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Discussion Starter #1
Ok, first things first.
What is UNDERSTEER: well here is the text book definition:
Understeer is a term for a car handling condition during cornering in which the circular path of the vehicle's motion is of a markedly greater diameter than the circle indicated by the direction its wheels are pointed. The effect is opposite to that of the oversteer and in simpler words understeer is the condition in which the front tires don't follow the trajectory the driver is trying to impose while taking the corner, instead following a more straight line trajectory.
This is also often referred to as pushing, plowing, or refusing to turn in. The car is referred to as being 'tight' because it is stable and far from wanting to spin.
As with oversteer, understeer has a variety of sources such as mechanical traction, aerodynamics and suspension.
Classically, understeer happens when the front tires have a loss of traction during a cornering situation, thus causing the front-end of the vehicle to have less mechanical grip and become unable to follow the trajectory in the corner.
What it looks like via a picture:

In lamens terms: when you turn a corner and the front wheels loose grip and you end up going straight.

Why I wrote this post: while I was at my local track before I got my rear shocks re-valved (stiffer) I noticed that my Mazda 6 had a ton of understeer.. as many of you probably already know.. I would go into the turn and then my tires would refuse to turn and I would have to take my foot off the throttle or tap the brake to stop the tires from breaking from the tarmac.
Let’s start off on how my car is set up..
It’s a 03 mazda 6i with 4speed atx
130hp/tq without nitrous (cant use it on circuit track)
stock rims, and Yokohama YK420 tires
weight with me in it was 3050lbs. (my car is striped)
rotora oem rotors, bendix Ct3- Ceramic brakes pads front and back
suspension setup TEIN basic coilover system (rear shocks revalved due to blow out) 2 inchish drop, and stut bar up front.
not the best set up car for circuit track but good enough to learn what to do and what not to do:
With that said I have been to driving school I do know about turning and such. But for those who don’t… there are 3 main features of a standard corner:
turn-in, apex and exit.
Turn-in is, like it sounds, the broad term given to pointing the car into the corner.
The apex or 'clipping' point is the corner's neutral point, the place where the transition between entry and exit is made.
And the exit phase is where the driver will blend the throttle back in as the steering is progressively wound off
The correct usage of a turn with a car with oversteer:

most pros say that the best way to eliminate understeer is to let up on the throttle on your Turn-in, thus shifting the weight back to the front tires and giving them more taction and then gradually getting back on the throttle during the apex and then be wot on the exit move.
Works very good…
What not to do I found out:
tapping the break before a turn does the same basic thing in theory… but the weight transfer is so much great that you actually loose grip from the rear tires thus creating over-steer. (just as bad on a front wheel drive car with not so much hp/tq) and you will most likely find yourself in a 360 degree spin-out.


So that’s the basics of keeping understeer out of the equation on the track…
And here are some products that will help your 6 handle the turns better as well. (just remember that the car is only as good as the person who’s driving it)


Wheels… stickier then better…. If you can afford it. Go with stickies.

Suspension: there are tons of suspension companies that make coilover kits for our cars. Replacing spings alone wont do much, by it self, besides lowing the cars center of gravity which is a plus.. here’s a link to a topic on that: http://forum.mazda6club.com/index.php?showtopic=39938

Brakes… slotted are best I was told.. it vents the gasses out of the pad/rotor and they stay cooler longer.. stainless steel lines also reduce the sloppiness feeling of the brake pedal… if you have money there are a few big brake upgrades for our cars: here is the link from our favorite vender around this forum:
http://www.therpmstore.com/product_info.ph...products_id=130

and various other braces(ie. Strut, sway, tower, ladder, trailing) can all be found here: http://corksport.com/store/category/5iwn/a...nsion_misc.html and will all aid in making the chassis stiffer, which means the reduction of body role.

Another thing that will help out a bit is downforce… as gay as these may or may not look.. these and parts like these actually help:

they push your font end down during good speed thus keeping your weight of the car on the front end and the tires on the ground…
There is my $.05 of the topic.. others please ad their $.02 to this.. let’s get this topic under control!
WE NEED NOT FEAR THE UNDERSTEER!
 

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Awesome info... That early apex was killing me w/ the Impala SS at Rev it up... The car was stock of course and the weight transfer would screw me up everytime!

Now in the cobalt SS I did fine... It was easier to throw around I guess...

Very good information just for everyday driving as well... Something everybody should figure out and live by!
 

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Chambers, your post reads like an advertisement for every damn aftermarket part ever made! Calm down, man- buy yourself a larger rear sway bar and be done with it.

