Formula 0.5 Car Setup Guide

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Formula 0.5 Car Setup Guide

Post by slobb11 » Mon Dec 14, 2009 9:12 pm

The Formula 0.5 Car Setup Guide

Although the following guide is written with the Formula 0.5 cars in mind, I will touch on the physics and methods involved in car setups, so most of the points below should also apply to any other cars.
This guide is NOT meant to set your car up for you. It is to assist YOU to setup your car for yourself.

Rather than just explain the effect of any given change, I’ve tried to explain WHY this effect happens, and what other options can create a similar effect.

I have tried to simplify as much as possible for two reasons….
1. So as not to unnecessarily confuse anyone.
2. Because I am not a professor of physics

If you feel that any of the below is incorrect (I make no guarantees that it isn’t), please let me know and I will attempt to rectify it.
However, I’m not interested in hearing that something’s wrong because you THINK it is, or even because you KNOW it is, or because your Uncle Phil does things differently.
If you feel something is incorrect, find a trustworthy reference indicating so(Wikipedia, The National Auto Club, etc) and include a link for me.
I don’t feel like spending hours of my time performing research based on someone else’s (possibly incorrect) opinion.



An Overview


The Basics

Firstly, it must be said that a car has a certain amount of grip…short of adding downforce or changing tyres you cannot increase the total amount of grip a car has. What you are trying to do with your car setup is distribute this grip to the right wheel, at the right time.
In order to do this, you must first understand what grip is….
Grip (in race car terms) is the result of downward force being applied to the wheel, forcing the tyre onto the racing surface. The more weight on a wheel, the more grip it has.
As an example…when you accelerate smoothly, the car’s weight balance shifts towards the rear of the car. This reduces the weight on the front wheels, so understeer is induced. The inverse happens when braking smoothly.
Your goal is to find the balance between oversteer and understeer in every situation by fine-tuning the suspension….Be it accelerating out of a corner, braking into a corner, coasting through a corner, etc.


A More In-Depth Look at Balance

Almost all adjustments in a car’s setup are related to at least one or two other settings.
For example….The effect of the brake balance setting is governed by the suspension setup. If the rear wheels are locking up under braking, you COULD move the brake balance forwards to reduce braking force at the rear end of the car. OR you could stiffen the front slow bump and soften the rear slow rebound. BOTH would prevent the rear wheels locking up, but they are achieving this in different ways.
By moving the brake balance forwards, you are simply reducing the amount of braking the rear wheels are doing to suit the amount of grip they have. Whereas by softening the rear slow rebound and stiffening the front slow bump you are preventing the weight of the car from moving forwards and keeping more weight on the rear wheels, thereby increasing the amount of grip the rear wheels have under deceleration to suit the amount of braking you’re asking them to do.
A simpler way of looking at it would be this….
One option is changing the amount of work each wheel has to do, to suit how much grip it has.
The other option is changing the amount of grip each wheel has, to suit how much work it has to do.

You will see the word “balance” a lot in this guide, as I feel it is the key foundation of car setups.
Newton once said, “For each and every action, there is an equal and opposite reaction”….smart dude.
Every change you make to your car, has a negative effect as well as a positive effect.
As mentioned earlier, you’re simply distributing the weight balance of the car…so when you allow the weight to move to the rear, you’re ALSO allowing weight to move away from the front.
If you give yourself more front-end grip on corner entry, you’re also sacrificing rear-end grip on corner entry.
If you remove oversteer on corner exit, you’re also adding understeer on corner exit.
The secret is to find the balance between all of these and more….

No one said setting up a car would be easy ;p





A LOOK AT EACH SETTING


Downforce

As mentioned earlier, aside from changing tyres, the only way to add grip to ALL wheels is by increasing the aerodynamic downforce. But of course, this also increases drag on the car resulting in lower speeds on the straights.
The choice of how much downforce to apply for any given track is based on the layout of the track.
Do a few laps, and see how much time you’re spending off the throttle, as opposed to how much time you’re spending with your foot flat to the floor.
Also, it can be useful to compare your sector times to other drivers. If you’re slightly quicker in sectors 1 & 3, but drastically slower in sector 2 (where there happens to be a long straight) this should tell you that reducing your total downforce would be a good idea.
As always, when applying downforce you must think of the balance between oversteer and understeer. More front downforce will increase the grip of the front wheels, while more rear downforce will increase the grip of the rear wheels.


