How to dial in more oversteer?

[mikeman]

I have Hotchkis 32mm front and rear sway bars on my car. I'm thinking I may have too much understeer due to the 0mm bias I have between the bars. I remember Justice Pete stating that you want a 4mm to 6mm difference in bias between bar thickness.

I am running the three way adjustable rear bar on the stiffest setting. From what I have been able to find out, I think each hole is worth 1mm so the max setting I have on the rear bar would be equal to a 34mm bar. Does that sound right?

Since I do not want to take off the front bar and go with a smaller one, what kind of changes can I make to gain back the bias Justice Pete recommended?

Changes to the front and rear tire pressures?

More negative camber setting to the front end alignment?

Thanks.

[SSEssence]

Is there a reason why you dont want to change the front sway bar setup? I'm running 27mm front and 32mm rear Pedders sway bars and the setup is amazing, it handles perfect. Making the rear stiffer may help but the ride quality is going to suffer for sure.

[VR Baron]

Nothing you can do except change to a softer front bar. The most you want on a front bar is a 27 mm solid bar. Which is fine for stock or drop springs. Your front 32mm hollow bar is like a 29 solid. Way to big for any rear bar. You rear bar is more like only a 30.5 solid on the stiff setting, or something close to that. There is a lot of factors affecting a bars actual rate or size, not all are the same size for size.SSEssence has it right for the street with his bars as to bias.

[SSammy]

I honestly don't think you have much choice. What size tires are you running front & back? If you are running staggered, running a square setup helps, but won't make up for 0mm bias. If you are already running square and experiencing understeer you'll definitely have to swap to a smaller front sway. I run BMR adjustable 29mm front, 32mm rear sways with a square tire setup. Both on center holes gives me balanced handling.

[mikeman]

Originally Posted by SSEssence

Is there a reason why you dont want to change the front sway bar setup? I'm running 27mm front and 32mm rear Pedders sway bars and the setup is amazing, it handles perfect. Making the rear stiffer may help but the ride quality is going to suffer for sure.

I spent more money in getting it powdercoated since it got all scratched up in the garage when I was waiting to install it. So, I won't get the money back that I have invested into it.

Also, I do like how it improved the front end lean when going around turns at speed compared to the smaller stock bar. However, I do know that when it comes to handling, having it super stiff in turns is usually not the best way for handling balance.

I have the rear bar on the stiffest setting, but I honestly can't tell of a big difference between the middle setting the stiffest setting. It feels the same to me. The only resaon I did that was to gain back some of the front to rear sway bar bias that was recommended.

[VR Baron]

Originally Posted by mikeman

I spent more money in getting it powdercoated since it got all scratched up in the garage when I was waiting to install it. So, I won't get the money back that I have invested into it.

Also, I do like how it improved the front end lean when going around turns at speed compared to the smaller stock bar. However, I do know that when it comes to handling, having it super stiff in turns is usually not the best way for handling balance.

I have the rear bar on the stiffest setting, but I honestly can't tell of a big difference between the middle setting the stiffest setting. It feels the same to me. The only resaon I did that was to gain back some of the front to rear sway bar bias that was recommended.

Yeah sometimes hard to tell difference in position. Holes are only 15% or so from one to the next. And with the stiff front bar probably harder to tell. A big front bar does help roll and turn in response on the street, but as you push in corners will make understeer worse. Your bars are like a 29 and 30 solid as I mentioned before, so bias is no different then stock, but a lot less roll. If you have to keep the front bar,the biggest rear is a32 solid, or like mine, a 35 hollow on stiff. Best you can do

[mikeman]

I remember another member on here having the same setup in bars, 32mm Hotchkis hollow front and rear sway bars, and he mentioned that dialing in more negative front camber helped with increasing the handling balance that the lack in sway bar bias gave him.

In other words, he was able to use the sway bars he already had and made camber adjustments to the front suspension alignment to gain the front tire grip back as needed. I would like to try this approach if possible.

The car does handle great in turns and there is virtually no lean. Even with the Stabilitrac on, I can induce throttle controlled understeer/oversteer at will. However, I know my max grip has probably been compromised due to the lack in bar bias that is recommended.

[mikeman]

Originally Posted by SSammy

I honestly don't think you have much choice. What size tires are you running front & back? If you are running staggered, running a square setup helps, but won't make up for 0mm bias. If you are already running square and experiencing understeer you'll definitely have to swap to a smaller front sway. I run BMR adjustable 29mm front, 32mm rear sways with a square tire setup. Both on center holes gives me balanced handling.

I'm running a square setup. I'd like to get an aggressive street alignment, but I don't trust the dealer or those big box tire chain stores to do it properly. I may need to go to a specialty race shop and spend the $$$ to get it done properly and to my specifications.

