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Do you ever accelerate in the midst of a turn and ....

14K views 61 replies 46 participants last post by  Major Anarchy 
#1 ·
Curious if others get this too. If you are in the middle of a turn and get on the gas does your STI seriously push to the outside of the turn? Just curious. Mine has always done this. If I am in the middle of a turn and I get on it then I NEED to turn the steering wheel at the same time in order to maintain my current direction. If I don't turn the wheel when I push the accelerator down then the car will immediately push to the outside.

Just curious. Any explanations? The best I could come up with was that when you hit the accelerator you get 65% to the rear wheels which causes the push?

t
 
#2 ·
RE: Re: RE: Also blacked out 04 steering wheel

Pushing to the outside of a turn would be understeer, which would come from weight transfer/front heavy car/undersized sway bars/too much power to the front wheels or anything else that would reduce grip to the front two wheels.

The STi and most AWD vehicles (hell, just about all production cars) understeer. The good news is that you can correct it with some minor mods and an alignment.
 
#3 ·
If I get on the gas hard, no it doesn't do that. If you learn to be more aggressive with our throttle you will notice the car doesn't do it. I used to be the same way as you. Then one time I got pissed and just floored it. The car squated as the weight transferred to the rear and outside then just turned through the corner. If your light with your throttle input the car will understeer as described above. If your more agressive the weight transfer can actually benefit you.
 
#4 ·
Re: RE: Re: 2004 STi vs. 1986 Lincoln Mk. VII

The only way I have gotten around this is to take some of the power from the back and put it up front with the DCCD.

And if you do a search this has been covered in other parts of the forum. (Just to keep you from getting reminded).

But I to would like to know if anyone has a "great" solution to this problem. I have read everywhere from different sway bars to pinks and top hats to ajustable struts. I'm not that price sensitive, but damn some of these options can run into thousands of dollars.

Any help...
 
#5 ·
the technique WE R ND describes works better than any suspension change that I know of, the problem is that it is counter intuitive to most drivers (magazine writers especially). Also the 2005 front diff responds less dramatically than the 2004 to this aggressive input, so the reaction will not be as noticeable. The 2004 really tightens its line when you stomp the gas just before the apex. Coming from a 2002 WRX to a 2004 STi, I noticed that LESS steering input was required because the limited slip front diff was pulling the front of the car through the corner rather than being pushed and the rear wheels were inducing oversteer due to the active center diff doing its thing. I nearly clipped the curb just before the apex of quite a few turns until I got used to dialing in less lock and enjoying the amazing feeling you get from feeling the car work so well.

Suspension changes will make it less prone to understeering, but that is more costly than adapting to the excellent system that is just waiting for you to learn to use it to it's full potential.

Bottom line is to experiment with more aggressive pre-apex throttle application. the rally based heritage is designed for this style of driving and you will get the most out of the car if you treat it that way. It's also a LOT of fun to practice. :D just do it in a safe place, like a driving school or autoX.
 
#6 ·
RE: 18" rims

As Xman said, I've noticed that being more aggressive with the throttle really gets you tucked in nicely and it just rockets out of a corner (makes getting on on-ramps very fun. :))
 
#8 ·
You need to be on the gas as soon as you turn in. Sounds like you are going in too fast and then when you get on the gas the car pushes. Try going in slower and getting on the gas when you turn in. You'll be able to exit MUCH faster and your steering input wont change half way through the turn.
 
#10 ·
I think what people are trying to describe is weight transfer and static/sliding friction...

WARNING--GEEK ALERT!!!--WARNING

There are two factors that determine whether the car understeers or oversteers. There is the weight transfer issue--if the car is under braking, the weight shifts away from the rear wheels and the car oversteers. If the car is accelerating, the weight shifts away from the front, and the car oversteers.

The problem is, the weight transfer also puts more frictional load on the respective tires, e.g. while in a braking turn, the front wheels have to do more of the work stopping the car, and if you ask too much of them, they lock up. Sliding friction is less than rolling friction, so all of a sudden, the FRONT wheels have less traction and you're back to understeer.

Likewise, if you stomp on the gas and you break away the rear wheels, the car will be begin to oversteer.

So in short:

Braking very hard (with tires skidding) - understeer
Braking hard - oversteer
Accelerating hard - understeer
Accelerating very hard (with tires skidding) - oversteer

GEEK ALERT OVER!
 
#11 ·
Pick up "Speed Secrets II"...it's an pretty easy read and gives a basic idea of the physics behind understeer/oversteer and how to correct from both.

