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  1. Vehicle Suspension
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  4. Rear Axle Suspension Enhancement
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RoadActive Suspension Custom Leaf Spring Enhancement Kit
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RAS

RoadActive Suspension Custom Leaf Spring Enhancement Kit

Part Number: RAS27ZR
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$494.00
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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 RAS27ZR can be ordered online at etrailer.com or call 1-800-940-8924 for expert service.
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RAS Vehicle Suspension - RAS27ZR

  • Leaf Springs
  • Rear Axle Suspension Enhancement
  • RAS
  • Standard Duty

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.


Features:

  • Custom kit converts your vehicle's factory leaf springs into a mechanically active suspension system
    • Actively strengthens leaf springs for improved ride quality with or without a load
  • All-in-one suspension system improves stability, handling, and control
    • Eliminates axle wrap, wheel hop, and bottoming out
    • Reduces dangerous sway and body roll while cornering
    • Keeps your ride level when towing or hauling a heavy load
    • Improves traction while breaking and accelerating
  • Variable-rated coil tension springs automatically adjust to your vehicle's load
    • Activate immediately to support the extra weight
    • Disengage when unloaded, allowing your leaf springs to perform as intended
  • Customizable coil springs can be adjusted during installation to accommodate your towing or hauling needs
    • Independently adjustable for side-to-side leveling of off-center loads
  • Helps extend the life of leaf springs, shock absorbers, shackles, and even tires
  • Durable, epoxy e-coated steel construction
    • Corrosion-resistant brackets on the ends of each unit have a salt spray rating of more than 800 hours
  • Easy, bolt-on installation - no drilling, cutting, or welding required
    • Unit secures under the leaf spring and around the factory U-bolts
    • Fully assembled kit and hardware are included
  • Maintenance-free - adjustments and monitoring aren't needed once installed
  • Made in the USA


Specs:

  • Weight capacity: 2,000 lbs
    • RoadActive Suspension will not increase your vehicle's weight-carrying capacity
  • 5-Year warranty
  • 30-Day money-back guarantee


All-In-One Suspension System

When towing or hauling a heavy load, you may encounter a number of problems that can make your driving experience difficult or dangerous, such as sway, body roll, or bottoming out. When your vehicle is weighted down, your factory leaf springs can't counteract these problems to the extent that they are supposed to. The weight will overpower the leaf springs and cause them to twist or flatten out. When that happens, they cannot support, level, or stabilize your vehicle effectively. Additionally, because your factory leaf springs are passive, they won't begin to tackle problems such as sway until those problems have already started.


Diagram of RAS Installed

RoadActive Suspension (RAS) kits enhance those passive leaf springs by converting them into a mechanically active, all-in-one suspension system. RAS kits have variable-rated coil tension springs that automatically adjust to your heavy load. Other suspension systems only solve a few problems and usually at the expense of other improvements your factory leaf springs may need. RAS, on the other hand, is a unique kit that provides everything you want in a suspension system without any trade-offs. It eliminates bottoming out like air springs, reduces sway and body roll like sway bars, keeps your ride level like helper springs, and improves traction and braking control like traction bars. This improves your vehicle's stability, handling, and control while you are towing or hauling, as well as when your vehicle is unloaded. RAS also makes your overall driving and towing experience safer and more comfortable, which greatly lessens driver fatigue.


How RAS Works

Close-Up of RAS Tension Spring

Each RAS unit has a powerful variable-rated coil tension spring that converts your passive leaf spring into a mechanically-active system. Once your vehicle is loaded, the tension springs immediately activate to absorb and support the weight. This allows your leaf springs to maintain their bowed position and keeps them from flattening out or flipping over, which greatly hinders their ability to bear a heavy load. The tension springs are variable-rated, which means that the heavier your load is, the more assistance they provide to your leaf springs. Because of this design, RAS reacts instantaneously, whereas hydraulics, air springs, and other suspension systems take time to react. And unlike your factory leaf springs, RAS stops sway and sag before they even start to happen. Additionally, when your vehicle is unloaded, the tension springs disengage, allowing your leaf springs to perform as intended without hardening your ride. RAS won't hinder your leaf springs' movement, nor will it cause any friction between any of the brackets.