What not to do I found out:
tapping the break before a turn does the same basic thing in theory… but the weight transfer is so much great that you actually loose grip from the rear tires thus creating over-steer. (just as bad on a front wheel drive car with not so much hp/tq) and you will most likely find yourself in a 360 degree spin-out.
So that’s the basics of keeping understeer out of the equation on the track…[/b]
Just lifting on the throttle is usually enough. Any transition towards loading the front will cause a moment of oversteer until the front tires become loaded.

And here are some products that will help your 6 handle the turns better as well. (just remember that the car is only as good as the person who’s driving it)
Wheels… stickier then better…. If you can afford it. Go with stickies. [/b]
Stickier tires do not inherently decrease understeer unless you're running them up front only. Tires with a higher saturation point do. So, look for tires with a higher load rating so they'll deal with the high loads the front tires see more effectively. Wider tires typically do this. In addition, the tread on a wider tire will tend to deform less (have a lower slip angle), decreasing understeer even within the tire's limits.

Stickier tires add grip. Everywhere. Adding it equally front and rear doesn't change the behavior of the car, it just changes its limits. That said, sticker tires are usually MUCH less progressive, so they're far harder to learn to drive on.

Suspension: there are tons of suspension companies that make coilover kits for our cars. Replacing spings alone wont do much, by it self, besides lowing the cars center of gravity which is a plus.. here’s a link to a topic on that: http://forum.mazda6club.com/index.php?showtopic=39938[/b]
The best way to counteract understeer is with roll resistance in the rear. Firm rear springs, firm rear sway bars. Adding camber up front helps a ton too. However, don't automatically assume that any suspension upgrade will help. Tein coilovers certainly don't offer much help, for example.

An otherwise stock Mazda6 with a RB rear sway is awesome. Actually, anything with the RB rear sway is great. A rear sway, Racing Beat or not, should be one of the very first upgrades for the Mazda6.


Brakes… slotted are best I was told.. it vents the gasses out of the pad/rotor and they stay cooler longer.. stainless steel lines also reduce the sloppiness feeling of the brake pedal… if you have money there are a few big brake upgrades for our cars: here is the link from our favorite vender around this forum:
http://www.therpmstore.com/product_info.ph...products_id=130[/b]
You were told wrong. Slotted brakes will not prevent understeer. They are inferior to blank discs and marginally better than drilled brakes, which are by far worse than blanks. Stick with blanks- they're cheaper and better, a win-win. With a 120mph speed limiter, the stock brakes rotors are adequate once mated to high-temp brake pads. You'll always be able to lock all four wheels.

and various other braces(ie. Strut, sway, tower, ladder, trailing) can all be found here: http://corksport.com/store/category/5iwn/a...nsion_misc.html and will all aid in making the chassis stiffer, which means the reduction of body role.[/b]
Making a chassis stiffer does not in any way prevent body roll. It allows your dampers to work better. Chassis flex is undamped and therefore bad. However, don't expect chassis braces to make much of a difference unless you're running seriously stiff, well-valved shocks.

Body roll is a function of weight transfer and roll resistance, a somewhat complicated subject. Lowering your car actually increases its tendency to roll. The easiest way to reduce roll is with firmer springs and sways.

Another thing that will help out a bit is downforce… as gay as these may or may not look.. these and parts like these actually help:

they push your font end down during good speed thus keeping your weight of the car on the front end and the tires on the ground…[/b]
Aerodynamics aren't going to help much because understeer presents itself most at lower speeds where aerodynamics don't have much effect. You get lift in the rear at speed, and that's generally sufficient to balance the car out without any tacky aftermarket add-ons.

WE NEED NOT FEAR THE UNDERSTEER!
[/b]
I fear the understeer.

My car was tuned such that lifting in a turn caused drastic rotation. I had to brake in a straight line and stay on the throttle mid-turn to keep the car neutral. It was fantastic. Lifting on the throttle caused the car to turn-in incredibly fast, so I could essentially steer the car with a throttle.
 

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Discussion Starter #4
i was hoping you would chim in stretch.. good point on the tires... forgot to mention that.

also.. about the brakes.. i knewsomeone was going to call me out on that.. the reason i put that slotted are better then oems are ingerneral they keep a the heat off the brakes a little better. ala.. less fadding.

and your also right about the areodynamics... but every little bit does add up.
 

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Yikes.

Slotted brakes will not prevent understeer. They are inferior to blank discs and marginally better than drilled brakes. Stick with blanks.

Sticker tires do not inherently decrease understeer unless you're running them up front only. Tires with a higher saturation point do. So, look for tires with a higher load rating so they'll deal with the high loads the front tires see more effectively.

