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  1. Vehicle Suspension
  2. RAS
  3. Leaf Springs and Helper Springs
  4. Towing/Load Leveling
  5. Rear Axle Suspension Enhancement
  6. Standard Duty
RoadActive Suspension Custom Leaf Spring Enhancement Kit
etrailer Installation
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RAS

RoadActive Suspension Custom Leaf Spring Enhancement Kit

Part Number: RAS4612
In Stock
$539.00
Vehicle Suspension

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etrailer Installation
We'll connect you with nearby partnered installers who know this exact setup.
2,000-lb Capacity. Convert your vehicle's leaf springs into a mechanically active suspension system. RAS adjusts to your load to level your ride. The system also increases stability, handling, and control by improving traction and reducing sway. Great Prices for the best vehicle suspension from RAS. RoadActive Suspension Custom Leaf Spring Enhancement Kit part number RAS4612 can be ordered online at etrailer.com or call 1-800-940-8924 for expert service.
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  • Reviews (542)
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RAS Vehicle Suspension - RAS4612

Highlights

  • Custom Fit for Your Vehicle: Mounts to existing attachment points
  • 2,000-lb Load Support: Levels your ride and keeps handling steady when towing or hauling heavy loads.
  • No Ongoing Upkeep: Once installed, it needs no adjustments or monitoring for hassle-free use.
  • Better Control and Stability: Reduces sway, body roll, and bottoming out for a smoother, safer drive.
  • Instant Load Response: Coil tension springs automatically adjust to weight for balanced traction.
  • Simple Bolt-On Install: Mounts under your leaf springs with included hardware—no drilling or welding.
Made in USA

Features to know about

Stay Level and Confident Under Load: 2,000-lb Suspension Support

Heavy trailers and bed loads can make the rear end sag and the front rise, throwing off steering and braking. The RoadActive Suspension kit adds up to 2,000 lbs of load support by turning your factory leaf springs into a mechanically active system. The variable-rated coil tension springs automatically adjust to the weight you’re carrying, keeping the truck level and the tires planted so you maintain traction and control whether you’re towing or hauling.

Comparison image showing leveled ride height achieved by RoadActive Suspension under heavy load conditions.

Cut Out Sag, Sway, and Body Roll: Active Coil Spring Control

When cornering or hitting uneven terrain, sway and body roll can make driving tense. This setup strengthens your leaf springs to stabilize the truck before sway even starts. It absorbs load force energy instantly, reducing side-to-side motion in turns or gusty wind. The result is smooth, predictable handling when you’re towing a camper or loaded down with gear.

Prevent Axle Wrap and Wheel Hop: Mechanically Active Design

Under heavy torque, standard leaf springs can twist and cause wheel hop that kills traction. The RoadActive Suspension system stops that by reinforcing the spring pack with coil tension springs that absorb rotational force. It keeps your springs bowed and your tires gripping, preventing bottoming out and extending the life of your shocks, shackles, and tires.

Close-up view of RoadActive Suspension installed on a vehicle axle, showing how the system prevents axle wrap and wheel hop by stabilizing the leaf springs.

Set It Once for Your Hauling Needs: Customizable Tension Setup

Every truck carries weight a little differently, and this kit lets you set it up just right. During installation you can adjust each spring to between 25 percent and 40 percent tension using included spacers. You can even fine-tune each side independently to level off-center loads like toolboxes or lifts. Once set, there’s no maintenance or monitoring needed—just steady support every time you load up.

Close-up of RoadActive Suspension coil tension spring being adjusted with spacer during installation to customize suspension support.

Install It Easily—No Drilling or Cutting

This fully assembled kit bolts straight onto your existing leaf spring hardware using the factory U-bolts. There’s no cutting, drilling, or welding required. Heavy-duty epoxy e-coated steel construction resists corrosion, with brackets rated for over 800 hours of salt spray testing. It’s a solid upgrade that installs quickly and keeps working for the long haul without adjustment.

Fully installed RoadActive Suspension kit mounted on a vehicle’s rear leaf springs showing proper bracket placement.

Close-up of epoxy-coated steel construction and corrosion-resistant brackets on a RoadActive Suspension unit.

