Causes for Understeer???

[1G/TS-ituner]

Hey i'm looking to finally upgrade my suspention from stock, and as i've gotten more comfortable pushing my car to it's own limits i've noticed it gets ridiculous understeer, which usually compensates from giving it more gas to correct, but that results in the whole car sliding in the direction of entry into a turn which is not a good thing, i'm wondering that asides from getting 17" rims with eagle f-1 tires thats on my first list of things to get if i should go with a mild shock and strut layout, or go with coilovers???

I'm also planing on getting swaybars for the front and rear, strut tower bar, and a better rear one too.

In all honesty, I prefer oversteer since it's easier to correct. Anyone who can shed some light on the best way to go without spending ridiculous amounts of money let me know. thanks in advance!

 

[DG-FNR]

The cheapest?

Slow down.

A lot of corner-entry understeer is self-inflicted.

DG

Learn: http://autocross.dsm.org/books.html

 

[AllWheelPeel]

A stiffer front swaybar will increase understeer.
A stiffer rear will reduce understeer,and is IMO one of the best mods
you can do for your handling.
I instlled both and ended up using the stocker on the front.

 

[Defiant]

Well, the damned motor and transmission are hanging out ahead of the front wheels, for one thing. Handling cars don't allow that sort of thing.

 

[Defiant]

And, turnbuckles on the cowcatcher.

 

[FyxxterZC]

Dunno about the faster comment, but I've found on an autox course that if I raise the front and lower the rear pressures, I get a better rotation of my 95 gst. Usually stagger them 4-6 psi. Which usually gives me snap oversteer with enough speed, but it's progressive and controllable. First gens totally different though, as is awd, I haven't taken my 1g awd to an autocross yet. But I have taken a 1g awd I had a few years back to an event. Stick with a stiffer rear sway and the front stocker. There are other ways to deal with it but it gets complicated when you go into differential tech and suspension upgrades. Truth is defiants right, too much weight in the front and no way to get it "centered". While I love my dsms, I'll be the first to admit they're not the greatest car for autocrossing. Besides an evo, a second gen has the potential. First gens though just by feel from the last 1g awd I autocrossed, just didn't want to rotate at all. Hope this helps.

 

[DSM PERFORMANCE]

I had KYB AGX + PU on front tab only, and the car was oversteer.
I now have add PU everywhere and ST sways front and rear, and now the car is neutral (!!!) surely because of the fr sway bar.

 

[bjones18]

Hey i'm .....

In all honesty, I prefer oversteer since it's easier to correct. Anyone who can shed some light on the best way to go without spending ridiculous amounts of money let me know. thanks in advance!

Oversteer is not easier to correct...hence the 911 (porsche... not the disaster).
Oversteer/understeer comes in many fashions....steady state, low mu, high mu, transient, throttle-on, throttle off, and braking.

Steady State Factors include: weight distribution,F/R tire size, grip, & pressure, F/R static camber, F/R camber gain, F/R wheel rates, F/R bar rates, F/R toe compliance, F/R roll steer, F/R roll center heights and many more. Note the F/R of each factor... you are balancing the front and rear slip angles.

1. Buy a book, "How to make your car handle" - Fred Puhn.
2. Measure your Steady state understeer
a. Paint a large circle - say 60' diameter.
b. make a removable protractor on your Steering Wheel - SW(center is zero).
c. drive around the circle at 10, 15, 20, 25, 30 etc. mph and record the steering wheel angle.
d. plot your SWAngle vs speed.

This will show your progression of SS understeer/oversteer with lateral G's

More and more SWA = understeer
SWA decreases with increasing speed = SS oversteer.

Very few people have the ability to catch-correct an oversteering car. Believe it or not...your inner ear senses vehicle yaw rate. When you are driving 80mph you have just about one heart-beat to "catch and correct" an over-steer lane change. Take a HiPerf driving class Bondurant, Barber, etc.

Keep in mind that if you set your car up "neutral" without fuel. A full tank of gas, a suitcase, and "throttle-off" can make for some sideways-sliding with coming off the freeway.

