Good full stiff on the front to reduce the understeer. I like no bar in the rear like Eagle stated. I would recommend just leaving the oem bar and try that setup and if that doesn't help the rotation then remove the passenger side end link to disconnect the rear bar and see if you like that better. If that does not work then you can add the Whiteline rear bar and start adding more bar.

Getting your suspension tuned properly is a slow stepwise process and you really only want to do one thing at a time so you know exactly what is working and what is not. One thing is for sure with the Z...you can't have too much front bar!

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Full stiff on front? I'm seeing two different trains of thought on this thread and throughout the forum. Albeit, everyone's car is tuned different, but is there some rational to this?

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

LMAO, yes there are many opinions on this subject and you are free to pick which ever method you like but you asked for suggestions and recommendations so you got them. A few of us have been down this road and have received solid advice from others which include professional racecar drivers that also work on their cars. Eagle knows what he is talking about as he the fastest NA track day Z driver I know and I have seen his times drop dramatically since his last upgrades and tuning to his suspension.

Anyway, a soft setting on the Whiteline will be stiffer than the oem bar. Just be careful because it you get it wrong you can end up with snap understeer and that is about as scary of a mistake you can make with your suspension. Trust me as it has happened to me a couple of times during spirited driving and my seat has stains that can't be removed, lol. Good luck and keep us updated.

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I would really advise against full stiff rear, I would actually do the opposite. Heck I don't even run after market rear sways. Being full stiff rear is going to make the Z very very unpredictable at the limit, sure you might start to oversteer not but it's not going to be the fun type, it's going to snap at you

if you have camber arms then I would actually go even more negative to like -2.5

Found this Gem in another thread; looks like a pretty comprehensive guide into suspension tuning:

Car Suspension Tuning Guide| Rapid-Racer.com.

Any thoughts??

probably a good guideline, but remember every car is set up differently, though I honestly haven't heard many good things about stiffening the rear sway on the Z. most people keep it OEM or the softest setting unless you want to make the car unpredictable and snap oversteer a lot

While you’re waiting for the work to be done try raising your front tire pressure. The PS4S’s have a little more rollover than other tires on turn in and respond well to slightly higher pressures. Plus it’s free and easy to try as a starting point. Also measure the ride height front/back to see if the front of the car is higher than the rear. Lower it if it is.

It's not a simple question or a simple answer. Assuming your doing all the right things with the brakes throttle and steering inputs (not an easy thing to do). Here's a nice little flow chart.
https://drivingfast.net/wp-content/u...osis-guide.png

While I agree that in a typical setup for an FR car that is seeing track duty this would make the car snap oversteer, the problem is the OP is saying that his car is massively understeering now and after reviewing everything he has and the things he's not willing to change, he is really backing himself into a corner. So either he stiffens the rear via the sway bar, full stiff is probably too aggressive so maybe soften the front sway bar to the softest setting instead and leave the rear in the middle or wherever it's currently at. Or he has to play with camber and toe, my guess is that if I'm running a square setup with -3.25 front camber and -2.4 rear he's going to need more negative camber than me to get close to the same feeling i'm getting. That brings in a whole new problem with tire wear due to the camber.

Thanks for having my back Bob, you da man :tup: In all seriousnes everything i've learned about suspension has been from my driving coach, my friends who have been doing time attack for years, the racers who have come before me on this forum and the past 12 months of tracking that have allowed me to test and tune and see what really works and doesn't.

@igota21incher The ball's in your court dude, there are different schools of thought on how to tune the car to your liking but it really comes down to you. Caution should be exercised whatever the case may be.

LOL, your results says it all. Yep, one ride with Steve and I learned a ton. I won't get some more time with him at course like Streets or Buttonwillow. Something more technical than Auto Club. He was the one that told me to get rid of rear bar. I need him to drive it and give some additional advice on my suspension. It is a little more complicated having a big arse wing, spiltter and canards.

Let me know the next event you are going to attend after this month and maybe I can go play too. :tiphat:

The one thing I have learned while on the forum is this. Go with a square setup. 285,305, or 315's. Go with the stiffest front bar you can. Hotchkis is the stiffest. Remove the rear bar. For spring rates start at 14k fronts and 11-12k rears. Progressive springs are not for the track. If you go with slicks these rates will be much greater. Front Camber start at -3 and for rear camber start at -2. First mods after some seat time are oil cooler, better brake fluid and pads, front brake cooling ducts, and a good LSD diff. So, you can pick and choose what you want to do with your current setup but it will still feel like ****.

Solid advice from all (esp the track guys)! I have scheduled some shop time next Saturday; will report back as soon as I’ve had a chance to take her on some winding roads.

Question. Will this car ever see the track? You said that you are getting understeer in the twisties. So it's street. Track set-up on the street will KILL tire life. Pick your poison. You screwed up on your front tire size.:shakes head: Should have went with a 275/35-19. And now you want a work around. Ain't going to happen. Get the SPL upper control arms. For the street. Front camber at -2.0, caster at +6 to +7, toe should be 1/16" in. Rear camber at -1.75, rear toe at 1/16" in. If you set the rear toe to zero, and out. You will get a condition called snap-oversteer. It doesn't happen all the time, but when is does. You will be cleaning out your shorts! :eek: It's scary when you are looking at the guy behind you, eyeball to eyeball. :eek: Front sway bar full stiff, rear bar full soft. The front of the Z has too much roll in it. You WILL have to change the dampening on your coilovers. If not. You are SCREWED! If you are not willing to make changes. You are doomed!

My set-up. I'm running bigger tires then most anyone.

Front 285/35-19 PS4S on 19x9.5, +25. Rear 345/30-19 PSS on 19x12, +28.
Front camber -2.5, caster +6.5, 1/16" toe in.
Rear camber -1.8, 1/16" toe in.
Hotchkis front sway bar, stock rear sway bar.
Rear diff is a OS Giken set-up at a 1.5 way, with 70% lock up.
My whole suspension is out of the SPL catalog. No rubber bushings.
I turn off my VDC and have done the YAW sensor mod too.
My Z likes to dart around. It's a bit nervous. :tup:

Go to the track so you can pinpoint exactly where the car is understeering.

You need more front camber in this car, there is too much weight up front to only have -1 camber.

If you can get the specs you want with SPC, you don't need to get SPL arms.

Show off!!!

This is a great place to start and works well for a dual purpose track and street car that sees some twisty road time. If you are just dd the car there is nothing wrong with having front camber at -1.0 to -1.5 to extend tire life and if you want to maximize straight line speed....well that's a whole other story.

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