Specs

Weight and Capacity

  • Weight capacity: 2,000 lbs
  • Note: RoadActive Suspension will not increase your vehicle's weight-carrying capacity

Labeled technical diagram showing RoadActive Suspension components installed on a vehicle’s rear leaf spring system.

Warranty

  • Warranty: 5-Year warranty
  • Guarantee: 30-Day money-back guarantee

4612 RAS Custom Active Suspension System for OEM Leaf Springs - Rear Axle

Installation Details RAS4612 Installation instructions

This Product Fits The Following Vehicles




Ratings & Reviews

4.7

542 reviews
Review sort icon
2,000-lb Capacity. Convert your vehicle's leaf springs into a mechanically active suspension system. RAS adjusts to your load to level your ride. The system also increases stability, handling, and control by improving traction and reducing sway.

by:

Fantastic! Completely changed the way the truck tows. Kinda rides rougher unloaded, but not too bad.



by:

I installed the Road Active suspension standard duty kit on my 2017 Tundra. I was hoping for a smoother ride with and without a load and I was not disappointed. I don’t do heavy hauling, just a center console boat that weighs about 3000 pounds with trailer. My truck definitely has a smoother ride. It is especially noticeable on rough spots like bridge crossings, etc. I set the springs somewhere in between the light and heavy settings. I used a quarter as a spacer. It raised the rear of my truck one inch. I definitely recommend the Road Active suspension and etrailer is the best place to buy it.



by:

Overall, very happy with the product. GMC didn't have any way to improve the truck from squatting when I hooked up my trailer. This kit didn't stop the squatting but significantly reduced the bounce on bad dips in roads, bridge/road transitions and bad railroad crossings.



by:

Hands down the engineering behind the product was well executed and would recommend it to anyone who's travels involve pulling any type of trailer. You will feel a much smoother ride even when not pulling a trailer at all.



by:

Made all the difference in the world! Also, easy to install. Yes, the ride is stiffer, but when I'm dragging the 10K of weight in the trailer, it's worth it.



by:

I received this kit in a very timely manner always do from etrailer have some issues with the instructions that come from roadmaster not a trailer the bump stop spacer didn’t say that you need to use the original bolt from the bump stop so it slowed me down greatly on the install however I took it out on a quick run without a load I do feel that this has made the unloaded ride smoother tomorrow I’ll be taking the trailer out for a bit and we’ll see how it works there and I’ll update this rating.



by:

I found this items cheaper on another site but etrailer match and then beat the price.
Item installed super easy, more work jacking up the truck and taking the tires off. Can be installed with out removing tires just make it easier to get it in. The item did lift the back of my truck 1 inch. See Pics.



by:

I Have had this suspension on multiple trucks and i love it . It takes the sway out of the truck when entering a exit ramp and taking sharp turns with a trailer or without, also reduces wheel hop and increases payload in the bed of the truck.I would recommend for all trucks pulling trailers.



by:

Easy install 2011 Tacoma crewcab long bed. Helped with sag when towing microlite travel trailer. Keeps the rear end raised in the rear a little when unloaded, but I like that look. Only complaint and its nothing big when truck is unhooked and empty when i get out I can hear alittle noise from RAS. Sort of like a bedspring coil. Night pic is with RAS installed daylight pic is with out installed



by:

I love the product since i have a 2021 toyota tacoma crew cab long bed with a campertop a robber mat and a jack thats around 450 pounds that a have at all times my truck was sittind low a lilbit plus it was swagging on the road i have summo spring to help my suspention but it was not enoght so i did my research but this was my better option i just installed it yerterday july-8-2021 and went for a ride where i ussually drive everyday and WOW now my truck rides very smood plus it lift my tryck 1 inch on the back now my tryck seats level it took me about 2 hrs but i did right i just follow the intructions and done i love the product the only thing that im concern is that the left side underneat the springleaft there is a breik line that is too close to the roadmaster suspention i hope that with the time dont hit that line because if it does thats the line for the breiks and i will be in trouble replacing it other wise evreything works great i recomend it 100% thanks guys i will buy it again?????best $500 that i spend on my truck



by:

