020
Easy install, I got them rolled down and used zip ties to keep them that way, it made it easy to slip them in the coils, then snipped the zip ties. Aired them up and they lifted my jeep. Looks like they are going to work great for heavy loads.
by:
J
09/21/2022
Installed on 17'Jeep Wrangler to help with sag when towing trailer. Works perfectly to keep the rear end up. I don't suspect they will last forever,but they are hefty and definitely worth the price. Installation requires patients.
by:
Tom
08/17/2023
2017
Jeep
Wrangler Unlimited
Great service as usual !
by:
Neils
03/19/2021
2014
Jeep
Wrangler Unlimited
by:
Stanley
07/03/2025
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!!!
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
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.
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.
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....
by:
Tom
07/13/2026
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.
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
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
Gwendolyn Y.
7/25/2025
That's an awesome shot, Jefferey! Where were you camping at?
by:
Greg
06/12/2026
toyota
Sienna
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:
Dan
09/12/2026
It was more of a challenge getting the air bladder inside the coil on my Rav4 than advertised but got it finally. Luckily I had a vacuum pump for bleeding brakes and that helped suck it down as small as possible. There was no way the bladder would "return to its normal shape" without inserting 5-10 PSI once the top and bottom were within the coil then it unfolded and seated itself just fine. Also the upper protection bumper was not a tight fit on the threaded bolt and wanted to fall off but sticking a 3 inch piece of zip tie between the threads and the bumper did the trick.
by:
Tim O.
09/23/2026
Had a problem with my AirPads and contacted the ETrailer and spoke with Spencer, and he was extremely pleasant and very knowledgeable allowing me to get the replacement product in a timely matter before we went on our camping trip! I would recommend an E trailer to anyone looking to buy trailer parts!
by:
Steve W
08/23/2026
Installation was not complicated but was not easy either
It took some effort to get the air bags folded up enough to slip them into the coil springs, I used a couple of zip ties to keep them compressed until in place
The air bags and all the other parts seemed to be high quality
It took some effort to get the air bags folded up enough to slip them into the coil springs, I used a couple of zip ties to keep them compressed until in place
The air bags and all the other parts seemed to be high quality
by:
John
08/16/2026
2025
toyota
Sienna
I installed these in my buddies 2024 Toyota Sienna Hybrid FWD. I installed with valves up and it took about 4 hours. I had to remove the springs to remove the stock upper bumpers. He's in a wheel chair and has a lift on the back. Going to test it out this week.
by:
Jarrod
07/14/2025
2016
Toyota
Land Cruiser
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:
Joseph
01/27/2024
Great product. I must say that they were a little tough to install. A very tight fit. Fortunately for me I had the availability of a vacuum pump. With that I was able to evacuate all the air out of the bags which made them flatter, with that, it made it easier to slide them between the coil springs. I tow a small camper trailer, I usually run around 20 psi in the bags. This keeps my vehicle level and adds for a smooth ride. A great product.
Joseph
1/28/2025
After a year, the air bags have been superior in their performance. I have had no issues with them. Still running 20 psi in them when Im towing my trailer, deflating them to 10 psi when not. I see only slight rubbing signs on the bags from the coil springs, but hasnt effected the performance of the bags. Great product. Im very happy with the performance of the bags. Still a great product.
Robin H.
1/28/2025
@Joseph glad to hear it! Firestone makes great products.
by:
Jeffry
09/19/2026
2022
Ford
Maverick
Air bags are too small and don't do anything to level the truck or improve handling. Even at the full 35psi. Would not recommend.
by:
Daeton
04/14/2025
2022
Jeep
Gladiator
These were just as described as far as quality and look. The installation of them were a little more difficult than they show in the video but can easily be done by someone with basic skills. I would recommend if you have the ability to remove the springs and then just insert the bags that way as I couldn’t get one in without doing that. Otherwise the install is pretty straightforward. Haven’t used them with a load or towing yet but hopefully they will work as designed.
Brooke M.