Eliminates Axle Wrap and Wheel Hop

RAS Eliminates Axle Wrap

When under a heavy load, leaf springs are especially susceptible to axle wrap, which can cause wheel hop. Wheel hop is when the tires lose their grip on the road, causing a jarring, up-and-down movement. Axle wrap occurs when the circular motion of the tires cause the leaf springs to twist or rotate. If the leaf springs twist far enough, wheel hop can occur. RAS stabilizes your leaf springs by absorbing the force of the load they're trying to support. This eliminates axle wrap and wheel hop, as well as prevents your vehicle from bottoming out. Because of this, less strain is put on your vehicle. And by reducing some of this wear and tear, RAS helps extend the life of your leaf springs, shock absorbers, shackles, and even tires.


Reduces Sway and Body Roll

RAS eliminates sway and body roll

When driving along a curve while towing or hauling a heavy load, the back end of your vehicle or trailer can start to shift with that weight. If your factory leaf springs have flattened or twisted under this load, they won't be able to prevent it from shifting. Because of this, your trailer will sway away from your vehicle. This makes driving challenging and dangerous, as it increases the risk of body roll, which is when your vehicle drastically leans to one side. This can often cause you to completely lose control of your vehicle. Body roll is especially prevalent with multi-passenger vans and vehicles towing long campers, trailers, or boats. RAS provides a much safer ride by reinforcing your factory leaf springs and stabilizing your load. This helps prevent sway from occurring and reduces the chance of body roll while cornering, turning, and swerving. RAS also lessens the rocking motion that happens during windy conditions or when a semi passes by on the road.


Levels Your Ride and Improves Traction

RAS Levels Your Ride

When your vehicle is overloaded, the bulk of the weight transfers to the rear axle. Your factory leaf springs then become overwhelmed by this weight, as they are not strong enough to support it. This causes the back end of your vehicle to sag and the front end to rise, which means that the front tires have lost some of the grip they need with the road. In addition to loss of traction, it can also cause poor headlight aim, unintentional swerving, and an extremely bumpy and uncomfortable ride. RAS bolsters your factory leaf springs and enables them to provide support for your load without compromising ride quality or comfort. This keeps your ride level from front to back whether you are hauling a load in the bed or towing a boat, trailer, or camper. RAS also ensures that your tires have the traction they require while braking and accelerating, which improves the overall driving experience.


Customizable Coil Tension Springs

Adjusting Spring With Spacer

RAS is also customizable. During installation, the coil tension springs can be adjusted to 2 different tension settings or anywhere in between for improved road handling and support. To do this, rotate the springs while keeping the threaded rod still. As you turn the spring, use one of the 2 included spacers as a gauge to measure the widening gaps between the coils. In order for the RAS units to work as intended, you must tension the coils to a minimum of 25 percent with the 1mm white spacer and no more than 40 percent with the 2mm spacer. The springs can also be independently adjusted to compensate for off-center loads such as a handicap lift.


Easy, Bolt-On Installation

RAS Once Installed

This custom-fit kit comes fully assembled and is easy to install. Each RAS unit simply bolts onto your factory leaf spring with the included hardware, and drilling, welding, and cutting aren't required. First, position the eye hook bracket so that it wraps around the top of the factory leaf spring eye. Then the axle bracket secures under the leaf spring and around the factory U-bolts on the other side of the leaf spring pack. Once the maintenance-free RAS units are fully installed, you won't need to monitor them as you would with air springs.


Corrosion-Resistant Steel Construction

RAS Construction Close-Up

RAS is extremely durable and corrosion-resistant. The units are constructed of high-grade alloy steel, and they have an epoxy e-coat on the coil springs to provide extreme corrosion resistance. The brackets on the ends of each unit resist the effects of water and other elements, and they have a salt spray rating of more than 800 hours.



