Sway bars

[Bluemustang]

These are reversed. OEM rear is 123 lb/in, also. How did you get the 182 lb/in?

PP front: 295 lb/in
PP rear: 123 lb/in

Even full soft you're running more than twice the ARB stiffness contribution compared with stock, while having nearly identical F/R stiffness balance from springs (stiffer all around). I don't have exact rates for the GT350 bars. I do know that the front is ~350 lb/in. The rear (non-R) bar is only mildly stiffer than the PP as it's thicker wall only. The 23.6 mm R rear bar is quite a lot stiffer (ballpark 225 lb/in) but not nearly as stiff as your 28.5 mm Steeda even on soft. Bar torsional stiffness increases by the diameter^4, so even small changes make a difference.

Bmac just nailed it so I don't need to add more. But, just to put it in perspective, I was running the BMR rear bar at full SOFT (25mm, way softer than Steedas) and I was getting readily accessible oversteer at low speeds turns and inside tire hop. Now I have stiffer rear spring than Roadway but still it illustrates just how much the bar stiffness matters. Running 22mm GT350 bar and it's perfect. I kept the BMR front, still at full soft (essentially same stiffness at GT350/R bar).

I don't think these car need a lot of bar to control body roll. Let the springs do that.

Edit: I can now add more power A LOT earlier and hold it through the turn into exit.
A slight understeer can be corrected with more throttle. An easily accessible oversteer, not so. Can get you into trouble very quickly. Ask me how I know lol

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[Roadway 5.0]

These are reversed. OEM rear is 123 lb/in, also. How did you get the 182 lb/in?

PP front: 295 lb/in
PP rear: 123 lb/in

Even full soft you're running more than twice the ARB stiffness contribution compared with stock, while having nearly identical F/R stiffness balance from springs (stiffer all around). I don't have exact rates for the GT350 bars. I do know that the front is ~350 lb/in. The rear (non-R) bar is only mildly stiffer than the PP as it's thicker wall only. The 23.6 mm R rear bar is quite a lot stiffer (ballpark 225 lb/in) but not nearly as stiff as your 28.5 mm Steeda even on soft. Bar torsional stiffness increases by the diameter^4, so even small changes make a difference.

Dyslexia strikes again on the bars, though the rear PP bar rate of 182 I received from a pretty reliable source.

I suppose what I find odd is that my car wallowed with understeer with the PP bars, feels a touch under with the full soft Steeda bar (I drove this way for 6 months), and two days of driving on the medium setting feels very good. I admit that I've only driven at 50-60% EDIT[with the newest setting]EDIT, so maybe it is just a slow speed perception.

 

[Roadway 5.0]

Bmac just nailed it so I don't need to add more. But, just to put it in perspective, I was running the BMR rear bar at full SOFT (25mm, way softer than Steedas) and I was getting readily accessible oversteer at low speeds turns. Now I have stiffer rear spring than Roadway but still it illustrates just how much the bar stiffness matters. Running 22mm GT350 bar and it's perfect. I kept the BMR front, still at full soft (essentially same stiffness at GT350/R bar).

I don't think these car need a lot of bar to control body roll. Let the springs do that.

I'm beginning to think that I must enjoy the dynamic of oversteer. It's the only explanation for why I'm sparring with engineering logic. I think you and @BmacIL have waned me off from adjusting the bar to full stiff though; thanks to you both for the insight.

 

[Cardude99]

I may need to look into some sway bars in the future. The understeer I have is no joke. I see a lot of cars during autox that seem to run on rails, maybe some new sway bars would help get me there.

 

[Bluemustang]

I'm beginning to think that I must enjoy the dynamic of oversteer. It's the only explanation for why I'm sparring with engineering logic. I think you and @BmacIL have waned me off from adjusting the bar to full stiff though; thanks to you both for the insight.

No problem dude. Tbh, it's mostly Bmac lol. The problem I have with sway bars is I find them a big compromise. They make your independent suspension less "independent". The system doesn't work as well with overly stiff bars even ignoring the balance. That's why I like them to "supplement" what's there if you will. More of a tuning tool than a principle means of controlling body roll. I feel like the springs and bars to a better job for this.

 

[BmacIL]

I admit that I've only driven at 50-60%, so maybe it is just a slow speed perception.

Technically, you can't have over/understeer below the limit ;-)

 

[Roadway 5.0]

Technically, you can't have over/understeer below the limit ;-)

Touché!

 

[BlownGP]

There's a few Ford factory options that might work for you. One is the Performance Pack bars, the other is the GT350 bars. I installed a set of GT350R sway bars on my GT and they work great, but if you're looking for a bit less bar, Performance Pack and normal GT350 bars would probably work well. I think I paid about $120 for a set of new GT350R sway bars.

That's what I plan on going with.

I have a stock suspension GT premium and It handles pretty damn good on the curves I have taken.
Just put some wider wheels on, so I'm curious to see the difference.

springs and shocks/struts are next.

 

[NightmareMoon]

Touché!

While I agree, you really can't get true oversteer/understeer without being "at the limit", seeming subtle changes to alignments and shock settings can cause some interesting feel changes in how a car rolls through a corner.

Roadway, what wheel widths are you on?

 

[BmacIL]

While I agree, you really can't get true oversteer/understeer without being "at the limit", seeming subtle changes to alignments and shock settings can cause some interesting feel changes in how a car rolls through a corner.

