I converted a ‘05 F250, extended cab 4X4 5.4 Gasser to a 6.0 Diesel, with Diesel front coils and F350 rear leaf springs. Factory stock parts and completely rebuilt. I am running 285/75/18 K03s. It has good Bilstean shocks. At highway speeds, it is floating and swaying badly. Is a 5.4 4X4 stablizer bar different than one for a 6.0 diesel? I plan to add a rear stablizer bar. Is the front bar different, when a front/rear combination is used?

 

I don't know the answer to your specific question, but I do know that your floating/swaying should be negated by proper suspension geometry. Make sure your parts don't have excessive wear (steering linkage and radius arms). Have you got an alignment since after the installation? What is your caster angle?

While I agree that swaybars are great additions for stability onroad, they aren't really doing anything until you make a turn or quick maneuver. Going down the road straight, the swaybars aren't doing anything.

 

I would imagine the 6.0 would use a larger/ stronger bar due to the added weight of a diesel over a gasser.

I imagine when putting the bars on that there was tension to line it up with the links. also, do the bars sit nearly parallel to the ground?

when you say swaying badly, are you driving empty or loaded. even without anti-sway bars it should be solid unless you are trying to slalom down the highway. with Bilstein shocks the ride should be firm but controlled
you should easily be able to drive the truck safely with no anti-sway bars

 

I replaced everything in the front end steering, suspension and drive axles. It had a front end alignment, on a fresh set of tires, just last week. The sensation at high speeds is a pivoting / swinging movement. The rear is wagging the front, left and right. Is there a known difference between a 5.4 and a 6.0 front stablizer bar? If your truck is factory equipped with front and rear stablizer bars, is the front bar different than a front only stablizer bar?

 

From the compendium of all the great minds on the internet:

You’ve stiffened the suspension (Diesel coils + F-350 leafs) and added quality shocks, but still getting float and sway at highway speeds. That tells us the issue is most likely sway control, not spring rate or damping.The 6.0L diesel sway bar is beefier. The diesel engine adds a few hundred pounds over the front axle, so Ford equipped those trucks with thicker front sway bars to control body roll and sway.Your 5.4L sway bar is likely not strong enough for the current front-end weight, especially if you're running larger tires (285s), which can exaggerate sway and float.Swap in a 6.0L diesel or F-350 front sway bar—it’s plug-and-play since you already have most of the suspension converted.

Should I still add a rear sway bar?Absolutely, especially since you’re running F-350 rear leafs, which are great for load but not known for lateral stability. A rear sway bar will balance the suspension and reduce body roll and tail sway, especially with the high sidewalls of 285/75s. Hellwig and Addco make great aftermarket sway bars if you’re not finding a stock F-350 bar easily.

Double-check tie rods and track bar—loose or soft bushings there will also cause wandering and float at speed. If your steering box has some miles on it, it might also be contributing. You’re on the right track. Swap in the 6.0L sway bar up front, add a solid rear sway bar, and you’ll transform how that truck feels at 70+ mph.

 

Thank you to the group.