The understeer cure

[InsanityInc]

Alright, well, unless your car is in good shape and has a lot of power mods so you can power over the car, 240s generally have understeer (FR, what can you expect). But I found a pretty cheap way to fix that. Just get a front strut tower bar (important that you DON'T get a rear one). The improved stability in the front makes the car waaaay more balanced and far easier to power oversteer. However, I do have a hatchback which supposedly has less rear structural rigidity, so this might not be as huge of a difference in a coupe.

[swwifty]

or you could just dial in some negative camber in the front for free and have less understeer and more oversteer

[InsanityInc]

Negative camber doesn't make that much of a difference at all. I'm saying that my car has no real understeer at all anymore. 2 degrees of negative camber in the front isn't going to do that.

[Dattebayo]

Ive noticed that mine is more tossable now that I have a NISMO power brace on the front.

I think it would be even easier if i installed a strut brace.

[InsanityInc]

Ive noticed that mine is more tossable now that I have a NISMO power brace on the front.

I think it would be even easier if i installed a strut brace.

Yeah,what the heck is that thing anyway? I've seen it on the nismo site. And yeah, a strut tower brace takes like 5 minutes to install.

[HashiriyaS14]

Honestly, probably the easiest and cheapest way of dialing this in (to a certain extent) is with tire pressure.

I was able to drastically alter the handling of my WRX with tire pressure adjustments (along with some slight tinkering with the stock camber adjustment bolts).

I run fairly even and stiff tire pressure for daily driving, however you can always make those fronts softer and rears harder for when you want to swing the tail out (*not* recommended for highway driving at all).

[swwifty]

negative camber on a car will make a huge difference if it already has none. If you already have -2 to -3 in the front, try taking some negative camber out in the rear. Tire pressure is a good way to do small adjustments to car handling. You can't adjust too much with tire pressures because then you will get too much rollover if you go too low.

Besides, a front strut tower bar should only make the car understeer more, not oversteer. In my experience I've found that tower bars are worthless. You'd be better off getting swaybars, or new spring rates.

[Dattebayo]

The NISMO power brace replaces the 2 tension rod brackets with a single unit exactly the same as the brackets with a big strong bar welded between them; connecting them together in the corners.

It made the front handling real responsive and the front body hardly flexes at all in tight turns. Easy as hell to put in too...

[InsanityInc]

negative camber on a car will make a huge difference if it already has none. If you already have -2 to -3 in the front, try taking some negative camber out in the rear. Tire pressure is a good way to do small adjustments to car handling. You can't adjust too much with tire pressures because then you will get too much rollover if you go too low.

Besides, a front strut tower bar should only make the car understeer more, not oversteer. In my experience I've found that tower bars are worthless. You'd be better off getting swaybars, or new spring rates.

Sorry, but a 5ish mm bigger contact patch under hard cornering at best isn't going to dramatically change your handling. And if strut tower bars are worthless in your experience, then you have crummy experience (though, they do have notably less effect on cars with transverse engines as the front area of the car is generally more rigid due to the much smaller engine bay). Not to mention how would improving the dynamic capabilities of your front suspension increase understeer? You are aware that understeer occurs when the front starts losing traction, right? A strut tower bar does quite a lot to prevent deformation of your suspension geometry, which is very important.

[swwifty]

I'm not looking to get into a flame war with you, but I do have a bit of experience in setting up suspensions.

I know what understeer is, thanks. The bigger the contact patch is = the more grip on that tire (as a rule of thumb). If you make the front end of a car stiffer its going to understeer more. I agree to a certain extent that it helps maintain suspension geometry, and it will help keep the chassis more rigid; however, it can cause the car to understeer more.

How are you judging the performance of these parts? Track, Autocross?

[InsanityInc]

I'm not looking to get into a flame war with you, but I do have a bit of experience in setting up suspensions.

I know what understeer is, thanks. The bigger the contact patch is = the more grip on that tire (as a rule of thumb). If you make the front end of a car stiffer its going to understeer more. I agree to a certain extent that it helps maintain suspension geometry, and it will help keep the chassis more rigid; however, it can cause the car to understeer more.