Aerodynamics aren't going to help much because understeer presents itself most at lower speeds where aerodynamics don't have much effect. You get lift in the rear at speed, and that's generally sufficient to balance the car out without any tacky aftermarket add-ons.

The best way to counteract understeer is with roll resistance in the rear. Firm rear springs, firm rear sway bars. Adding camber up front helps a ton too.

An otherwise stock Mazda6 with a RB rear sway is awesome.
[/b]
Stretch, was is the best MOD for the 6? RB's rear sway, IIRC
 

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Discussion Starter #6
straight from rotora:

Basic OEM Disc: Developed with the same parameters as the original equipment in both quality and finish. For daily driving, basic OEM disc is preferred.

Slotted Disc: Segmented slot pattern for improved pad grip and pedal feel. Cleans away debris between pad and disc. Minimize warpage and brake fade resistance. Ensures maximum heat and gas dissipation. For more severe applications (including SUVs), slotted is preferred.

Drilled & Slotted Disc: Segmented radius drill & slot pattern for improved pad grip and reduce noise. Cleans away debris between pad and disc. Ensures heat and gas dissipation. For street and light track use, drilled & slotted is preferred.
 

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straight from rotora:

Basic OEM Disc: Developed with the same parameters as the original equipment in both quality and finish. For daily driving, basic OEM disc is preferred.

Slotted Disc: Segmented slot pattern for improved pad grip and pedal feel. Cleans away debris between pad and disc. Minimize warpage and brake fade resistance. Ensures maximum heat and gas dissipation. For more severe applications (including SUVs), slotted is preferred.

Drilled & Slotted Disc: Segmented radius drill & slot pattern for improved pad grip and reduce noise. Cleans away debris between pad and disc. Ensures heat and gas dissipation. For street and light track use, drilled & slotted is preferred.
[/b]
Chambers, the subject has been beaten to death and I don't care to partake in another brake discussion. Slotted or drilled brakes are inferior to blank disks on this car. Any good vendor who personally races will inform you of this. Ask BrakeSwap or [email protected] Brake companies sell slotted and drilled rotors for the look, and ultimately that's what sells best. Big brake kits can get away with this because the BBK sizes are such overkill, but they're still much more prone to failure than blanks of similar size. Slotted/drilled OE-size rotors are a huge no-no. Your spelling is probably correct: slotted "breaks".

Like I said, I'm not willing to discuss this. It's been beaten to death already- you can believe the people who actually race or the the people trying to sell you something. Your choice. In any event, the discussion does not belong in an understeer thread.


Stretch, was is the best MOD for the 6? RB's rear sway, IIRC
[/b]
msumlin, rear sway. Racing Beat. It's not the best fitment, but it sure does work. I loved that thing. Any larger-than-stock rear sway would be a drastic improvement though.
 

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like stretch said, rear swaybar. done.

it fixed my v6 pretty good.

now i want linear springs so i can properly load the car in a corner and have a better feel for when the car is going to brake away oversteering.
 

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Discussion Starter #9
understeer is dangerous! it single handedly hacked this website! crazy shit!
 

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also, if you still fear understeer, trailbrake into a corner. :)
all the oversteer you want.
if you do it right.

another technique would be left foot braking. :) that is awesomeness.


wow weird double.
 

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most pros say that the best way to eliminate understeer is to let up on the throttle on your Turn-in, thus shifting the weight back to the front tires and giving them more taction and then gradually getting back on the throttle during the apex and then be wot on the exit move.
Works very good…[/b]

This works for me with my 3.0 v6 and MTX. The rear end starts to come out, just a little when I apply the gas at mid/late apex. Fun!!
 

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and various other braces(ie. Strut, sway, tower, ladder, trailing) can all be found here: http://corksport.com/store/category/5iwn/a...nsion_misc.html and will all aid in making the chassis stiffer, which means the reduction of body role.
[/b]
Another suspension/chassis part that will go a long way in diminishing chassis flex , a part commonly used in the Mustang world ; ''subframe connectors'' (metal bars between and welded to your front & rear frames)
Making a chassis stiffer does not in any way prevent body roll. It allows your dampers to work better.
Chassis flex is undamped and therefore bad. However, don't expect chassis braces to make much of a difference unless you're running seriously stiff, well-valved shocks.
[/b]
..........

