[VR Baron]

Originally Posted by Msquared

I've already done that. I didn't take anything out of context. Calling something "book theory" isn't the dismissal you think it is: it's in a book for a good reason. It also happens to work in practice as well. There was no opinion in anything I wrote.


I don't know what "medium stiffness" means. Show me the case where an otherwise stock car went faster in Street class autocross competition with a smaller-than-stock swaybar. Is it possible to modify a car with too much wheel rate? Sure it is. But we're starting with an SS on stock springs and swaybars: surely you'd agree that this car comes with much softer springs and swaybars than would be ideal for any track or autocross event? How in the world could more roll be better for autocross times?! It can't.


I think it was pretty clear that he was targeting SCCA's F Street class (used to be called Stock), and we all know the parameters there. Most people would understand that a car on different tires and with a different alignment (but not camber plates or other mods to increase alignment) is still "stock." To take exception to that is being kind of petty. He didn't ask about tire or alignment recommendations - he asked about aftermarket adjustable swaybars.


I gave him a bullet-pointed list of his options for increasing rear swaybar rates, including the relative stiffness values at various settings, and which ones I would recommend starting with. I'm pretty sure my answer was right on the nail. BTW, you do understand that buried in your reply was agreement with me that he should try a stiffer FE4 rear bar, right? OTOH, if he'd followed the rest of the advice you others gave, he'd get a smaller rear bar for more roll, wider wheels and tires that are illegal for his class and cost $4000 because they are uber-light, and tires that are no longer in production and no longer the fastest option.


Handling and speed is not a black art. It's all physics and - especially with enough resources and knowledge - highly simulatable and predictable.

I never said a smaller sway bar is better. He said a stock car. Period.I said what obviously is causing his roll with out getting overly complicated about it and all the possible things he could do that exist like you did, as he just wants a bar for now Or he just might as well go to cam c and spend tons of money to go faster as you said. I know, done all that as I said. Medium means not soft or stiff obviously, sorry I talk like that but not getting into the weeds about this as is pointless.You are assuming a lot about his car and what he means, just like we all found out in his later post.

But you win. Not here to argue on his thread about what sway bar to get

[weemus]

I apologize for answering in an overly basic and callous opinion. I assumed much.

I believe sway bar link material is not limited, according to stock class, so I would consider that as part of the equation on the bar (maximizes it’s effectiveness).

Also on a side note on track, in stock class, you can go +7 mm per side? Wheels are $$$ but standard 5mm hub centric spacers will widen that track on the cheap. I did that on all 4 corners to maximize track within the rules and its still has enough thread engagement.

[weemus]

https://racer.com/2017/07/18/autocro...rets-swaybars/
Front bar which when limited is always what should be done first (maximize front grip)

https://racer.com/2017/07/19/autocro...waybar-tuning/
Think of the bar as a system, i.e. mounts and adjustable (spherical if you can) links should be used to maximize bar effectiveness.

[Norm Peterson]

Originally Posted by VR Baron

Generally softer to a point grips better as the car can roll more to get weight onto the tire to stick.

Softer is the effect that generally improves mechanical grip here. Not the amount of roll, which (ignoring adverse camber effects) as far as mechanical grip is concerned is simply the observable evidence that the suspension is not rigid.

Improvements in mechanical grip and increased amounts of roll are both downstream consequences of suspension "softness". Neither of them is an input.


Norm

[Msquared]

Going softer on one end of the car with a smaller swaybar does increase that end's grip, but it's at the expense of decreased grip at the other end. So to be clear, it isn't going to increase the overall grip of the car unless the car is actually too stiff in roll. I can't think of a production car that's ever come with too much roll stiffness such that it benefitted from an overall reduction in roll resistance. In general, the more a production car rolls, the more overall grip it will give up in cornering because the suspension doesn't keep the tires at optimal alignment to the pavement.

RE those articles quoting Guy Ankeny, it is often true that a rwd car in Street class benefits from a bigger front bar rather than a bigger rear bar. But not always. It depends on how the car handles with the stock bars as well as how much power it has and how well it puts that power down: if it's neutral or oversteering and has trouble putting power down then it may indeed benefit from a bigger front bar so it can put power down better. This is generally the case for the 1LE in B Street, for example.
Having never driven a stock 6th-gen SS, I don't know how it handles, so I didn't attempt to tell the OP whether his plan to increase rear roll stiffness is the correct one.