No, it really won't cause it to understeer more. By your logic, putting 205s on the front and 255s on the back would make a car oversteer. Which is completely wrong. By putting in a front strut tower brace, you increase the limits of the front of the car, making it much harder for the front to break traction. If your front is solid and your rear is breaking traction, you get oversteer.

[skydragoness]

No, it really won't cause it to understeer more. By your logic, putting 205s on the front and 255s on the back would make a car oversteer. Which is completely wrong. By putting in a front strut tower brace, you increase the limits of the front of the car, making it much harder for the front to break traction. If your front is solid and your rear is breaking traction, you get oversteer.

Post this topic in the Suspension forum and see what Chet says The strut tower bar obviously made a difference, but I would be interested to see if someone put a aftermarket sway bar on the front only and see if understeer diminished or increased.

[InsanityInc]

Sway bars are a whole different animal though. They do increase the rigidity of the front like the tower bar, but they also have the negative effect of reducing the independentness of the front suspension which could probably lead to a very on/off understeer condition.

[swwifty]

I think your totally misunderstanding me. Did you see my first post? Do you not agree with that? If you don't use alignment to tune how a car handles at all, then your not left with much else. Spring rates, swaybars, tire pressures, tire sizes, and a few other misc. things.

How are car handles depends on A LOT of factors. I agree with you that a car with wider tires in the rear will not oversteer, it will be more prone to understeer with smaller width tires in the front. I think your mis-understanding my logic. If you put a stiffer swaybar up front, higher spring rates in the front, or a strut tower bar, it will make the car less willing to turn. In my experience strut tower bars have minimal effect on how a car handles. A strut tower might make the car more responsive to steering input. It'd start somewhere else if I was looking to make a car handle better.

I'll ask again, how are you judging if the car is handling better or not?

[InsanityInc]

If you put a stiffer swaybar up front, higher spring rates in the front, or a strut tower bar, it will make the car less willing to turn.

Oh, you had it until you threw in the strut tower bar. A strut tower bar and a sway bar do not do the exact same things. Putting a bar across your chassis has a completely different effect from putting a bar connecting a travelling part of your struts.

Quote »In my experience strut tower bars have minimal effect on how a car handles. A strut tower might make the car more responsive to steering input. It'd start somewhere else if I was looking to make a car handle better.[/quote]And what does your experience include? It would seem that car manufacturers disagree with you, as many newer sports cars are coming from the factory with strut tower braces.

Quote »I'll ask again, how are you judging if the car is handling better or not?[/quote]By driving the car.

[swwifty]

Oh, you had it until you threw in the strut tower bar. A strut tower bar and a sway bar do not do the exact same things. Putting a bar across your chassis has a completely different effect from putting a bar connecting a travelling part of your struts.

I agree with you that it increases the stiffness of the chassis, but that stiffness can cause understeer.

Quote »And what does your experience include? It would seem that car manufacturers disagree with you, as many newer sports cars are coming from the factory with strut tower braces.[/quote]Tuning real race cars, and my own personal car for autocross and the track. Car manufacturers setup cars to understeer from the factory. Most people are unaware of how to control a car at the limit, so cars are setup to understeer from the factory at the limit. Why? Because most people hit the brakes when they loose control of a car which will help regain control of a car that is understeering. If they were setup to oversteer from the factory people would instantly wreck from hitting the brakes while oversteering.

Quote »By driving the car.[/quote]Sometimes a car can feel faster and actually be slower.

[skydragoness]

And what does your experience include? It would seem that car manufacturers disagree with you, as many newer sports cars are coming from the factory with strut tower braces.

I'm kind of watching this thread, but i'd like to point out that the 93-97 Corolla had very unpredictable handling at the limit for a fwd car. Toyota fixed the problem by adding a strut tower brace for the 98-01 year and onwards.

[Veriest1]

Quote »

By driving the car.

