Holy Understeer!
 

Hi Guys--after installing the following mods, I've managed to create a massive amount of understeer which is killing my enjoyment on the twisties. After doing some research, the new (unfavorable) handling characteristic may be attributed to the large stagger between the front/rear tires. From what I've read, this could be remedied by increasing camber in the front and installing some sway bars. With the following mod list and suspension settings in mind, could anyone give me some solid recommendation for a street friendly way to improve the handling where the car is able to communicate every turn without plowing through it or kicking the back end out excessively?

19x9.5 +15 255/35 (f) 19x11 +13 305/30 (r) on Michelin PS4S
KW v3 set to middle dampening settings from KW--I like the ride quality on these settings so would no prefer to mess around with compression/rebound.
SPC front and rear camber kit
Whiteline front and rear Sway Bars with end links
Dropped down to two finger gap front and rear--would not like to go any lower.

Current Alignment Specs:
http://www.the370z.com/members/igota...65620301-o.jpg

I was thinking to increasing camber to -2 in front and keeping rear at around -1.5 to assist with turn-in.

In addition to the camber settings, which sway bar settings would you recommend on the whitelines?

I heard that soft front and middle rear is a good starting point?

Thanks in advance!

someone can chime in to help you with the suspension setup. but i dont think "massive" under-steer would come from the tire stagger.

if it was a bit of under-steer possibly. i have ran 265/35 and 305/30 setup for the last 4-5 years and the handling/grip is really good.

more negative camber
more positive caster
ditch the rear sway bar
more front tire
mebbe lower tire pressure in front

The rear end is just so darn grippy in corners compared to the front, which leads to the front not being able to communicate the turn leading to the 'pushing' feeling.

Would increased camber up front remedy this along with a full stiff setting up front on the sway bar and soft in the rear?

Anyone experience something similar when going with such a wide stagger?

You probably know this already but...

Make sure your tires are in good shape, worn front tires are going to cause you to understeer all day everyday.

Maybe look at this from a tuning perspective.

1. First choose the right wheel and tire setup
2. Choose your coilovers and alignment
3. Adjust your rebound and compression
4. Use swaybars to fine tune the handling.

If any one of those are off, like the first one...you're going to end up compensating for it elsewhere.

Stock stagger creates enough understeer at the limit that it's more than just a nuisance. Increasing that stagger is only going to further exaggerate it. You want to reduce understeer at the source of the problem? Go to a square wheel and tire setup. Any tire in my opinion over 285 is overkill for this car, especially if it's NA.

The car will rotate easier and you'll be able to control that rotation much better with throttle input. Anything else you do will be masking the inherent nature of that configuration. Although I know you said you don't want to mess with your compression and rebound settings. If you stiffen the rear it should make the car want to oversteer more and by that logic I would not recommend removing the rear sway bar as it will induce more understeer.

If you can...get a true square setup.
If you cant...play with your coilover compression and rebound but write down what they are currently set at so you don't lose that baseline.
Then...stiffen the rear a bit more from what it is now, maybe move in 1 or 2 click increments, see if the understeer has gotten better until you've reached your ideal setting.

If it's still understeering, maybe then see about setting up your sway bar to a stiffer setting. You are running up against your wheel and tire setup and I would not recommend you try to mess around with your alignment too much to try and fix this because your setup is going to be all over the place. Might as well start with the wheels and tires and do it right from step 1 onward.

Where is the understeer happening? Turn-In, mid-corner, or exit?

Thanks for the thorough explanation, however going with a different wheel and tire setup for the street is a no-go since I decided on the combo for a cosmetic approach, I will eventually have a dedicated track set for when I do start tracking. With that being said, is there a way to dial it out with camber/sway bar adjustments? At this point I’ll take the stock understeer feeling since the car was more responsive at the limits..

More noticeable at turn in; once in mid corner I have laid off the throttle enough to communicate the turn, but at that point all the fun is gone ;)

you should probably throw away the SPC stuff and get SPL FUCAs for full camber/caster adjustment

I think I have enough adjustment with the SPC parts. The real question is what settings to adjust to ;)

A valid point is that SPL FUCA allows both camber (static camber) and caster (affects camber as you turn the front wheels) adjustments, whereas the SPC ones that are usually mentioned only allows camber.

Given you said that tire size change is off the table, I would start with changing your front static camber to -2 degrees.

Oh, you really got a 21 incher? :roflpuke2:

Stock understeer more responsive? I drove on that setup for awhile and had no idea how bad it would understeer until i did my first track day. It was particularly heinous in the skid pad at Streets of Willow CW. That was anything but responsive to me, wheel completely cranked, full lock and the car would not turn, on throttle or off throttle.

Anyway, if you're not gonna bother touching your rebound and compression which is IMHO the easier and less expensive thing to do, then yeah...you have no choice but to try alignment and swaybar settings.

Try going stiffer on the rear bar and see if that helps. If not then you can try adding camber and toe. Toe out in the rear will make it want to oversteer, increasing camber up front will get you more grip on corner entry and should increase oversteer as well. Your camber settings will need to move up into the -2 and -3 territory to get the result you want.

Highly recommend the SPL stuff too especially if you have track aspirations.

Ways to Correct Oversteer
Lower front tire pressure
Raise rear tire pressure
Stiffen front shocks
Soften rear shocks
Raise front end
Lower rear end
Install narrower front tires
Install wider rear tires
Stiffen front sway bar
Soften rear sway bar
Reduce front negative camber
Reduce positive caster
Stiffen front springs
Soften rear springs

Ways to Correct Understeer
Raise front tire pressure
Lower rear tire pressure
Soften front shocks and stiffen bump
Stiffen rear shocks
Lower front end
Raise rear end
Install wider front tires
Install narrower rear tires
Soften front sway bar
Stiffen rear sway bar
Increase front negative camber
Increase positive caster
Soften front springs
Stiffen rear springs

I autox'd my Nismo '13 probably a month after I got it and noticed the major understeer. The tires that came with the car were "OK". They were Pirelli summer tires (don't know the specific type).....Anyway, I gave the car some camber up front and put on some RE71s and the problem went away!

All great ideas guys! I'm going to do my alignment this weekend with the sway bar install.

I'm going to try -2.0 (f) and -1.5 (r) camber settings with the whiteline sway bars set at full soft front; full stiff rear and see if that helps, unless anyone would advise against it.