Brake Balance

The brake balance setting adjusts the application of the braking force between the front and rear wheels. THIS IS ALL IT DOES.
If your car feels perfect everywhere EXCEPT under heavy braking, this is the setting to look at. However, if your car has a couple of areas that are in need of improvement then you may find that this isn’t the right setting to be adjusting just yet.
For example….If your car is a bit loose under heavy braking, but is ALSO a bit loose under light braking, then you should probably be looking at increasing the unloaded grip at the rear wheels by adjusting the suspension.


Springs

The Formula 0.5 mod has the spring rate locked for simplicity’s sake. However I will briefly cover springs in order to provide a better understanding of the entire suspension setup. Without understanding what the springs do, one can’t hope to successfully understand dampers, which I will describe shortly.

The springs are what the weight of the car rides on. They are also what the car balances on.
I specify these two aspects separately because they are two very different roles that the springs serve.
When thinking about suspension set up, one must differentiate between the ride (how the car behaves over bumps and imperfections in the racing surface) and the balance (how the weight of the car shifts depending on the forces the car is currently under).

BALANCE
As the weight balance of the car shifts, the springs must compress and extend to allow it to happen. The stiffness of the springs sets how much force is required for the weight to shift, and therefore to what degree it shifts. A softer spring rate allows for more weight transfer between the wheels.
If, for example, you were struggling to get the power down out of corners due to excessive oversteer, one solution would be to soften the rear springs allowing more weight to transfer onto the rear wheels. However….given that any adjustment you make to the spring rate affects both the compression AND the extension of the springs, and that it is the force of the springs that push the wheels onto the road when they are unloaded, doing so would reduce the rear end grip under braking.
As with downforce, springs are best considered as a setting to look at when the car handles poorly in MANY situations, as opposed to just A FEW situations.
In the case of fixing one specific problem area, I would advise focusing on the damper adjustments.

RIDE
When a wheel hits a bump in the road, or perhaps a curb, the springs must compress in order to absorb this impact. A stiffer spring rate will result in the spring not compressing much, and the car popping up into the air. Wheels that are in the air, quite unsurprisingly, don’t offer a lot of grip. However, it is also the spring that pushes the wheel back down to the road surface again, so softer springs take longer to apply the weight back down onto the tyre while unloaded. Finding a happy medium that allows you to take minor bumps without losing too much grip is the key.


Dampers

Dampers adjust the rate at which the springs can compress or extend.
Bump damping adjusts the rate at which the springs can compress, while Rebound damping adjusts the rate at which the springs can extend.

In “balance” terms….the harder the damper setting, the slower the weight balance of the car changes, and therefore the less it changes.
In “ride” terms….the harder the damper settings, the less effectively the spring will be able to absorb any impact. With softer dampers however, the car will want to continue bouncing after any kind of impact, as it is the damping which prevents this “pogo” effect.

In the Formula 0.5 mod the fast damping has been set to a safe default and locked off, so you have far less to adjust. But some mods allow for independent adjustment of the fast damping, and slow damping.
This ability to independently adjust slow and fast damping makes setups easier to understand, because fast damping affects the ride over bumps, while slow damping affects weight transfer.

Here are a couple of problems that can be specifically targeted with damper adjustments, and an explanation as to why the specified solution will solve the problem in question.

Oversteer on corner entry, while braking ….
Stiffening the front slow bump will prevent the weight of the car from transferring forwards (as it is inclined to do while decelerating). By inhibiting the weight from moving forwards, you are keeping more weight on the rear wheels, and therefore improving their grip. BUT (there’s always a but) by inhibiting the weight from moving onto the front wheels, you will also be reducing the amount of grip they have available, so don’t overdo it or you’ll start understeering into corners.
Another option, would be to soften the rear slow rebound. Remember that one of the main jobs of a damper is to impede the springs from extending, so softening the rear slow rebound will better allow the springs to force the rear wheels onto the road while the weight shifts forwards.
If you were understeering into corners, then increasing the rear slow rebound would reduce rear-end grip, and therefore improve your turn-in.

