My 13 and 14 year-old daughters installed an OEM rear sway bar on my 18 F350 a few weeks ago. It took them about an hour and a half, and that includes taking it off and flipping it over to get the correct orientation around the rear bell housing. I ordered the parts from Tasca that were posted on another forum post; cost roughly $120. Afterwards, we went and drove on the highway, and I took the wrap-around under an overpass pretty fast. They could both tell the difference instantly. Its not as good as a friend's corvette, but still pretty impressive for a truck that you have to crawl up into. I recommend getting one.

 

I've owned only the current DRW but in my limited experience, the myth seems to be holding up (ie. remaining a myth). My rig has both the snowplow and camper packages, which +1 the front suspension but on the dually, I believe the rear sway bar isn't included. I'm thinking it would actually make it too stiff unless a guy were always maxing out his cargo capacity? My cargo capacity is 6,114 pounds and max towing capacity is 12,100 pounds. I've gotten to about 75% of both and had no problems with stability or sway - in fact, I remain extremely impressed with thisDRW performance under load. So my comment was only slightly tongue-in-cheek. That said, I'm always willing to learn. What data is your comment based on and why do you call this a myth? Not asking to be snarky - truly interested.

 

I must be the only one who didn't feel the sway bar did much... I added a Hellwig big wig to my F250 and the only thing I really noticed was more noise from some squeaky bushings. I pulled it off and tried to give it away local, as it is too big and heavy to ship, and didn't feel any difference on my hour long, 40 mile work commute. I think my recently added auto leveling air bags will make the biggest improvement for hauling things.

 

Now airbags - that's something I do plan to install on my DRW once we're ready to start hauling a couple ATV's behind the rig with the large slide-in camper on it as well. That's more load-leveling and making sure the springs aren't getting too stressed, though.

 

No worries. And I totally agree, the DRW is an awesome, stable hauling platform. I love my '17 450 and haul a truck camper regularly with confidence.
I bet if you look under your rig, it has a rear sway bar. Every truck with the camper package has one. (Also, I think all DRWs do regardless of camper package, but I I'm not sure on that part).

Picture this. A SRW truck, looking from behind on level ground. Rock the truck back and forth. You'll see the body roll left and right, while the axle remains stationary on the ground and does not move at all. Now, add another tire outboard on that stationary axle and continue rocking the truck. The truck still rolls back and forth the same, and the axle is still static and stationary on the ground. Now add 100 wheels on each side. Make the rear axle 50 yards wide. The truck body still rolls back and forth exactly the same, and the axle still remains static and stationary on the ground. The body roll has nothing to do with the number of tires on the axle.
Now, underinflate the tires, and you can see the axle move as you roll the truck side to side. Thus the truck with real "squishy" tires will tend to roll a little more (same body roll in relation to the axle, but now add the additional axle roll). Yes, a DRW is less prone to "squishy" tires, but if you keep SRW tires inflated for the rated load, they don't significantly squish. Or take the truck beyond the design maneuverability limits on the brink of rolling it. Then, that wider axle will provide more stability and take the truck further from the roll point. But, the body roll in relation to the axle position will still be exactly the same on a DRW as a SRW. As long as the axle remains on the ground with all tires on the road, body roll is independent of axle width.

 

FYSA from the ford specs on the factory sway bars (for 4x4 trucks)

SRW 250/350 (gas or diesel) gets 28mm front sway bars, and has the option to get 22mm sway bars in back (camper package)

DRW 350 gas gets 24mm front/22mm rear.

DRW 350 diesel gets 28mm front/25mm rear.

DRW 450 gets 35mm front/31mm rear.

 

nuctrooper, that's good information. Reps send for putting that together.

Larry, the rear sway bar doesn't come into play offroad nearly as much as the front sway bar does and I suspect even the front sway bar may not have as much effect off road on a solid front axle as it does an independent front suspension. I think the way I use my truck will be similar to yours. I really don't mind the ride and I have my tires aired up to what the door frame sticker says (65/80?). I don't think of it as harsh unless the road is really bad. Normal highway driving is great.

 

nuctrooper, that's good information. Reps send for putting that together.

Larry, the rear sway bar doesn't come into play offroad nearly as much as the front sway bar does and I suspect even the front sway bar may not have as much effect off road on a solid front axle as it does an independent front suspension. I think the way I use my truck will be similar to yours. I really don't mind the ride and I have my tires aired up to what the door frame sticker says (65/80?). I don't think of it as harsh unless the road is really bad. Normal highway driving is great.

 

It'll be a stiffer ride when you hit bumps on just one side of the truck. They suck off road as well. I disco the front bar if I'm off roadin' for real.

But they should help kill a little bit of the trucks heavy understeer.

 

I stand corrected. Thanks for the info! I was certain I didn't have a rear sway bar but will run out later today/tonight and check it. Perhaps that's the reason I've been so impressed with the truck's stability all this time, even with the huge camper in it.

*edit* I installed my own camper tie-downs months ago and don't recall seeing the sway bar but I probably missed it. Will definitely let you know cause I'm real curious now!

 

When I was re-engineering the suspension on my BMW M5 I read a book by Colin Campbell called "Design of Racing Sports Cars." According to him, handling is all about managing your tire's "slip angle" which is the difference between where the wheel is pointed and where the vehicle is actually going. Slip angle is zero when travelling straight and increases for front and rear tires with increased steering angle and vertical load. Note this is a non-linear increase and a driver can tell when they are approaching the tires limits as large changes in steering angle produce small changes in direction the vehicle is going. (bear with me, this really is on topic)

Most manufacturers set vehicles up with understeer (front pushes to the outside when cornering) as oversteer (rear pushes to the outside) can easily get a driver in trouble. You can reduce understeer by increasing rear roll stiffness. Basically you are transferring more weight to the outside rear tire which increases its slip angle. Viola! The vehicle feels like its on rails! Unless you added too much stiffness in which case you need new underwear

Three things to add.
First, you may increase roll stiffness through stiffer springs or a stiffer sway bar. Soft springs and a thick sway bar will give a better ride over expansion joints and speed bumps but will unsettle the chassis more when one tire hits a bump. Many race cars are set up with stiffer springs and a smaller sway bar so they can run on the rumble strips at the inside of the track and because you get less brake dive and squat on acceleration. OK, that was off topic...
Second, reducing front roll stiffness has the same effect on handling as stiffening the rear. Note in Nuctrooper's post DRW trucks have proportionally more rear roll stiffness - both in sway bar and stiffer rear springs. But then, there are twice as many tires to distribute the vertical load to so slip angle is greatly reduces.
Third, optimal roll stiffness and front/rear bias absolutely depends on the driver and how the vehicle will be used. Like the OP, I chose an F350 with 18 inch wheels and 3.31 gears. I opted to add the factory rear sway bar as we will be carrying a relatively light popup truck camper and will likely spend some time on dirt two tracks. Hopefully the factory bar provides a good compromise for on/off road while keeping this modest load under control. Had we been planning to get a larger truck camper I'd have likely gone with a Big Wig.

 

Yep - there's a factory sway bar on my dually! Learn something new every day.