for me, the understeer of the STi seems to be its achilles heel - this is the impression i get from the various reviews i read in magazines. so this makes me wonder #1)is this because of the particular driving style used (or not), or #2) is it because of the weight distribution of the vehicle? which is it? whats the solution?
STi understeer...and solution?
Suspension/Stiffening
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·Well from what I've experience (and this is my opinion only), is that it understeers only when the car is pushed to it's limits (race track). I've pushed this car a fair bit already in hard corners and do not detect any underteer at all. But I doubt most of us will ever push this car to it's potential limits on regular street driving.
The solution depends on whether you want trailing throttle oversteer or power oversteer. For example, Porsches (except some really high-strung turbos) will understeer at the limit under power. Letting off the throttle allows the car to tuck in. Forcing the DCCD to be in open mode should help with this affect (I suspect the computer is locking things up on acceleration through the corner). Plus a little negative camber never hurts.
I'm not sure how to set up an AWD for power oversteer though.
Regardless, this should be an easy problem to solve...if Dodge Neons can be made to turn, an Impreza should be able to learn the same tricks.
I'm not sure how to set up an AWD for power oversteer though.
Regardless, this should be an easy problem to solve...if Dodge Neons can be made to turn, an Impreza should be able to learn the same tricks.
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it's also probably a good idea to wait until understeer becomes a problem for you before you start trying to "fix" it. why spend time and money on a problem you don't have? go with your own driving, not what a magazine tells you.
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Most if not all 4WD cars do understeer, it is part of the characteristic of torque distribution between the front and rear driving wheels. Most Porsches do not understeer, but the C4 and the C4S. Their understeer is very understated however as they can mechanically distribute up to 95% of the torque to rear wheels and have 60% of their weight on the rear.
The STi and Evo have 60% of their weight on the front, which is not the most desirable thing but they have done such a good engineering job that, unless you are at the limit, that weight transfer is not a problem. This is of course for road courses and not rallies. The driving style is quite different between the two.
Also, the driving style between a 4WD, front-wheel or rear-wheel drive cars is quite different as well. In a 4WD car the most effective method of cornering tight turns is to slow down before turn-in. Once you are at the appropriate speed, turn exit is much more controlled and faster than that of other 2-wheel driven cars. In Rear wheel driven car, it is easier to get in to a corner with higher speed, scrub speed of by loading the fronts, then applying throttle to shift weight to the rears and slightly oversteer the car for exit. This usually proves having a slower corner exit but more controllable and comfortable.
In a 4WD, if you enter a corner too hot you will get the notorious mid-corner understeer, in which the only way to recover is lift-off throttle and reduce speed, which would loose you even more corner exit momentum. It is very difficult to induce oversteer in a 4WD car, thus the reduction of speed in mid-corner being the only solution. Hence the importance of turn-in speed
Setting up the suspension of a 4WD is also much more difficult than a rear-wheel car for example, because the car is a front and rear-wheel driven car So, you find compromises in either setup choices, it is almost like "all-season" tires if you don't mind my expression. I am not experienced on 4WD car suspensions, so I will not put in mis-information here on how to setup with aftermarket products.
However, as its has been suggested, the best way to go about it is to wait and learn what others are doing at the race track (which is the primary reason I am on these boards right now). Also, front camber adjustments are very helpful in cornering, but one has to be careful not to compromise straight line stability by going overboard. Obviously, one way is to have camber plates with easy adjustments depending on the occasion, but if any racing is performed with the car, you will have to check with the rule book if it is allowed. For example, in SCCA autoxes, a camber plate will immediately put you in to the "modified" or "street prepared" class
The STi and Evo have 60% of their weight on the front, which is not the most desirable thing but they have done such a good engineering job that, unless you are at the limit, that weight transfer is not a problem. This is of course for road courses and not rallies. The driving style is quite different between the two.
Also, the driving style between a 4WD, front-wheel or rear-wheel drive cars is quite different as well. In a 4WD car the most effective method of cornering tight turns is to slow down before turn-in. Once you are at the appropriate speed, turn exit is much more controlled and faster than that of other 2-wheel driven cars. In Rear wheel driven car, it is easier to get in to a corner with higher speed, scrub speed of by loading the fronts, then applying throttle to shift weight to the rears and slightly oversteer the car for exit. This usually proves having a slower corner exit but more controllable and comfortable.
In a 4WD, if you enter a corner too hot you will get the notorious mid-corner understeer, in which the only way to recover is lift-off throttle and reduce speed, which would loose you even more corner exit momentum. It is very difficult to induce oversteer in a 4WD car, thus the reduction of speed in mid-corner being the only solution. Hence the importance of turn-in speed
Setting up the suspension of a 4WD is also much more difficult than a rear-wheel car for example, because the car is a front and rear-wheel driven car
So, you find compromises in either setup choices, it is almost like "all-season" tires if you don't mind my expression. I am not experienced on 4WD car suspensions, so I will not put in mis-information here on how to setup with aftermarket products.However, as its has been suggested, the best way to go about it is to wait and learn what others are doing at the race track (which is the primary reason I am on these boards right now). Also, front camber adjustments are very helpful in cornering, but one has to be careful not to compromise straight line stability by going overboard. Obviously, one way is to have camber plates with easy adjustments depending on the occasion, but if any racing is performed with the car, you will have to check with the rule book if it is allowed. For example, in SCCA autoxes, a camber plate will immediately put you in to the "modified" or "street prepared" class
FSelekler said:....Most Porsches do not understeer, but the C4 and the C4S. ...