Understeer while accelerating out of corners….
This is caused by the front wheels not having enough grip while you’re accelerating. So let’s give them some more…
Again, you have two options:
You could soften the front slow rebound, to better allow the springs to push those front wheels down onto the tarmac.
Or you could prevent the weight from moving towards the back of the car by stiffening the rear slow bump.

By now, I hope you have a good understanding of how to control the weight balance using the dampers.

As a side note…the Formula 0.5 mod has the front independent dampers locked off to safe defaults. However, adjusting the Front-Third Damper settings (found under the “advanced” tab) will have the same effect as adjusting the front left and right dampers simultaneously.


Anti-Roll Bars

NB: Take with a grain of sand...this section is not totally accurate
Anti-roll bars work to prevent the body of the car from rolling. Generally body roll is considered to be a bad thing in a race car, but don’t be too quick to eliminate it altogether. It is the act of the body rolling that transfers weight onto the wheels that need it the most, the outside wheels.
The disadvantage to having a lot of body roll, comes when you need to change the direction of the car rapidly, such as very sharp corners, or S-bends.
When taking a right-left S-bend for example, if your car has too much body-roll all the weight will roll to the left hand side of the car as you drive through the right hand corner. Upon trying to turn into the left hand corner, all the weight will still be on the left wheels and you’ll have very little grip for the left hander. By minimizing this body-roll, the weight will be able to shift back to the right hand wheels much faster.

When adjusted independently, the anti-roll bars can also be used to change the balance of the car between oversteer and understeer.
By softening the front anti-roll bar in relation to the rear, the front end of the car will better be able to shift its weight to the outside front wheel, while the rear remains unchanged. This allows more grip in the front without affecting the rear, and therefore induces oversteer.
The inverse happens when you harden the front anti-roll bar.

Likewise, softening the rear anti-roll bar will better allow the rear-end of the car to transfer its weight to the outside wheel, granting improved lateral grip, while the front remains unchanged. This will induce understeer. Stiffening the rear anti-roll bar will have the opposite effect, and induce oversteer.


Ride Height

When adjusting ride height, the most obvious consideration is ground clearance. If the car’s undertray bottoms out onto the track surface at any point, all the valuable downforce being generated by the car’s aerodynamics is instantly being applied to the undertray rather than the tyres. This will result in a sudden and drastic loss of grip.

However there is more to ride height adjustment than just ground clearance.
Bernoulli's principle states that as a fluid or gas (in this case…air) is accelerated through a small channel, its pressure lowers.
By lowering the car, you are forcing the air to accelerate as it passes between the undertray and the ground. This reduces the air pressure under the car, literally sucking it down onto the track.
This phenomenon is known as “ground effect”.
The positioning of the ground effect can be altered by raising or lowering one end of the car independently of the other. For example, lowering the rear end of the car will add more downforce to the rear without affecting the front end.
Last edited by slobb11 on Fri Mar 26, 2010 10:58 am, edited 8 times in total.
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Re: Formula 0.5 Car Setup Guide

Post by slobb11 » Mon Dec 14, 2009 9:12 pm

My brain hurts :(


Well that's the hard part out of the way....
A trouble-shooting section still to come, which will consist of a list of "Problem", "Possible Solutions" type things.


UPDATE:

As promised....

To get the most out of these troubleshooting tips, it's important to make sure that you know EXACTLY what the problem is.
Knowing that you have a problem with oversteer doesn't help unless you know where you're oversteering, and in what conditions.
Hopefully this will prove useful to someone :)

Oversteer in many situations
Increase rear downforce
Reduce front downforce
Soften rear anti-roll bar
Reduce rear ride height
Increase front ride height

Understeer in many situations
Increase front downforce
Reduce rear downforce
Stiffen rear anti-roll bar
Reduce front ride height
Increase rear ride-height


Oversteer while turning under heavy braking
Shift brake balance towards the front end
Soften rear slow rebound
Stiffen front-third slow bump

Oversteer while turning under coast
Soften rear anti-roll bar
Decrease front downforce
Increase rear downforce

