Handling traits and charecteristics

[Sideways]

Been digging around and found a LOT of useful information on how to make the Z cars handle "better"- A few posts have been more helpful then others and seem to have the experience to back it up which is always a large plus. All the way from simple set ups to the rather pricey, but so far ive been unable to find this little bit of info save for a random odd mention here and there.

 

So would any of you mind including your set ups (Springs, shocks, camber plates, lsd, anything you can think of thats important), and describing how the car handles with that set up? Are you loose the whole way around? Do you get some push on entering that starts to slide as you get on the gas? When/if the car does oversteer- Is the car easily predictable and controllable with the throttle, or is the car twitchy and nervous when the rear steps out? Do you dread bumps in the road causing some bump steer bringing the rear end out? Snap oversteer ever an issue? Or do you (hopefully not) plow like a mule the whole way around?

 

All information is much appreciated

[260DET]

In my experience a rear ARB equipped S30 can step out without warning when being pushed hard or when the road is wet. Some things to look at: remove the rear ARB or else use a light one ~15mm in diameter, more bump on the rear dampers, a touch of negative camber and neutral toe or even a mm of toe in.

 

Then there is understeer. Mine was sorted by a combination of some front toe out, wider front track, damper adjustment and 3 degrees negative camber.

 

Having said all that I bet someone comes along now and says they have had no under/oversteer problems. Depends how hard you drive mate

[Sideways]

Im very used to the handling of my current car, naturaly it understeers but with a little poking itll slide like no ones business, however the sliding is very natural and very easy to control (1986 corolla gts). Theres no "snapping" and its very progressive and easy to control with the throttle, something im hoping to obtain with a Z. Just wondering what kind of car im getting my hands on- As with most cars im very sure its how youve got it set up, which is why im asking what everyone here is running, thanks for the answers

[johnc]

What are you building the car for: Drift? Autocross? Road Racing? Street? Rally? My guess is drifting because of the emphasis in your posts and your member name.

 

A RWD vehicle's sliding behavior (not oversteer, we're talking about sliding) is mostly controlled by yaw intertia, alignment, tire compound, engine torque, differential type, and driver. Alignment and tire compounds are the biggest contributors to how the slide is initiated. A zero toe rear setup, hard compound tires, and a low yaw intertia create a car that slides easily and is difficult to control.

[Sideways]

Theres no emphasis on what style i want to be honest, more or less my only goal is a "fun" car. Im not particularly asking for advice on how to set up my car- Just trying to understand what the cars suspension geomtry and chassis allow for easily within limits.

 

John ive enjoyed reading many of your posts in the past, so if i may ask- how would you say your car handles?

[johnc]

Just trying to understand what the cars suspension geomtry and chassis allow for easily within limits.

 

There's no limit. You can setup the chassis to do whatever you want it to do given enough time, talent, and money. A properly setup and driven 240Z can run down a Z06 Corvette, Viper, EVO, STi, or GT2/3 Porsche. Because of the vehicle's light weight in racing trim (under 2,200 lbs) it can brake, corner, and accelerate with the above cars using less horsepower, smaller brakes, and skinnier tires. You may end up spending close to the price of a Z06 Corvette to do it, but a 240Z can run with the big dogs.

 

John ive enjoyed reading many of your posts in the past, so if i may ask- how would you say your car handles?

 

I don't have a 240Z at the moment (I'm building and racing a 350Z right now) but my Rusty Old Datsun did everything I listed above in a number of open track events during 2003 and 2004.

 

http://www.betamotorsports.com/products/rod4sale.html

[260DET]

From memory John's S30 , the ROD, had a stiffened chassis, which is essential if you want to get serious.

 

The only other comment concerns the suspension type, S30 has strut suspension all round, which like all suspension types has its own basic characteristics eg with strut suspension camber change is directly proportional to body roll.

[wheelman]

I've got a pretty stiff setup on my 240 and it tends toward oversteer, which is the way I like it.

Heres the setup.