You were told wrong. Slotted brakes will not prevent understeer. They are inferior to blank discs and marginally better than drilled brakes, which are by far worse than blanks. Stick with blanks- they're cheaper and better, a win-win. With a 120mph speed limiter, the stock brakes rotors are adequate once mated to high-temp brake pads. You'll always be able to lock all four wheels.
[/b]
You are going to have to drive your car pretty hard and apply extreme pressure with the 6 to have the brake pads 'gas up' .... we're talking real horsepower here ! ..... brake pads do not 'glaze' and emit gases since the mid '1980's .... it's just marketing propaganda passed on one generation to the next brainwashing us all (including mild racers) .....

..... Add to that , that we love modifying our cars , addiing better looks to it and distinguishing ourselves from the boring rest and the vendors have a winning formula with us .

Take ANY contact % off the rotor and you have loss of braking % ..... that is why blanks are better (for us) ...... and that is why slotted are preferred by REAL racers compared to drilled/slotted & drilled . Besides other factors such as heating - cross-drilled- will heat up much faster(as well as cool down quicker) therefore be vulnerable to cracking especially when not drilled in the right reinforced area of the rotor !

As a professional diploma trained semi truck driver , let me part with you my knowledge on these points :

we do not have these exotic rotors on our rigs , and think about it .... all the heat created by the sheer friction of the weight of our rigs .... now multiply this downhill ! The heat created is phenomenal ! And the way to minmize it is to brake beforehand and certainly NOT by applying/realeasing brake pressure multiple times downhill as this will be far worse than just keeping applied lighter pressure all the way necessary and then letting go to cool once & for all .

Let me illustrate my point on the NOTs : you're going downhill .... you apply brake press. harder cause you've accumulated speed , then you let go once reduced .... then you pick up speed once more ... and all over you redo the latter multiple times . Well ! You end up heating & glazing (due to heated pads letting off gases resulting in loss of contact between pad & rotor-gases are in between preventing applied pressure) your pads & rotors with extreme heat 'cause of the more intense brake-pedal pressure applied momentarily combined with letting off pressure of brake pedal = feeding oxygen to an already very hot pad & rotor resulting in more intense heat - as if feeding air to fire !

Now what TO DO, by applying pressure before downhill ... and then with a lower gear and with continued applied LIGHTER pressure all the way down (until not needed) will be a lot safer causing a lot less heat and not running out of brakes once downhill .....

.... for a curve ; you brake in the straight beforehand ..... and then once proper speed in the apex you keep applying 'light' throttle (very important) just enough to keep you on the 'pull' without increasing speed : this will compress your suspension giving you lower center gravity & firmer springs .... then when reaching 'exit' of the turn you will gradually increase your throttle - wot .

These rules are precious in the trucking industry with the driver , helping us to keep from : tippin' over in a curve with our HIGH center of gravity , and lose brakes due to fading/glazing ..... and they use these very same principles in track racing ..... and can save your life as a daily driver as well if you apply these simple principles of physics to your cars in these diff. conditions .




Body roll is a function of weight transfer and roll resistance, a somewhat complicated subject. Lowering your car actually increases its tendency to roll. The easiest way to reduce roll is with firmer springs and sways.

An otherwise stock Mazda6 with a RB rear sway is awesome. Actually, anything with the RB rear sway is great. A rear sway, Racing Beat or not, should be one of the very first upgrades for the Mazda6.
[/b]
Why should it be the first ? .... before increasing 'roll' ; I would like to have firmer springs , subframe connectors to prevent chassis flex at all four corners , having a strut tower + G Load under engine mount brace + rear shock tower brace (in case of Mustangs) before increasing added cornering stress with the rear sway .... not that it's a bad thing ; just want my car to handle it when pushed REALLY HARD ..... but for mild daily driving or a bit of improved tracking it works for you guys now with the sway bar ..... but imagine with the above set-up : much improved speed in all cornering aspects garanteed ! Just as you mention it at the top , Stretch ; It allows your dampers to work better.

This is my free & educated PO and you are free to do what you want with it , hopefully I will have helped some of you open-minded fellow sixers :)

Peace
 

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Gee, what about driving technique? Part of the problem could very well be too hot on the entry speed. Easy to do when you have the red mist in your eyes. But I will certainly agree, based on my own problems dialing out understeer with my ix, that lowering the car, increased front camber, and a larger rear sway bar will definetly reduce understeer.
 

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i agree with the driving style question.

dawei was just in here not to long ago asking how to stop oversteer. when your agressivley throwing the car into a corner and braking, you can get it to rotate. not necessarily under control, however, as dawei found out.
 

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Hey guys, you forgot to mention tire pressures, and their affect on tread patch. The more tread that hits the ground the more traction you'll get. By adjusting the tire pressure so you get more equivalent tread patch is a great way to help reduce understeer on a 6.

