I have never driven an AWD car yet, only fwd/rwd platform. I'm really curious since I heard from a friend, during hard cornering, if you let off the throttle it will create understeer, same goes for full throttle(obviously). Is the only way to cure this problem besides slowing down, light/half throttling through the corner to fix this? I don't know how the new technology advances play in today's Evo. I'm curious how much truth is to this.

 

Letting off the throttle with create OVERsteer. Weight shifts to the front causing the rear end to become light. Full throttle through a corner depends if the tires have grip. If the rear tires grip, you'll understeer. If the rear tires begin to break loose, you can throttle/oversteer on a corner exit, you just have to get the rear tires to spin a bit. It rear all depends on HOW you entered the corner.

You can always brush the brakes upon corner entry, but I'd suggest practicing that on a track because in an Evo, you WILL oversteer and/or spin out if you trail-brake too aggressivley.

So go out and drive at a slightly spirited pace and learn the car and see how it feels. Don't go too fast until you're comfortable.

 

I haven't driven my Evo much in a track situation, but I have some auto-x experience.

In stock form the Evo likes to understeer a bit. You really have to toss it in to get oversteer. I often find myself feathering the throttle through sweepers to keep my line and fight the understeer.

Trail braking does work well on the Evo and you can get a little oversteer out of it. It really depends on you method of attacking to corner. With auto-x, it's sometimes faster to hit a much later apex and use the Evo's power and straight line grip by extending the upcoming straight a little.

An upgraded front sway and stiffer springs help give the front a little more grip and reduce understeer as well.

 

In an EVO X (and you could say EVO IX), full throttle, turn the wheel to where you want to go, and the car will figure it out

+1

The EVO handles more like a properly set up FWD car in that theirs a lot of weight up front, and power starts off at the front wheels. With more entry speed and trailbraking into the corner properly (or just lifting), you can induce oversteer. On power at best with the stock clutches you will get close to neutral but if you do a big enough flick early on, you rotated the car enough where the little understeer won't affect your exit.

If you replace the clutches you can get more rear bias -like a RWD car and drive off the corner like a RWD or RWD based (911 Turbo, Skyline) AWD system.

All in all, the EVO turns in extremely well and is more fun because of it than a WRX.

 

A bigger front sway actually gives the car more understeer, but with the added grip of the front tires it ends up feeling like less understeer because of the added grip. Its pretty interesting. I have the link to the actual site which explains it in technical terms for our AWD cars around here somewhere if anyone wants to dispute that

 

I'm interested. Please post the link.

Thanks.

 

K I'll look for it. It explains it a lot better than I did.

 

"you get a +3 or +4 addition in front grip from the camber curve improvement but a -1 in front grip from the "additional weight on the tire" part of the equation that comes from having a larger bar, so overall traction in the front of the vehicle is increased. Of course body roll is decreased, but as a bonus turn-in is quicker.

The car feels like it is understeering less because the limit of grip is a lot higher, while in reality at the limit the car is actually understeering a bit more. Hence why some folks say the car understeers less on a bigger front bar, and then others who haven't tried it bust out the "book and GT4" knowledge and proclaim that a bigger front bar will make the car understeer more.

...

Increasing just the front bar, the front tires see a larger percent of total weight transfer which increases front tire loading and reduces front tire grip slightly (and also the opposite effects on the rear tires)... BUT you also get a reduction in roll which reduces how positive your camber goes in hard cornering for a large increase in grip. The end result is a good increase in cornering grip with perhaps a very slightly higher bias towards understeer. Now, before a thousand people jump on that last statement, let me explain. I know that people are also putting on big front bars and saying "I got less understeer". I would contend that what their butt-dyno is telling them is not the whole truth. The real story is, the increased grip (from roll reduction) allowed them to go faster in places where they previously had understeer. So yes, perhaps they experience understeer less dramatically than before, but the bias has still shifted towards understeer more... it's just that the limits are now significantly higher so this bias is less apparent. I'd say that the front tires see a moderate gain in grip while the rear tires see a significant gain in grip."