The gobbledeegook about swaybars taking away independence from the suspension has been disproven repeatedly over the years. Wheel rate is wheel rate: the tire doesn't know if the displacement-based rate and consequent load it's seeing is from a swaybar or a spring. It just sees the load change as the suspension moves. So in roll or articulation it doesn't matter if half the wheel rate is provided by the swaybar or if it's all provided by the spring - the exact same forces and movement will occur.

As an aside, way before I bought my C4 Corvette, I codrove it with the previous owner at a regional autocross. He had Ankeny-spec'd custom-valved Bilsteins on it for that event. They were so stiff that the suspension was effectively locked half the time and the car was practically undrivable. Those things came right back off the car because they were awful. FWIW.

[democidist]

Shoutout to kropscamaro16 for being the first to answer the question.
.
So, after reading Msquared's reply I decided that I wanted to go with the Hotchkiss bar, but literally everywhere I checked they would have to order it and wouldn't be able to get it to me until November. I didn't want to wait until next season for the change so, I went to a local GM parts distributor and got myself a FE4 rear bar. Which was harder than you'd think because apparently they don't know what a sway bar is because GM calls them "stabilizer bars". I've done three autocrosses since installing the bar and it's much better. It does have a little more oversteer than I'd like now, but it is controllable.

[Norm Peterson]

Originally Posted by democidist

Shoutout to kropscamaro16 for being the first to answer the question.
.
So, after reading Msquared's reply I decided that I wanted to go with the Hotchkiss bar, but literally everywhere I checked they would have to order it and wouldn't be able to get it to me until November. I didn't want to wait until next season for the change so, I went to a local GM parts distributor and got myself a FE4 rear bar. Which was harder than you'd think because apparently they don't know what a sway bar is because GM calls them "stabilizer bars".

This kind of falls under the heading of trivia, but GM's terminology is really the correct one. Commonly shortened to "sta-bars" at the automotive engineering level, which is something I picked up from occasionally participating in a forum having a number of OEM-level automotive engineers as frequent contributors.

"Sway bars" as used in casual enthusiast conversation is probably best considered a nickname.

"Sway" has more to do with what a trailer can cause your car to do in a side-to-side, tail-wagging-the-dog manner than with roll.

Trailer sway is important to know about, as it can quickly lead to whipping and create a dangerous situation for you and others on the road. It’s a side to side motion that begins when you reach a certain speed while towing a trailer. A persistent side to side swaying motion is not normal and could likely lead to whipping if speed increases.

Norm

[Mountain]

Originally Posted by democidist

So, I've been getting into AutoX with my 2017 Camaro SS with no performance modifications done to it. I'm trying to stay in F-Street, which allows for a single aftermarket sway bar (front OR rear). I've been told that to help with the understeer I'd either want a softer front, or more likely, a stiffer rear. Do any of you have recommendations? I know that Phastek has a couple of options for adjustable sway bars. Do any of you have experience and can maybe even tell me what setting to put it at? Thanks!

I'll answer your question directly: BMR front bar with alternate bushing shells or the FE4 (SS 1LE/ZL1) front bar if you feel your car is lacking in transitions/the front end is a bit lazy and you feel there is excessive roll from the front end.
>Why: On an otherwise stock suspension for an SS or SS 1LE, the stiffer rates of the Hotchkiss can be a bit much, offering very little adjustment (excessive understeer), in all actuality. The BMR allows you to roughly start at stock (well, "stock" SS 1LE) and go a bit stiffer in two steps useable to different tracks/courses/weather conditions. The FE4 (SS 1LE/ZL1) front sway bar is one step up from stock on an SS and is a very cost-effective and noticeable upgrade, roughly starting off at the least stiffest point of the BMR. Overall, the front spring/sway bar setup isn't too terrible on the SS 1LE, but is a bit lacking on the SS.

If you want some more oversteer, wanting the rear end to rotate more, go with the Hotchkiss rear bar.
>Why: The Hotchkiss rear bar is the only bar out there that doesn't have crazy stiff rates. The bar starts off about the same rate as the FE4 rear bar (SS 1LE/ZL1) and has two steps stiffer. The other benefit to this bar is that the bushings are non-bonded and free-up the rear suspension movement. Honestly, you really don't need to adjust the rear rates on these Camaros too much from stock, either SS or SS 1LE, at all.