 

[mach1one]

Dunno about the faster comment, but I've found on an autox course that if I raise the front and lower the rear pressures, I get a better rotation of my 95 gst. Usually stagger them 4-6 psi. Which usually gives me snap oversteer with enough speed, but it's progressive and controllable. First gens totally different though, as is awd, I haven't taken my 1g awd to an autocross yet. But I have taken a 1g awd I had a few years back to an event. Stick with a stiffer rear sway and the front stocker. There are other ways to deal with it but it gets complicated when you go into differential tech and suspension upgrades. Truth is defiants right, too much weight in the front and no way to get it "centered". While I love my dsms, I'll be the first to admit they're not the greatest car for autocrossing. Besides an evo, a second gen has the potential. First gens though just by feel from the last 1g awd I autocrossed, just didn't want to rotate at all. Hope this helps.

The last auto-x I went to in my 1G AWD this past weekend, my times were pretty competitive. Out of 84 entrants I finished 34th, and 11 of the people that finished ahead of me were instructors. I have GR2s, ST 1" rear swaybar, and balding 712s for susp. mods, that's it. Best thing I ever did was learn how to drive a better line.

And if you air the rear tires up less in an awd, understeer will be worse. If anything the rear should be 5 psi more. More rear pressure = stiffer sidewalls = controllable oversteer. I tried 45f/41r on one sun event, understeer was bad. The next event I ran 45f/50r, much more manageable. The car didn't push nearly as bad and the few times I did start to push the car too hard, the rear would slowly start to step out.

Best susp. mods you can do is tires. Then rear sway. Then learn to drive the thing before dumping real money into the susp. All the money is wasted if you don't know how to use it. Case in point, my good friend has a cobra w/ all the goodies, tri-link, panhard bar, coilovers, brembo brakes, and on and on. I beat him by .7 sec this past event. He wasn't too happy, but once he learns to drive he'll blow me out of the water. Unless I can get some more mods in before that



Oh and listen to DG. The man knows his stuff!

 

[TheStock]

I'd read a few days ago in a suspension book that the stiffer you are in the rear the more oversteer you will have. And visa versa for the front. So since our cars naturally understeer, it's better to stiffen up the rear to balance it out. Too much though and you've created another problem.
I plan on getting the Illumina's and using them to fine tune the balance.

 

[DG-FNR]

So since our cars naturally understeer, it's better to stiffen up the rear to balance it out.

Ah, Grasshopper, It's Not That Easy.

1) That book is talking about cases where "all else is equal". On a purpose-built raing car (like a Formula Ford or a Formula Atlantic) that is likely the case, and the car will respond in the direction you expect when you make a change. Stiffen the rear on a Ralt, and you will tend to increase oversteer.

But on production-based cars, all else is rarely equal. There can be (and usually is) other factors in play that wind up having a greater effect on the total handling balance than the factor you are choosing to work with. It is not at all unusual, on a production-based car, to stiffen the front and increase front grip.

On a 2G DSM, you have tire camber curves and the influence of the diffs to worry about. These factors can often conspire against you to do things that don't go "by the book".

2) When you attempt to balance the car, you have a choice: either unstick the end with excess grip, or create extra grip on the end lacking it. Both methods (usually) work, but one method makes the car very much faster than the other. Care to guess which one?

If a car is understeering, you want to try and figure out where the understeer is coming fron and address that. Unsticking the opposite end is the action of last resort (and on an AWD car, may not work)

DG

Learn: http://autocross.dsm.org/books.html

 

[MrAWD]

Another interesting thing that affects understeer/oversteer on our cars is our driving style. Some people are more smooth then the others. Others like to unset the car and force oversteer, which they use to go through the turn.

The point is that car will behave differently if brought to the edge smoothly versa in a jerky way. Once you upset the balance of the car, while getting close to the edge (or over it), thanks to the complexity of the AWD drivetrain and uneven corner weights, cars will do very strange things. Some of those would be a snap oversteer or heavy push, or just a four wheel drift. And it will be very hard to say what will happen if you do one of the things to cause the unbalance!

So, it is very important to find the difference between a plain old understeer/oversteer (might be call a terminal as well) caused by the balance of the car, versa what will car do when brought close to the edge and then upset by doing something strange. On the list of those you could find things from left foot braking, quick lifting of the throttle, right foot braking, excessive steering change, and probably few more that could be done.

Once you know that car is doing something because of it’s setup, then you can safely go and improve that and make the car faster. Unfortunately, very few of us here are capable of knowing the difference between those. Unless your last name is Dadio or Tunnell, chances are that we are digging in the dark. That is the main reason lot of us went through the modifying phase all and all over again just to realize that we have been running in the circle. The good part here is that you learn things along the way, become a bit of a better driver too, so things are not that bad. But, still it ends up as a big waste of time and money compared to the path that you could have gone if you where a bit smarter!