Roadway, what wheel widths are you on?

Very much true. The roll characteristics can make it feel say, pointy or wallowy. That said, you really don't know the true balance of the car till it's at/near the limit.

In addition, bars should be used IMO, as a mid-corner balance modifier. If you are looking for changes to entry/exit behavior or grip, shock settings, alignment settings, and springs are the things you should adjust.

 

[2015Etrac]

That's what I plan on going with.

I have a stock suspension GT premium and It handles pretty damn good on the curves I have taken.
Just put some wider wheels on, so I'm curious to see the difference.

springs and shocks/struts are next.

That's what I had, a stock GT Premium. The Koni shocks and GT350R springs made a HUGE difference. I also added the BMR CB005 and a GT350R strut tower brace. It was about $1500 for everything, but it totally changes the car. You can knock a few hundred off if you chose a non-adjustable shock and a different strut tower brace, but I liked the looks of the GT350R brace.

 

[ModularKid21]

So the factory gt (non pp) spring rates are 160/668. The springs I have now are 198/874. So if I’m getting this correctly, that increase in spring rate is essentially solely responsible for the increase in my cars handling ability? It’s hard for me to wrap my head around my sway bars not having much of an affect on the handling of the car. Especially when the car handles the way it does. I have yet to drive the car at its limits yet as I just got around to doing the alignment, so I’m still waiting to experience the issues with the roll center. I don’t claim to be a suspension expert so I’m learning just as much from this thread as the next guy

 

[BmacIL]

So the factory gt (non pp) spring rates are 160/668. The springs I have now are 198/874. So if I’m getting this correctly, that increase in spring rate is essentially solely responsible for the increase in my cars handling ability? It’s hard for me to wrap my head around my sway bars not having much of an affect on the handling of the car. Especially when the car handles the way it does. I have yet to drive the car at its limits yet as I just got around to doing the alignment, so I’m still waiting to experience the issues with the roll center. I don’t claim to be a suspension expert so I’m learning just as much from this thread as the next guy

Well of course the sway bars do significantly affect the handling. They do it very differently from springs, though. Springs affect the handling in all phases of the corner: turn in, middle, exit. They also control brake dive and acceleration squat. Sway bars also affect all phases of the corner, but more in the middle, controlling peak roll stiffness, than the entry and exit. Sway bars are a great tuning aid for tuning in the handling balance. What they don't do anything for is braking or acceleration, as both sides are moving up or down together.

Too stiff with a bar can cause issues that come from the left and right side being connected via a torsion spring. One way is that bumps on one side can upset the whole chassis as it drives load to the other connected wheel. The other way is that a really stiff bar will lift the inside tire during hard cornering, reducing overall grip capacity, but more importantly on something like the Mustang, can significantly limit the ability of the torsen limited slip diff from putting power down. The diff needs weight on the inside tire in order to bias torque properly.

This is all why I recommend people use sway bars as a tuning aid, not as the primary way to reduce roll. That's what springs are for. Keeping the bars as a more minor part of the package means you'll have less L/R cross talk, a more consistent and easier to drive car, and one with power you can exploit fully.

 

[ModularKid21]

Well of course the sway bars do significantly affect the handling. They do it very differently from springs, though. Springs affect the handling in all phases of the corner: turn in, middle, exit. They also control brake dive and acceleration squat. Sway bars also affect all phases of the corner, but more in the middle, controlling peak roll stiffness, than the entry and exit. Sway bars are a great tuning aid for tuning in the handling balance. What they don't do anything for is braking or acceleration, as both sides are moving up or down together.

Too stiff with a bar can cause issues that come from the left and right side being connected via a torsion spring. One way is that bumps on one side can upset the whole chassis as it drives load to the other connected wheel. The other way is that a really stiff bar will lift the inside tire during hard cornering, reducing overall grip capacity, but more importantly on something like the Mustang, can significantly limit the ability of the torsen limited slip diff from putting power down. The diff needs weight on the inside tire in order to bias torque properly.

This is all why I recommend people use sway bars as a tuning aid, not as the primary way to reduce roll. That's what springs are for. Keeping the bars as a more minor part of the package means you'll have less L/R cross talk, a more consistent and easier to drive car, and one with power you can exploit fully.

All of that theory makes sense to me, but having not properly experienced all of these things is where I think I’m missing out. I also don’t track my car, but from my experiences, a modest increase in spring rate (to help with the aforementioned braking/accelerating/handling but to not kill ride quality) and bigger sway bars works quite well on a primarily street driven car, as the op stated his car would be used for. But the concensus in this thread and others seems to contradict that. Just got me thinking is all

 

[BmacIL]

All of that theory makes sense to me, but having not properly experienced all of these things is where I think I’m missing out. I also don’t track my car, but from my experiences, a modest increase in spring rate (to help with the aforementioned braking/accelerating/handling but to not kill ride quality) and bigger sway bars works quite well on a primarily street driven car, as the op stated his car would be used for. But the concensus in this thread and others seems to contradict that. Just got me thinking is all

I guess I would ask why bigger sway bars if no track or autocross intent? There are many ways to improve handling without them. If one never gets near the limit, they're a good way to make the car feel stiffer in roll without sacrificing ride much.

If you push it, you'll find there's reasons enough to choose wisely about how to implement them.

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