G37 Track Set Up. Oversteer Help.
 

Hey guys, I wanted to see if anyone has any experience or insight to help me resolve an oversteer issue I'm having with my G37 sedan on track. I know it's a longer wheel base than the Z but figured the majority of the set up should be the about the same.

In this video at points 4:20, 6:20, 9:35, and 12:18:



In this video at 2:25 I did lose it. I'm not sure why the backend came around soo late but I think I made it worse by getting on the throttle while trying to correct it.:
(youtube is still processing the HD version as of the time of this post)



Here is the set up relative to the issue:

- Tanabe Pro CR Coilovers 10k Front/9k Rear. Pretty damn soft dampening.
- Eibach front bar set to full stiff
- Factory rear bar
- Square 18x9.5 +45 PF01's with square 275/40 MPSS's(+35 front with spacer, still +45 rear. Rear spacers/studs to go on soon)
- G-Loc R12/R10 combo
- Bell Raceworks diff brace
- Kinetix front camber arms(Will be coming off soon, they aren't meant to add negative camber without modifying them)
- Aim for 38 hot front/ 36 hot rear PSI

Fresh alignment specs:

Front Left/Right camber: -.9/-1.1
Front Total Toe: 0
Front Left/right Caster: 5.7/5.8

Rear Left/Right camber: -1.5/-1.6
Rear left/Right toe: .11/.13
Rear total toe: .23


About myself: Very much a newbie with about 10 HPDE's under my belt and only 6-7 in the RWD G. I built some bad throttle application habits by driving with traction on that I'm working on slowing down and unlearning now. I've taken one skidpad/car control course which was beyond helpful and getting me off the right foot as far oversteer correction is concerned.

Problem is I don't trust the car to remain predictable with the traction off/yaw sensor bypassed. I know I carry more speed than I should at times into some corners but the rear end wants to come around even when I slow my entry speeds down.

I was working with a coach over the weekend who drives a Nismo 370z and he noticed the same thing. The car just feels sketchy and it's really slowing down my progression as a driver. I'm not chasing lap times just trying to become a better driver and hoping to eventually get into time attack stuff down the road(not in the G). With that said my current PB at Laguna Seca is a 1:52.0 and I can consistently run 1:53's.



Here are my thoughts:

1. The car isn't corner balanced but the ride height is even front/rear at the pinch welds.

2. Could the +10mm front to rear wheel stagger be causing this kind of issue.

3. +2 psi Front tire pressures compared to the rear helped a little.

4. Too much traction upfront compared to the rear is causing the rear to be loose. Should I run a staggered tire set up to reduce some front grip? I really don't want to do that. Maybe set the front bar to soft or even go back to stock bar?

5. I wanted to add more negative camber up front(why I got those camber arms, even though they actually reduced my max negative camber compared to the factory arms) but that will only increase front grip and make the oversteer worse?

6. Maybe add some front spring. 10k front/9k rear might be too close in relation. Going a little passed my knowledge base.

Maybe try a staggered setup. The square setup will make the car oversteer more. I thought on the track you want the car to oversteer. Maybe removing the rear sway bar. This is just my opinion some more experienced track guys can chime in.

That may be a solution. I followed the advice of experienced track guys on how they set up their cars but that might have been the wrong approach for my driving style. I'm thinking I prefer a touch of understeer at least until I get more comfortable with oversteer and my ability to drive at the limit.

For starters your springs are too soft with race pads. Too much weight transfer under braking causing nose dive and rear to walk. Adding rear wing would help keeping rear more stable as well.

We have the exact same G37 Sport sedan (even same color!), but mine is a year older.

I have done a few HPDEs in my stock G37 and it is rock solid. It never did anything that surprised me and every corner was entered and exited knowing what to expect and it was very easy to steer with the throttle, when I wanted to. Miles of smiles :)

With the suspension mods you have done, you have added a lot of variables.
• Changed the front scrub radius by 35mm
• Changed the front track by 35mm and the rear by 45 mm. Since the track has been widened, there is more leverage on the suspension, so the effective wheel rate is softer/lower.
• Different spring rates and compression/rebound damping.
• Possibly different spring preload.