So, be smart and drive smooth!!!



Fedja

 

[jtmcinder]

Another way to talk about smoothness (which is a key issue, to be sure) is to consider is the match between the frequency of the suspension and the rate at which you are feeding in inputs. If you are on stock or near-stock springrates, then the natural frequency of the car's suspension is quite low. This means that you must feed in inputs quite slowly or the car will not be able to keep up. For example, on a stock-sprung car, when you feed in some steering it takes a moment for the new steering angle to take effect. Yes, the wheels turn at once, but the car doesn't start turning at the new angle at once because lots of things must occur before the car takes a set. In contrast, when you run very high springrates, the car has a much higher frequency and can respond much quicker.

One mistake that many people make -- and I belong on this list, big time -- is to raise the springrates too soon. Bringing the car's frequency up to what you are doing as a driver will lower your lap times, but it could very well prevent you from learning to drive. I strongly suggest that beginners stay with low springrates for their first year if their goal is to one day be a really good driver. Learn to drive the car as it is before changing it. Otherwise, you might cement into place some very bad habits -- as I have -- such as jerking the wheel around and stabbing at the pedals.

The person that I am most impressed with when it comes to driving a 2G DSM is Sam Krauss. What he can do on stock springs is downright amazing.

- Jtoby

 

[Acezwild88]

i use to understeer alot and so i had my girlfriends dad ride with me who is a race instuctor and i finally can drive smooth and not jurking the car around i dont remeber the last time i understeered when i was in a racing situation. so i got rid of a lot of understeer with just learning how to drive better. also when your in a turn if you saw the wheel a little bit you will keep better traction. when your coming out of the turn squeeze on the gas and dont just slam on it. and dont brake in the middle of the turn hope that might help some. if i was you i would only replace the rear sway bar. o ya and make shure to let out when coming out of a turn use the whole road " that dosent mean go over the double yellow" good luck

 

[DG-FNR]

One mistake that many people make -- and I belong on this list, big time -- is to raise the springrates too soon. Bringing the car's frequency up to what you are doing as a driver will lower your lap times, but it could very well prevent you from learning to drive.

I disagree.

Increasing the response rate of the car means that it reacts to driver inputs quicker and more positively - which means better feedback, which means more information coming from the car to the driver telling him how he's doing.

A sloppy, soft, inprecise car is more forgiving, so your mistakes don't punish you as badly. But without that punishment, there can be no progress. Driving a car that is hyper-responsive will teach you to get smooth really quickly, because it just won't let you get away with driving all herky-jerky.

There's a reason why the top National-level Stock-class drivers spend so much money on shocks - they can use the shocks as "fake springs" and increase the response rate of the car while retaining the stock springs. In fact, Mark Daddio (clever fellow that he is) would run insane levels of front rebound, so as to jack the car down onto the bumpstups and then use those as his "main" suspension springs (and because he was Daddio, he was capable of driving a car with that quick of a response rate)

What I *do* recommend newbies do is stay on the nasty-ass hardest street tires they can. Street tires tend to have low limits and gentle breakaway characteristics, plus they give a level of audio feedback that is missing from a race tire. Staying on street tires for a while will teach you to balance the car at the limit and keep it there. Far too many drivers get on super-high-limit race tires (where the breakaway characteristics are much more abrubt) and spend the rest of their careers consistantly underdriving the car.

DG

Learn: http://autocross.dsm.org/books.html

 

[jtmcinder]

I disagree.

That goes without saying, doesn't it, mon petite troll.

You are confusing two issues: the ability of the car to keep up with the driver and the ability of the car to keep up with the course. What I was talking about was the former, along with the long-term problems of upgrading the car before the driver. What you are talking about is the latter.

Of course, a car that reacts faster is better for autocrossing. What competitors in Stock are doing is upgrading the car as much as they can given the rules.

My point was that a driver needs to react in a way that matches the car. The definition of smooth (other than minimizing jerk) is to avoid over-driving. And this mod is free.

- Jtoby

 

[Revolution]

Sometimes it's good to understeer ,and sometimes it's not. When I was activly autocrossing I noticed that depending on how I approached a corner ( with all things like speed set aside) the car would be more manageble when it understeered only to place me in the right place to tackle the uncoming corner.