Oversteer while turning under heavy throttle
Soften rear slow bump
Stiffen front-third slow rebound

Oversteer while alternating direction (S-bends)
Soften rear anti-roll bar
Increase rear downforce
Reduce front downforce

Understeer while turning under heavy braking
Shift brake balance towards the rear
Soften front-third slow bump
Stiffen rear slow rebound

Understeer while turning under coast
Stiffen rear anti-roll bar
Increase front downforce
Decrease rear downforce

Understeer while turning under heavy throttle
Soften front-third slow rebound
Stiffen rear slow bump

Understeer while alternating direction (S-bends)
Stiffen rear anti-roll bar
Increase front downforce
Decrease rear downforce


Sometimes making a drastic change to one of the suggestions will be the best solution, while at other times making small changes to several or even ALL of the suggestions may be best.
Experimentation is the only way to know ;)
Last edited by slobb11 on Mon Jan 25, 2010 10:29 pm, edited 2 times in total.
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Re: Formula 0.5 Car Setup Guide

Post by Harding Jr » Tue Dec 15, 2009 12:35 am

That's awesome man! I went straight to the bit I am having trouble with at the moment and it explained it perfectly, terrific stuff! _b
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Re: Formula 0.5 Car Setup Guide

Post by Rolo » Tue Dec 15, 2009 7:58 am

Nice work Mofo.... your guides are always well written and helpful, cheers. :smokin:

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Re: Formula 0.5 Car Setup Guide

Post by mrsinista » Tue Dec 15, 2009 9:34 am

excellent guide mofo, your explanation of the anti roll bars is the best ive read.

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Re: Formula 0.5 Car Setup Guide

Post by Ryan » Tue Dec 15, 2009 9:50 am

shot mofo _b that will be helpful. cheers
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Re: Formula 0.5 Car Setup Guide

Post by reaver » Tue Dec 15, 2009 2:03 pm

Looking good, You've done a nice job of making complicated concepts accessible _b

I found this section interesting:
slobb11 wrote:Ride Height

When adjusting ride height, the most obvious consideration is ground clearance. If the car’s undertray bottoms out onto the track surface at any point, all the valuable downforce being generated by the car’s aerodynamics is instantly being applied to the undertray rather than the tyres. This will result in a sudden and drastic loss of grip.

However there is more to ride height adjustment than just ground clearance.
Bernoulli's principle states that as a fluid or gas (in this case…air) is accelerated through a small channel, its pressure lowers.
By lowering the car, you are forcing the air to accelerate as it passes between the undertray and the ground. This reduces the air pressure under the car, literally sucking it down onto the track.
This phenomenon is known as “ground effect”.
The positioning of the ground effect can be altered by raising or lowering one end of the car independently of the other. For example, lowering the rear end of the car will add more downforce to the rear without affecting the front end.

Especially the last sentence, as I still don't have a great understanding of how rake (the difference in the ride height of the two axles...which course changes as a function of velocity in accordance with the car's aerodynamic profile and its relative spring rates) affects the magnitude and positioning of undercar downforce.

I'd originally thought that lowering the front ride height increased undercar downforce, and raising the rear ride height relative to the front then moved its position forwards by progressively lowering air speed (and hence lowering the pressure differential between the under-car air and the ambient air pressure above the car) as the air travelled under the car. In practice though I wonder if rake makes a huge difference when it comes to positioning of the undercar downforce because it seems to me as though it'd be dominated by the more significant pressure/velocity change that occurs where the diffuser tunnels begin, which as I understand them are designed specifically to create a venturi effect (have you read about the Ferrari Modena's aerodynamics? Worth a look) - a significant rake change might be 30-50mm, which when applied to a 3-5m wheelbase is a tiny change of angle compared to the rate at which diffuser tunnels seem to climb relative to the surface of the road...anyhow, not arguing with you, just musing really and seeing if you have anything to add, might try to do a bit of reading over the break or talk to my brother about it while I'm down in Chch with him...