Items I would look into:
• Suspension travel. Is the rear hitting the bump stops when on the track? If it does, the wheel rate goes way up, and you loose traction.
• With a 275 rear tire, maybe -1.5 degrees is too much negative camber and not all of the tread is on contact with the road. As I recall, the G37 has a good rear camber curve and doesn't require much negative camber.

Bottom line:
If your car oversteers more than you want, you need to decrease the rear roll stiffness or increase the front roll stiffness.


Also, this may be of interest to you:
http://infinitig37.com/G37-BC-Coilover-Review.html

First video at 1:52 that is some instant snap oversteer in mid-corner!
Makes me think if the rear ran out of suspension travel.

Put some tie wraps on the shock shaft to check the maximum shock travel.

Throw those arms away
Call SPL
Buy all their arms

Sell the tanabe
Get some fortunes with a higher rates

Crank up the camber all around

My guess is the softness suspension is causing a lot of weight transfer mid term, overcoming available grip already compromised by the weak alignment

But I’ll let the track rats chime in

I think SonicVQ is onto something here.

http://www.the370z.com/brakes-suspen...ing-rates.html

Isn't a 9k spring rate equate to around a 500lbs/in? That's same as the OEM Nismo 370z rear, which would be quite soft for the sedan. Combined with the shorter travel, up-sized tires, you may just be suddenly hitting bump stop, infinitely increasing the rear spring rate in an instant.

If you are running a square setup you need to disconnect the rear sway bar and see how the car does. Most people with a square setup will not run a rear sway bar because of the issue that you have.

You need more spring up front rear okay, get some trackable coilovers. If you are running r compound tires you need to shoot for tire pressures between 34 and 36 hot. Your ride height should be within an 3/4 of OEM. Get all SPL suspension components as mentioned. Camber in the rear is okay and you need at minimum -2.5 up front. As was mentioned, the brake pads you are using are very aggressive and should only be used with r compound tires or slicks. Xp 10 and 8 are just fine. I ran them on my boosted Z with r compound tires even when I got to HPDE 4 and was carrying some speed.

If all else fails or you don't have the money to get your suspension setup properly, go back stock or close as possible. Then change one significant component at a time.

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These Coilovers are designed for street comfort so that does make a lot of sense. Problem is even when I brake earlier and the car is more settled before turn in the car still oversteers.

Yeah I know the SPL's are the be all end all but they're just extremely overkill for my use case. The car is a daily that I want to use to get better as a driver on the track with. I've spoken with a few guys that race in a Nissan series in Socal that use these arms(modded) with good results. I'm not building a race car so I don't think mind giving up caster adjustment and spherical bearings/joints for cost/comfort. Basically trying to build a well balanced car.

With that said I'm not adverse to stepping up the spring rates a little to get off the bump stops if that is what's going on in the rear here.

Thanks for the insight! I will say that when I was on stock sport springs and shocks with square 245/45's and the Eibach front bar the car didn't feel as lively as it does now. I had much less experience then though and couldn't really "feel" what the car was doing + my pace was much slower.

I'll try and see if I'm hitting the bump stops in the rear as you suggested when I get some time or during my next track day.

The car snap oversteers at T10 at Laguna a lot lol.

I've attached images of the rear suspension to see if it helps any. The rear springs are progressive from the looks of it and rear shock body is shorter with what appears to be more travel. I also keep the rear at max ride height allowed which equated to around G2F 26.75". I'd like to go higher but that is max adjustment available.

Bumping up the tire pressure up front did help so I feel like more front spring or bar would also help but I don't want to be chasing my tail. I want to add more negative camber upfront(-2.5) to help tire wear but It will just give me more traction up front relative to rear making my current oversteer issue worse.

I was originally wanted to go with the R10/R8 combo but the Z1 guys said while those compounds worked well for the Z, they weren't enough for the heavier G. Might need to step back down.

The "best" tires that I'll put on this car will a 200tw "cheater tire". Something like a RS4 or N'ferra. No R compounds are in the plans for this car.