3621-T RAS Custom Active Suspension System for OEM Leaf Springs - Rear Axle



This Product Fits The Following Vehicles





Customer Reviews

RoadActive Suspension Custom Leaf Spring Enhancement Kit - RAS27ZR

Average Customer Rating:  4.7 out of 5 stars   (777 Customer Reviews)

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:

Installed this system on a 1999 F-250 SD. I pull a 35 foot 5th wheel trailer that has a pin weight of 2,180 lbs. (I know the exact weights as I have weighed each axle, unloaded and loaded.) Before the RAS install, the trailer would cause the rear of the truck to sag, pitching the nose up just a bit.
I installed the RAS system, and knowing my truck is loaded to the max, I decided to use the 2mm spacer. After the install, the height at the rear bumper was 2 1/4 inches higher. Before the RAS install, the trailer would cause the rear of the truck to drop a full 4 inches. With the 2mm spacer adjusted RAS, the trailer caused the truck to drop about 2 inches in the rear, but the rake of the truck now remains with the nose lower than the rear.
After the initial install, I drove the truck unloaded. The ride was about the same as before, maybe just a bit smoother, hard to say for sure.
This past weekend, we took the truck and trailer to Branson, MO and back, about a 825 mile round trip. What a difference! We hadn't driven 2 miles from home when the wife said, wow, this is a different truck. The ride was fantastic. It eliminated surging we would sometimes encounter on some roads. Bumps and undulations in the road were so much better.
I was really skeptical about this, especially considering the price. But you couldn't pay me to take it off now. I consider the RAS essential equipment now, right up there with EGT and boost gauges, 4" exhaust, diesel brake and added TPMS to all tires. I've been pulling that same 5th wheel for 22 years with that 25 year old truck, and this last weekend was the best pull I've ever experienced. Just wish I had had the RAS on the Alaska highway a few years ago. I am amazed at the improved ride. Couldn't recommend it any higher.



by:

I am a competitive shooter and take my camper to all my shoots. I have a cap on my truck and the decked drawer system. I also carry 400 lbs of ammo at any given time. When pulling my camper on the highway or over bumps and railroad tracks it was kinda scary. This system stopped the squat and removed the sag at acceleration. I installed sumo springs as well (without spacer) for added sway control when loaded down with trailer. The RAS was great right from the start. It reminded me of the 80’s then we would put traction bars on old hot rods to stop rear squat on acceleration. Same kind of feel with my truck. Some much nicer. With the trailer it removed 1.5 inches of squat on the rear and got my front and back within 1” of variance and before install it was around 2.5 to 3. Took only fifteen minutes per side to install once the tires were off. Great product….



by:

Received these ahead of schedule and all intact. I watched the video on etrailer.com and youtube, very helpful.
The installation is not difficult if you are handy with tools. Aside from it deciding to rain on me during install it was not bad. Suggest you lay out all your tools and include a couple of adjustable wrenches. First off, unscrew that gold screw alot, when you think there is enough, go more, the first side I was short. I wiped down the truck springs to remove any dirt there and set up then tightened by hand, you can't go far that way but gets you started. On the rod with the 2 nuts that will lock together when done, I gave myself about 3" of thread and locked them together to hold the threaded rod while adjusting, no way to hold the end nut, this worked out well. The one thing I would have done different is the adjusting nut is 14mm, I only have a 6" ratcheting 14mm, doable but at the end it tough, I wish I had a 10" or so, there was space in my install. I set mine to high since I pull a 5th wheel so adjusting was the hard part.
I will not know until spring if this helps with the towing as the camper is now stored but very hopeful from others input. If anything changes I will update.



by:

I bought these after a 1000+ mile trip towing my trailer (~8000# loaded) with my 2013 F-150 (HD Payload & Max Towing Package). Installation was super easy. I did not need to take the tires off. There was plenty of room to get behind the tires and place and adjust the springs. Once installed they definitely give the truck a rake. I didn't measure pre-installation because I didn't expect the lift to be so great. I used the black disc to adjust the springs.
It's not too extreme but you can definitely see a difference compared to stock.
As you can see in the pictures, with the springs the drop with a trailer attached is greatly reduced and the truck sits level. Towing was great. I used a WDH before and being able to with springs only and a sway bar is pretty nice. Drop with trailer attached is only about 2.5 inches (see pics)



by:

Straight-forward installation on a 2007 Pleasure way Excel RV (I did it myself in a few hours) although I did have to modify the air bag mounting bracket with a slot to allow RAS hardware to fit. Great installation instructions. Vehicle height is now correct and could be made level by tension adjustment during install. Handing is improved, I was able to remove aftermarket sway bar which improved ride. I have been considering installation of stiffer rear shocks to soften rebound now that the rear spring rate is increased.



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:

Admitedly, I haven't even rolled my '07 Silverado 2500HD classic out of the garage yet, but I'm already very pleased. I had to go to a neighbor for a 10mm hex key socket and was slowed down by my 7yo kid 'helping', but it was still only 90 minutes my jack stands were in use. Easiest thing to do!
My only small downsides so far:
* needed to find a 10mm hex key that I apparently don't own, not sure why they picked that fastener
* wish I put some loc-tite on; just to make me feel better
* distance to drop the axle so the suspension fully hangs was way further than I expected; barely had my jack stands tall enough to get the job done.

These aren't really bad on the product, just notes for future customers. We're towing the 5er about an hour an a half this coming week, hopefully it steadies up a lot!



by:

I had the airbags in the back for years. These far out way them. This is the best thing I ever did!!



by:

Sure beats air bags or blocks! My Gmc canyon diesel is a great puller, needed help with suspension hauling load limit. Easy to install and works great. On high setting it raised the truck rear an inch or two even empty but the way gmc set up the suspension I consider it a good thing.With my tandem axle 16' trailer loaded it's a saving grace.



by:

I own a 2020 F150 raptor, it lacks spring rate in the rear to hold up a lot of weight, other than that it’s a beast Pulling trailers.
Investigated air ride and I discovered It didn’t have the articulation that I needed.
The springs are the fastest way to have additional lift.
I can install them and uninstall them in minutes .
Great product.



by:

This product was very easy and quick to install. It changed the ride on my wife's lifted F150 so much and was noticable immediately. It firmed up the ride and made it way more comfortable towing, loaded, or just plain driving.



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:

I bought this last summer (2022) for my 2020 F150 to haul the travel trailer (summer) and to have the quad in the box (fall) during the hunting season. I mainly used it during the weekends as I work from home during the weekdays. I adjusted the tension just before the winter because I haven't haul anything during winter. As it is now spring, I wanted to adjust back the tension for the rv season and I found everything rusted out (I am.in Canada and use the truck only 2-3 times a week).

I was pleased to use the product back last summer but because of all the rust I found this spring, I'm having a hard time adjusting them and I am also quite scared for next seasons as rust is making adjustments hard.

By having this for less than a year, I am now dissapointed in the product. Before buying this, I looked a lot into airlift a lot but because of reviews, I changed my mind to go with RAS.

Rust is now found on the main threaded rod locking nuts the bolt/tube underneat locking the device was rusted and seized.



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:

This product has worked well for me. I have used this on previous trucks towing a camper. It helps level out the load on the truck. This product does not work on trucks with top overload springs. Unless you remove the top overload springs. If your vehicle is still under warranty taking off the top overload spring may be a problem. But this product has worked well for me on a half ton truck.



by:

Definitely stiffens up the leaf spring suspension not impacting the ride. Just feels like a lot more support.



by:

Works great at leveling my truck with my travel trailer.



by:

absolutely did not take 45 minutes to install and still missing a locknut that was not contained in a sealed bag with cardboard box container causing lost parts. Now i have to locate special threaded nut.