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Re: Formula 0.5 Car Setup Guide

Post by Bull » Tue Dec 15, 2009 4:44 pm

Ive always been under the impression that higher ride height on front = understeer, higher ride height on the rear = oversteer

At least thats the way it works on my Kart and the Super Saloon I crew on

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Re: Formula 0.5 Car Setup Guide

Post by slobb11 » Tue Dec 15, 2009 5:36 pm

The exact effects vary between cars and are way Way WAY too complicated for me to understand. The question really is....how does rFactor model something that even Formula 1 designers struggle to understand.
I believe they look at the simpler picture which is as Bull describes it....
Lower to the ground = more downforce at that end of the car.
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Re: Formula 0.5 Car Setup Guide

Post by Harding Jr » Tue Dec 15, 2009 8:22 pm

slobb11 wrote:The exact effects vary between cars and are way Way WAY too complicated for me to understand. The question really is....how does rFactor model something that even Formula 1 designers struggle to understand.
I believe they look at the simpler picture which is as Bull describes it....
Lower to the ground = more downforce at that end of the car.
I think it has very little to do with downforce, in such cars as Stockcars or Gokarts as Bull has mentioned it still reacts the same way where there is much less downforce, but altering the ride height can severely alter the setup.

I think it's more a case of weights. Think of parking your car on a 10degree slope/hill pointing down, there will be more weight on the front axle than on the rear axle. I thinking the change in ride heights front relative to back on a much lesser degree reflect where the passive weight of the car is.
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Re: Formula 0.5 Car Setup Guide

Post by Bull » Tue Dec 15, 2009 8:31 pm

GoKarts and Supersaloons do rely a lot on downforce Harding, even tho the SNZ Rule Book says other wise :P

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Re: Formula 0.5 Car Setup Guide

Post by slobb11 » Tue Dec 15, 2009 9:37 pm

Harding Jr wrote:
slobb11 wrote:The exact effects vary between cars and are way Way WAY too complicated for me to understand. The question really is....how does rFactor model something that even Formula 1 designers struggle to understand.
I believe they look at the simpler picture which is as Bull describes it....
Lower to the ground = more downforce at that end of the car.
I think it has very little to do with downforce, in such cars as Stockcars or Gokarts as Bull has mentioned it still reacts the same way where there is much less downforce, but altering the ride height can severely alter the setup.

I think it's more a case of weights. Think of parking your car on a 10degree slope/hill pointing down, there will be more weight on the front axle than on the rear axle. I thinking the change in ride heights front relative to back on a much lesser degree reflect where the passive weight of the car is.
I'm not sure about saloon cars, but in track racing we're talking in 5mm adjustments. There's no way a 5mm adjustment of the ride height would make bugger all difference to the weight distribution of the car.
If your car is 4.5m long and you raise the rear by 5mm, you would be adding 0.06 degrees to the angle of the car. I've never personally parked my car on a slope of exactly 0.06 degrees off horizontal so I can't promise out of experience here....but logic suggests to me it ain't gonna do much.

If you were to add a 10 degree forward rake to the car, you would need to raise the rear by 793.47mm. Just shy of 80cm ;p
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Re: Formula 0.5 Car Setup Guide

Post by Bull » Tue Dec 15, 2009 10:12 pm

Gotta remember adjusting ride height also adjusts suspension travel and sometimes the stiffness of the springs as well, which does affect weight distribution.

I think Ride Height adjustment has a lot of variable, hence why as you say even the F1 teams havent got it 100% sussed, but its probably easiest to just say lower the car, the more grip at that end _b

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Re: Formula 0.5 Car Setup Guide

Post by Bold » Tue Dec 15, 2009 10:50 pm

The other effect of raising the ride height is to raise the centre of gravity. So with a Go-kart raising the rear means the kart will lean further in the corners, making it easier to lift the inside wheel, giving less grip.
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Re: Formula 0.5 Car Setup Guide

Post by slobb11 » Wed Dec 16, 2009 7:27 pm

Bold wrote:The other effect of raising the ride height is to raise the centre of gravity. So with a Go-kart raising the rear means the kart will lean further in the corners, making it easier to lift the inside wheel, giving less grip.
Correct me if I'm wrong Bull....but as I recall, Go-Karts have 0 degrees camber on the rear wheels (my KT did anyway), which causes the loss of grip when cocking a wheel.
EDIT: Scratch that. Don't correct me, because I'm not wrong. Can't have camber on a solid drive axle ;)

Lifting a wheel is never good, but with a car running 2-3 degrees camber it isn't such a problem, as the inside wheel is doing bugger all at the best of times.
As mentioned in the guide above, body roll can be a good thing as it transfers weight onto the outer wheels more effectively.
In racing cars of any kind (particularly open-wheelers) the grip bonus offered from a lower ride height is almost purely down to aerodynamics.