Sometimes a car can feel faster and actually be slower.[/quote]

A better question would have been, have you noticed an increase in RPM's at corner exit or the need to enter corners in a higher gear since doing this mod? If the strut tower bar did correct some understeer (most likely by keeping the tire in contact with the road and preventing massive chassis flex in a approximatly 10 year old car and allowing the suspension to work better) then one of these situations will have occured.

However, you still need the rear bar as this will be a patch it type fix and you'll get better handling out of a good suspension set up with coilovers/spring and shock combos and/or adjustable swaybars. If my suspsions are correct your front suspension if now doing more work than the rear and if it's the stock suspension you probably need to start replacing things so it can do the work rather than breaking.

Quote »It would seem that car manufacturers disagree with you, as many newer sports cars are coming from the factory with strut tower braces.[/quote]They were putting strut brace type devices on cars back in the 60's. My dad's stock (and in need of some TLC) '65 Mustang has braces going from the sides of the engine bay to the firewall. So it's not just newer cars.

[quot... oh forget it....

Camber has a large effect on how a car handles because a contact patch that is 5mm larger is a big deal when talking about the limits of the car. A good example of this would be banked turns. When a turn is banked to the inside the speed through said corner can be exceedingly higher than that of a corner of the same radius but flat instead of banked.

Edit: Quote »Alright, well, unless your car is in good shape and has a lot of power mods so you can power over the car, 240s generally have understeer [/quote]You will still have understeer. What you're talking about is inducing oversteer through power to "counter" the understeer so to speak. It usually works and the same thing can be done with a low power car through trail braking.

Edit 2: There was a really good thread about this over in the suspension forum a month or so ago... I'm trying to dig it up.

[InsanityInc]

Quote »Sometimes a car can feel faster and actually be slower.[/quote]Yes, but see with the magic of my speedometer/tachometer, I can concretely say my car does in fact handle better. And I can very easily recognize that the car has much more neutral handling and is more prone to oversteer, by that floating sensation the back end gets when it starts to oversteer and by the way that the car exits turns.

Quote »You will still have understeer. What you're talking about is inducing oversteer through power to "counter" the understeer so to speak. It usually works and the same thing can be done with a low power car through trail braking.[/quote]Well, yes, techincally you still have understeer, but in practical terms when you're power oversteering you no longer have understeer.

[Veriest1]

Quote »Yes, but see with the magic of my speedometer/tachometer, I can concretely say my car does in fact handle better. And I can very easily recognize that the car has much more neutral handling and is more prone to oversteer, by that floating sensation the back end gets when it starts to oversteer and by the way that the car exits turns.[/quote]I suspected that's what you were doing. And on the induced oversteer thing I was just trying to make it a bit clearer. It seemed obvious that you knew what you were talking about.

Here ya go... zerothread?id=102471

Quote »courtesy of team integra

strut barI see it all the time, people talking about all sorts of different bars claiming their Integra has superior handling to a McLaren F1. Well at least they have the power of possitive thinking on their side.

It's important to know exactly what types of bars are available and what their functions are. There are 6 different types of bars available for the Integra, 4 of them to stiffen the chassis and 2 to dictate cornering balance. This article covers the 4 strut/tie bars which work to stiffen the chassis. Information on the other 2 bars can be found in my Sway Bars article.

The main purpose of these bars is to brace the chassis at critical points. Normally during hard cornering the chassis will twist and flex due to the immense amount of force generated by 2600 lbs of metal wanting to move in a different direction than you are steering it. What this translates to is sluggish handling, and the chassis will end up playing catch up with itself.

All opposing forces to the chassis however come directly from the suspension components, so the solution is to brace both ends of the suspension together. If the bars do their job, the chassis will be held tightly together, and the forces that were once flexing the chassis are now going into turning the vehicle. This results in more responsive handling, and the vehicle will be able to make sudden changes in movement much quicker.

1. Front Upper Strut Tower BarConnects the front strut towers in the engine bay. The most popular bar that enthusiasts purchase mainly because of it's effect to the looks of the engine bay. Be wary though, just because it looks nice doesn't mean it will perform. For front-heavy cars such as ours the chassis will undergo the majority of flexing in the front and a quality bar on top is a must. The Integra GS-R and Type R come stock with this kind of bar.