I have a 2020 Silverado 1500 6 cyl Duramax with the Diesel Off Road package (3.73 diff). Travel trailer loaded is probably about 6,000 lb. I took several measurements during and after the spring kit installation. All measurements increased about an inch including the stock suspension with trailer and equalizer bars and with the spring kit installed at 1 mm spacing. A one inch improvement overall. I took the truck on a short drive and didn't notice any difference in ride (wasn't stiffer) which is what I wanted. Good to know that I can adjust the springs to the 2 mm spacing if I want to increase the suspension assist. Going camping next week and looking forward to see how it improves handling and porpoising.



by:

The bed of the truck measured 37.5" with a tool box weighing 200 lbs. The truck felt weighed down with passengers weighing 600lbs. Total weight 800lbs with a tank full of gas. After the install the truck rides smoother and certainly " like new". The stopping distance and acceleration distance have shortened drastically. I'm planning on loading up the bed and the Roadmaster Active Suspension RAS4611. My wife even drive it and she could feel the difference. "It drives like a muscle car." Buy it. Install time at a reputable mechanic shop was a 30 min. Install. I received them today at 1 pm and got it installed at 3:00 pm and finished the install at 3:30pm. It's an investment worth the price over traditional air bag system. Mechanic installed this on 2011 Nissan Titan SV.



by:

Balances ability to tow my 1800 squaredrop Hiker camper with 350 tongue weight as well as roof top tent on Leer 180 camper topper. Better handles load and side to side tipping on '21 Ranger. Keeps sage to a minimum.



by:

I have put these on every pickup that I have owned and not only does it assist with heavy loads, my tires have gone past 80,000 miles before needing replacement. All Chevy Duramax 2500's and 3500's!!



by:

Did not fit my 1995 F-150. ETrailer was very helpful in an effort to make any adjustments needed. We all decided that they were a "no go" for installation. Return was made easy. I have bought several other pieces of gear since. Thank Etrailer.



by:

i installed these on my 2001 ford f-250 4x4 and this is a huge upgrade whether your towing or empty.truck rides and handles better than it ever has. easy straight forward installation. you will need a t-55 for the front bolt and a 12mm ratchet wrench for the adjustable bolt that tightens the spring and a couple of 22mm and a 19mm wrench or crescent wrenches for the jam nuts. i took the weight off of the leaf springs for easy adjustment of the coil spring and used the thinner of the two disc that came with the kit and it raised the rear of the truck up exactly 1 inch empty without a trailer connected. if you use the thicker disc it will raise it more.



by:

I haven't hooked up my camper yet but set the springs up with the white wafer and it raised my truck 1 1/2 inches which is the amount it dropped after I put on a fiberglass topper. The ride is just a bit stiffer but a lot less body roll I noticed. Not impressed with the 25 Silverado suspension compared to my previous 2017 truck. If the squat is still there after I hook up the camper, there is plenty of adjustment left.



by:

Great product, helps with sway and when the truck has additional weight it progressively compensates. I would add this to any vehicle with leaf springs.



by:

Helps immensely, 12x6 inclosed trailer from NY to Florida and back up to NJ no problems



by:

Easy install when I rotated tires. Forgot to measure height difference, but it did raise a bit. I like the adjustability and not having to remove springs and shackles to add a leaf. Will be towing the camper with improved support.



by:

I don’t think they are really made for the old PU. 1997 k1500 8 ft bed with a 750 lbs camper tong weight I think I had to put to much pressure on the Kurt stabilizer chains to get level. It looked like the newer truck reviews on YouTube were great thanks Dingler.



by:

2023 F150. Install was fairly easy. Set at 25%. Ride unloaded a bit stiffer, but handling much better. Lifted rear of truck about an inch. Towing 7500 lb camper down NYS thruway which is crowded with much unforgiving bumps and pot holes the ride was more manageable. The 25+ mph cross winds did make for quite a bit of sway still, not as bad as before adding the RAS. Still felt passing trucks trying to suck me in, not as bad as before.
I plan on cranking the RAS to 40% on next camping trip and hopefully give the RAS 5 stars.



by:

I’ve bought a lot of products from etrailer and as always everyone I dealt with is professional and knowledgeable of the numerous products they sale. I used every resource they offer to help me decide what type of suspension upgrade I was going to use to improve the haul and tow ability of my 2017 diesel chevy Colorado 4x4 crew cab short bed. I chose the RAS system from Roadmaster. I also called them and ask some very detailed questions about using my OEM shackle instead of replacing with the plates in the kit and was told that was fine and that others had also. I got professional and knowledgeable info that helped make my decision. The product is exactly as promoted and every review out there on the internet about how good or unchanged the unloaded ride is after installing are true. My truck rides better now and it was already quieter and almost as smooth as my wife’s Cadillac. If your looking to improve the drive, tow and haul ability of your leaf spring vehicle, and I say vehicle instead of truck because I don’t know if they have them for other leaf spring vehicles, you are not going to find a better easier to install product that does that for your loaded or unloaded vehicle, IMHO. I will update in a year after next spring mulch haul. I don’t expect zero squat but hope to reduce and improve loaded steering performance. Took longer to jack up truck and remove tires than install kit.



by:

I purchased the RAS system 6 months ago to help with rear end sag & control while towing our 22 ft 4200lb camping trailer. It improved sag & helped handling even when not towing! I don't get the bounce when driving on bumpy uneven roads the wheels stay planted on the road. I recently purchased a 8000lb camping trailer & my 24 1500 Silverado handles it very well, I will adjust the RAS to the next step up for the extra weight when time permits.
The install took just over an hour with help from a friend & a car lift which is good since I'm 70 years old.
Great product!



by:

Just perfect to level the rear of my GMC 1500 Denali with the 29' Airstream (900 lb tongue wt). Preload is set at 1mm. I tried 2mm and it was overkill for this application. I was pleased with how easy the install was. I had to use a two jack hack to get the rear tires off since my 19" lift floor jack didn't quite have enough reach. You lower the differential after the tires are off so the rear axle is hanging free for the install. See photos


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See what our Experts say about this RAS Vehicle Suspension

  • Could RoadActive Suspension Kit be Used on 2000 Ford F-150 with Add a Leaf to Rear Springs
    The RoadActive Suspension # RAS4612 hasn't been tested on your 2000 Ford F-150 with added leafs to the rear suspension. There's a chance it might work, but there's also a large chance you'd have to remove the added leafs to be able to install this. This would give more support than the added leafs anyway so either way this will be a good solution for you. Otherwise you can keep the suspension the way it is and use a Timbren kit part # TFR1525HD which is a confirmed fit and will give you...
    view full answer...
  • Can a Weight Distribution System be used with a 2016 Grey Wolf Ice House to Reduce Vehicle Sag
    Thanks for your picture, it really helped me answer your question. I would recommend you get a suspension enhancement system for your truck to help with the sag, because the 2016 Grey Wolf will not be able to use a weight distribution system due to its tongue design. There are two types of suspension enhancements I would recommend for your 99 F-150. The first is the Timbren # TFR1525HD. This kit will fit either a 2wd or 4wd F-150 and provide the leveling and stabilization you are looking...
    view full answer...
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  • Compatibility of RoadActive Suspension with Timbren Springs on 2000 Ford F-150 2WD
    The RoadActive Suspension Kit # RAS4612 is the only confirmed fit for your 2000 Ford F-150 2WD. When you mentioned it won't fit with the Timbren rubber spring, it threw a couple flags for me, so I just want to clarify. The systems are not designed to be used in tandem, you would only want to use one or the other in this case. The mounting plates on # RAS2612 and # RAS2691 are not a fit for your vehicle. That bracket type will not work on your vehicle. If you want to have further spring...
    view full answer...
  • Does RoadActive Suspension Kit Add Height to Rear of 2000 Ford F-150
    If your 2000 Ford F-150 is a 2WD you'd want the RAS system part # RAS4612 or if you have the 4WD system the correct fit is the # RAS4622. If you use the less agressive spring setting no height will be added to the height of your truck, but if you crank up the spring tension you might see an inch out back. You would not need replacement shocks.
    view full answer...

Do you have a question about this Vehicle Suspension?


Info for this part was:

Employee Jameson C
Expert Research:
Jameson C
Employee Mary K
Written by:
Mary K
Employee Wilson B
Updated by:
Wilson B
Employee Noah M
Updated by:
Noah M

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