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Discussion Starter #1
Bon Giorno y'all,

I am hoping to get thoughts from folks who have installed a front sway bar. How would you describe the improvement in handling, both for the street and track?
This is not to question whether a front sway bar offers any handling benefits. I am merely hoping to quantify the benefits/improvements before undertaking the rather involved installation.

FWIW, the car currently has the Progress rear sway bar, front and rear shock tower braces, and Öhlins coil-overs.

Thanks in advance!

- S
 

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I think people have suggested upgraded sway bars are unnecessary if you have quality coil overs. Only upgrading the rear bar is also not recommended.
 
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A bigger front bar will cause more understeer. If you are on soft spring rates (regardless if they are aftermarket coilovers or not), the inside rear wheel will lift with enough body roll, and you'll get massive amounts of oversteer. A rear bar will make this worse. If you are experiencing body roll and too much oversteer, a bigger front bar will help. Those of us who autocross in Street (stock) class use a big front bar to keep the rear end planted with our soft stock spring rates. What spring rates are your coilovers?
 

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Discussion Starter #4

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We all know upgrading the sway bars usually means better handling. You hear people say all the time "I put beefier sway bars on and now my car handles so much better." So I will say the say thing. I installed Karcepts sway bars front and rear and now my car handles a lot better and tracks flatter through the corners.

Now let me quantify it for you. I race on a 0.9 mile track with 13 turns. The turns are tight so it's easy to get oversteer/understeer in the turns. I have Ohlins 8/4 coilovers, 235/40R17 Dunlop Direzza III tires. On March 17, 2019, I ran a fastest lap of 1:05.677, a personal best at the time. I installed the sway bars on March 30 and the next day I was about to cross the finish line with a time of 1:04.5 but I looked at my projected lap time and got too exited and gave it too much gas out of the corner and spun out 30 yards before the finish line. The best for the day was 1:05.118, over half a second faster. Later, I got the sway bars dialed in and did a 1:04.098. That's a massive decrease in time from just coilovers only.

I agree that if you are running quality coilovers, which you are, and not doing track stuff then you don't need to upgrade the sway bars. And with that upgraded rear only sway bar you are risking inducing unexpected snap oversteer in a tight situation. I would not do it.
 
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Discussion Starter #6
I agree that if you if you running quality coilovers, which you are, and not doing track stuff then you don't need to upgrade the sway bars. And with that upgraded rear only sway bar you are risking inducing unexpected snap oversteer in a tight situation. I would not do it.
Thanks much for the thoughts.

I am a regular at the track, which is the primary motivator for considering the front sway bar upgrade. The rear sway bar is already upgraded (although the track owner called the Progressive bar I have installed a toy =) ), so are you suggesting to revert that? Or that the rear upgrade really should be accompanied by a front bar upgrade?

Thanks again,

- S
 

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Thanks much for the thoughts.

I am a regular at the track, which is the primary motivator for considering the front sway bar upgrade. The rear sway bar is already upgraded (although the track owner called the Progressive bar I have installed a toy =) ), so are you suggesting to revert that? Or that the rear upgrade really should be accompanied by a front bar upgrade?

Thanks again,

- S
If you are a regular at the track I would let your lap times be your guide. The rear sway bar can be installed in 15-20 minutes. See what your're faster on. But I think you'll go even faster with an upgraded front bar. It's all about getting the greatest amount of contact patch you can down so you'll also need to be prepared to make adjustments in camber, tire pressure and coilover damping as well to get the best results. And it won't be set it and forget it. Every time you go to the track you'll need to make small adjustments based on track conditions. I feel comfortable with my sway bar settings at this point but I am constantly making adjustments to tire pressure and coilover settings to find that extra 1/10th of a second.
 
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A bigger front bar will cause more understeer. If you are on soft spring rates (regardless if they are aftermarket coilovers or not), the inside rear wheel will lift with enough body roll, and you'll get massive amounts of oversteer. A rear bar will make this worse. If you are experiencing body roll and too much oversteer, a bigger front bar will help. Those of us who autocross in Street (stock) class use a big front bar to keep the rear end planted with our soft stock spring rates. What spring rates are your coilovers?
So you're saying that installing just a front bar will give you oversteer and understeer?
 