 

Ground control coilovers, 225 front, 250 rear

Camber/Caster plates. -3 degrees front, -1 degree rear

1" front bar, 7/8" rear bar (MSA kit)

Energy suspension urethane bushings throughout

Tokico Blue non-adjustable strut inserts

Sub-Frame connectors that tie the frame rails into the rear subframe.

Falken RT-615 Azenis, 225/50-16

 

I've experienced the snap oversteer mentioned above and I think it's mostly due to the large rear sway bar but it's been a rare occurance. Just about everytime it's happened I was hard on the throttle in a corner and crossed a surface feature or transition.

 

I might try swapping the stiffer springs to the front but I really prefer a car thats a little tail happy to one that pushes.

 

Wheelman

[Sideways]

Now thats the kind of post i was looking for. How agressive is the oversteer on your car? Is it (generally) a smooth transition with the rear end rotating linearly around the car, or is it rather quick and progressive? What kind of rear end are you using btw?

 

This is good information everyone- thanks.

[wheelman]

The rear end is the chapman strut independant the 240Z came with but I have an R200 diff with a PowerBrute clutch type LSD. The gear ratio is 3.54:1. I thought I'd listed that but I guess not.

 

I guess I should mention the car also has an LT1 V8 and 5 speed transmission so I have lots of torque to play with.

 

I've found the oversteer to be fairly abrupt. The car will be mostly neutral until I pass the limit and then lets go. It's a little hard for me to explain it all as I'm a bit inexperienced at auto-x and thats what I primarily use the car for. If I'm smooth with things (mostly the throttle) there isn't much oversteer but if I get to agressive with the control inputs it unsettles the car (DUH) and then the rear gets light. On the whole though the car has very good turn in (as opposed to pushing) and the rear will swing out a bit on tight manuevers taken at speed.

Does that help at all?

 

Wheelman

[JMortensen]

There are really way too many variables to make this discussion worthwhile in my opinion. I'm not going to close the thread, but I just wanted to make the point.

 

The biggest unknown is the person who is telling you how the car handles. I fought a never ending push on my Z, could never get the front end hooked up how I wanted, but one of my friends in particular would spin the same car EVERY SINGLE TIME HE DROVE IT. We both had autoxed for years and we would put in times that were generally within .3 seconds or so of each other, him in his 510 and me in my Z. This is why I feel that this whole discussion is basically pointless. It's like asking "What flavor of ice cream do I like?" We don't know. The best thing to do is figure out how you would like the car to handle and then build and modify it to suit your tastes.

 

Now if you said, "My car pushes, what can I do to correct that" or "Once the rear end lets go I can't get it back" then we could have a discussion about that, because the things that will cure a pushing or a loose Z are fairly universal, and what you would really want to do is figure out to what degree you want to utilize those adjustments on your car to suit your tastes.

[johnc]

Here's how an ideally setup mechanical grip 240Z should handle:

 

Low speed corners (under 50 mph) - the car should oversteer in steady state corners and on lift throttle. It should have a higher rear slip angle ratio under power. Car should put power down very well in 2nd or 3rd gear.

 

Medium speed corners (50 to 100 mph) - the car should be neutral to slight oversteering in steady state corners and on lift throttle. Car should have even to slightly forward biased slip angles. Car should put power down well and should transition from slight oversteer to slight understeer under power.

 

High speed corners - (100 to 150 mph) - the car should be slightly understeering in steady state corners and neutral on lift throtle. Car should have a forward biased slip angle. Car should put power down and should be slighty understeering under power.

[Sideways]

There are really way too many variables ...

 

to what degree you want to utilize those adjustments on your car to suit your tastes.

(Shortened for space)

 

I can see your point, though i cant fully agree. I agree it is fully up to the person driving their car and more importantly "how" they drive their car, and like all things theyre opinion based- Im just trying to see if i can find what the average person thinks more often then not. Like ive pointed out im not too interested in asking how to improve the handling- There are MANY threads on this forum that cover that in good detail. Just figured this might be a fun thread that could get some people thinking. And id say instead of asking what ice cream do i like, its more like asking to describe the ice cream youre eating

 

Johnc: Comming from how i like to drive my car i agree with that big time

 

wheelman thanks for the aditional info im sure that does make a notable difference in the handling traits of your setup

[JMortensen]

And id say instead of asking what ice cream do i like, its more like asking to describe the ice cream youre eating

Fair enough. Just be advised that I hate strawberries. You might hate butterscotch. Doesn't make either of us wrong. Likewise on the suspension preferences.

