I’m wondering what to do next to further improve the Z’s drivability on the track. Right now, I run on RA1 255/40R17 front and 275/40R17 rear. Only other suspension mod is a set of Koni Sport dampers.

I like the feel of the car now, but it would of course benefit from less understeer. My dilemma now is this. Would it be better to go with adjustable front A arms to get ~3 degrees negative camber or a set of sway bars?

I know sway bars work very well. But I’m trying to get a working setup with out touching the OEM ones. I don’t like the feel of stiff sway bars on the street and I’m just plain head strong.

Running a square tire setup seems to upset the electronics so I don't want to do that either.

I'm not dropping the car either.

In your opinion, would the added camber be enough to keep the car turning?

 

Negative camber should help here...

 

IMHO if you want to improve the Z's handling, both adjustable sway bars and front A-arms arms would help. My track model has seen a lots of track time and the aftermarket spring/sway/shock package I'm running works quite well at a moderate cost. The next step would be to go with adjustable A-arms, but since this is also my daily driver I've resisted this step so far.

Like you, I like the "feel" of my 350Z thus far, but the A-arms would certainly help with understeer. The other big advantage would be evening out front tire wear (particularly with R-compounds) while at the track. The risk you run with them is to pick up so much front grip that your Z gets tail happy at the limit. That's a distinct possibility without adjustable sway bars to dial-in rear roll stiffness.

David Muramoto
Senior Editor
Nissan Sport Magazine
www.nissansportmag.com

 

I agree wholeheartedly with David.
If you could lower the car just a half inch, not "slam it", that would help quite a bit with the lowered center of mass.
You might think about front and rear strut tower braces to help with the torsional twisting of the body. Those are not expensive to buy or install, and they definitely assist the handling for hard turn ins, but do not sacrifice ride comfort in easier daily driving.

 

Kolia,
IMHO w/ R-compounds you would get faster lap times with A-Arms rather than sway bars. And the A-Arm will give you more even wear with the R's!
When I made the change from -1.5 to -3 in front my lap times dropped by seconds. Yet, from my tire temps the Z w/ R's could stand even more negative camber in front and get faster. Yet, -3 is the max I can get out of my A-Arms. Just make sure your rear negative camber is more agreesive when you get the A-Arms.
And if you get the 350EVO a-arms (they still do make them - just have to wait 4 months for them) they are really easy to adjust at track! The rear is a pain in the a** as when you change the camber you affect the toe!
Both Sways and A-Arms are really easy to install on the Z. One benifit that most people overlook with setting up a stiffer sway bar, is that the driver doesn't move around as much, that will really improve lap times. And Sway bars are fun to adjust as you can really feel the difference.

On a side note, after tires - the second best improvement you can make to the car is to keep the driver fixed. You will be supprised at how much faster you will be by not having to brace yourself, and how much more energy you have at the end of the day.

 

The above picture is at the apex point of the Cotton Corners, running clockwise at Buttonwillow. This is after a fourth gear WOT run down the short straight, a hard brake and downshift to third, then slight trailing brake and rear rotation to point the car into the direction you want to follow, which is tighter to the right side so you can set up for a very late apex on the second turn that takes you up the slope for a right hander over the crest. Unlike a single turn, one sacrifices maximum speed through this turn to set up for the following turn as there is little benefit to carrying a couple of more miles per hour with no ensuing straight. A full track out to the edge of the surface puts you in "jail" for the next turn. Thus, very late entry and correct position after a very fast run is absolutely critical or you botch the next two segments leading to a straight that really does matter. Note the right front tire is just on top of the painted low curb at the very edge of the track and on the apex point. The car is under significant lateral load, yet with the stiffer sways and strut braces, and camber adjusted A arms, reasonably flat and stable.



The above picture is taken a fraction of a second later. Note the right rear tire is just on top of the painted low curb at the exact same apex point. This shows the car was pointed straight and not sliding or rotating any further and is back on throttle coming through the apex, which is what you want. Again, still flat and planted. If you look VERY carefully you will note that the front left fender/bumper is slightly higher in this photo, reflecting weight transfer to the rear under acceleration.



Same car a year earlier, on a different set of coilovers and without the strut braces fore and aft. Note the significantly greater "lean" or inertial body roll over, and the distress to the sidewalls of the tires, and lifting of the inside tire tread from the road surface. Needless to say, much slower in the turn as the adhesion of the set up would exceed maximum much sooner once the tires are up in space and not on the track surface!


Kolia's picture is really excellent, as you can see the tire sidewall rollover, as he is already unwinding the steering coming out of the apex point getting it pointed straight and on throttle, but the car is "tracking out" to the right side of the surface from the inertial momentum. The sway bars are keeping the inside tires down and gripping and the platform reasonably flat. That is one set of very hard working tires in that turn, because his sways and A arms with the negative camber settings are making it possible for them to do so!

 

Well, if you want to use pictures to show what the car is capable, here is what negative camber let my car do:

this is after I set the negative front camber to -3, before than I could not lift the inside tire off the ground. This means that I can get on the power sooner and use more power in a turn. And we all know that if you are on the gas faster and more in a turn than you will have faster lap times.

I am still getting significant body roll with stiffer sways and stiffer springs than stock as you can see in this picture:

 

Oh, wow! Keep the picture education coming; these are fantastic, gentlemen!

Do the pictures come with the track you run on? I only ask because the HPDEs that I've run do not have picture takers...