2. Rear Upper Strut Tower BarConnects the rear strut towers in the trunk. Same effect as the front upper bar. The JDM Integra Type R comes with this bar stock.

3. Front Lower Tie BarConnects the lower front control arms. The least popular bar due to minimum availabilty and that it's the only strut/tie bar that you cannot show off. Not only that, but for lowered cars ground clearance can be an issue as it will have to hang down further than anything else under the car. There are only a few companies who offer this bar for Integras. Neuspeed makes a front lower tie bar for the non-vtec Integras while Spoon and Cusco make one for all applications, thanks to member b18c2 for the info on that.

4. Rear Lower Tie BarConnects the lower rear control arms. Also a popular bar due to it being visible from outside the car and will stiffen the rear without taking up space in the trunk. The problem I see with most Honda/Acura drivers is that they all have those shiny DC Sports bars which are too flimsy to actually do anything performance-wise. If you are not going for the rear upper strut bar due to trunk space issues at least get a good quality tie bar to make up for it. The Integra Type R comes stock with this kind of bar.

Quality bars to look for would be Mugen, Spoon, Neuspeed and Comptech. Bars to stay away from that will have no effect on performance would be DC Sports, APC, OBX, and any cheap no-name brand.

While all of these bars combined do a great job in stiffening the chassis and increasing cornering response, they still won't prevent body roll or "leaning" of the chassis. They also will not change the cornering balance of the vehicle. I've heard people say that a strut bar will "minimize understeer" however this is not true. The chassis may be held together tightly but it is still free to shift it's weight upon cornering. That's where the 2 other bars I mentioned earlier called sway bars come into play. More information on that can be found in the Sway Bars article.

sway barOtherwise called anti-roll bars, sway bars will make the most dramatic difference in your Integra's handling characteristics. The main purpose of sway bars are to reduce body roll. Sounds simple, but the effects of simply reducing the body roll of a vehicle are many.

A sway bar consists of the main portion which attaches directly to the chassis by bushings (allowing the bar to twist), and lever arms which connect to both sides of the suspension through end links.

When one side of the suspension compresses, the lever arm moves downward causing entire the sway bar to twist so the lever arm on the opposite side also attempts to move the same direction and compress it's own side as well. This resistance to movement increases the spring rate of your suspension when cornering. When both sides of the suspension are equal, the sway bar will have no effect. Here is a chopped down and simplified diagram of how the sway bar works.

Of course no sway bar is perfectly rigid, differences in suspension travel on opposite sides of the vehicle will still occur, so a sway bar can be thought of being a big spring. The bar is able to bend and flex as needed.

There are many benefits from a sway bar's effects of resisting opposite suspension travel.

The most stand out benefit that everyone talks about is the ability to change a vehicle's handling characteristics. Excluding the Type R, our front-wheel drive Integras come stock with pretty heavy understeer. This characteristic can be observed during accleration through a hard corner. The vehicle will have a tendancy to "plow" forward not turn as well as desired by the driver. Most will suggest that this can be solved with a larger sway bar in the rear. But why?

Roll stiffness determines the cornering load at any given end of the vehicle. In a corner, with a stiffer front and flimsy rear, centrifugal force will throw the majority of the weight of the vehicle to the rear. This will cause the chassis to lean upward in front, removing weight from the front wheels and effectively losing turning traction. With both a stiff front and stiff rear, the weight is balanced properly on both ends, and neutral handling is achieved.

Another side benefit is steering response. The further the body rolls, the longer it takes for the vehicle to become stable into a turn. With less body roll, steering response is greatly increased as the car will set in to a turn much quicker with less suspension travel. The quicker a vehicle finishes it's suspension travel, the quicker it can respond to new steering inputs by the driver.

Honda's suspension geometery is also subject to change depending on the height of the chassis in relation to the axle. When body roll occurs, changes in toe and camber also occur. This is okay to a degree, but when suspension travel has reached an extreme level, you can bet your suspension geometery is not where you want it to be for optimum handling performance.

