Sway bar setting vs strut setting

MajHazrd

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My 2015 has had a "light tail" feeling on the track, but always sticks, I haven't had an oversteer occur accept once the tires get hot and slippery (with different tires than the RE71R).

Last time i was on the track I changed the strut setting from 1.25 turns from soft to 1.75 turns on the front and 1.25 from soft on the rear.

Looking for opinions if I should move the sway bar to the stiffest position and then soften the Struts back up or run the with the stiffer strut settings.
My thought is to bring the struck back to its middle setting give me more range for adjusting the struts for track conditions. And brings the sway bar in to control the amount of body roll.
My concern is, will the stiff setting on the BMR sway bar be to much and I'll end up with to much understeer.
Would I get other gains by going stiffer on the front sway bar?

My set up:
2015 Mustang GT PP
BMR SP083 handling springs (GT350R rate springs)
BMR adjustable swaybars front and rear
Koni Yellow Adjustable struts and shocks
Bridgestone RE71R 275/35/19, squared

Thoughts, suggestions, positives, negitives?





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fatbillybob

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Light feeling where? Under braking? At turn in? At exit? Etc.
 
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Mid to exit, after braking and back on the throttle, feel it most carousels. I thought is was just me imagining it at first, because it doesn't slide or twitch, just feels light. Then I was at a short track with 2 long carousel corners where, as usual had this light feeling. The track was tearing my front tires up so I stiffened up the front struts a half a turn hoping to slow the roll and maybe help the tires a little. It was over 100 degrees that day. That's when I noticed the light feeling was gone and that I was charging the carousels harder.
 

SteveW

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Based on your handling complaints in this thread and thinking only about rebound and sway bars you likely have too much front rebound and not enough front sway bar. Plus, too much rear sway bar and maybe not enough rear rebound control. I say try putting the front bar on a stiffer setting, go down a half turn on front struts. Put the GT PP rear bar back on and try the car out. Go stiffer on the rear shocks a 1/4 to 1/2 turn only after trying the car with the other changes.

We should still talk about alignment though...
 

fatbillybob

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What shocks have 1/2 click you can feel?
 

SteveW

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What shocks have 1/2 click you can feel?
OP has the Koni SA ones that just adjust in sweeps. Typical adjustment is 1/2 a turn and the full range is like 2 1/2 turns or something like that.

They only have a low-speed rebound adjustment.
 

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I’d leave the rear swaybar on a softer setting unless you just want more tendency to oversteer. Expect to use stiff rebound settings on the adj shocks for track use.

Swaybars can be used for general balance adjustments after the weight has shifted mid corner. Shocks will affect how that weight shifts. There’s some crossover but yeah.
 
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MajHazrd

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Steve and Nightmare Moon, that's the vain I was thinking, but wasn't sure. I don't have the experience with suspension tuning/tweaking. Good to know I'm on the right track and insight on what to expect and feel for on the track after the changes. I've done a lot more suspension tuning on dirt bikes. :)
I'm going to try the stiff setting on the front sway bar this weekend and back off the front struts. I'll bring tools to swap back to the mid setting if needed. Its easy enough to change.
Depending upon the feel. I'll start looking at the rear also, Its on the mid setting now, I could go one setting softer before swapping back to the stock.

For alignment, I'm not aggressive on the alignment. I use it for daily driving and long trips. i.e. i'm driving 11 hours to Hallet Raceway in OK on Thursday for Track Day on 11/7. Then I'll go on Hot Rod Mag's Power Tour or over to Woodward avenue in Detroit for events.
My son and I also have a 2000 GT which we have a much more aggressive suspension set up on.
I've attached the current Alignment settings for my 2015. I would be interested in hearing what changes would make improvement. Never know when an upgrade will happen. :)



2015 Alignment 2020.jpg


20201101_205049.jpg
 

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Step 1: put the GT PP stock rear bar back on

I don't think your shock &strut settings are off much from where they should be, based on mine and others' experiences with the Konis. That said, you shouldn't look at damper settings and swaybar settings at all interchangeably. They perform completely different functions. Damper adjustment will change the rate of weight transfer, not the amount or the steady-state balance of the car. The can have an effect on the car balance on turn-in and corner exit, however. Swaybars are interconnected torsion (mostly) springs that transfer load across the axle (and a bit front to rear). They have a significant influence on the overall balance of the car. Swaybars actually reduce the total grip capability based on inside/outside tire loads alone, but usually offer enough balance or geometric benefit to offset that. Too much can be a detriment thought. I'd set the BMR front bar to the medium setting, and pair with the stock rear.
 

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If you do play with settings, play with one setting at a time. Don't change the front bar AND change the shocks at the same time or you'll never know which change did what.

Personally, I'd drop the rear bar to its softest setting and leave the front bar on medium. As Brian is saying, stiffer swaybar settings would reduce grip a little (all things being equal), and shifting the rear a softer setting would probably be better than increasing the front stiffness.
 

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Also, as far as alignment suggestions, for your usage I would recommend another 0.5-0.7 deg of front camber (-1.8-2.0) and about 0.3-0.4 deg less rear (-1.6-1.8 or so). Without the added front camber you will seriously punish the front tire shoulders at the track, even with additional air pressure to prevent roll-over.
 

SteveW

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Step 1: put the GT PP stock rear bar back on

I don't think your shock &strut settings are off much from where they should be, based on mine and others' experiences with the Konis. That said, you shouldn't look at damper settings and swaybar settings at all interchangeably. They perform completely different functions. Damper adjustment will change the rate of weight transfer, not the amount or the steady-state balance of the car.
Knowing that shocks control the rate of weight transfer doesn't really explain what this means to how the car handles. I came up with some concepts to explain that thanks to some comments by you and Norm.

In my pea brain rebound impacts handling during two phases of weight transfer:

1. Increasing rebound control on the corner of the car that is being unloaded will speed up the transfer of weight to the end of the car being loaded.

Like from the rear tires to the front tires under braking or throttle lift mid-corner to induce rotation. Or from left and right in transitions.

2. Rebound control can also be used to hold weight onto a loaded contact patch a little bit longer.

Like to utilize trail braking techniques from a braking zone down to the apex. Or on the rear tires under acceleration.
 

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Shock adjustments tend to be more subtle, and more likely to give you the opposite result you expected. Anti-roll bar adjustment are more straight forward, and typically easier to feel.

Or to answer the title, "Sway bar setting vs strut setting?" is like asking "Oranges vs apples?".
 

ZX3ST

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Just another suggestion here. I had similar light feeling in the rear under hard braking. It pretty much went away after I replaced the rear LCA and toe link bushing with bearings. YMMV.

I will also agree with the alignment adjustments.

EDIT: Apparently reading comprehension escapes me today. Didn't realize we were talking mid corner. Sorry OP.
 
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MajHazrd

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Thank you all for the input. I put the front sway bar back to mid and the rear to soft. Set the front struts to 1.5 (vs 1.75) and rear shocks to 1.25 turns.
I did a track day at Hallet Raceway in Oklahoma which has a lot of off chamber corners and it did very well. I ran one 1:28 min lap, most of the time between 1:30 and 1:32 lap times.

I'll continue to test and tune as time goes. Now I need to figure out my clutch situation!
 

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