Thinking about sway bars? Take a look here for some great information

[drewbot]

Originally Posted by SkAsphalt

The KoolBRZ guy is constantly blasted all over the forums for misguiding people. I think that is his forte.

He went to Suberman school of car dynamics

[KoolBRZ]

While you all were (im)patiently waiting for my next reply, I scraped the underside of my bumper twice, and the underside of the midsection of my car once. Determined to raise my lowered car at least 1/4", I adjusted just the preload of my front struts 1 turn tighter, and test drove it. It would have still scraped, but the front end took in the bumps better, more of a thump, then a tha-wump. So determined that more was better, I adjusted the rears 2 turns tighter and lowered the threaded mounts 2 turns, then to lift up the front, adjusted those mounts 4 turns. Took it for a test drive. Wow, back end slides out on the corners now, and the back end kicks a little vicious on the bumps now. Got back home and measured the fender clearances. Turns out the back end is 1/2" taller than the front. Oops. (Note to self. Measure BEFORE test drive.)

Now Oh Masters of Humiliation, you have the fodder you desire for continued humiliation of myself to keep my rampant ego in check. (Notice that the only recommendation I gave was to measure before the test drive.)

I do want to talk about turn-in, weight balance, weight transfer and it's effect on handling in the corners. I have felt more of the affects of weight transfer while cornering with the softer springs and sway bars I have now, and would like to better understand the best ways to adjust for them. I'll just forget about using the words oversteer and understeer for now.

[KoolBRZ]

Originally Posted by wparsons

You've already been corrected on this twice, but lets make it an even three

The definition of understeer and oversteer mean that one end has to be breaking traction, if not the car is just steering.

You can have all 4 wheels sliding but still be under or over steering as well, so try not to think of it in terms of which tires are sliding.

The easiest way to picture it is by thinking about the radius of the corner you're taking. If the path you're on has a longer radius than it should based on steering input, you're understeering. If the path you're on has a shorter radius than it should based on steering input, you're oversteering.

If the path you're on matches the radius it should based on the steering input, you're just steering.

What about when the understeer/oversteer occurs during/after weight transfer, as in, the weight transfer causes it? The reason I ask is because I think I'm getting weight transfer oversteer. It is more apparent with a softer sway bar than with a stiffer sway bar. Is the right term "weight transfer oversteer", or would it be weight transfer turn-in? It is a repeatable phenomena.

When you describe turning in and the radius being longer or shorter than the turn-in, I think of it as the correction required to keep on the same line through the turn. Do I have to correct at all, that's just steering. Do I have to turn sharper to maintain the same line, that's understeer. Do I have to relax the turn-in to maintain the line, that's oversteer. That's how I think of it.

The rear wheel turning effect I've been talking about is caused by weight transfer. When weight transfer is controlled by a stiffer sway bar, the less weight transfer takes effect, and the less I have to compensate to maintain a line throughout the corner. With a softer rear sway bar, the weight transfer effect is stronger, resulting in my car turning a shorter radius than the actual corner. I have called that "oversteer".

[wparsons]

What do you mean by weight transfer oversteer? It's very easy to cause oversteer by transfering weight to the front tires (lifting mid corner), is that what you mean?

As for feeling what the intended radius is, take a corner at 5km/h and note your steering angle and the path the car takes, that's the intended radius. Then if at speed the radius for the same steering angle is bigger you're understeering, if it's smaller you're oversteering.

One side note, if you're understeering, increasing steering angle just makes the understeer worse. The proper correction is to lift off the gas and back off the steering angle until the front tires are gripping again.

[Hyper4mance2k]

Originally Posted by KoolBRZ

What about when the understeer/oversteer occurs during/after weight transfer, as in, the weight transfer causes it? The reason I ask is because I think I'm getting weight transfer oversteer. It is more apparent with a softer sway bar than with a stiffer sway bar. Is the right term "weight transfer oversteer", or would it be weight transfer turn-in? It is a repeatable phenomena.

When you describe turning in and the radius being longer or shorter than the turn-in, I think of it as the correction required to keep on the same line through the turn. Do I have to correct at all, that's just steering. Do I have to turn sharper to maintain the same line, that's understeer. Do I have to relax the turn-in to maintain the line, that's oversteer. That's how I think of it.

