Rear Sway Bar on 2022 4-Door SAS not on 2021 SAS

[jorgem31]

Read that the 2022 4-door SAS had a rear sway bar added as standard equipment. Was looking for more info on here about it but could not find anything. Anyone know why?

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[flip]

At one time I thought they said this was part of the rough road upgrade. Here are the parts, have no idea if it will fit pre 12/13/21 built vehicles.

View attachment rear sway bar.pdf

 

[ATLBronco75]

I don't know why anyone would want one.

 

[jorgem31]

I don't know why anyone would want one.

I more wondering why it was added. Obviously Ford addressed something of concern.

 

[jorgem31]

At one time I thought they said this was part of the rough road upgrade. Here are the parts, have no idea if it will fit pre 12/13/21 built vehicles.

View attachment rear sway bar.pdf

$510 in parts.

 

[flip]

Looks about right. Bar will come with the rubbers and straps, then just need left and right links and nuts/bolts.

 

[ATLBronco75]

I more wondering why it was added. Obviously Ford addressed something of concern.

I guess you don't have your truck yet? It has pretty horrendous body roll around the rear roll center. Particularly under trail braking in turns. Sway bars don't do much to improve traction but they do reduce body roll and make people more comfortable.

I've tuned a lot of suspensions for autocross racing and I'm pretty confident driving a car with the inside rear wheel off the ground. Not everyone is. Rear swaybars fix that.

 

[jorgem31]

I guess you don't have your truck yet? It has pretty horrendous body roll around the rear roll center. Particularly under trail braking in turns. Sway bars don't do much to improve traction but they do reduce body roll and make people more comfortable.

I've tuned a lot of suspensions for autocross racing and I'm pretty confident driving a car with the inside rear wheel off the ground. Not everyone is. Rear swaybars fix that.

I feel it but figured that was just a by-product of driving a tall narrow vehicle on spongy tires.

 

[RagnarKon]

According to my father (retired Ford engineer), it helps the stability of the vehicle while cornering at abnormally high-speeds. Front bars are basically required these days on most vehicles. Rear stabilizers also help if you have a lead foot, but typically isn’t required as the frame/body of the vehicle almost acts as it’s own stabilizer bar.

My guess is the Bronco had a little more oversteer than Ford was comfortable with when people were out in the desert getting frisky with their Broncos. Maybe during the development of the Bronco Raptor they were able to gather more data and figured it was a good idea to add one. Not sure, I ain’t an automotive engineer... so…
EDIT: I thought about it incorrectly, see @freetors post.

 

[BroncoKong Jr.]

I read here (somewhere) that the rear suspension was tuned for a softer ride on rough terrain so they added the sway bar to compensate for increased body roll

 

[‘21OBX]

At one time I thought they said this was part of the rough road upgrade. Here are the parts, have no idea if it will fit pre 12/13/21 built vehicles.

View attachment rear sway bar.pdf

I’ll have to check but I don’t believe my ‘21 even has the brackets on the frame.
my wife’s ‘22 non sas has brackets on the frame but nothing installed.

 

[freetors]

I just wanted to correct a few small points here so people don't read this and parrot incorrect information.

I've tuned a lot of suspensions for autocross racing and I'm pretty confident driving a car with the inside rear wheel off the ground. Not everyone is. Rear swaybars fix that.

Adding a rear sway bar actually increases the likelihood of lifting a rear wheel while cornering. Now, the bar on the rear of a bronco is probably so wimpy that this will never happen (unless you're in the process of rolling over). The mathematics of lateral load transfer (LLTD) let us calculate this pretty well if you know you're spring rates, motion ratios, approximate cg and roll center heights, plus a few other dimensions. A classically "neutral" handling car would have a 50:50 ratio of LLTD, although there other factors that can influence the true handling balance, and it should be noted this only applies to steady state cornering, not transient manuevers.