I hate general advice from most autocrossers because it is usually so overly generic and stuck in old "rules of thumb" that don't necessarily apply as well with many newer cars. You really should be judging a specific car and then, further, for the specific driver. Some people like to drive more like kart drivers, with more of a touch of oversteer, and some prefer a slight touch of understeer, with more of a circuit-sports car mentality.

[democidist]

So, I made a reply to this thread months ago, but for some reason it wasn't displaying for me. So I made this post, only to later find out that the first post did work, but I'm keeping this one anyways because it goes into a bit more detail. Anyways, here it goes.

Originally Posted by kropscamaro16

afe power on my car no complaints do about 5-8 track days a year

Thank you for being the first person to answer my question.

Originally Posted by Msquared

But here are some suggestions for increasing your rear roll stiffness, including the adjustable bars you actually asked about (be patient and we'll get there!):

• Believe it or not, just changing the rear "D" bushings that mount the bar to the frame to harder urethane will stiffen the stock bar's effective rate. That's a super cheap and easy thing to try.
• I think the next stiffest (compared to stock) rear bar you could get would be the SS 1LE (FE4) bar. If you can get that part cheap, you could start there. It's not adjustable, I know, but it is stiffer than your stock rear bar. And with rear bar rate increases, sometimes a little goes a long way. The next stiffest is the BMR non-adjustable rear bar, which is supposed to be 16% stiffer than the 1LE bar. But I'd probably skip that in favor of what's next:
• The softest adjustable rear bar I know of is the Hotchkiss. At its softest setting it is 25% stiffer than the 1LE bar. The medium setting is 35% more and the stiffest setting is 50% more. Keep in mind that even at its softest setting, it will be quite a bit stiffer than your stock rear bar: start with the softest setting for sure. But this is why I'd start with the 1LE rear bar and see how that works. Finally, the BMR rear adjustable bar has rates that are 46/70/98% stiffer than the 1LE rear bar, which means anywhere from ~66%-230% stiffer than your stock bar. IMO, that's way too big a jump since you can't change the front to go along with it.

I'll spare you the long story of how I ended up settling on this option, but I eventually decided to go with the FE4 bar (which is used in the SS 1LE and Non-1LE ZL1). I used it on, I want to say, three autoX's and here's what I found:

• It is much closer to balanced now.
• It has a tad more oversteer than I'd like, but it's manageable. I'm glad I didn't go with anything stiffer.
• Judging by the tire wear, it is balanced (or at least close enough).
• My performances/times have also improved, which could be unrelated because Correlation != Causation, but I'm happy with the change overall.

[Msquared]

Originally Posted by democidist

I'll spare you the long story of how I ended up settling on this option, but I eventually decided to go with the FE4 bar (which is used in the SS 1LE and Non-1LE ZL1). I used it on, I want to say, three autoX's and here's what I found:

• It is much closer to balanced now.
• It has a tad more oversteer than I'd like, but it's manageable. I'm glad I didn't go with anything stiffer.
• Judging by the tire wear, it is balanced (or at least close enough).
• My performances/times have also improved, which could be unrelated because Correlation != Causation, but I'm happy with the change overall.

Sounds like it was the perfect choice. Glad it worked out, and it's good that you provided this feedback for others to see.

[Msquared]

Originally Posted by democidist

I'll spare you the long story of how I ended up settling on this option, but I eventually decided to go with the FE4 bar (which is used in the SS 1LE and Non-1LE ZL1). I used it on, I want to say, three autoX's and here's what I found:

• It is much closer to balanced now.
• It has a tad more oversteer than I'd like, but it's manageable. I'm glad I didn't go with anything stiffer.
• Judging by the tire wear, it is balanced (or at least close enough).
• My performances/times have also improved, which could be unrelated because Correlation != Causation, but I'm happy with the change overall.

It sounds like you got the exact changes you wanted. Glad it worked out, and thanks for providing some follow-up feedback.

[KyBoy]

I have aFe Control adjustable sway bars and aFe Control lowering springs. I am currently using the stock end links. I'm on the stiffest setting on the road and middle setting front. 2SS is ON rails right now. MRR 017 wheels with Michelin PS4S in 1LE configuration.