Advice for Track Handling Setup - Round 2
 

Looking for some advice on "round 2" in my quest to dial in a track handling setup.

Last winter (2016) I went with a square set-up, installed SPL Upper Control Arms and moderate camber alignment to address understeer. Throughout the 2017 track season I experienced what I would consider “uncomfortable oversteer”...where I spun out twice and was loose enough to decrease my confidence…which often kept me running with Traction Control on.

I would like to bring the car back to a more neutral handling such that I can regain my confidence and run without traction control. I would almost rather push a little now as opposed to spinning out.

Current Setup:

• Front: -2.75 Camber; +.05 Toe with Total Toe = +.12
• Rear: -2.5 Camber; +.15 Toe with Total Toe = +.35
• Square Set up with 275/40/18 RE-11
• Tire Pressure has been equal all the way around (40 PSI…taken immediately coming off track).
• Stock Sway bars (front and rear)
• The only suspension component replacements have been the SPL upper control arms.

Interested in hearing your insight, wisdom, experience, advice...

Hotchkis front sway might be a good place to start.

To be blunt, your current alignment is not ideal for balanced controlled.

Big notes are- Too much rear camber, too much toe, and tire pressure is about 3-5psi too high.

Hot temps with that much camber should be around 35-37psi.

These are quick fixes that should be done. IF this is not suffice for your driving style. Next would be to increase the front swaybar size. Too large of a bar may cause unwanted weight jacking problems (there are a plethora of reasons you don't want this).

Rear camber should be well under -2 degrees, ideally -1.5 to -.5 depending on how you drive.

If you tend to get on the gas quick and hard off of corners, less camber is your friend. If you pitch the car into a corner slow and smooth and modulate the gas very little through the turn, then you can get away with more camber in the rear. This only works well if you know you have good front in grip and a stable rear.

Contrary to belief, a squared setup isn't the most ideal layout. The rear of the car experiences more yaw and pitch which puts more lateral load across the tire. A smaller tire will start to load up quicker and slide faster if the front tires have more grip. Secondly, the rear has less natural downforce (Weight) to keep the wheels planted. So this is the reason the rear tires should be larger to keep the car in a balanced state during extreme yaw situations.

The downside to this (the reason most people don't like staggered) is that a larger rear tire can/will cause increase turn in understeer. This in most cases is the most unsettling and annoying handling characteristics to have in a car. Having to wait for the car to turn in will ultimately ruin your line and thus ruin your speed by having to adjust mid corner. Alternatively correcting an oversteer moment can be slightly faster if you catch the drift early in the slide, but this means you have to be constantly ready to modulate steering and throttle control. This tactic is best only when you are extremely confident with your knowledge of the road driven.

With your current alignment, you'd benefit from having larger rear tires and a larger rear sway bar.

As stated previously, the TIRES will benefit from a larger front swaybar and less camber in the rear. Overall this is a cheaper and slightly more stable option.

Go with the Hotchkis front sway bar. If that isn't quite enough try disconnecting the rear sway bar (same effect as removing it entirely) and that should calm the car down.

MaysEffect - I greatly appreciate your articulate response and thoughtful reasoning.

I tend to agree with too much camber and too high of tire pressure. I think my first step will be to dial back the rear camber and adjust the tire pressure as you suggest. Do you think backing off just the rear tire pressure down to 37 while keeping fronts a bit higher would be OK?

My "beginner/intermediate" driving style is likely till too aggressive on the throttle during exit...and I am sure I am not as smooth as I should be on turn in.

Regarding the Sway bar...any thoughts on keeping the stock front and going softer on the rear...or even no rear sway bar at all?

Thanks Gomer - Sounds like stiffing the front is a popular approach. I will research this as well....

Plenty of us run square with no more issues than running staggered. As stated a stiff front sway bar will help greatly, lower your tire temps as re-11's will get greasy when hot and will oversteer regardless of setup. Also as stated, your alignment needs adjusting significantly.

Change your rear camber to -1.5 to -1.75. Lower your rear air pressure about 3 psi. Increase your front sway bar size.

Your tires may be heat cycled. They grip good when starting your session. Just when you start getting up to speed and feeling comfortable, about the 15 to 20 minute mark. They start to get greasy. Is this how your sessions go?

The Z has one helll of a camber curve built into the rear suspension.

I personally wouldn't mess around with removing ASB's unless you have the dampers and springs tuned accordingly.

You may run into issues with properly correcting your alignment if you don't have adjustable toe and camber arms on the rear.


The issue would be slightly increased oversteer moments compared to understeer moments.

Most points covered here, you can start with less rear tire pressure, but from my experience with RE71-R, maybe could apply to RE11, they are more happy with less camber, I used to run around -2.4 front and -1.8 rear with stock toe, between 32-35PSI all around, and the wear was equal at track and the car managed to use full tire traction available. But I am on coilovers, front sway, swayless at rear. There was some oversteer incidents with my setup but happen when I am very aggressive.

I have run re-11 for a while both on the street and track. At the track I run the with 2 psi more in the front than rear and I tried to keep the psi down under 36 psi. My front camber was -2.6 front and -2.0 rear. The question for you is whether or not you are more comfortable with a little oversteer or understeer? The majority of us prefer a little oversteer and therefore as pointed out a square setup is more prone to. That being said I am not into drifting it is simply easier to control for me than understeering.

I'll agree with HotRodz...

Try to get your tire PSI to be about 35 when hot.
- Start at like 28psi?

I find 40psi hot gets the tires too greasy.

:twocents:

Thanks for all of the input...

Plans will be to
1) Reduce Rear Camber to below -2 (somewhere around -1.5 to -1.75)
2) Reduce Tire pressure to 35 - 37 (Hot).....and experiment with 2 PSI lower on Rear vs. Front.
3) Install Stiffer Front Sway Bar....and either leave OEM Rear or install adjustable Rear Sway Bar

Follow-up Questions:
A) Regarding Front Sway Bar....Eibach 2-way adjustable, Hotchkis, or Whitleline? Any preference given that my objective is more track than DD?
B) Is an alignment required following the removal and installation of Sway bars?
C) Should I consider changing out the End-Links at this time?

A) Hotchkis is currently the largest off the shelf front bar available, there have been quality control issues with the whiteline front bars, not sure if this has been rectified
B) No
C) Yes, unfortunately they cost more than the bar's themselves

A: Go with the Hotchkis front bar. I've had both the Eibach and the Hotchkis and the Hotchkis is just better as it's bigger.

B: Swapping the sway bar won't affect the alignment.

C: Adjustable end links probably aren't necessary at this point but they would let you adjust out any preload that might be present on the sway bar. This becomes more important when corner balancing and setting up a much more "built" suspension setup.

Regarding an adjustable rear bar, I don't know of any adjustable aftermarket bars that aren't stiffer than the factory bar. YOU DON'T WANT STIFFER. I had heard at one time the rear bar off a G37 is softer than the one used on the 370z so that might be an option.