AWD Understeer

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Old 08-26-2009, 11:38 AM
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Alex57r
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AWD Understeer

Hey guys, this question might be silly, but I want some input from anyone who has experience with driving a car with a chassis setup for understeer like the G37X.

Of my 16 past cars, most were RWD like Mustangs and Camaros, a Q45 and a Lexus GS430 and a few were FWD like Maximas and Acura TL. I have been around the block a couple of times "so to speak", but last night I experianced something that was rather new to me.

Since I have had my car for 4 months now, I kind of accepted the fact that high speed handling kind of sucks, which I wrote off to the skinny 18 inch A/S tires. Last nite I was driving on a freeway which has moderate turns and on one of them I tried to downshift and actually accelerate into the turn which I have been afraid to do in this car.

To my surpise, there was a dramatic improvement in the car's line through the turn. The front tucked in and the rear actually felt more planted. I tried it a few more times and realized that the tires were just fine. It was the car and the way I have been driving it. The car UNDERSTEERS LIKE CRAZY!!!

I downshifted a few times before the turn and tried it again, and holy moly the handling is actually REALLY good. I was pleased overall, but realized that of all my drivign skills, correcting understeer is not one of my best, especially since my last car (GS430) did not understeer at all.

So the question is, whats the best way to apply throttle safely to correct for understeer without causing oversteer. I am talking safely and smoothly on public roads. At what rpms is the pull just right? In what gear? At which point is it best to accelerate?

All input appreciated. Thanks.
Old 08-26-2009, 12:16 PM
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G37-6MT
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What likely happened to last night was the car dedected some sliding from the understeer and the AWD kicked in and pulled you through the turn.

The X model does understeer a fair amount because the suspension is soft, but the AWD feature should help. If it was FWD, any throttle input would just make it plow more.
Old 08-26-2009, 12:22 PM
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Alex57r
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Originally Posted by G37-6MT
What likely happened to last night was the car dedected some sliding from the understeer and the AWD kicked in and pulled you through the turn.

The X model does understeer a fair amount because the suspension is soft, but the AWD feature should help. If it was FWD, any throttle input would just make it plow more.
Nah, there was definately no slidding. It was the throttle input that straightened it for sure. You might be right though, its the suspension that makes it understeer, not the AWD???

So do the RWD cars not understeer if you don't apply any throttle during the turns?
Old 08-26-2009, 12:46 PM
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G37-6MT
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Then I don't understand. When a car understeers, it plows forward instead of turning. The plowing is sliding.

I still detect some mild understeer at times even with the S package on my car. The suspension could be a bit tighter IMO. It's definitely not a track ready suspension, but a nice compromise for the street.
Old 08-26-2009, 09:27 PM
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pnk
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I hear you on the G37X understeer. It bothered me enough that I started two earlier threads, one on whether I could get aftermarket sway bars for the G37X (answer: no).

The second thread was on suggestions on how to get a G37S in Boston (answer: difficult but possible). I am getting the car this Saturday, but given the level of difficulty, I don't recommend it lightly.

For you, I recommend upgrading the springs as others had suggested to me before I went down the G37S path.

pnk
Old 08-26-2009, 09:35 PM
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oOmikeyboy
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A stiffer coilover suspension would help i think. Do regular coilover setups work on the X?
Old 08-26-2009, 09:37 PM
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ONEighty
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Originally Posted by oOmikeyboy
A stiffer coilover suspension would help i think. Do regular coilover setups work on the X?
Nah, but BC recently made a set of coilovers for the 1st gen X's. Hopefully they'll make something for the 37's as well.
Old 08-26-2009, 09:49 PM
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classy37
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Originally Posted by pnk
I hear you on the G37X understeer. It bothered me enough that I started two earlier threads, one on whether I could get aftermarket sway bars for the G37X (answer: no).

The second thread was on suggestions on how to get a G37S in Boston (answer: difficult but possible). I am getting the car this Saturday, but given the level of difficulty, I don't recommend it lightly.