Lastly, reducing the body roll will help the driver to maintain balance in the cockpit and concentrate on driving. The centrifugal forces of the corner are already pulling on the driver hard enough, when the car leans over the driver is then also subject to the force of gravity.

Sway bar sizing

The diameter of a sway bar determines it's stiffness. You can compare the stiffness of your stock sway bar to a bar you are thinking of purchasing by using a simple formula.

% stiffness compared to stock = (new diameter/stock diameter)^4

For example, if you have a GS-R with a 14mm rear sway bar and upgraded to a 22mm Type R rear sway bar you would calculate

(22/14)^4 = 6.10

This means a 22mm sway bar is roughly six times as stiff as the stock sway bar. Big difference don't you think? Subtract 1 at the end of that equation and you'll get a figure telling actually how much stiffer the bar is. So in that equation you'd come out with 5.10 or 510% stiffer than stock.

It's important to make sure the company you are buying your sway bar from includes proper mounting hardware. Stiff sway bars can easily tear out of the chassis during a hard corner if not mounted properly and your spring rates are too low to assist the bar in minimizing suspension travel. From what I know off hand, Comptech's sway bar is very good and comes with proper mounting hardware and will not tear out of the chassis. Comptech even guarantees it. Also BSQ makes a kit to allow a Type R rear sway bar to mount onto a non-Type R chassis so it will not tear out.[/quote]I figure the reduction of understeer you've seen is the result of taking out A LOT of chassis flex that was causing your suspension to not function properly. That was the gist of my previous post but it's a little more simplified there and hopefully people won't think I'm contridicting myself to badly now.

[Veriest1]

Another way to cure understeer... zerothread?id=114680

Quote » Yeah, I love the way it handles. Doing the math paid of in spades on it, as a few of the SEDA guys can attest. The PS2's are sick grippy, and matched spring rates and shock dampening make for smooth, but quick transitions. Also the slightly lower front v. rear stance helps remove the slight bit of understeer it had, not I can feel the front push just a tad before I feel the outer rear start to lose grip if I put more throttle into it...very nice and predicatable.[/quote]

[InsanityInc]

I figure the reduction of understeer you've seen is the result of taking out A LOT of chassis flex that was causing your suspension to not function properly. That was the gist of my previous post but it's a little more simplified there and hopefully people won't think I'm contridicting myself to badly now.

Oh, I pretty much guarantee that's exactly why. Especially when you consider that the car has a pretty long hood, and the strut towers are about in the center of the bay, making them fairly unsupported. As opposed to say their location in something like a minivan (right next to/part of the firewall). I imagine that s13s just have a chassis design flaw there that can easily be corrected and to great effect.

[Veriest1]

Having the strut towers further out keeps the engine behind the wheels much better and allows for better handling. It's not a design flaw really but, rather, the way it should be.

Notice in this pic how little car is in front of the wheels on my M3. That's right very little fender and mostly plastic. The radiator actually almost sits between the tires. That's part of the reason people love these cars.

[Veriest1]

Look at the way this GT3 spec 240 is set up. The entire engine bay has been moved back. To sit behind or between the tires/shock assembly.

[Veriest1]

This is a W Body Saturn called the Intrigue (I think that's the name) ... essentially a Grand Prix. No matter how much this bay has been moddified the engine still hangs out in space and tries to push hold the car inline when ever the wheels are turned.

[Nismo_Freak]

Negative camber doesn't make that much of a difference at all. I'm saying that my car has no real understeer at all anymore. 2 degrees of negative camber in the front isn't going to do that.

2 degrees of negative camber will make a large difference in the way the car handles on the limit. Especially in a 240, where the front suspension has horrible camber gain aspects. The key in a 240 is a relatively large amount of static negative camber paired with a good amount of caster angle to facilitate the dynamic camber gain.