The rear wheel turning effect I've been talking about is caused by weight transfer. When weight transfer is controlled by a stiffer sway bar, the less weight transfer takes effect, and the less I have to compensate to maintain a line throughout the corner. With a softer rear sway bar, the weight transfer effect is stronger, resulting in my car turning a shorter radius than the actual corner. I have called that "oversteer".

I think what you're noticing is the suspension loading up and then car actually turning in. With more roll the turn-in isn't as sharp. Turn-in is how quickly the car responds to the inputs you provide. So... Stock car, you throw the wheel into a turn and the car turns almost as quickly as you turn the wheel. With near perfect turnin you approach the limits quicker and the car is more predictable.
With softer sway bars the weight transfer adds to the amount of time it takes to get the car to turn after the steering input is made. You throw the wheel, the body shifts its weight to the outside wheels, wait..., then the car turns. I think that's what you're talking about. I think you're thinking the car is changing it's turning radius when in actuality you're just noticing the increase in delay between input and reaction. You think the car is turning, but its not; not yet. Then the car bites, and you think more steering input is needed, so you think the car is under or oversteering when it's not. Let the suspension work and let the car settle and see how much input is actually needed.
Too bad you just missed the SCCA Novice autoX school at Bremerton Raceway. Bremerton Sports Car Club also does one. You may want to look into attending a novice day so you can sit with an experienced driver and you can go through inputs and reactions from the car one at a time.
I went to the BSCC novice day in 2005 and it changed my driving for the rest of my life.

edit: I used to do this a lot when I first started racing. I'd throw the car into a tight turn and when the car loaded up, it feels like its starting to oversteer, then I would over-correct. I had my friend sit with me in his Miata and he would yell "let the suspension work," every time I threw his car into a C box, or a really tight radius turn. Once I learned to feel the suspension working it became much easier to control oversteer -when it actually occurred.

[86_Insider]

Originally Posted by KoolBRZ

What about when the understeer/oversteer occurs during/after weight transfer, as in, the weight transfer causes it? The reason I ask is because I think I'm getting weight transfer oversteer. It is more apparent with a softer sway bar than with a stiffer sway bar. Is the right term "weight transfer oversteer", or would it be weight transfer turn-in? It is a repeatable phenomena.

When you describe turning in and the radius being longer or shorter than the turn-in, I think of it as the correction required to keep on the same line through the turn. Do I have to correct at all, that's just steering. Do I have to turn sharper to maintain the same line, that's understeer. Do I have to relax the turn-in to maintain the line, that's oversteer. That's how I think of it.

The rear wheel turning effect I've been talking about is caused by weight transfer. When weight transfer is controlled by a stiffer sway bar, the less weight transfer takes effect, and the less I have to compensate to maintain a line throughout the corner. With a softer rear sway bar, the weight transfer effect is stronger, resulting in my car turning a shorter radius than the actual corner. I have called that "oversteer".

You are over thinking your terminology. Keep it basic, because even the best drivers and engineers around come back to the basics.

There is oversteer and understeer. Doesn't matter where it comes from or what causes them. They are what they are.

There is weight transfer, which can be felt as body roll or slop when a car is soft. There is always weight transfer though, even when a car is stiff. It just isn't as apparent.

Like stated you are just feeling body roll and it makes the rear end feel unstable, especially at higher speeds. That doesn't mean you have oversteer.

We can post back and worth all day, but being in the car with someone is the best way to go. I have had to do it that way plenty of times to give clarification to some of my students.

[Racecomp Engineering]

Originally Posted by KoolBRZ

When weight transfer is controlled by a stiffer sway bar, the less weight transfer takes effect...

All else equal, a stiffer rear swaybar INCREASES rear weight transfer. It correspondingly decreases front weight transfer because total weight transfer remains the same (at least in our all else being equal scenario). This is how you get more front grip from a larger rear swaybar.

That is basic suspension 101.

Please read some books and do some research (just be careful what you read on the internet). It seems like you're really interested in this kind of thing so spend the time to get the basics down before trying to experiment or get into anything more advanced. I'm not saying that to be a ****, but to save you some time and help you approach your next problem in a better way.

I try to not come down on you too hard because honestly I see a lot of people get things wrong...even some well respected names on here. I've been wrong before too and I'm still learning more everyday.

But you would really benefit both in terms of people being annoyed with you less often and spending less time experimenting on set-ups.

Again, kudos to you for being interested in this kind of thing and experimenting, but just work smarter, not harder.