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So you're saying that installing just a front bar will give you oversteer and understeer?
He's saying that you'll get more understeer with a stiffer front bar. Without it, you can get enough body roll to lift one of the rear wheels which leads to understeer. The stiffer front reduces overall body roll and helps keep the rear tire down.

I have the Karcepts sway bars front and rear. They have five settings per side which means you have 9 different stiffness settings front and rear. I have found for my particular set up and use that anything beyond a 2/2 setting in the front and 1/1 setting in the rear is too stiff and too much understeer and oversteer depending on the corner. The car would be absolutely undriveable, and probably dangerous, at 5/5 as it would have no grip at all.

But that's on 235/40R17 tires with 200 tread wear. If I were to put a 245 in 40 TW on the car I could go stiffer on the sway bars as the beefier, stickier tires would take more. I also think if my particular track had faster corners I could also go stiffer on the settings than I have now.
 

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So you're saying that installing just a front bar will give you oversteer and understeer?
Big front bar = more understeer.
Stock car with soft springs and stock bar = oversteer because the car leans so much you get one rear wheel that starts to spin (even with a Torsen diff) and the back slides out.
Big rear bar = oversteer

You use the bars to balance the car. You first set up tires, then springs and dampers, then bumpstops, then sway bars to balance it all out. Sway bars make a bigger difference the soft the suspension is.
 

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There are race classes where we are allowed only ONE sway bar upgrade, so we do that one bar. But we do other stuff to fix the understeer that results with just an upgraded front bar. For SCCA CS in our 2019 Miata that means Penske HARD rear bumpstops and full stiff rear shocks to balance the front bar. We can make it work, but unless stuck with rules that limit you to one bar it is a BAD IDEA. Sadly, because cars in classes limited to just one bar upgrade can be made fast, it has become Internet group think that one bar upgrade is a good idea. Video below is me taking top of SCCA CS in our 2019, upgraded KARCEPTs front bar, Koni Sport shocks with rear set full stiff and our Penske hardest rear stops. It works, but that's a compromise we don't like and do it only because that's the best we can do with the rules of SCCA Street class.


Our Fiat 124 has our Karcepts bars FRONT AND REAR. And our Ohlins Coilovers with upgraded Swift Springs. This car races in SSM and other classes that permit coilovers and upgrading both front and rear sways. The suggestion that having good coilovers means you don't upgrade sways is not accurate, but it is true we prefer to start with coilovers and have the customer drive that result and then come back and talk to us about the results with coilovers BEFORE we add the sways. Our Fiat with this setup is faster than our ND Miata by quite a bit, particularly on bigger and more flowing courses like the one below:




With every car we want to add roll resistance to balance the grip. So, the more grip you got, the more rate you need in coilover springs and sways. Today we are at COTA with SuperLap Battle in our Turbo NC and this bad boy has 32mm front Rx8 sway, Rx8 rear sway, 13kg front springs, 9kg rear...and that's still not enough rate for our 17x10 grip package, will be doing new coilovers and more rate for next event.

 

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Big front bar = more understeer.
Stock car with soft springs and stock bar = oversteer because the car leans so much you get one rear wheel that starts to spin (even with a Torsen diff) and the back slides out.
Big rear bar = oversteer

You use the bars to balance the car. You first set up tires, then springs and dampers, then bumpstops, then sway bars to balance it all out. Sway bars make a bigger difference the soft the suspension is.
Yeah, I know, I used to build pro touring cars. Mustangs. Modern stick axle Mustangs, have a similar 54/46 front to rear weight balance as these cars. We would use a big front bar for the turn in and keeping the nose down in the corners. In a stick axle with the torsion you want some rear lean because the alternative is to drift . Our stick axle Mustangs rear end
already didn't articulate for shit, putting big sway bars on the back only made it drift,.

But with a torque arm, some coilovers and a Torsen, we could control rear end action with spring rate, without further tying the two rear wheels together. So my question was has anybody done that and I guess that question has been answered. Although a few of the answers might have been a little incomprehensible to me, I am but a caveman
 
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