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Discussion Starter #1
ok guys, I was looking at the BESTMOTORing video the 350Z Shock, in it this japanese pro driver states that the 350z suffers from a little bit of understeer. I can't seem to notice it, but anyway, being an ex integra owner and having considered the wrx before buying the Z, I know that this other two suffered from it. the cure for this on the fwd and awd cars is basically to upgrade the rear sway bar.
How do you guys think this strategy will work on the Z33? by the way my Z is a base model, I don't know if this makes a difference with the understeering issues... any opinions?
 

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Running a stiffer swaybar on one side of the car will usually provide more lateral grip on that end, so it'll want to turn more.

Stiffening the rear bar more than the front will mean the car turns in better, and dials out some of that understeer. If you replace the front bar as well as the rear, it just means that the drop in understeer won't be as great as if you only replaced the rear.


The concepts aren't really drivetrain specific - its just how much effect you want will depend on the drivetrain. No matter whether your car is FWD, RWD, or 4WD, stiffening up the rear end (whether with swaybars or spring / damper rates) will make the car more taily. Its just that 4WD and RWD cars will have to run higher numerical rates due to the extra mass at the rear of the car, compared to a FWD vehicle.


The rear swaybar on the Z33 is actually hollow, so its not that strong. In Australia, the Bilstein option suspension comes with springs and dampers all round, and a rear swaybar.

In the end, you need to tune your suspension to your driving style. I find the Z33 quite understeery in stock form, but most cars are shipped from the factory like that.

It is far less understeery than the previous cars I've owned but try driving on a wet skidpan, where the Z33's grip advantage is negated, and you'll feel the understeer. I'm spoilt, since before I bought this car I'd been driving S15s which are a lot lighter and more neutral in handling.

If you don't find the vehicle understeery, then don't worry about it. It could just be that your driving style suits the understeer, and should you go about dialling in more dartiness, the car might be too twitchy for your liking.

I'd advise going to consult a suspension specialist and have a chat with them. Preferably someone who's done work with several Z33s, to see what previous owners have wanted and how their mods have gone. They'll be able to give you advice based on their knowledge of the concepts of setting up a car's suspension, tuned to how you drive, and hopefully some experience on setting up Z33s specifically.
 

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Wow! Great info that I didn't know. And another mod for the Z...yay.
 

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I just installed a set of Koni Adjustable Dampers in the car.

I can emulate running a stiffer rear swaybar by stiffening up the damper rates compared to the front, but it means that I'll have less bump absorption, especially in the straight-ahead.

On the street its not an issue, since I don't really want or need awesome handling so I'll tune it full soft. On the track, where its generally pretty smooth, it also shouldn't be too much of an issue unless I hit a ripple strip or curb. I need to find more time to tune it - maybe in the new year, or if I come into some money after I do the rest of the suspension.

If I'm going on a spirited drive on some back road, not being able to absorb rear end bumps means the tail might unload and step out. I still enjoy a good country run with some friends, so I'll have to spend a bit of time and care setting up the car for this.


I've got a suspension guy (who's worked on plenty of street cars and supersprint / race vehicles) and so I'm working it out with him. To be quite honest, he advised me to leave the dampers alone and just get swaybars after driving my car on a racetrack.

On the street, he acknowledges that if I want to improve the ride, I'll have to get dampers and possibly springs. After a weekend of driving on them, I'm tossing up between getting progressive-rate springs and swaybars as my next mod (I want both eventually).
 

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That's good to know. Sounds like what you're saying is that the swaybar does enough for the daily driver and the track. But, your combo you mentioned last also sounds like a good idea. Plus, it's probably cheaper than buying coilovers or adjustable dampers.
 

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Discussion Starter #6
well i do feel some body roll, even though some say there is almost non, that is why I'm interested in the sway bars in the first place. so I'm definatelly going to check what are the options that I have. since I don't want her to go all tail happy on me, should I go with both bars instead? any brand sugestions? I was thinking of Cusco which offers an adjustable front one and a standard rear one.

Oh, and what about the absence of the LSD on the base car, does this makes a difference when opposed to the LSD equipped cars and this understeering issue?

BTW: nice going guys, lots of info so far, keep it comming! :clap: :thumbsup:
 

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Originally posted by SmoothZ
Sounds like what you're saying is that the swaybar does enough for the daily driver and the track

The Australian-spec suspension is different to the US (depending on the time of manufacture), so my exact setup won't really mean too much to you. I have a Touring model, and even on the 18" wheels I've been told its a softer ride than Track owners.

But, in standard trim, if you're happy with the ride of your car then you won't need to go coil-overs all round if you're just looking at fine-tuning the car's handling. The spring / damper setup is good enough for a daily-driven vehicle being used occasionally on the track - it just needs swaybars to dial out some of the understeer.


If I were to buy springs for the car now, it'll cost me pretty much the same amount as getting a coil-over kit. The difference is that I can pick my spring rate (somewhat) and then tune the adjustable dampers to suit.

The issue for getting a kit is that most coil-overs I can easily get are Japanese, and their spring rates are usually too high for Australian road conditions. I'm considering either Eibach Pro-Kit, or Tein H.Tech, springs since they're both progressive springs that are more street / comfort oriented while still maintaining sporty handling.

If I buy the coil-over kit of choice (Tein Flex) then the ride goes quite firm. I've spoken with a fellow Australian Z33 owner who has them installed, and offered to take me for a ride before I make a decision. He says its not too bad, but I'd like to get a feel for it before I spend that much money.

