Ford F-350 2011 - 2026 | Mega-Duty Kit
Ford F-350 2011 - 2026 | Mega-Duty Kit
Ford F-350 2011 - 2026 | Mega-Duty Kit
Ford F-350 2011 - 2026 | Mega-Duty Kit
Ford F-350 2011 - 2026 | Mega-Duty Kit

Ford F-350 2011 - 2026 | Mega-Duty Kit

SKU: 3611-SLMD

Regular price$649.00
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Shipping calculated at checkout.

Fitment

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Factory Overload Spring
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  • 1-3 Day Free Ground Shipping 1-3 Day Free Ground Shipping i
  • 5 year warranty 5 year warranty i
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Get the best of both worlds with RoadActive Suspension® Mega-Duty — our strongest suspension upgrade engineered for heavy payloads, serious towing, and demanding truck applications.

Mega-Duty strengthens your factory leaf springs by up to 50% while improving unloaded ride quality, handling, and overall control — without the hassle or maintenance of airbags.

Designed for 3/4-ton and 1-ton trucks that tow and haul regularly, RAS® Mega-Duty helps reduce:

• Up to 2" of squat
• Excessive bounce & body roll
• Sway & axle wrap

Independently tested at the Transportation Research Center (TRC):

• 23% reduction in road transmissibility
• 43% improvement in pitch stability
• Approximately 30% stronger spring rate than HD

This fully mechanical 3-in-1 system combines the benefits of a helper spring, sway bar, and traction bar into one simple bolt-on upgrade with zero maintenance required.

If truck has factory overload spring, top overload spring must be removed for installation of RAS. Mega-Duty will provide more strength than the factory overload spring.

If you're squatting with your F-350 — Mega-Duty is the answer.

RoadActive Suspension provides a 30 day money back guarantee, from date of purchase. However should the kit be returned, it must be re packed in the original packaging with all components included. On orders with free shipping (where shipping was paid for by RoadActive Suspension), refunds will reflect the invoiced amount, minus that shipping cost billed to us by our shipping provider. In addition, the customer will be responsible for the return freight charges.

It works with your suspension — not against it.

Each kit is tailored to your specific vehicle

RoadActive Suspension is uniquely assembled for your model and typically ships within 1-2 business days! RoadActive Suspension is the only suspension upgrade on the market that adds strength to your rear suspension, provides same as or better than stock unloaded ride quality and doesn’t require readjustments or maintenance.

Each RAS kit comes fully assembled out of the box and ready for installation. Follow your application guide that is in the box and you will be ready to test your RoadActive Suspension after an installation as simple as 45 minutes! If you are not satisfied with your RoadActive suspension we offer a money back guarantee.

Reduce Rear Squat & Bounce

Improve Stability

Improve Roadhandling & Stability

Make RVing Safer

Reduce Axle Wrap

No Readjustments or Maintenance

We already know what you're going to ask.

No, installing RoadActive Suspension (or any other rear suspension helper) does not automatically void the factory warranty. The Magnuson Moss Act states that it is illegal for a vehicle manufactuer or dealership to void a warranty just because a part has been installed. The manufacturer or dealership may only void the warranty if they are able to prove the aftermarket part caused or contributed damage to the vehicle. Even then, warranty to the impacted component(s) is the only portion of the warranty that may be voided. In this case, all other parts of the vehicle remain under warranty.

RAS uses a variable-rate tension coil spring that attaches directly to your rear leaf springs. It works like a muscle, progressively engaging as load or force is applied. This keeps the leaf springs in an upright bowed position to prevent sag, improve stability, and enhance bounce isolation.

Most applications see a 2–3" reduction in rear squat. The exact amount will depend on multiple factors such as vehicle size, load size, load placement, leaf spring condition, and the tension setting of the RAS.

Expect same-as or better-than-stock unloaded ride with less bounce and more control.

Yes — in as little as 45–60 minutes with jack stands and hand tools. No drilling, no air lines, no maintenance.

Airbags add complexity, cost, and ongoing maintenance. Other helper springs only address sag and can compromise ride comfort.RAS is 3-in-1:it controls squat, reduces sway, and improves traction — all with zero maintenance.

Customer Reviews

Overall rating: 3.9 / 5 from 13 reviews.

Customer video review of Ford F-250 2011-2026 | Mega Duty Kit

2025 Ford F250 King Ranch. I haul a 12,000# 5th wheel camper that almost maxes out the payload of the truck. The stock leaf spring squat 4 inches and it would porpoise with dips in the road. The squat is now about 2 inches and the front is not pointing up. The porpoising was greatly reduced. The empty ride was also improved and with the coil spring's natuaral behavior, it does not feel rough. I installed the mega spring version because my traler's heavy weight and nearly maxed out pin weight of my truck. They are not cheap, but cost much less than switching to a 1-ton truck.

Ford F-250 2011-2026 | Mega Duty Kit

Customer photo review of Ford F-250 2011-2026 | Mega-Duty Kit

The first one I bought, I put on an F150 and it made quite a difference. Now that I have an F250 I had to put it on this one because I enjoy how it treats the truck and rides.

Ford F-250 2011-2026 | Mega-Duty Kit

Customer photo review of Ford F-250 2011-2026 | Mega Duty Kit

Installed on a seven year old 2019 F250 with 70,000 miles. I have been towing a 37ft fifth-wheel since new. The problem is axle wrap and wheel hop when towing the fifth-wheel up my steep gravel driveway. The bed was also sagging unloaded. When towing it sags to the point the steering was getting light. During the installation the spring was set to max level using both spacers. The unloaded bed has returned to the stock ride height. When towing, the bed is now level. Just returned from a 6,800 mile vacation from Tennessee to Yellowstone, then to Tucson and back home. During the trip we traveled on a LOT of two lane roads. The surprise was passing semi truck at 75 miles an hour and zero trailer sway. Also went through many “high winds” cross winds area without any issues. One of the concerns was how will the ride quality change. The perception was the load would be very stiff unloaded. To be fair, the suspension was old and tired. After installing the enhancement kit the unload ride was very similar to when the truck was new. Firm and smooth. Most people know the more weight you put on a heavy duty truck the better it rides. This is true when using the RAS product. The improved was the front wheels are now planted to the road. No more light steering. BTW, no more wheel hopping up my 13deg gravel driveway (1,800ft long, 250ft elevation change). The biggest question, is if I would buy again? Oh yeah, but I will not wait until the truck is seven years old. HUGE improvement over stock.

Ford F-250 2011-2026 | Mega Duty Kit

Great product. 2003 Ford F250 V10. This item helped with squat and feeling better planted, more control. Highly recommend.

Ford F-250 1973 - 2010 | Mega-Duty Kit

Ask if a person has a lift kit because your kit doesn't work with rough country 6 inch lift and I can't return after I beat the hell out of it trying to get it place

Ford F-250 2011-2026 | Mega Duty Kit

You didn’t state that the upper overloads would have to be removed. You gave the option for trucks with or without overloads. But the product is the same for both. Only difference is in the install instructions. Very angry. And you won’t email me back to allow me to return the unused product. Never recommending to anyone.

Ford F-350 2011 - 2026 | Mega Duty Kit