G37 Track Set Up. Oversteer Help.

2.2Lude

Not sure why you are soo worked up.
Read my replies I'm clearly not "asking for advice and turning it all down". Slapping everything SPL on to my car isn't going to magically solve my issues.
Of'course there is a cost to benefit factor everyone has to consider. I mean I guess if $$ isn't an issue then yeah by all means go nuts with some JRZ's or other high end suspension system.

Aside from the FUCA's I can achieve my desired alignment spec's with the cars factory equipment.

Nearly any set of FUCA's will get me to my desired -2.5 degree's of camber up front. I understand the drawbacks to non-SPL or Voodoo arms and those compromises are ones I'm willing to live with for a car that see's daily duties and 10ish track days a year. I'm not competing or building a race car, just something that is comfortable for me on the street with enough track-ability to help me improve as a driver.

In the rear my ride height doesn't necessitate any additional arms or SPC toe bolts to get to the spec's I want. Yes eccentric bolts aren't the most reliable and can slip, I'm aware of that. In the future if I find my alignment changing I'll address it. For now I've not had any issues.

It is your opinion but I'm not wasting my time/money on seat time just because I'm not willing to go SPL everything and switch coilovers. I'm very open to switching coilovers, upping my current rates, or going to back to the stock set up in order to identify and solve my problem.

In any case if you think I'm wasting my time and yours please see yourself out of this thread.

2.2Lude

I'll give softening the front bar a shot, that will be the easiest thing to test on the car and a good starting point.

I guess I just have my terminology mixed up but yeah I was referring the segment which includes the RS4 and RE71's not the A052 and Eagle R3 class. They keep changing these category names lol.

I'm hoping reducing the front grip will help solve the issue but I'm not soo sure. Furthermore, if I increase the camber like I need to upfront I fear it is just going to make the balance worse.

I need to check still but do you not believe that I'm running out of rear suspension travel?

Rusty

IF you want to improve.

SPL arms.

Alignment spec's.
Front; camber -2, Caster +6, toe .06D in
Rear; camber -1.7, toe .06D in.
This will give you a set up that will live on both street and track.

Hotchkis sway bar. You need to stiffen the front up. Stiffer bar induces more understeer.

Your dampening isn't helping by being soft. Too much weight transfer. Stiffen the compression in the front and stiffen the rebound in the rear.

DO NOT use the VDC. Turn that motherfvcker OFF! What happens with it on. When it senses the rear stepping out. It WILL apply one rear brake caliper to straighten the car out. It WILL have you pointed in the wrong direction.

The Mich PSS tires will hang for about 20 to 30 minutes before they lose grip and begin greasy.

Get a notebook and start taking notes. Weather conditions, tire pressure, fuel level, anything that will affect the handling. After awhile, you will see a pattern.

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2.2Lude

So does softening the front bar or stiffening the front bar increase understeer?

OptionZero

This is like wanting to lose weight and not wanting to diet and exercise because you’ll get sweaty

Your alignment works together with your springs and dampers to make sure your tires have grip; your problem is suddenly losing grip

And stiffer front bar usually leads to more relative understeer but all track people agree the front needs more stiffness to ADD grip on front

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2.2Lude

Thanks for bringing that up. This is something that was always a bit hard for me to understand when I was originally doing research last year on how to get a base set up in place for my car. Admittedly, I kinda just went with it thinking it'll work out without fully understanding it.
I read a lot on this site from members like yourself and others that have provided input.

Maybe you can help me wrap my head around the concept better.
Traditionally a stiffer front bar will INCREASE understeer by REDUCING GRIP correct?

So how does a stiffer front bar both INCREASE understeer and INCREASE/ADD grip?

Or is it just something that comes into play with a square tire set up to improve the front grip with wider tires but use a stiffer bar to increase understeer and balance the cars front/rear traction?

OptionZero

Think of a blacksmith forging a sword. For a blade to work is must be sharp, so the blacksmith has to grind the edge to a fine point. Grind it too much, the blade becomes too thin, it breaks, and you aren’t cutting anything with it

There is enough flex in our chassis in stock form that our front suspension isn’t able to properly work to keep the front tires planted in corners. Stiffer front bar is needed to reach a certain threshold where all the arms and spring/camper can actually do their job and keep your tires connected to the road.

That’s the best way I can explain it. Don’t think of it simply as “stiffer end - less grip” like we’re in Gran Turismo. In the real world, cars are flawed and we’re doing our best to achieve the dynamics needed to do better. Our front suspension is an area where Nissan’s design was lacking, or at least compromised to favor every day driver safety instead of track performance.

This story is the same for your spring rates. Too soft overall means weight is being transferred wildly when you attempt any dynamic movements. Your entry speed and turn on doesn’t appear that sudden, but the heavy sedan, with a heavy rear end bias, is sending so much momentum in the form of weight transfer that you’re still spinning out even with relatively soft driver input.

That is why everyone says you need stiffer suspension, and better alignment. You want the stiffer suspension to fight the weight transfer and make the tires do the work, which in turn demands a better suspension so your tires have more grip to eat the forces you’re putting on it

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SonicVQ

This is a good book that I read in the mid 80s... AND everything in it is true today:
https://www.amazon.com/How-Make-Your.../dp/0912656468

It might be a good idea to get a correct foundation of understanding so you can develop what works for your driving style, in your car, with your setup. Then you can make your own informed decisions, test them, and re-evaluate.