Wikipedia has a good write up on Bernoulli's principle for anyone that wants to examine it further.



Incidentally...my references to "Formula 1 teams barely understanding it" was in regards to ground effect, not ride height. Although the two are related, they aren't one and the same.
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Re: Formula 0.5 Car Setup Guide

Post by Bull » Wed Dec 16, 2009 7:31 pm

slobb11 wrote:
Bold wrote:The other effect of raising the ride height is to raise the centre of gravity. So with a Go-kart raising the rear means the kart will lean further in the corners, making it easier to lift the inside wheel, giving less grip.
Correct me if I'm wrong Bull....but as I recall, Go-Karts have 0 degrees camber on the rear wheels (my KT did anyway), which causes the loss of grip when cocking a wheel.
EDIT: Scratch that. Don't correct me, because I'm not wrong. Can't have camber on a solid drive axle ;)

Lifting a wheel is never good, but with a car running 2-3 degrees camber it isn't such a problem, as the inside wheel is doing bugger all at the best of times.
As mentioned in the guide above, body roll can be a good thing as it transfers weight onto the outer wheels more effectively.
In racing cars of any kind (particularly open-wheelers) the grip bonus offered from a lower ride height is almost purely down to aerodynamics.

Wikipedia has a good write up on Bernoulli's principle for anyone that wants to examine it further.



Incidentally...my references to "Formula 1 teams barely understanding it" was in regards to ground effect, not ride height. Although the two are related, they aren't one and the same.
Correct, they run a solid rear axle so can't adjust the likes of Camber.

However lifting a wheel doesnt necessarily mean its altering the angle of the outside tyre, as kart chassis nowadays flex a lot and it is purely the chassis flexing rather then the whole Kart rolling over so to speak ... much like when a sprintcar lifts its left front wheel, the other 3 are still firmly where they normally would be, its just the chassis twisting.

EDIT Just read your EDIT so scrap that, lol

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Re: Formula 0.5 Car Setup Guide

Post by Wood » Wed Dec 16, 2009 10:46 pm

reaver wrote:Looking good, You've done a nice job of making complicated concepts accessible _b

I found this section interesting:
slobb11 wrote:Ride Height

When adjusting ride height, the most obvious consideration is ground clearance. If the car’s undertray bottoms out onto the track surface at any point, all the valuable downforce being generated by the car’s aerodynamics is instantly being applied to the undertray rather than the tyres. This will result in a sudden and drastic loss of grip.

However there is more to ride height adjustment than just ground clearance.
Bernoulli's principle states that as a fluid or gas (in this case…air) is accelerated through a small channel, its pressure lowers.
By lowering the car, you are forcing the air to accelerate as it passes between the undertray and the ground. This reduces the air pressure under the car, literally sucking it down onto the track.
This phenomenon is known as “ground effect”.
The positioning of the ground effect can be altered by raising or lowering one end of the car independently of the other. For example, lowering the rear end of the car will add more downforce to the rear without affecting the front end.

Especially the last sentence, as I still don't have a great understanding of how rake (the difference in the ride height of the two axles...which course changes as a function of velocity in accordance with the car's aerodynamic profile and its relative spring rates) affects the magnitude and positioning of undercar downforce.