On an another note, turning your steering wheel more when you start to understeer heavily(not necessarily in the event description you gave) is a bad idea...as your tires are designed to work facing directly forward...changing the angle of approach even further when the tire is already losing grip will make the understeer worse.

http://www.amazon.com/exec/obidos/tg/detail/-/0760315108/102-0092725-9335371?v=glance
 
#12 ·
I'm no expert, but this is what works for me!

I've discovered 1 thing when I was doing some laps last summer, and this winter... The beauty to our AWD is, when you are in the middle of the turn and it tends to be a little understeer, the secret to correct it is put the paddle ALL THE WAY to the floor! then the car will correct itself (steering into the road's direction)! It always worked for me...
but as soon as you are a little freaked out of the oversteer... it's over for you! Just keep the paddel down there! that is the fastest way to drive an AWD (w/ DCCD in auto).

It worked in snow too, but too a little wider street (w/DCCD in auto or Lock)!
At least that's what I've found... took a lot of guts and grass!
 
#13 ·
For the record, YES, I know about entering a turn with the throttle already applied. I hang out with a BUNCH of very very experienced road racers. A LOT of their stuff has rubbed off on me ... especially turning, braking, etc. I was just describing something that didn't happen with my camaro (at least not like this). Yes, when driving 'for real' I won't be going from no gas to applying the gas in the middle of the turn. Yes, I understand this. Yes, I also understand a crapload about understeer and how to correct it. Did I mention that I am with some sick road racers? lol. I'm just curious about how/why the AWD system operates like this. It is extremely aggressive. Like I said, if I drift into a turn (like I NEVER would do when really driving) and then really apply the gas the car takes off toward the outside significantly more than any car I have ever owned. One would think that it should be less with the AWD ... but something about the AWD makes it happen more.

t
 
#15 ·
RE: Tell Me & I Will Build It

ParkerSTi said:
The only way I have gotten around this is to take some of the power from the back and put it up front with the DCCD.
Seriously??

I do the total opposite. With the DCCD full rear (green light) I get throttle oversteer at will.

My current "fun" technique (ie. not fast but fun) is to get in the corner a little too hot and then induce a lift throttle over steer (done by rapidly letting off the throttle). As the rear starts coming around in a nice drift, I rapidly floor the throttle. Makes some of sickest drift that I can think the car can do.

If anyone has another technique to really induce large drift, you let me know. But seems to be the perfect technique so far.

By the way, during a rally I did this winter in slippery conditions, I didn't need to touch the DCCD at all. I left it in auto and was impressed how the car knew what I was thinking. Started most of the drifts under braking and kept it going with the throttle. This technique doesn't work well in the dry though unless you Scandinavian flick the hell out of the car under braking. Not cop friendly if done on public roads...
 
#16 ·
I agree with WolfPlayer. This has bothered me a great deal since the day I got my STi. The only way I've found so far to compensate for it is by adjusting my DCCD bias to its full rear setting.

What I find so disconcerting is that with its more driver-centric orientation, the STi does this and my MY00 2.5RS didn't do it at all. If I applied the throttle in the midst of a turn with the 2.5RS, it just held the line I already had and accelerated. With the STi, the car aggressively pulls itself straight (that is, to the outside of the turn).

To be honest, it's why I haven't auto-crossed the car at all yet; because I can't count on being able to make part-throttle adjustments mid-turn without having to drastically compensate for the result with the steering wheel.

And yup, I've had an allignment.

If a sway bar would fix this, then I'd buy one in a heartbeat.

Zen
 
#17 ·
ZenBoy said:
I agree with WolfPlayer. ... I can't count on being able to make part-throttle adjustments mid-turn without having to drastically compensate for the result with the steering wheel.
OK. Somebody who actually came right out and experiences exactly the phenomena to which I am referring. Anybody have any ideas as to WHY the car reacts like this (even though it doesn't matter because people don't drive like this when they are driving 'for real').

t
 
#18 ·
RE: Will an 05 armrest extension fit an 04?

I think I know what he's talking about. It's certainly not understeer, because I feel it even on highway curves at the posted speed limit. I figured it was the front diff starting to lock under power (or unlock when letting off the gas)., forcing the front wheels to try to turn at the same speed...I'm certainly not an ME, but it kinda makes sense to me. It would also explain why nobody notices it on a rear drive car, or a WRX. (no front diff).