[BRAAP]

Fair enough. Just be advised that I hate strawberries. You might hate butterscotch. Doesn't make either of us wrong. Likewise on the suspension preferences.

 

 

 

W.O.T. with Triple Chocolate fudge at opposite lock..

 

It doesn’t get much better..

[tube80z]

I've got a pretty stiff setup on my 240 and it tends toward oversteer, which is the way I like it.

 

I've experienced the snap oversteer mentioned above and I think it's mostly due to the large rear sway bar but it's been a rare occurance. Just about everytime it's happened I was hard on the throttle in a corner and crossed a surface feature or transition.

 

I might try swapping the stiffer springs to the front but I really prefer a car thats a little tail happy to one that pushes.

 

For cars that are not generating downforce spring rates can run in the 2 to 4 hertz range. And by this I would say your setup is really on the soft end. Taking an example of a car that has a total weight of 2500 pounds (driver, fuel, etc.), 100 pounds of unsprung weight per corner, and a 50/50 front to rear distribution we get the following.

 

2 Hz is a wheel rate of ~215 lb/in

2.5 Hz is a wheel rate of ~335 lb/in

3 Hz is a wheel rate of ~480 lb/in

3.5 Hz is a wheel rate of ~650 lb/in

4 Hz is a wheel rate of ~850 lb/in

 

My car is normally in the 3.2 to 3.5 Hz range. And over time I've discovered that having more rear tire is a faster setup for a autox Z. For your V8 car I think you'll find that this helps a lot with the oversteer your getting when trying to put down power in a corner.

 

Cary

[wheelman]

So are you saying I should increase the spring rates and the rear tire width or just run a wider rear tire?

Given the choice I'd rather not go to stiffer springs (it's already pretty stiff for street driving) but I had already planned to move to wider, stickier tires as soon as the Falkens are worn out.

Figured I look for 8" rims for the front and 9" for the rear and then get appropriately sized tires.

 

Wheelman

[JMortensen]

You could also try some toe in out back and that would help quite a bit too, assuming you have the G Machine bushings or some other way to adjust rear toe.

[tube80z]

So are you saying I should increase the spring rates and the rear tire width or just run a wider rear tire?

Given the choice I'd rather not go to stiffer springs (it's already pretty stiff for street driving) but I had already planned to move to wider, stickier tires as soon as the Falkens are worn out.

Figured I look for 8" rims for the front and 9" for the rear and then get appropriately sized tires.

 

Wider rears will help a lot when you have as much torque as you do. The info on springs was just to show the different ranges and what stiff really is. My guess is your stiff ride has more to do with shocks than anything else. The wider rears will allow you to use more throttle while the car is turning without the car trying to step out on you. This will make a huge dent in your run times.

 

Cary

[260DET]

For cars that are not generating downforce spring rates can run in the 2 to 4 hertz range. And by this I would say your setup is really on the soft end. Taking an example of a car that has a total weight of 2500 pounds (driver, fuel, etc.), 100 pounds of unsprung weight per corner, and a 50/50 front to rear distribution we get the following.

 

2 Hz is a wheel rate of ~215 lb/in

2.5 Hz is a wheel rate of ~335 lb/in

3 Hz is a wheel rate of ~480 lb/in

3.5 Hz is a wheel rate of ~650 lb/in

4 Hz is a wheel rate of ~850 lb/in

 

My car is normally in the 3.2 to 3.5 Hz range. And over time I've discovered that having more rear tire is a faster setup for a autox Z. For your V8 car I think you'll find that this helps a lot with the oversteer your getting when trying to put down power in a corner.

 

Cary

 

So with that sort of weight orientated platform you have a basic setup? Tune it with ARB's? Its just that with a lot of HP to me the emphasis shifts to getting power down. Where wider rear tyres may or may not balance out the setup.