I'd originally thought that lowering the front ride height increased undercar downforce, and raising the rear ride height relative to the front then moved its position forwards by progressively lowering air speed (and hence lowering the pressure differential between the under-car air and the ambient air pressure above the car) as the air travelled under the car. In practice though I wonder if rake makes a huge difference when it comes to positioning of the undercar downforce because it seems to me as though it'd be dominated by the more significant pressure/velocity change that occurs where the diffuser tunnels begin, which as I understand them are designed specifically to create a venturi effect (have you read about the Ferrari Modena's aerodynamics? Worth a look) - a significant rake change might be 30-50mm, which when applied to a 3-5m wheelbase is a tiny change of angle compared to the rate at which diffuser tunnels seem to climb relative to the surface of the road...anyhow, not arguing with you, just musing really and seeing if you have anything to add, might try to do a bit of reading over the break or talk to my brother about it while I'm down in Chch with him...
The effect of rake on the centre of pressure acting on the car will be very subtle, I'd be surprised if its even modeled in rFactor (but then they even have a spring mass damper model to simulate fuel sloshing around in the tank o_O ).

Disregarding super aero cars LMP, F1 etc

High Ride at Front = Understeer
High Ride at Rear = Oversteer

Higher ride hight = higher cente of mass = more weight transfer to outside wheel = less grip.

To clarify anti-roll bars...

Basically a quirk of tyres on tarmac surfaces is that the amount you push down on a tyre and the amount of grip you get from the tyre is not a 1:1 thing. If you push down with 1kg you might need to push sideways with 1kg to slide the tyre, however if you push down with 100kg you might only need to push sideways with 80kg to get it to slide. Im not sure why, perhaps the tyre acts a bit like glue and sticks about the same no matter how much you press down on it.

Anyway... This is the reason why a low centre of gravity gives you more grip. There is less weight transfer to the outside wheels - the force pushing down on each tyre is more even, so if you add up the sideways force required to slide all four tyres it will be greater than if you have a high centre of gravity.

Anti-roll bars work by pushing the inside wheel up and pushing the outside wheel down (this opposes the cars tendancy to roll). For extreme cases look at a V8 Supercar lifting an inside front exiting a corner and a Mini 7 lifting an inside rear during corner turing turn in. Very stiff front and rear anti-roll bars respectively. A stiffer anti-roll bar reduces grip exactly the same way a high centre of mass does - by increasing the load on the outside tyre.

Anti-roll bars are a neccesary evil as excessive roll can do nasty things depending on the suspension geometry of the car. They will give faster response to driving inputs - useful for chicanes and fast corners and are also a fool proof way of balancing the car.
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Re: Formula 0.5 Car Setup Guide

Post by Obsc3ne » Wed Dec 16, 2009 11:57 pm

For the guys who just want a set-up without wanting to undertsand why they are suddenly beatin Ggaav, use the attached program
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Re: Formula 0.5 Car Setup Guide

Post by Harding Jr » Thu Dec 17, 2009 12:51 am

Obsc3ne wrote:For the guys who just want a set-up without wanting to undertsand why they are suddenly beatin Ggaav, use the attached program
Sorry to tell you this, but upon installing this my Anti-Vir found their to be a Trojan in this file. Warning to others not to download until a clean copy is uploaded _b .

EDIT: Sorry may only be at my end, I tried downloading and installing from this webpage here and received the same results (Trojan)

EDITs EDIT: Short bit of researching, it is a false positive in the program only picked up by AVG :larf:
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Re: Formula 0.5 Car Setup Guide

Post by slobb11 » Thu Dec 17, 2009 11:23 am

Please keep in mind that this is a very simplified guide, aimed at giving people a BASIC understanding of the physics. If we delve too deeply into physics it's only going confuse people and scare them off.


Wood, you raised some interesting points.

I totally agree with you about the non-linear traction curve of tyres relative to downwards force. However, don't forget to allow for the fact that, while cornering, the outside wheel (due to camber) has a contact patch much larger than that of the inside tyre. So any weight on the outside tyre will have a proportionately larger effect than weight on the inside wheel, based on this very equation.
I will look at revising the guide regarding roll affecting tyre loading affecting slip angles when I get a chance. The hard part is finding a simple way of wording it.


In regards to centre of gravity.....
rFactor only models one centre of gravity for the car, so although overall ride height will have some effect on COG, adjusting the ride height of just one end of the car won't have any effect on THAT END'S centre of gravity.

Also...the game makes no disctinction between open-wheelers and tin-tops. It doesn't have a virtual wind-tunnel to calculate aerodynamic forces that would be acting on a particular model. Basically it just goes off the numbers that are fed into it, so ground effect in rFactor will still be applied to tin-top cars that, in real life, don't have a perfectly engineered undertray. The degrees of these effects are set in the HDV and are quite basically modeled.