In 20+ years of car forum participation, any handling question just becomes a sea of contradicting answers.

cv129

My thoughts:

The bar restricts the amount of weight being transferred from one to the other side of the car. The weight transfer can both increase and decrease grip.

Front wheels - At any combination and speed and steering angle…too little weight transfer means you won’t get the maximum grip the outer tire provides, because there isn’t enough weight pushing down on the tire. Therefore the general saying of “stiff front bar = under steer”. Then at the other extreme….disconnect the front bar, let all the weight freely transfer side to side. In the same cornering scenario, most likely, it’ll give you a split second of strong directional change response. However, while downward force in the tire is good, the added momentum is the negative byproduct. Without the front bar, your outer front tire is left to fight all the momentum, and quickly others overwhelmed.

So the relationship between bar stiffness and over/understeer isn’t a single direction curve. I would imagine it to be more convex, and certainly chassis dependent.

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Setrab | RE-71 | SPL | JRZ | Nismo | ARK | Whiteline | RacingBrake | CJM Oil Pan | Ti shield

2011 Nismo#91

Its very hard to tell from just a video what's going on. I mean it helps but there isn't even any speed or G force data. I would guess that your cornering speed and entry speed is too high. You said that you adjusted your braking which is good but you need to adjust(reduce) your speed a specific point for the corner. As most people have already guessed weight transfer is the primary issue and your suspension is the primary cause. (you've already see this through the increase of front psi and decrease of rear psi), higher less grip front end and lower more grip rear) Better data will help better solve your issue, corner weights for example, or we are just going to all be through crap at the wall to find out what sticks. Get your read on with these.

Understeer And Oversteer: Adding Vs Removing Grip - Race & Track Driving (formerly Win HPDE)
Autocross to Win (DGs Autocross Secrets) - Weight Transfer
The other sections are very helpful too.

The G37 is a heavy soft luxury sedan and while you can drive any car on a track it's never going to be great.
Essentially you are going to have to make a decision do you want a comfortable luxury car and drive within it's limitations or a uncomfortable performance vehicle and find the next limit which will need more $$ and less comfort to solve. IE a money pit.

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2.2Lude

Thanks for the input everyone.

SonicVQ: I ordered up that book on eBay, should be here soon. I'll dig in.

Everyone else, I appreciate the explainers on why this car handles the way it does and why it requires a stiffer front end to help increase grip.

Looking at set up concepts in only black and white is obviously the wrong approach as different cars, different set ups, driving styles all play a role.

After everyone's input, I got the front camber down to -2.2 and added a some front toe in .04 each side. I also added the 10mm spacer + studs in the rear to even out the track width.

Got back out to Laguna last Saturday and the car felt balanced and much less oversteer prone. It actually started understeering at T2 and I had to really try to initiate rotation by trail braking.

As Nismo#19 mentioned, I'm learning to drive this car within its limits.

Sharad909

One thing for sure, it's easier to add under steer then searching for over steer. There is nothing wrong with having a balanced track/street car. Yes you can daily on sephical arms but you can also track on OE arms. I competed in the Nissan Challenge 21 and had huge improves in the car and times throughout the year. The most dramatic mods for me was alignment, corner balance, and sway bars. If I was you, add more camber front and rear, get corner balanced (huge difference!) and practice driving.
My alignment specs are pretty aggressive but my car sticks, very well! It wasn't meant for daily use lol
And do what Hotrodz said, maybe soften the sway up front or add a stiffer one in the rear.

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Sharad909

I just saw your response lol
Let us know how it goes!

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12 370Z- Touring- Sport- 6MT-
Z1 Anti Starv, 34R Setrab Kit, 20/25MM | Konig 18x10.5 W/ Hankook RS4 | PowerStop TrackSpec Pads | TTP Single Exit , & Swift Springs | Previously Owned: 18 Q50- 480RWHP- 12.2 @118- Sold, 92 240SX Built SR

street2soul

Before you go down the spring/damper rabbithole, consider this a try:

For the mid corner snap oversteer, it appears to me your roll center may be too low, if your car is lowered especially in the rear. Car is transitioning to a sudden snap at the grip threshold because your rear rolls too suddenly and is not controlled. You may need to raise back the rear ride height and it will most likely improve rear slip consistency and improve snap oversteer

To me, it appears that for T1 corner, the oversteer is coming from trail braking not bleeding off enough while you're at full lock. I'm sure if roll center is your issue, that is contributing it to the oversteer happening at full lock while you are trailing off the brakes

JARblue

Based on your build, there is nothing there that should throw off a solid track experience. As an aside, I think you need a good LSD to go along with the build. Good call on making adjustments to the alignment rather than throwing more parts at the car. It sounds like it was an improvement.


It's great to get all the best information from everyone on the internet that knows everything (that's not a jab at the guys posting here - they know their shìt for sure). But you are the driver and seat time will be your best friend to help you understand all of the recommendations from the guys on this thread so you can apply them appropriately to your situation. As you get faster, you'll be more in tune with the variables that affect your driving experience.

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