I'm running 225/40/18s on my 6, and am running what I believe is 44 lbs up front and 38 in the rear (believe because I think my guage is a little fubared). This is what is working for me on my Kumho's (spx I believe ... I don't really remember). My falken st115's were a at 42-39. So you need to find the best for your setup.
 

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tire pressure is the best way to adjust balance at the track. Our cars fit into the SCCA GS class for auto-x and to keep in stock class (those who want to anyway) only the front sway bar can be changed. some people will say "oh no that'll cause understeer" well yeah, if you don't correct with tire pressure. increasing the strength of the front sway bar alone will help keep the front from diving under breaking (keeping the rear tires on the track) and help keep both front tires planted while exiting the turn and with our open diff that's important.

if you're understeering, increase the rear pressure. if the rear breaks loose too much, reduce. an air tank is cheaper than sway bars. ;)
 

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Heres a quick definition of understeer

un·der·steer-
To turn less sharply than the operator would expect. Used on vehicles, especially automobiles.


Nascars Definition: This is when the front tires are not getting enough grip on the racetrack. This causes the car to want to continue straight ahead when the driver turns the wheel.

This is the opposite of "loose." More commonly used in other forms of motorsports.

Pronunciation: un der steer

Also Known As: push, tight

Examples: In order to fix my car's terrible understeer we put softer shocks on the front.
 

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tire pressure is the best way to adjust balance at the track.
...
if you're understeering, increase the rear pressure. if the rear breaks loose too much, reduce. an air tank is cheaper than sway bars. ;)[/b]
I wouldn't say its the best way, but it's the easiest and sometimes the only way. Alignment and sway bar changes can be made quickly (in most cars, not the '6!) and that's usually a better method of tuning. Over or under-inflating a tire causes a loss of grip on that tire, which may give you the handling bias you want, but losing grip is kind of counter-productive. Firming a rear sway or changing camber can (but not always) change the handling bias while increasing overall grip.

Still, fiddling with tire pressures is just about the only way GS autocrossers can get rotation, no doubt.

having a strut tower + G Load under engine mount brace + rear shock tower brace (in case of Mustangs) before increasing added cornering stress with the rear sway .... not that it's a bad thing ;[/b]
Chassis bracing was (and is) extremely popular on the Mustang because its chassis is jello compared to the '6. Furthermore, with the Mazda6 having double wishbones, it stresses the suspension in different, more rigidly attatched places. For example, the shock towers have no lateral stress whatsoever- it's all vertical. A strut bar does absolutely zilch to help that. In a Mustang, there are lateral forces on the strut towers that can be helped by strut tower reinforcement. That's why chassis stiffening is much less exciting for the '6.
 

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maybe best wasn't the 'best' word to use. ;) I just meant that for most people it's the easiest and sometimes only way to change balance between runs. I usually only have a few minutes and I like to use that to think about where I need to slow down and go faster. Generally in the auto-x community you'll always hear that balance (to your driving taste/style) is more important than overall grip so the sacrifice is almost always worth it. Of course it's all within reason. I wouldn't advise anyone to over or under inflate their tires and I suggest setting them back to spec for the drive home and so on to avoid abnormal wear ...as if auto-x didn't cause hellacious wear on tires anyway lol
 

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the Mazda6 having double wishbones, it stresses the suspension in different, more rigidly attatched places. For example, the shock towers have no lateral stress whatsoever- it's all vertical. A strut bar does absolutely zilch to help that. That's why chassis stiffening is much less exciting for the '6.
[/b]
So you're telling me all those people in this club who have put a strut tower bar in the engine bay and one under , wasted their money , as it does absolutely NOTHING ! I have a hard time believing that the car doesn't flex whether it be lateral/vertical , 'cause if chassis flex occurs then these strut areas also should automatically be affected as a result .... that's the way I see it : if this area pulls then this other area does also and furthermore the way I see it ; bracing all areas you can will pay dividends in your body structure rigidity (not counting solid longevity) and handling will be felt immediatly .... so to me a good place to start are the subframe connectors (I see you didn't quote those so I gather you agree) . I gather that the 6 is already tightly assembled .... but with time it will get looser and therefore I want to keep her tight while she still is .... they still do flex new and if I can strenghten these areas with these parts I only see it improving its characteristics ....

This is the way I see things as of now .... maybe you can help me see differently I'd be interested if you can , and I don't mean to argue with you ; just my perception/experience stated above .... let's elaborate and I'll be happy to learn if there is place for it .
 
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