I'm also debating whether to invest the money in one of those DIY setups where you can do the alignments yourself. The newest versions have a self-leveling feature that make it easier to do in a normal house garage.

[VR Baron]

Originally Posted by mikeman

I remember another member on here having the same setup in bars, 32mm Hotchkis hollow front and rear sway bars, and he mentioned that dialing in more negative front camber helped with increasing the handling balance that the lack in sway bar bias gave him.

In other words, he was able to use the sway bars he already had and made camber adjustments to the front suspension alignment to gain the front tire grip back as needed. I would like to try this approach if possible.

The car does handle great in turns and there is virtually no lean. Even with the Stabilitrac on, I can induce throttle controlled understeer/oversteer at will. However, I know my max grip has probably been compromised due to the lack in bar bias that is recommended.

You can try it. More negative camber will give more grip. Max you will get with stock ftont struts is -2 degrees

It helps, but proper bars are way you do it. Seems Hotchkis bars better for high horsepower where you don’t want a big rear bar as the bigger bar and the power can make the rear slide out if gassing it in a turn.

[mikeman]

Originally Posted by VR Baron

You can try it. More negative camber will give more grip. Max you will get with stock ftont struts is -2 degrees

It helps, but proper bars are way you do it. Seems Hotchkis bars better for high horsepower where you don’t want a big rear bar as the bigger bar and the power can make the rear slide out if gassing it in a turn.

Thanks. I will try more negative front camber to see if that helps.

[olblue75]

Man I hate to say it you just might have to bite the bullet, if you want it to handle better just find a 1LE front bar an be done. I swapped bars twice before finally finding a front 1LE bar an a JPSS 32mm rear bar handles great!!

An sell your current bar somebody will want it for street driving.

[VR Baron]

Originally Posted by olblue75

Man I hate to say it you just might have to bite the bullet, if you want it to handle better just find a 1LE front bar an be done. I swapped bars twice before finally finding a front 1LE bar an a JPSS 32mm rear bar handles great!!

An sell your current bar somebody will want it for street driving.

Olblue75 knows and like the rest of have said us bars are really the only way to go to notice. But it’s up to you as to how much is good enough.

Also what size tires and wheels do you have? If staggered stock sizes that makes understeer even worse. As I said, and best I could come up with with Hotchiss stiffness data and swaybar calculators your rear bar is close to a solid 28,29 and 30 mm solid bar for holes 1,2 and 3. Try getting a factory front 25mm bar from a zl1. It’s not expensive and has 40 % plus stiffer then the stock 23 mm bar. That way you can adjust the rear and dial in what you want. It will still roll some but not bad, and if you have stock tires some of the roll is coming from them also

[mikeman]

Originally Posted by olblue75

Man I hate to say it you just might have to bite the bullet, if you want it to handle better just find a 1LE front bar an be done. I swapped bars twice before finally finding a front 1LE bar an a JPSS 32mm rear bar handles great!!

An sell your current bar somebody will want it for street driving.

I think that's probably what I will eventually end up doing. Before I decided on the Hotchkis rear bar, I wanted to get the JPSS bar, but Justice Pete was already bankrupt at that time. Trying to find a JPSS 32 mm solid rear bar for sale is rarer than a hens teeth. lol!

[mikeman]

Originally Posted by VR Baron

Olblue75 knows and like the rest of have said us bars are really the only way to go to notice. But it’s up to you as to how much is good enough.

Also what size tires and wheels do you have? If staggered stock sizes that makes understeer even worse. As I said, and best I could come up with with Hotchiss stiffness data and swaybar calculators your rear bar is close to a solid 28,29 and 30 mm solid bar for holes 1,2 and 3. Try getting a factory front 25mm bar from a zl1. It’s not expensive and has 40 % plus stiffer then the stock 23 mm bar. That way you can adjust the rear and dial in what you want. It will still roll some but not bad, and if you have stock tires some of the roll is coming from them also

It sure can get kind of confusing with the adjustable ones. For me, at least. lol! Right now, I basically have a 2 mm bias due to the rear bar being on the third setting. I'm currently running square setup with stock rims and tires.

If 5 mm or so is the magic number for almost perfect balance, then all I have to do is gain a mere 2 mm somewhere. Of course, I realize it's more than just pure numbers and there is a lot more at play here.

I thought about varying the front to rear tire pressures. It seems from what I've read about the subject in the autocross forums, increasing the front tire pressure relative to the rear will decrease understeer and provide more grip for the front end.

However, I don't know what tire pressures to begin at to notice a difference in handling. 28 psi front vs 35 psi rear? 32 psi front vs 35 psi rear? Ultimately, I guess I will have to experiment to see what the car likes best.