I'm sorry that's ********. You can't post in the track section asking for advice about suspension and then NOT get SPL stuff because you're worried about cost comfort. The only reason not to use the best arms available is if you're in a racing series that specifically prohibits it

YOU CAN TOTALLY DAILY A CAR WITH SPL ARMS - i dont know where the stupid assumption that adding spherical arms will suddenly make your car unlivable come from

spring rate/damping and tires have a far bigger effect on how your car will feel


your sensibilities are way too soft. if you want a car that actually is trackworthy, get over your ******** and do it right
without proper alignment capability, you're wasting your ******* time

why bother coming here asking for help if you're gonna turn it all down because you wanna half *** this ****? Why are you wasting money on track time at all if you aren't even going to do something as simple a real coilovers and alignment?

this is sad

You also might soften your front bar as well. That will induce more understeer.Those tires are not cheater tires. The rs4 is good tire for endurance and getting more session in. The cheater tires are AO52, Falken 660 and Eagle r3. Really doesn't matter as you need to get the balance back in the car.

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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.

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?

IF you want to improve. :driving:

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.

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

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

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?

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

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.

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.

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.

http://www.the370z.com/members/2011-...-money-pit.jpg

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.

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.

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

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

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.
:tup: :driving:

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.

:iagree: Jar is spot on!!! Find one or two people to put your faith in while listening to the rest. Not everything that works for one or many will work for you because of your driving style and the uniqueness of your car. Find others that track Gs and ask them for help. A couple that come to mind are @apexgarge and @g35_tracker on Instagram. Both are very fast and experienced.

Hey Rusty, are you toe recommendation each side or total toe?

I tried .04D in each side and the car now pushes like never before.

Thanks for the input everyone else as well.

The car doesn't oversteer nearly as much anymore and pushes now on slower tighter corners. I'll play with the alignment settings more to find a good balance. I went with .04 in each side of toe upfront from 0 and that seems to have made a massive difference.

I did exactly what JARblue was recommending. Consulted an instructor of mine who races professionally and he helped me through it. He believes its the front toe adjustment that changed the handling soo much. Seat time has also been tremendously helpful in understanding the car.

I'm also going to look into grabbing a set of SPL front and rear end links before I get the car corner balanced. On my previous TSX corner balancing didn't make much of a difference at all, but that I wasn't as experienced of a driver and it was a completely different car/set up.

Total toe.

I had a feeling.

.08D in front and .22D in rear might be causing the pushing now.
I'll play with that.

I'm hoping this isn't an issue, I haven't had time to check rear travel either though. The main reason I hope it's not the roll center going Infinite is that would mean I need to start swapping Coilovers.

While not completely averse to it, I'd like to try and stay with my current set up if at all possible. The rear is at the Coilovers max allowable height and only a .8" drop from factory height with a 9k spring rate.

Do you have true coilovers or the oem style in the rear?

9K rear spring seems in the right range if it is in the OEM bucket location with 10k front spring rate. If you have 9K rear springs in true coilover style, that is way too high to match the 10k front. But I assume you're already aware of that.

Yeah OEM divorced set up, for a true type the spring would probably closer to 6k.

Update: Feels like I've got it all sorted now. Testing was done at Thunderhill West so I guess I'll really know next time I'm out to Laguna(Mid corner tuner 10 snap oversteer) but I think I'm good.

While technically within spec, I don't know where I got my previous .13 toe-in/each side value from but it was way too much. From educating myself more, talking with people I trust, and getting feedback from you guys I dialed the rear toe-in way down but had to run -2 degrees of camber on the factory eccentric bolts. So I grabbed some new camber arms, lockout bolt kit, and toe bolts to get everything exactly where I wanted it.

New specs:

-2.4 Front camber
0 toe

-1.5 Rear camber
0.03D Toe-in/each side

I previously tried .03D toe-in/each side upfront as recommended but the steering became too unresponsive for me, great on the freeway though. Zero road tracking.

Anyway with these settings and hot temps of 37 front/35 rear the car felt very balanced. Turns in nicely and the car stays planted throughout a corner, I'm 100x more comfortable in the car. I don't see myself really changing much on the suspension set up from here on out with few exceptions down the road. 200tw tires once the MPSS are done, adjustable end links and corner balance after corner weighing, and possibly a SPL anti bump steer kit as I feel some binding. Otherwise it's all seat time.

Beat my previously PB of 1:34 by 2 seconds :driving: and even saw 1:31 on the predictive timer, just needs a better driver.