Regardless, I'll be getting swaybars for the car (since I can use them with separate spring / dampers or a coil-over kit). Whether I replace the springs, or get a full coil-over kit and sell the Konis, will depend on how the Tein Flex feels on Australian roads.
 

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I too have the Touring with the 18" wheels. My ride is fairly stiff and every crack or rock on the road is bumpy to me. Any woman in the passenger seat looks like she's jiggling her :boobies: all over the place. I've been hearing good things about the Eibach Pro-kit, so we'll wait and see.
 

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Originally posted by fuapiti@Dec 14 2004, 12:20 AM
well i do feel some body roll

since I don't want her to go all tail happy on me, should I go with both bars instead? any brand sugestions? I was thinking of Cusco which offers an adjustable front one and a standard rear one.

Oh, and what about the absence of the LSD on the base car, does this makes a difference when opposed to the LSD equipped cars and this understeering issue?

Oh, there's bodyroll. Just not very much of it. Here's a picture of me at Wakefield Park (a few hours south of Sydney).

See that nasty bend half way around the track (where the track surface changes colour)? That's a downhill, flat from third into fourth and braking into second gear turn. The shot is me pretty much half-way around that double-apex, probably kissing the rev limiter in second.

As you can imagine, that puts a massive amount of lateral load on the car. You're flat throttle once you turn-in to that bend, and in second gear you're getting a lot of acceleration. Even under that kind of extreme load (I don't think I've ever put as much lateral load on the vehicle as around that particular corner) the bodyroll is minor, which goes to show you how well set-up the car is.


The thickness of the bars (and whether they're solid or hollow, most aftermarket ones will be the former) will determine how much effect you get. If a rear swaybar is designed for the car by people with half a clue, and to be the only replacement, chances are it won't make the car too tail happy.

If you're buying a rear swaybar that's part of a front-and-rear kit, then because the designers have assumed you've put both on and have more swaybar effect in the front too, the rear one will probably make the car quite taily by itself.

Cusco, as a brand, make great handling products. I don't know of anyone with Cusco swaybars on their Z33, but from what I've seen on S15s they're set up very well.


You'll find that a LSD, as a rule, makes the car understeer more. The LSD provides more traction at the expense of the car's willingness to yaw. A viscous LSD, like in the higher-spec Z33's, doesn't have a particularly strong effect so its not that bad. It can be noticed in the right conditions, as I've found.


Given that I find it near impossible to overwhelm my traction in its current state, I haven't even considered replacing the LSD in my car yet (unless someone can tell me one that provides the same or better traction while removing the understeer that my viscous one provides). Should I ever get that FI kit I've got my heart set on, though....
 

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Originally posted by SmoothZ@Dec 14 2004, 08:07 PM
Any woman in the passenger seat looks like she's jiggling her :boobies: all over the place

So the suspension tune is perfect, then? :D
 

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Adding stiffer springs isn't the same as a swaybar or anti-roll bar. Stuffening the rear will help with the understeer but a sway bar keeps the chassis flatter without suffering as much of a harsh ride. You can just add a stiffer rear sway and it will make it turn in better. It's not just about stiffer as also balance. If you buy a full kit you'll get a slightly bigger stagger for the rear which will reduce understeer.

And 2004 Zs got a damping revision which makes the ride more compliant (less boob jiggle)
 

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FYI - You can reduce understeer by lessening the tread width differential. For example, going from the stock 245 fronts and 275 rears, go to something for even, like, maybe 265 fronts and 275 rears. SCC did an article on this and the were able to eliminate the understeer and get the car to pull much better numers on the skid pad just by changin the tires to 265/18's all aroung.

Of course you're going to need wider wheels up front, but most of you already have that with your aftermarket wheels, anyway. Only problem is that most tire companies make tons of tires in 245 and 275, but not very many in 265. A while back, I was looking to do the same thing, but in my searching I could not find a matched set of 265 and 275 tires that I liked, at least not in a 35 or 40 series tire.

Also, the reason understeer is built into a car is because most drivers are unable to properly handle a car when the rear starts coming around on them, especially when caught by suprise. It's not taught, and the only reason people like us can is because we've gotten practice by doing it on purpose.

For safety reasons, it's much better to have a car slide in a straight line (like a car with understeer is prone to do) than for a car to be in an uncontrolled, and therefore, unpredictable slide. It's much safer, also, for a car to be involved in a front end collision than in side impact collision.
 

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Hey,
I just installed some adjustable sways on my car (Whiteline) Australian brand. I also have the Hotchkis springs installed. The springs didn't do too much but lower the car slightly (15mm & 19mm in rear).

But the sways do magic!!! Best mod to do. Will reduce your cars bodyroll, give crisper turn in (more grip to front) & allow you to push much further around corners, just what the zed was designed for!

To answer your question, soft front is good, medium to higher rate in rear good too.

Simple rule of thumb, whichever sway you increase rate it will increase grip on the other end:

increase rear bar thickness = more grip to front (oversteer) less grip to rear
increase front bar thickness = more grip to rear (understeer) less grip to front

Most bars will increase both front & rear with the rear rates being much higher.

This is the best mod you can do (IMO), I don't know why more people haven't! The real joy of the zed is it's handling, this just intensifies it & adjustable bars give you plenty to tune to your particular liking!
 
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