 

Mood Dude is hard on it with that lift! It looks like just a wee bit of camber to the turn is helping out too. I like the negative 3 degrees front camber setting. My G is -3.5, but anything in that zone is fine and it really depends on your other features on springs and dampers, strut braces, sways, wheels etc etc.

Good pictures. Here is one from Sears point going over the top of Turn 3A at the crest:


Then another showing inside tire lift at Turn 2:


And then a "flat" shot at turn in to Turn 3 at Laguna Seca:

 

It depends on what HPDE group you run with, some invite photographers and some don't.

What else do you want to know?

From my pictures, I am thinking of changing my front spings from 670# to 770# so that I can transfer the weight faster to the front under braking and slow the weight transfer to the rear under power. Since right now I run the same springs all the way around and with a TT set up, my front is 4% heavier than the rear. Therefore, right now I am working the front springs harder than the rear.

 

Eagle1 - wondering if you have changed the VLSD? Ever since I have changed to a -3 front and -2 rear, I can take a corner so much faster and get on the power sooner that I am now destroying my VLSD. I am wondering if I stiffen up sway bars on the rear so that will put more load on the inside tire, if I could prevent the inside tire from spinning especially under left hand turns?
As you can see in this picture that when I trail brake I am lifting the inside rear tire:

 

Thanks for the input. I appreciate your insights.

My car is bone stock appart from the Koni dampers. My picture isn't such a great exemple. This is turn 15 at Le Circuit Mont-Tremblant, just after the Namerow hairpin. It's a low 4th gear turn, taken at WOT. Balancing the car on the rear helps a lot to keep it turning, but it is slidding a bit at that point. It's a fun, relatively fast turn. Plus it's down hill a bit.

The scarry turn is the 1, 2 and 3 series that go down hill and offcamber, than uphill, then down hill again then flat into the 4-5 90 degrees esses. It's also pretty bumpy and I'm affraid swaybars would be "comfortable".

Sounds like I'll need camber bolt as well as A-arms next spring.

For the harnes, I'd need a roll bar and new seats to go with it... I've got airbags everywhere in that thing... Scary combination...

 

Mood Dude: I ditched the VLSD early on for a Nismo LSD (mechanical). Apart from making the car a little bit of a "bad boy" in slow turn scenarios, like supermarket parking lots and garages, it is all good. Also the lightweight (10 lb) flywheel. These two make for much crisper performance under more demanding requirements.

 

Mood Dude:
What wing are you running on the back of your rocket? And what angle?
Do you have a rear diffuser? Looking over your picture again, I was wondering whether a rear underbody diffuser between the pipes might not give you another 75 lbs or so of downforce to help with that inside rear tire. Obviously too much wing angle or aero will give you drag, but getting lift on the inside rear on a rwd car is not what you want. Have you considered a rear strut tower bar for the front and the rear? That might also save you a half inch or more of body flex that could be contributing to that lift.....and it is easy to install and not expensive.

 

Eagle1, are talking about lower strut braces ?

The Z has both front and rear upper strut tower braces from the factory. The rear one being part of the white body itself.

Doesn't the G have those ?

 

Sorry if I was too summary. Talking about an upper strut tower brace. For the front across the top of the engine bay, and for the rear hooking the top of the two shock/strut towers. The G does not have an upper strut tower brace as standard, either front or rear. For the rear you can now get one for the G from Stillen. For the front, it is a very complex problem. There is one from VRT, and another from ARC. A space and angle challenge. With the longer body and heavier weight, the front brace makes a very noticeable difference to the handling. I was not aware that the Z had upper braces fore and aft as stock, and thought that you had to get them as aftermarket mods.

Here is the stut tower brace put into the G. It also shows the plenum spacer.

 

Damn you twin turbo guys! Lol

The front one in the Z is an adjustable one. Pretty neat thing. No picture though...

 

I have the ARC front tower bar, and the Z already has a pretty beefy rear tower strut bar, I also have the GTspec ladder bar and rear bars, yet the GTspec front bar won't fit around the APS oil pan.

That wing is a Top Secret wing - the only one for the Z that actually is designed to give downforce. I run it at a 6 degree angle on the outside (as the inside is at 0). No areo parts added under the car - and if I had more money I would probably do that. Yet, I am going to spend my money on a new LSD (probably Quaife), do some exhaust changes (since everyone complains that that can't hear my car on track) and work on oil cooling and a accusump.

Kolia - Good for you on the Camber choice! And also that you figured out that you need a roll bar for a harness. I have taken out all my airbags as they would be more dangerous in with a roll bar and harness set up.

 

Its easy to make a persuasive arguement for either change but postings on an Internet message board aren't the truth.

Sometimes an increase in static negative camber and the comensurate increase in front grip is offset by increased front roll and a net dynamic camber loss. Sometimes a decrease in roll means more negative camber gain in bump and a net increase in grip. Maybe an alignment change increasing caster will solve the camber issue.

To get at the truth you need a stop watch and a tire pyrometer. Lap times and tire temps will tell you more about which change gets you better handling and lap times then anything posted here. Beg, borrow, or steal the parts you want to compare and schedule some test time.

 

John:
If we are going to get into the process of maximum fine tuning the elements to get what is "best", an entire step beyond basic modifications that have been discussed above, he needs to be told how to do it.

Patiently explain to him how to take the readings, what they mean and what to look for. Otherwise it is not going to help him.