Sorry, but a 5ish mm bigger contact patch under hard cornering at best isn't going to dramatically change your handling. And if strut tower bars are worthless in your experience, then you have crummy experience (though, they do have notably less effect on cars with transverse engines as the front area of the car is generally more rigid due to the much smaller engine bay). Not to mention how would improving the dynamic capabilities of your front suspension increase understeer? You are aware that understeer occurs when the front starts losing traction, right? A strut tower bar does quite a lot to prevent deformation of your suspension geometry, which is very important.

I find it incredibly ironic that you are argueing that camber doesn't "drastically" affect car balance, yet you claim a strut bar will change the attitude of the car.

You should read further into the strut bars purpose, you will find that it reduces dynamic camber loss by not allowing the strut towers to pull apart.

Understeer happens when the slip angle of the front exceeds the rear slip angle. The car does not have to exceed the tires sticksion limit in order to have an understeering situation.

5mm of contact patch is a good amount.

No, it really won't cause it to understeer more. By your logic, putting 205s on the front and 255s on the back would make a car oversteer. Which is completely wrong. By putting in a front strut tower brace, you increase the limits of the front of the car, making it much harder for the front to break traction. If your front is solid and your rear is breaking traction, you get oversteer.

You can setup a car with 195's in the front and 375's in the rear to oversteer like it's on ice.

Tire sizing is meerly a guideline to go by, not the end all.

The key is getting the lowest load index, and lightest tire, you can run for the amount of duty the tire will see in terms of loading. Air pressure modulates the load index of the tire ultimately.

Likewise, you can install a complete 20-pt. roll cage and that doesn't necessarily mean the car will handle better. You still have to tune the chassis inline with the suspension setup.

Sway bars are a whole different animal though. They do increase the rigidity of the front like the tower bar, but they also have the negative effect of reducing the independentness of the front suspension which could probably lead to a very on/off understeer condition.

Sway bars don't increase rigidity. They have very little static rigidity due to the endlinks, they are built as torsional "springs".

You are correct about the independent operation, but the snap over/understeer situation is when you have improperly matched dynamic rates (spring rate vs. sway bar rate). Most racing springs add linear wheel rate whereas the sway bar is a torsional device, meaning it will add wheel rate progressively. When you have soft springs and aftermarket sways you will have quite a bit of body roll momentarily due to the sway providing low rates until it is loaded. This sudden travel loads the sway quickly and the wheel rate gains very quickly, whereas if the springs were stiff you get more of a linear (yet still progressive) rate gain; making the car more stable.

The rate of a bar is dictated by the diameter, there is also a bigger difference in rate between a 20 and 21mm bar than a 13mm and 14mm bar.

[Veriest1]

Quote »The key in a 240 is a relatively large amount of static negative camber paired with a good amount of caster angle to facilitate the dynamic camber gain.[/quote]Those who autocross stock class Miatas typically have as much caster as possible dialed in and then dial in as much camber as they can with their stock suspensions limited tuning capabilities. Would this be for the same reason or only for a "faster turn in" as some have claimed (not in this thread or even this forum) on tight auto-x courses. And should such an approach be used on 240's? Your wording makes it seem as if negative camber is more important on 240's and I'd just like to be sure of what you were saying.

[Nismo_Freak]

Those who autocross stock class Miatas typically have as much caster as possible dialed in and then dial in as much camber as they can with their stock suspensions limited tuning capabilities. Would this be for the same reason or only for a "faster turn in" as some have claimed (not in this thread or even this forum) on tight auto-x courses. And should such an approach be used on 240's? Your wording makes it seem as if negative camber is more important on 240's and I'd just like to be sure of what you were saying.

Well on a stock class, you want to run like that.

On a highly modified car you need to run some testing on your camber setup and make alterations from there.

[HashiriyaS14]

Look at the way this GT3 spec 240 is set up. The entire engine bay has been moved back. To sit behind or between the tires/shock assembly.

The engines in those are amazing. SOHC KA24's that make like 300hp@10,500rpm. I waaaaant one.

[Nismo_Freak]

The engines in those are amazing. SOHC KA24's that make like 300hp@10,500rpm. I waaaaant one.

The engine does not get revved that high during the race. It would be highly highly unreliable.