Well I was refering only to 911 types (928 and 944 are pretty much 50/50 balanced). Yes you are correct that C4's understeer...but you are mistaken about C2's and RWD 911 types. (I currently own a 90 C2 and regulary take it to Road America, I've also owned an 80 SC, and driven others). As you push the go pedal down, the front end lifts, causing understeer. Trailing throttle lift at apex can cause you to rotate the car. Only Turbo's can power oversteer, and then you are in deep doo-doo as you lift the throttle causing even more oversteer. (Check out turn 5 or the Kink at RA for a real world example)
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Hmm. Well, I have to give it to you, I do not have any experience with the 964 or Road America for that matter. My experience has been diferent with 993 and the 996. However, you are correct as well that in slow corners both of them will understeer as well, but correcting it with 1/3 to 1/2 throttle is quite effortless in my experience; obviously depends on the circuit and coner
However, with the very large tires on the rears (11" rims on Turbos and C4S of 996 and 10" on C2s), there is no way not to understeer in 911s But, mainly because the pivot point of the 911s are so far back that historically 911s' been oversteering vehicles at the limit to the level of getting scary. I am sure you remember the '74 model Turbo when it first came out
However, with the very large tires on the rears (11" rims on Turbos and C4S of 996 and 10" on C2s), there is no way not to understeer in 911s
But, mainly because the pivot point of the 911s are so far back that historically 911s' been oversteering vehicles at the limit to the level of getting scary. I am sure you remember the '74 model Turbo when it first came out Not STi but WRX question......
So far I have not detected a tendency to understeer in my STi. I have pushed it until the RE070's have howled and the only thing I felt was all four tires sliding or throttle on oversteer I have been driving my WRX in competitive autoX for three seasons now and the STi is much much better, limited trail braking and throttle on cornering is awesome, not easy to do, but awesome.
So far I have not detected a tendency to understeer in my STi. I have pushed it until the RE070's have howled and the only thing I felt was all four tires sliding or throttle on oversteer
I have been driving my WRX in competitive autoX for three seasons now and the STi is much much better, limited trail braking and throttle on cornering is awesome, not easy to do, but awesome.I was on the track for the first time Saturday and was very happy with the handling. We ran tire temperatures and the heavily loaded right side was as perfect as I have ever seen (42 psi all around).
With the DCCD set to Auto the car had maybe a little less understeer than most AWD's, but when we set it up to Man and 65% torque to the rear the understeer was significantly less. A friend who is a suspension consultant to NASCAR, Champ Car and (I hate to say it) IRL teams came for a ride and was amazed, first of all at the total lack of drama at pretty high cornering forces for a street (?) tire; secondly at the large effect the DCCD had.
I have a Stealth Twin Turbo (475hp) AWD as well and it's great until you try to push it to the limits in the corners, when it understeers like a pig. This DCCD is what I have been waiting for, for years - and it works. With some larger wheels and slicks or R compounds this is going to be a great street/track car. In our first Solo 2 event in the STI, we already beat everyone in all the stock classes and all but 2 with R compounds as well. I wish I could get some wheels for it to put some R compounds on. It will be really fast.
Great car!
With the DCCD set to Auto the car had maybe a little less understeer than most AWD's, but when we set it up to Man and 65% torque to the rear the understeer was significantly less. A friend who is a suspension consultant to NASCAR, Champ Car and (I hate to say it) IRL teams came for a ride and was amazed, first of all at the total lack of drama at pretty high cornering forces for a street (?) tire; secondly at the large effect the DCCD had.
I have a Stealth Twin Turbo (475hp) AWD as well and it's great until you try to push it to the limits in the corners, when it understeers like a pig. This DCCD is what I have been waiting for, for years - and it works. With some larger wheels and slicks or R compounds this is going to be a great street/track car. In our first Solo 2 event in the STI, we already beat everyone in all the stock classes and all but 2 with R compounds as well. I wish I could get some wheels for it to put some R compounds on. It will be really fast.
Great car!
ok, after getting to autoX the STi at a driver school, I did encounter the understeer when coming into a tight turn with too much speed. The car responds much better when brought in with less speed and letting the front LSD power you out.
The RE070's are good, but they are not autoX tires by any means.
The RE070's are good, but they are not autoX tires by any means.
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HERE IS THE SOLUTION....
Buy an RWD car.
Buy an RWD car.
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