- Andrew

Also, a more technical definition of understeer/oversteer would have the words slip angle in it.

[J.Villain]

Originally Posted by 86_Insider

You are over thinking your terminology. Keep it basic, because even the best drivers and engineers around come back to the basics.

Until you have the car atleast working fairly neutrally in most cases the basics are all you need. You would be surprised to see how far that will get you. Whenyou are learning an autox test n tune day is like a gift from god. Got adjustable shocks? If you do set both ends the same do a run, loosen one end do a run and then set it back and loosen the other end and do a run. Don't have adjustable shocks? Try it with your tire pressure. Drop the pressure on one end 5lbs and do a run and then set it back and drop the other end and do a run. Watch the wear on your tires side walls as well. Mearly changing the tire pleasure may not make a perfect handling car but it can sure break one.

As a plus once you understand that then you will start to understand how adding just a little.more/less brake helps with turn in or a little more/less throttle on exist helps plant the backend making you go faster or lifts the nose making you wash out etc, etc.

You have to understand the macro things before you can start to drill down on the micro things. And believe me very, very well paid people in racing with engineering degrees, support teams, super computers and insane budgets have lost their jobs over the micro things.

[Captain Snooze]

Originally Posted by KoolBRZ

There is also the opinion of many that a stiffer front sway bar causes oversteer, while a stiffer rear sway bar causes understeer, and since there wouldn't be any rear sway bar, then the front sway bar would be stiffer then the rear, wouldn't it?

Why are we having this discussion again? It had been refuted on the 26th Jan.

Originally Posted by Captain Snooze

"a stiffer rear sway bar will greatly reduce the understeer the car experiences."
http://www.americanmuscle.com/overst...explained.html

"If the car understeers a lot, fit a bigger rear sway-bar."
http://www.autospeed.com/cms/article...igans&A=112694

" Increasing the proportion of roll stiffness at the rear axle will have the opposite effect and decrease understeer."
https://en.wikipedia.org/wiki/Anti-roll_bar

"The following steps can be taken to decrease oversteer:... softer rear springs"
http://www.nsxprime.com/FAQ/Track/highperfdriving.htm

"Understeer Corrections....Stiffer rear springs"
http://www.clarks-garage.com/shop-manual/susp-15.htm

"Reducing understeer by adjusting spring rate
Increase rear spring rate - this will increase the rear roll resistance which will reduce understeer but increase oversteer."
http://www.pugaddicts.co.uk/2014/04/...adjusting.html

[Koa]

Originally Posted by KoolBRZ

While you all were (im)patiently waiting for my next reply, I scraped the underside of my bumper twice, and the underside of the midsection of my car once. Determined to raise my lowered car at least 1/4", I adjusted just the preload of my front struts 1 turn tighter, and test drove it. It would have still scraped, but the front end took in the bumps better, more of a thump, then a tha-wump. So determined that more was better, I adjusted the rears 2 turns tighter and lowered the threaded mounts 2 turns, then to lift up the front, adjusted those mounts 4 turns. Took it for a test drive. Wow, back end slides out on the corners now, and the back end kicks a little vicious on the bumps now. Got back home and measured the fender clearances. Turns out the back end is 1/2" taller than the front. Oops. (Note to self. Measure BEFORE test drive.)

Now Oh Masters of Humiliation, you have the fodder you desire for continued humiliation of myself to keep my rampant ego in check. (Notice that the only recommendation I gave was to measure before the test drive.)

I do want to talk about turn-in, weight balance, weight transfer and it's effect on handling in the corners. I have felt more of the affects of weight transfer while cornering with the softer springs and sway bars I have now, and would like to better understand the best ways to adjust for them. I'll just forget about using the words oversteer and understeer for now.

Kool a consistent observation is that you are very intelligent, passionate, and interested in knowing and working with the physical world via automobiles...

One caveat is that you perhaps rely too much on your perception of physics and comparing anecdotal evidence to arrive at a perceived reality before going to other sources to verify what your evidence is saying versus what your brain is signifying that evidence to mean. I do it all the time. Just what I've noticed brotha <3

[Sleepless]

I found that until I did an HPDE school or AutoX, I had very incorrect interpretations of understeer and oversteer. Until the tires actually loose traction, in a safe environment, I don't think it is possible understand or discuss understeer and oversteer.