Because even on a straight, level road, the Excursion is not in a static, unchanging position. Road bumps, wind, steering input, lane changes etc will bring the suspension into play, allowing the wander effect to affect how the Ex behaves.

Stewart

 

Wander has nothing to do with leaning and the bar only affects leaning so I'm not buying it.........sorry.
That much leaning (if any) barely takes up the slack in the bar bushings. I think somebody made some other changes at the same time and gave the credit to the sway bar.

 

It does, but you're just not thinking it through. Lemme see if I can help....

Short of putting something like Competition Engineering Slide-a-Links on a suspension (which are not available for Excursions), which allows a user to put a pre-load on the rear suspension, everything on the suspension is reactive, not proactive in what it's supposed to do. So I can see why you're not "buying it" when it comes to the rear anti-sway bar helping when going down the road, on a level surface, straight-line.

Excursion Steering Wander is kind of a two-fold problem. When travelling down that straight, level road you and I keep referring to, the Wander isn't just when the Ex steering feels loose and allows the rig to kind of "wander" within the lane. While that is a small part of the problem (mainly maintenance issues and parts operating within factory specs such as ball joints, ties rods, steering boxes, hubs, etc), the main problem is the result of the steering input the driver does when he tries to maintain a straight line in that lane.

When the driver adjusts the steering wheel to correct the rig and keep it within his/her lane of traffic, that affects the suspension and will cause the body to lean. It's that affect on the suspension that will cause an effect in the Steering Wander.

Because the problem lies in the weak OEM Excursion springs, when they deflect, they are imparting Steering Wander. To what degree depends on a lot of factors. When steering is corrected, for whatever reason, this will affect which way the Ex leans, and THAT'S when the rear anti-sway bars come into play because it will dampen/reduce the amount of body lean which reduces tha amount of spring deflection which causes the shimmy/shake in the Steering Wander.

Going down the road in a straight line on a level road, any perceived wander issue will be less than if you changed lanes, went around a curve, or were towing a trailer. But it is still there (at least it was for me), just at a much lesser degree. Get passed by a semi on a straight, level road while pulling a trailer though and you will feel that shimmy/shake come out of nowhere and you will know why the knuckles on both hands are white.

Hopefully that helps you see what I'm trying to explain, Brent.

Stewart

 

Seems far fetched to me but.................whatever.

 

You lean even on a flat road, because there is a human driving not a computer. Human's are not perfect and they pull the wheel too far, not far enough even when on flat ground just compensating or anticipating traffic in other lanes. Driven a lot at hwy speed on flat ground, with and w/o rear bars and having one makes it more stable even on flat out straight ground.....because a human is driving and we are not perfect.

Edit: Ok so I know better than to read bottom up and not get the all the "way up" before responding, I see this was covered later in the thread.....but stand by my original comment. Rear bars help even on flat level ground, if being driven by a human.

 

Also there is no truely "flat and level " road.
The roads all have crowns to help move water off
the side(s).
There are multiple sections on our highway
where the road crown changes and it reminds
me of the boat-like steering of my former tahoe.

 

This is the kind of thing that can be argued for days but if my truck develops a wander I will be looking at front end parts.

 

Nobody is arguing Brent. We're all just trying to explain a fact to you in a way that you understand. Just because you don't buy it or want to believe it doesn't make it any less true.

Stewart

 

Actually, I think both Stewart AND Brent are correct.

Brent is right in that while flat, true, and level, the sway bar is not affecting anything.

Stewart is right that a moving vehicle is hardly ever flat, true, and level. Our X's are probably less so than most other vehicles on the road.

I suppose it could be said that the rear sway bar kind of acts for the X like a friction anti-sway bar for a trailer in that it helps prevent the sway from being too noticeable.

Isn't it great when were ALL right?

 

OK.....debating.
...................or more true

 

I took the advice to add a helwig to the rear and it does make a significant difference, I drove my X back from texas and didn't really notice the wander much, my wife however refused to drive it because she was constantly steering it and was afraid she would be driving out of her lane. I added the helwig bar and she is now comfortable driving it and did a few 3 hour stretches on our drive to florida. I have no regrets and think it is $200 well spent.

 

Are you towing? Any other changes like tire pressure? How could it make a significant difference if you never noticed a difference? Is she imagining things?

 

I didn't say I didn't notice a difference. I think due to driving ****ty tractors and fork trucks I'm just more accustomed to driving vehicles that need constant steering input, so it wasn't something I thought about on the initial drive. My wife however drives a fusion and that needs almost no steering input.

 

OK, not very convincing though.

 

She's not imagining it, she just notices it more probably because she isn't as strong as her husband, and isn't used to driving a vehicle that requires that much strength/input from the driver. An Ex really is harder to steer than most vehicles. The bar makes it easier for a smaller, less "capable" driver. (no offense to your wife jspence105 really am trying to defend her here because I get the concept of smaller arms/muscles and how different it feels behind the wheel)