To clarify what I think Wood is trying to say here...
Wood wrote:Anti-roll bars work by pushing the inside wheel up and pushing the outside wheel down (this opposes the cars tendancy to roll).
When a car is turning right, there are centrifugal forces pulling it to the left.
The tyres (at ground level) are preventing the bottom of the car from sliding left, while there is no anchoring point at the top to prevent the top from moving left. This causes the car to lean to the left.
In order for the car to lean to the left, the left hand suspension needs to compress, and the right hand suspension needs to extend.
All anti-roll bars do, is impede the left and right suspension from working independently.
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Re: Formula 0.5 Car Setup Guide

Post by Wood » Thu Dec 17, 2009 1:39 pm

slobb11 wrote:I totally agree with you about the non-linear traction curve of tyres relative to downwards force. However, don't forget to allow for the fact that, while cornering, the outside wheel (due to camber) has a contact patch much larger than that of the inside tyre. So any weight on the outside tyre will have a proportionately larger effect than weight on the inside wheel, based on this very equation.
This doesn't change anything, anti-roll bars reduce grip by subracting weight from inside tyre and transfering it to the outside tyre.

Adding large amounts of camber to a car is simply making the best of a bad situation. V8 Supercars have a high centre of mass and beefy front anti-roll bars. This means very little weight on the inside front. In this case it makes sense to optimise the outside tyre. If the engineers could find a way of getting more weight on the inside tyre they would, but short of cutting off the roof or widening the track they cannot. A purpose built non aero car (formula ford) has pleanty of weight and contact patch on the inside tyre.
slobb11 wrote: In regards to centre of gravity.....
rFactor only models one centre of gravity for the car, so although overall ride height will have some effect on COG, adjusting the ride height of just one end of the car won't have any effect on THAT END'S centre of gravity.
After thinking some more, I think you are correct. My original reasoning was if 50% weight is on the front tyres and 50% on the rear and then you lower the front and raise the rear by some amount, the average mass acting on the front wheels will be lower than that acting on the rear wheels. Google points to some complex interaction between roll centres centre of mass and weight jacking that I don't understand. What ever the cause, the relationship still stands.
slobb11 wrote: To clarify what I think Wood is trying to say here...
Wood wrote:Anti-roll bars work by pushing the inside wheel up and pushing the outside wheel down (this opposes the cars tendancy to roll).
When a car is turning right, there are centrifugal forces pulling it to the left.
The tyres (at ground level) are preventing the bottom of the car from sliding left, while there is no anchoring point at the top to prevent the top from moving left. This causes the car to lean to the left.
In order for the car to lean to the left, the left hand suspension needs to compress, and the right hand suspension needs to extend.
All anti-roll bars do, is impede the left and right suspension from working independently.
This is sort of correct but be careful not to confuse body roll with weight transfer. If a car had no suspension at all there would be no body roll but still weight transfer.
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Re: Formula 0.5 Car Setup Guide

Post by Inspector » Thu Dec 17, 2009 3:02 pm

Lots of people saying lots of stuff
:dazed: So has anyone got a nice stable setup they want to share to us guys who enjoy racing but have absolutely no idea what any of this stuff means?
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Re: Formula 0.5 Car Setup Guide

Post by maxlev » Thu Dec 17, 2009 5:56 pm

Inspector wrote:
Lots of people saying lots of stuff
:dazed: So has anyone got a nice stable setup they want to share to us guys who enjoy racing but have absolutely no idea what any of this stuff means?
So, I wasn't the only one whose eyes glazed over. :dazed:

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Re: Formula 0.5 Car Setup Guide

Post by slobb11 » Fri Dec 18, 2009 5:29 pm

Thanks Wood, I'll revise the guide.
I'm way hungover at the moment, so might wait a few days before attempting that lol.
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Re: Formula 0.5 Car Setup Guide

Post by Heppy » Sun Dec 20, 2009 9:41 am

Crickey, will read this thread soon,(Haven't got a spare 3 hours at the mo to digest it all :eek: ) looks like some good guff though, see you's all tonight :driver:

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