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:

Definitely work as advertised. Only thing I would note is at the 2mm adjustment there is a slightly firmer ride. But barely noticeable.



by:

Rarely adding an aftermarket "upgrade" to any of my vehicles am I 100% satisfied with the outcome. There is usually a trade off with something. However, this is one of those upgrades that has zero con's that I've discovered so far. I was struggling to keep the leaf springs on my modded out 3rd get Tacoma from "flattening" out because I always have at least 900 lbs of payload in my bed. Adding the RAS has prevented this from happening. I also thought that they would affect off road performance, since I've never seen them in an off road application before, they don't. People on the trail often ask "What the heck?" when they see them on my rig. I tell them that RAS is the easiest to install, most cost effective solution to manage sag without sacrificing ride quality. There is the famously noted "Taco lean" and it's most prominent after fueling up. RAS will help iron this out. I've had them on for about a year now and they haven't needed any adjustments. Kinda like (Ronco), "set and forget it". I don't know their duty cycle is but, I wouldn't hesitate buying them again!



by:

Very easy installation after watching the trailer videos. It worked better than I had anticipated and really improved the handling when towing our camper.



by:

Installed this today on my 2023 Ford F150 Lariat 4x4 with the tow package. The kit arrived within 2 days of ordering. The box was slightly open but the springs appeared undamaged. I elected to do the install myself and opted to get a 4 ton floor jack to replace my very old 3 ton. I’m very glad I did. After blocking the front tires and setting the parking brake, I loosened the wheels and raised the rear at the differential using a small 2x4 block to span the contact points. I took the wheels off and originally set my jack stands in front of the leaf spring on the frame. Lowering the truck onto the stands was not effective. There wasn’t enough travel to provide relief to the springs. I ended up setting my jack stands on some 1x16 scrap pieces and put them under the spring attachment point. This gave me just enough room on my floor jack to unburden the springs. Once I got over this small hurdle the install went smoothly. This took about an hour to very carefully construct as I didn’t want to drop my brand new truck on the ground. Brand new 5 ton jack stands would have eased my mind considerably. My install includes a spacer for the bump stop to offset it towards the centerline of the vehicle. The instructions weren’t intuitive and it took a few minutes to figure out the bolts. You need to insert the provided bolt into the spacer and attach the spacer to the frame with the original bump stop bolt. It’s the only one you can get a socket on in the depression. The bump stop then attaches to the provided bolt you inserted into the spacer using the provided nut. You will need a deep well 15mm socket for this attachment. Fortunately I had one. I set the spring using the 25% white spacer, reinstalled the wheels and set the truck back on the deck. The truck now sits 3/4” higher in the rear. I drove around and noticed that I was sitting a little higher as the site picture changed a bit. The truck didn’t seem to ride differently empty. If anything it seemed a little more cushioned though no less responsive. I towed my 9000lb travel trailer previously with a Ram 2500 6.7l diesel that had Sumo springs and a WD hitch. I got tired of the cost and maintenance and selected this Ford because it could haul the trailer. I chose the RAS over the Sumo springs because of how much squat I observed when I hooked up the trailer initially. I will update after I tow the trailer. My only concern at the moment is that the bump stop spacer isn’t going to provide enough clearance from the bracket.



by:

This was easy to install, and has worked great for my application. (Towing a boat with 600 lb tongue weight.)



by:

Removed my air bags on my 2018 F150 as they would always bottom out unless I had 20 lbs in them. Placed the RAS system and adjusted to the 2mm spacer. I immediately loaded a trailer with a palate of concrete and the truck only squatted a half inch. Truck rode phenomenal both loaded and unloaded. I wish I would have purchased this system years ago!


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Info for this part was:

Employee Daron K
Edited by:
Daron K
Employee Alex H
Written by:
Alex H

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