For you, I recommend upgrading the springs as others had suggested to me before I went down the G37S path.

pnk
What Springs? I can't find any aftermarket springs for the AWD.
Old 08-26-2009, 09:57 PM
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classy37
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Originally Posted by Alex57r
The car UNDERSTEERS LIKE CRAZY!!!
Originally Posted by Alex57r
I downshifted a few times before the turn and tried it again, and holy moly the handling is actually REALLY good.
Aren't these two statements contradictory? How can understeer be good? Oversimplifying a bit, isn't it basically when a vehicle does not quite 'make' the turn its trying to? Or is a limited amount, under certain conditions, actually a good thing? How?
Old 08-26-2009, 10:11 PM
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Tainui
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My experience with the 6MT is that it responds well to adding throttle mid corner (before the TT). The rear would squat and I could hold a nice, predictable line. Since the TT it requires a bit more finesse but the push goes away with a little throttle. This goes against everything they taught me in track school but it works every time on this car.
Old 08-27-2009, 05:11 AM
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pnk
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Red face

Originally Posted by classy37
What Springs? I can't find any aftermarket springs for the AWD.
Take a look at the following thread, which suggests a couple of aftermarket springs that people have used on a G37X:
https://www.myg37.com/forums/g37-sed...on-a-g37x.html

pnk
Old 08-27-2009, 11:49 AM
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Alex57r
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Originally Posted by classy37
Aren't these two statements contradictory? How can understeer be good? Oversimplifying a bit, isn't it basically when a vehicle does not quite 'make' the turn its trying to? Or is a limited amount, under certain conditions, actually a good thing? How?
Either I am not making myself clear or you misread the post. Understeer SUCKS, but I was surposed how much the handling impoves when you apply power/throttle while turning. It changes the understeer balance to somewhat neutral bias.

Originally Posted by Tainui
My experience with the 6MT is that it responds well to adding throttle mid corner (before the TT). The rear would squat and I could hold a nice, predictable line. Since the TT it requires a bit more finesse but the push goes away with a little throttle. This goes against everything they taught me in track school but it works every time on this car.
Yes, this is exactly what I feel, but I never went to track school so I need some advice. My feeling is that the car can handle alot better then what I have seen so far if I aply throttle correctly on the turn. So throttle Mid corner? Is that the trick? How much throttle before it starts to oversteer, if thats even possible? What if I am taking a turn fast while throttling and then have to slow down suddenly in the turn? Am I screwed? lol

I appreciate the springs advice guys. Thanks!
I am sure stiffer springs and stickier tires would help, but before spending thousands, I think it might make sense to learn to use what I already have...

Last edited by Alex57r; 08-27-2009 at 11:58 AM.
Old 08-27-2009, 03:07 PM
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JohnEnglish
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Yeah that's what happens with AWD cars. If you get in trouble you keep your foot on the gas.
Old 08-27-2009, 03:14 PM
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classy37
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Originally Posted by Alex57r
Either I am not making myself clear or you misread the post. Understeer SUCKS, but I was surposed how much the handling impoves when you apply power/throttle while turning. It changes the understeer balance to somewhat neutral bias.
Old 08-27-2009, 06:34 PM
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da mayor
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Originally Posted by G37-6MT
Then I don't understand. When a car understeers, it plows forward instead of turning. The plowing is sliding.

I still detect some mild understeer at times even with the S package on my car. The suspension could be a bit tighter IMO. It's definitely not a track ready suspension, but a nice compromise for the street.
the rwd sedans do get a different steering ratio which makes it feel different from the AWD version sedans. It's al about driver input on any car.

Coming from your Lexus that we used to speak about, it had a different feel but the body roll can be more pronounced the the GS430's compared w/ the G sedan.

Throw on some GT Spec chassis braces and you'll feel the handling get a little tighter - I felt a huge improvement in my FX45 compared w/o the GT-Spec lateral braces in the front and rear.


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