Some poeople think understeering is the end of the world and a car cant move unless it over steers,which is the wrong mentality to have. I realized that by slightly trail braking while approaching a corner and introducing new steering angles then slowly getting back on the gas that I could control the car better whether it understeered or not through that said corner.

I also realize that guys running 245 wide tires on rims that are 7 wide expearinced what I like to call "roll over" which they happen to mistaken for some type of (over or understeer).
I ran 215's b4 I bought my 225's and for some reason my 215's felt more responsive,probably because of this rollover nonsense.

Their are alot of causes for understeer mainly the driver,mainly because the the brakes arent being applied the way they should be. I cant comment on anybody elses driving habbits but I personally noticed that cretiquing myself was the biggest improvment I could have ever done.

P.s many knowledgable dsmers have said many things that are dsm specific in the past when making any dsm perform better,I suggest people try and search this information out. Most of us will never think that by upgrading our lsd's first ,they would make a world of a difference in our cars but they do.

Search out the wisemen or the engineers because they've been around the block and pm them specific questions. They will help you.
In the end Ive implamented what works for the guys whom are consistanbtly going fast into my car. It's nice when most of the work is already done for you.So why is everybody else still trying to reinvent the wheel?

I suggest to swap out the two lsd's in any awd for aftermarket replacements ,this is what im currently trying to do now. Faster response ,a better line ,all around just a better car,Im very jealouse of my buddy right now. He has a kaaz front and center lsd swap and his car just hugs the road where mine just whimperd to get gripp.

All things aside the info has already been brought to light in this forum in the past all we have to do is just search and copy ,search and copy .Have fun reading.

 

[jtmcinder]

Keep in mind that anything other than a true one-way front diff will probably increase your corner-entry understeer.

No free lunch and all that sort of thing.

- Jtoby

 

[DG-FNR]

You are confusing two issues: the ability of the car to keep up with the driver and the ability of the car to keep up with the course.

No, I am not.

Assuming a sloppy car with soft springs and shocks, there is a delay between any given driver input and the car reacting, and it takes a larger input to get any given level of response.

On the plus side (in terms of lap times) this makes the car relatively insensitive to rapid driver inputs. You can jerk the wheel around all you want without penalty, because the car does not react fast enough to driver inputs to upset the car.

On the minus side (in terms of lap times) the car's response is so slow that it encourages large-amplitude driver inputs - it's the only way to get the car to react in time to keep up with the course.

Spending a lot of time in a sloppy, unresponsive car teaches you as a driver that 1) you can make a lot of rapid inputs without penalty (car cannot keep up with driver) and 2) that rapid inputs are often required to go fast (car cannot keep up with course)

Neither of these traits are conducive to teaching smoothness.

Now, to get the car to go faster, we increase the response rate - now the car can keep up with the course; it can react fast enough to sucessfully negotiate the various course elements. In so doing though, we reduce (or even remove) the forgiveness of rapid, high-amplitude driver inputs. The car will no longer allow you to get away with jerky inputs (where the sloppy car would let you do that all day)

The only way to drive a responsive car is to learn to drive it smoothly (but aggressively). The more responsive the car, the harder this point will be driven home. I know of no better driver trainer than a super-responsive vehicle - like a kart.

DG

 

[MrAWD]

Increasing the response rate of the car means that it reacts to driver inputs quicker and more positively - which means better feedback, which means more information coming from the car to the driver telling him how he's doing.

This is just partially correct. The car will react quicker for sure, but that is not necessarily a better feedback at the same time. A beginner/intermediate driver might get all of that information too quickly and respond abruptly to them. It would very well make the car faster then the driver can absorb at the time and it will just punish him/her with more frustration and more time loss. To go even further, people who upgrade their cars to something that is better then them, usually blame the car for all of its evil doing and start to change things all the time, getting into another loophole, which is very hard to get out of it.

A sloppy, soft, inprecise car is more forgiving, so your mistakes don't punish you as badly. But without that punishment, there can be no progress. Driving a car that is hyper-responsive will teach you to get smooth really quickly, because it just won't let you get away with driving all herky-jerky.

Hmm, this sounds like “no pain - no gain” thing!! It is not right that people can’t learn from the sloppy, soft, imprecise car which is more forgiving. And the biggest punishment is that someone else in the same car can beat them very bad. Had a guy once who was complaining how his at the time pretty much stock car doesn’t have this or that for a whole day. At the end of that day, I drove his car with him in there to shave off over 8 seconds. He was very humble after that!