Taken from this thread:http://forums.nasioc.com/forums/showthread.php?t=879235 which has alot of good info inbetween random people commenting.

Here is another good thread on swaybars: http://forums.nasioc.com/forums/show....php?t=1152714

And another by turninconcepts.com :http://www.iwsti.com/forums/suspensi...ngs-clint.html

 

Almost EVERY production car understeers at its limit. Corner entry will play a part on the overall corner. Yes, Evo's understeer, but it'll oversteer just as easy. It depends on if you trailbrak into the corner or go into the corner off throttle. Going into a corner too fast, you'll understeer and scrub off speed which is most likely most people problem.

I've also noticed, the more power mods I do, the better corner exit becomes because if you begin to roll into the throttle, the surge of boost will brake the rear tires loose and you can "throttle" out of the corner. I also have an '03 and I'm not sure how the ACD Evo's behave in these situations

My idea of a perfect corner

1: Hard on brakes, as you enter ease off the brakes, and you should feel slight oversteer
2: After you feel the car rotate, you should be able to add steady throttle without any understeer and keep the car fairly neutral
3: Once you start to unwind the steering wheel, roll into the throttle and the surge of boost (again ACD Evo's may be different, I'm not sure :-/) should give you a nice controllable oversteer feel.

Every corner is different and needs a different appraoch. And it all takes practice and learning the car.

Check this out
http://home.pon.net/hunnicutt/perfdriv.htm

 

from my personal driving experience in an autox situation slower is faster. if u keep ur foot planted on the accel u will turn but drag ur tires to much in the front and in turn slow down. but in a normal street or race track situation i think its best to keep the foot on the gas, letting off will cause understeer and possibly over steer (depending on speed), braking while letting off the accel in corner = oversteer. and Corner entry speed is a big factor!!

 

You can always left foot brake as well to turn in the car a bit during a turn

 

+56465

 

Just as an interesting aside...

I've noticed that with new, sticky tires the car likes to understeer. As the tires wear, the car transitions to oversteer. The last event on my (evenly worn) Hoosiers last year was essentially a drift course. The car would rotate on turn in and I would be full throttle + countersteering the entire turn. It wasn't very fast, but it was damn fun!

Another interesting aside... Dennis Grant has a pretty good writeup on autocross in general and datalogging in particular. He makes the point that his fastest runs are the ones with the highest average throttle position. You don't think about that much, but it makes a lot of sense.

As for the OP's question... in stock form, the Evo is set up to understeer, just like nearly every other production car. (If you want to know why, ask Porsche about the GT2 wreck at California Speedway). You can set it up for oversteer and make it feel a lot like a RWD if you start monkeying with the suspension.

 

I agree with what a few people have been saying, the Evos are made to understeer initially, this is "safe", most cars are this way. On the track, there ARE ways to get around it, usually its a pitch. Under braking, most stock cars have too much front bias on the prop valve to do much trail braking without something funny going on with the steering wheel. I had a great time though driving a stock MR around Thunderhill a year or so ago. It DID understeer, but it was perfectly manageable. The best thing you can do to fix this is camber plates and sway bars.

On my Evo I have just a rear sway and a crazy alignment setup to get it to drive a little bit more spirited-- as seen here:



The Evo's biggest issue (as with most AWD cars-- specifically Subaru and Audi) is that there is so much weight in the front of the car that its inertia wants to drag the nose back if you don't maintain a smooth drift around the corner and it likes to settle down into understeer-- as seen here:



Anyway, AWD handling is pretty much like FWD driving, you just have to keep as much speed through the corner until you can get the drive wheels to work for you and not against you. The biggest difference is that you can apply a lot more torque to the floor with 4 wheels than you can with just the front wheels which are often busy steering and/or braking.

 

Great post. Thanks.

So, basically, the front sway helps reduce body roll and positive camber while cornering and therefore extends the limit of grip on the front tires. However, when this limit is reached, the car is more likely to understeer.

Based on this, I assume that the addition of a larger rear bar would make the car a bit more neutral than with the front bar alone ... ?