4/14/2025
Thanks for posting the photos and for sharing what all you had to do to get them to work! It's what makes your review especially valuable to other readers. Thanks, Daeton
by:
Scott
05/28/2026
2026
Ram
1500
It fit great. And works like a champ... I couldn't be happier with these air helper springs! E trailer made it easy and they followed up with me to make sure i'm pleased with the product... Very happy with the service.
by:
Jody
07/13/2026
Parts are very good quality but installation instructions for my 14 Jetta were very poor. Had to air to 25 psi to keep air bag from shifting in spring but did help stabilize vehicle.
by:
Off2Mtns
12/13/2017
2016
Toyota
4Runner
Installed on a 2016 4Runner in conjunction with a 1-1/2" Daystar coil spring spacer. Since the coil spacer is hollow, I left one segment of the factory bump stop in place to compensate for and match the height of the spacer. I also added a Firestone T-fitting on the airline for a single inflation point and located the inflation valve next to my trailer plug wiring. Quite a pain to wrestle the coil back in place with the added height of the spacer, but that is no fault of the airbags; pry bar proved critical to wedge the coil back in place since I did not try the bottle jack between the frame and axle trick. After nearly a year, no leaks, bags hold air well. I put 25 psi in them for towing our travel trailer, or keep them at 10 psi for normal running around. I have also found them useful to prevent or at least reduce bottoming out the soft rear suspension that happens when off road driving with even just a couple hundred pounds in the back. Even at 25 psi they ride great and you wouldn't know they are back there at 10 psi. Highly recommend for the low cost and added versatility!
Off2mtns
12/14/2018
Still working great after a year. Knock on wood... no leaks to date. I would consider these essential equipment for towing, and would highly recommend for heavily loaded backcountry travels as well. I did try them near their max pressure on one trip with 5 people, roof top tent, and gear for a week of camping this summer and it was too much and felt very unsafe ped the pressure back to sub-30 psi after driving a few blocks and all was great after that!
by:
Zane
03/18/2026
2017
Toyota
4Runner
Firestone airbags have worked well for my 2017 4Runner. When I'm not attached to my camper, I keep the airbags deflated to about 5 PSI. But when I put my trailer 3,500 lb. Onto the back of my 4Runner I get several in of sag. I pump up the airbags to about 20 psi and I level out the whole rig. What a perfect hybrid system to have. It's there when you need it. Perfect system for a sagging. Backside on a rear coil spring 4Runner. Thanks, e-trailer
by:
Curtis
11/26/2023
Great upgrade for carrying weight in the back or towing a trailer. They are a bit tough to install. I found twisting the bag over in the middle and inserting it between the spring to the trick. Insert the top side on the passenger bag first. Insert the bottom side first on the driver side take care with the week ass tubing because if it folds over on itself in a coil, it will remain pinched which I can see will cause problems in the future. The tubing was better 20 years ago than what they give you today. One tube replacement over $30!! Ridiculous !! I like the right height adjustability and my truck feels more stable with a load of weight in the back of my truck advertised in the video shown below.
Curtis
11/27/2024
Still working great even with the twists, I haven’t had any leaks. I did pick up some quick fittings if I did need to repair. I’m really surprised with hot summers and cold frozen winter weather use with no need for repairs.
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Show More Reviews
See what our Experts say about this Firestone Vehicle Suspension
- Recommended Suspension Improvement for a Jeep Wrangler When Towing a TrailerBoth the Timbren # TJRJK and the SumoSprings # CSS-1195R will help with sag and stability while towing. However, they will affect the ride when no towing as well. The Firestone Coil-Rite Air Helper Springs # F4173 are adjustable from 35 psi all the way down to 5 psi. This will give them up to 1,000 pounds of load-leveling capacity when filled, and then feel basically nonexistent when deflated. If you are still getting a lot of body roll when towing, or even when not towing, the SumoSprings...
view full answer... - Dimensions of Firestone Replacement Coil-Rite Air Spring F6006Firestone Replacement Coil-Rite Air Spring # F6006 is 6-1/2-inches tall x 5-1/4-inches outside diameter. The included spacer disk measures 3-3/4-inches x 1/2-inch. I took these measurements for your myself. This spring is a direct replacement for those in Coil-Rite Rear Axle kit # F4173.
view full answer... - Could Motorcycle Carrier be Used on Draw Tite Hitch DT78MR for 2015 Jeep WranglerYes, the trailer hitch part # DT78MR has a 675 lb tongue weight capacity so it would be rated high enough to use a motorcycle carrier and carry a 400 lb bike as well. You really need to check the owners manual to determine the tongue weight capacity of the vehicle too though and go by the lower rated figure. The # UF48-979033 would also work as a carrier too since it has a 500 lb weight capacity. For suspension enhancement the Firestone air bag kit part # F4173 would be a great option...
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Info for this part was:
Updated by:
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Updated by:
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Updated by:
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Updated by:
Daron K
Updated by:
Alex H
Written by:
Tyler C
Video Edited:
Jacob T
Video Edited:
Chris R
Video by:
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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.
Mike L.
10/2/2022
The air helper spring system is covered by a limited lifetime warranty on air springs and a 2-Year limited warranty on hardware