So back on the hyper-responsive car and what it will teach you is still in the air. I have seen people getting into the cars that are faster then they are and what they end up doing in such a car is jerky steering responses, which are very hard thing to cure. Basically, they start relying on the cars ability to turn when they get in too late and it works until the second or third cone of the slalom. Then the wrestling starts!

What I am trying to say is that you need a slower (all response wise) car to learn how to drive it. Otherwise, you will ended up with the car that is faster then you are and it will make you to react to it (kind of it will drive you) instead of you making it to do things that need to be done. Of course, some of the guys out there have a skills or genetics to overcome these situations, but I bet you that there are very few of them!


Fedja

 

[MrAWD]

Sometimes it's good to understeer ,and sometimes it's not. When I was activly autocrossing I noticed that depending on how I approached a corner ( with all things like speed set aside) the car would be more manageble when it understeered only to place me in the right place to tackle the uncoming corner.

No, it is never good to understeer. Period! If your car understeers, that will mean just longer time for it to get into the position where it needs to be. Also, if you need your car to understeer to get into the correct position, that implies that you already made a mistake and turned your steering wheel too much too early.

The worst one of all is that it will delay the point in time where you can go full throttle.



Fedja

 

[khanlon]

I do not have a side in the issue here, as good points are brought up on either side. However, I do have another point to add from my exeriences of autocrossing a stock 1G for three years.

By keeping a stock, softly sprung suspension the driver learns to look ahead and set up their corner entry appropriately to drive a good line through the turn. The reason a softer suspension is good for teaching this is because it is not very accepting of the mid corner corrections that new drivers often make when the look up halfway through a turn and notice they offline. I can not count how many times I have been driving through a corner with an inappropriate entry, tried to correct, and had the car just flop around but not change direction. Had I been driving a stiffer, more responsive car I would have been able to make that mid corner correction, then thought I did a good job because I got through the corner ok, but probably not realized that I could have been much faster if I set up for the corner properly in the first place. By smashing into the cone because the car would not respond quick enough forced me to look further ahead the next time around and ensure I took a proper line to begin with.

 

[jtmcinder]

On the plus side (in terms of lap times) this makes the car relatively insensitive to rapid driver inputs. You can jerk the wheel around all you want without penalty, because the car does not react fast enough to driver inputs to upset the car.

Nope. Inputs at a higher frequency that the car can handle always lower total grip. It is explained in at least one of the books you push at us, since I own no books that are not on your wonderfully exhaustive and therefore maybe hard to memorize all of list.

For those on a budget, here is an explanation for free: http://phors.locost7.info/phors14.htm

- Jtoby

 

[jtmcinder]

By keeping a stock, softly sprung suspension the driver learns to look ahead and set up their corner entry appropriately to drive a good line through the turn.

Great point. Yes, the slower the car to react, the more you must plan ahead (instead of letting the car dig you out of a hole), so the better you learn this good habit early.

- Jtoby

 

[DG-FNR]

A beginner/intermediate driver might get all of that information too quickly and respond abruptly to them. It would very well make the car faster then the driver can absorb at the time and it will just punish him/her with more frustration and more time loss.

To be sure, one can take the whole "faster response" thing too far, and wind up with a car that is beyond their abilities - but _anything_ taken to extremes is going to hurt.

I do believe though that, within reasonable limits, a car with faster response and more feedback makes a better driver trainer than a sloppy car with poor feedback.

To go even further, people who upgrade their cars to something that is better then them, usually blame the car for all of its evil doing and start to change things all the time, getting into another loophole, which is very hard to get out of it.

This, on the other hand, I agree with completely. I once saw a first-time DSM autocrosser spend an entire run with the front tires on fire, cross the line, stare at the time clock, and then start madly reprogramming his SuperAFC.

Yeah, because nothing cures driver-induced terminal understeer like a couple of points of AFR.

It takes a good deal of self-discipline to learn to be able to differentiate between car problems and driver problems.

Had a guy once who was complaining how his at the time pretty much stock car doesn’t have this or that for a whole day. At the end of that day, I drove his car with him in there to shave off over 8 seconds. He was very humble after that!

And you learned to drive like that by driving a sloppy, unresponsive car, right? ::

DG