If you have a vehicle with an LLTD heavily biased to one end or the other then it's possible to actually see negative load in the calcs. This means that you're actually picking up a wheel at this point!

As a fellow autcrosser you should know that the hot ticket for fwd cars is a lot of rear roll stiffness and this tends to pick up the inside rear while cornering. Conversely, rwd cars often times do really well with little to no rear sway bar and a beefy front sway bar. This heavy front LLTD bias can pick up an inside front tire while cornering. My s2000 will do this on grippy concrete.

According to my father (retired Ford engineer), it helps the stability of the vehicle while cornering at abnormally high-speeds. Front bars are basically required these days on most vehicles. Rear stabilizers also help if you have a lead foot, but typically isn’t required as the frame/body of the vehicle almost acts as it’s own stabilizer bar.

My guess is the Bronco had a little more oversteer than Ford was comfortable with when people were out in the desert getting frisky with their Broncos. Maybe during the development of the Bronco Raptor they were able to gather more data and figured it was a good idea to add one. Not sure, I ain’t an automotive engineer... so…

As I explained above, no auto engineer would add a rear sway bar to reduce oversteer because that's not how it works.

In the real world I bet most wouldn't be able to tell one way or the other if their bronco had a rear sway bar, seeing as the stiffness of the oem bar is going to be pretty darn low. And it's been shown many times over in the Jeep world that their RSB's have basically no effect on overall flex.

 

[kevin.gt]

There was a thread back in January. Not sure if there was a definitive justification for it. I seem to recall theories that it might be there to support a roof rack? I also found the video in this reply informative

 

[RagnarKon]

Adding a rear sway bar actually increases the likelihood of lifting a rear wheel while cornering. Now, the bar on the rear of a bronco is probably so wimpy that this will never happen (unless you're in the process of rolling over). The mathematics of lateral load transfer (LLTD) let us calculate this pretty well if you know you're spring rates, motion ratios, approximate cg and roll center heights, plus a few other dimensions. A classically "neutral" handling car would have a 50:50 ratio of LLTD, although there other factors that can influence the true handling balance, and it should be noted this only applies to steady state cornering, not transient manuevers.

If you have a vehicle with an LLTD heavily biased to one end or the other then it's possible to actually see negative load in the calcs. This means that you're actually picking up a wheel at this point!

As a fellow autcrosser you should know that the hot ticket for fwd cars is a lot of rear roll stiffness and this tends to pick up the inside rear while cornering. Conversely, rwd cars often times do really well with little to no rear sway bar and a beefy front sway bar. This heavy front LLTD bias can pick up an inside front tire while cornering. My s2000 will do this on grippy concrete.

As I explained above, no auto engineer would add a rear sway bar to reduce oversteer because that's not how it works.

In the real world I bet most wouldn't be able to tell one way or the other if their bronco had a rear sway bar, seeing as the stiffness of the oem bar is going to be pretty darn low. And it's been shown many times over in the Jeep world that their RSB's have basically no effect on overall flex.

So the rear sway bar isn't to improve oversteer... which is actually makes sense now that you explained it—bad guess on my part, was thinking about it incorrectly.

But, it should add more rigidity to the vehicle overall. So... why would Ford want/need that? It costs them more money to add this thing... so there must be some reason. They just trying to reduce overall body roll, or trying to improve handling a bit when the vehicle understeers, or... any guesses? Maybe the spring rates on the 2022 suspension are different so they added a bar to compensate?

(I could probably just ask my father this question, but he's off camping in the middle of no where at the moment, so couldn't ask him if I wanted to.)

 

[mj63]

Adding a rear anti-roll bar will allow you to partially decouple the roll and heave modes of the vehicle.
In other words, you can use softer springs (ride rate/heave mode) on that end of the vehicle while still achieving similar limit handling balance (because the Lateral Load Transfer Distribution is held mostly constant by changing the spring rates) since the springs no longer have to be the only thing adding roll stiffness on that end of the vehicle.

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