Pat
 
#19 ·
RE: FS: MASSIVE AMOUNTS OF ROYAL PURPLE @ GOOD PRICES

As I understand it, the front diff will start to lock under trailing throttle. On corner entry, this will tend to make the car push. That works counter to what normally happens when you shift weight to front and off the rear - which causes oversteer.

It's all a matter of degree and timing of the brake, turn and throttle application.


  • 1. Brake too early and the nose isn't weighted down at turn in (assuming you're not braking hard at turn in) so you understeer.

    2. Coast through the 1st half of the corner in gear and off the throttle, the front diff will lock a bit, which promotes understeer.

    3. Lift the throttle gently but all the way to get the nose to tuck and the diff will lock to promote understeer. The diff overpowers the weight shift oversteer tendency. (but this is what most people are taught to do coming from a fwd car or a rwd car at a HPDE)

    4. But if you do a *really* dramatic lift, then you get trailing throttle oversteer because the radical weight shift to the front which overpowers the front diff locking up. (which is only good for magazine photos, autocrossing or messing around in a parking lot)

    5. Do the 1st half of the turn on part throttle until just prior to apex. The front diff is more free since it's not on overrun nore are you slipping a tire (which will lock the diff too) so you can hit apex and make the car rotate.

    6. All of which is depended upon the speed of the turn and how loaded the car is in the turn. Higher speed sweepers tend to understeer and require less dramatic weight shift but also don't have as much differential action since the corner radius is bigger. Lower speed corners need to be driven really aggressivly and will tend to oversteer but the differential action will tend to lock up the front.

But I'm not an expert at this stuff either, just a lowly intermediate driving event student. :lol:
 
#20 ·
Re: Just installed my AccessPORT Stage 1

mccullpl said:
It would also explain why nobody notices it on a rear drive car, or a WRX. (no front diff).

Pat
That really depends on if you have a clutch LSD in the rear end (for a rwd car) Some of them can be tuned for a % lock under trailing throttle to stabalize the car in a brake zone and prevent lift off oversteer on turn in. Some porsche diffs do this as well as aftermarket diffs for BMW race prepped cars.

80/20 is common with an 80 lock under trailing throttle and 20 lock under power. It requires a neutral throttle from turn in to apex to free up the diff to allow the car to rotate. Part of the reason porshes require more skill to get to 10/10ths then most cars.

Open diffs don't do this, which is 99% of all RWD cars out there.
 
#21 ·
Sands said:
Open diffs don't do this, which is 99% of all RWD cars out there.
My RWD car sure doesn't do this, and it's got Positraction.

My 2000 2.5RS didn't do this, and it had a limited-slip rear differential.

The difference between those cars and my STi, at first glance at least, is that the STi has a limited-slip front differential as well.

mccullpl said:
I figured it was the front diff starting to lock under power (or unlock when letting off the gas)., forcing the front wheels to try to turn at the same speed...I'm certainly not an ME, but it kinda makes sense to me. It would also explain why nobody notices it on a rear drive car, or a WRX. (no front diff).
I think mccullpl has spelled out what I've been thinking as well - it's the limited-slip front diff. Under throttle, the diff is starting to lock up when it has enough torque distributed to it. This would also explain why adjusting the torque bias to the rear of the car helps the problem so much.

BTW, mccullpl I'm guessing that you meant to say that the RWD car and WRX have no limited-slip front diff, correct? The WRX definitely has a front diff, but not a limited-slip.

So, the question is, is there a way to minimize the impact of this without manually adjusting the DCCD?

Zen
 
#22 ·
350Z got our wing.. lol

I notice this same power on understeer even at light to moderate power levels. I think it is related to the front lsd changing the torque between the front wheels or maybe trying to keep equal torque when a non lsd front diff would just let the car roll through the turn naturally. I know my 03 EVO did not have this same sensation and it had an open front diff.
 
#24 ·
This conversation is getting a bit interesting...

There is a connection between what the diffs are doing at a particular place in a corner and what the driver is doing to the car as far as the amount, timing and rate of weight transfer.

On "active" cars like the STI, the driver need to work with the car to get max performance.

There are not many posts on this thread that have made that connection..... (IMHO that is)
 
#26 ·
RE: GOLD STi Wheels

Uh, about 7 posts up.....

And it's "work with" not "work" the car.

For a simple case, if you car understeers on enty (STI or not) then you need to change some driving styles to get it to be neutral on entry. i.e, trail brake more aggresively, or turn in under neutral throttle to free up an LSD, or go in a little slower... There are lots of ways to change driving style and methods to get the desired behavior out of car.
 
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