How to setup cars

[Mr Deap]

According to google, the weight distribution of the KTM XBOX R is 38/62,
38% front
68% back

Lets suppose you have spring rate that has an ideal natural frequency
Car engineer, Dev app:
F:1.8Hz R. 3.3Hz

Basically you always want to keep about that ratio when adjusting the spring rate:
So the back need about 162% of the rate than the front
The back end is about 38% of the front

When you change the stiffness, always keep about that ratio.

Dampers bump front 1
Dampers rebound front 8

Dampers bump rear 6
Dampers rebound rear 4

Both front damping has a gap of 1 at the very upper end of the spring & the back damping has a gap of 2 which is about the mid center. The default value has a gap of 2 for both end, which suggest the car has anti squat & got the damping at the upper range of the front spring & the lower middle range of the rear spring.

Without any anti squat whatsoever, the damping rate should be higher by 162% at the front which technically should have a range of 1 instead of 2.

Some car suspension geometry has anti squat geometry

If you increase the rear height, it reduce the effect of anti squat. It allow the rear suspension to compress more during acceleration & get reduced compression at the front. I suppose changing the range downward for the front while retaining the gap & the opposite going upward for the rear(maybe increase range) maybe make sense by changing the angle of the car.

It's all supposition, it could be complete nonsense.

With this car on default with simply adjusting the tire pressure, you can easily beat the AI. Although it always fascinating to play with the setup.

 

[Heath82]

That’s kinda technical explanation man, thank you. But what i made was to get as less understeer as possible. I started with dampers but I didn’t solve the problem, then i increased negative camber on front wheels to max, I expected some changes but at first chicane the car was still unstable. Then I decreased front height and the car was more stable. I ended up decreasing front and rear toe to have negative values. Then the car totally changed, it’s not the same anymore.. what i wanna know is: does it make sense? I didn’t go for many laps with this configuration, so I don’t know if i lost speed or if i ****ed up something, because i read that negative toe on rear is weird.. please look at default settings and look at my configuration and help me out to get what i made wrong or if i’m on the right way

 

[RasmusP]

Negative toe on the rear is totally fine as long as you can handle it. It breaks the rear lose so you start to slide earlier but in a softer way.
If the setup is that limited then it's worth a try

Higher rear compared to front will also give you a very controllable oversteer. You can imagine it like giving the rear more mass that's pushing the car to the outside. It's mainly used for drag racing as "the virtual mass" will push the rear down for more grip.

Please don't think that virtual mass is a correct term. It's the center of gravity that gets a different lever when acceleration forces are applying.

@Mr Deap could you link a picture with a squatted car? Not really sure what is meant with it. I get the drawing though

 

[Heath82]

Could someone giving a try and letting me know the thoughts? My configuration is the last message of 2nd page of this thread

 

[RasmusP]

Hey dude can you try this and let me know please?
Camber front 2.2
Camber rear 0.9
Toe front 8
Toe rear 13
Height front 24
Height rear 25
Dampers bump front 1
Dampers bump rear 6
Dampers rebound front 8
Dampers rebound rear 4

Well you did to the front dampers what I said about the rear
I drove a few laps and I really don't like the negative toe at the front, rear feels good though. Drifty but easy to catch!
The dampers.. it's difficult as I don't like that car in general but I'd go with the complete opposite!
Front Bump: 5
Front Rebound: 6
Rear Bump: 4
Rear Rebound: 8

 

[Heath82]

Cool! I’m gonna try your setup! I found this guide it helps you out to fix bad car’s behavior step by step, and i got my setup following this guide. What do yoi think about?
https://goo.gl/images/F31jaS

 

[Heath82]

About negative toe, if you look at the picture in the link, where is: understeer -> corner entry-> mid low speed-> it says: increase toe-out. But it’s not specified if front or rear. That’s why I increased both

 

[RasmusP]

Cool! I’m gonna try your setup! I found this guide it helps you out to fix bad car’s behavior step by step, and i got my setup following this guide. What do yoi think about?
https://goo.gl/images/F31jaS

The guide is very basic but "okay". Depending on the car the order of the settings will need to differ and also the guide doesn't show that you can also most of the times to the opposite to the other side.
Like "understeer" -> "decrease front anti roll bar". You could also increase the rear anti roll bar but that will also influence the braking behavior etc.

A car is a very complex system but the guide is ok

 

[RasmusP]

About negative toe, if you look at the picture in the link, where is: understeer -> corner entry-> mid low speed-> it says: increase toe-out. But it’s not specified if front or rear. That’s why I increased both

It's about the front. Probably forgotten in the guide. From my experience the rear toe will have more impact on mid corner or corner exit. Not so much at the entry!
btw could you record a video of your driving?
Smartphone or camera would be totally fine but I'd like to see if you should focus more on your driving skill than on setup

 

[Heath82]

Thanks a lot for your help!! I really appreciate. But I have ko way to record myself..but if you have a better scheme like the one in the link, something that would tell me what setting up step by step, this would help a lot. You are very good at it and i hope you can help me this way.. because i found very easy learning how to fix the car if i have a point of beginning

 

[RasmusP]

Sadly there is no easy way. "step by step" only works at the beginning until you reach a certain point where you basically need to know all settings by memory so you can combine them in your head and feel while driving what combination could make you faster as a whole.
This needs a lot of driving and testing the settings, what you're doing right now and also a lot of reading and trying to understand how a car works.

For now I would focus on doing slight changes with the guides you have now and better watch videos about how to drive better.
Theres a thread with lots of stuff and links in it:
https://www.racedepartment.com/threads/driving-style-and-setup-threads.146106/

 

[Heath82]

I know it’s not easy, you are a ****ing mechanical engineer!! You are very good at it!! But i just wanna enjoy the game, I don’t have so much time to test and test, it’s enough for me fixing the bad behavior of the car so it matches with my way to drive. That’s it! I just need to know what setting up if car understeers or oversteers, I mean, i can’t get the reason a car understeers or oversteers, i just get that it does! So i wanna know what parameters i gotta change to fix that. Can’t you give me a little basic guide about?

 

[RasmusP]

I already gave you all guides I know of and you found a nice flipchart too. The 21 step guide and your step by step guide are very good for that.
If you can't get the results you want with these, you either have to go a big step forward and invest a lot of time or you live with it and try to adjust yourself instead of the setup.
Some cars you will just not like or enjoy at all. No setup will change them in such a way that you will like them.
Also in assetto corsa a lot of cars don't need to "get fixed" but are very fast with the default setup so you have to adjust yourself, as bad as it sounds.

I always tried to tweak my lap times with a better setup. Nowadays I watch the replays and figure out what I need to do differently instead of blaming the car. So if I can't fix the car, I try to fix myself

 

[Heath82]

Ok my friend, just tell me something about my guide: i can ALWAYS set the opposite? I mean if guide says increase front bump you advice to increase rear bump too? And is this legit for everything?

 

[RasmusP]

Ok my friend, just tell me something about my guide: i can ALWAYS set the opposite? I mean if guide says increase front bump you advice to increase rear bump too? And is this legit for everything?

Increase front bump: opposite = decrease rear bump.
Making the front stiffer makes the rear "softer in relation". So making the rear softer makes the front stiffer in comparison.

You'll get more or less the same impact on over or understeer because in the end the relation between the front and the rear will be the same.

But, of course the overall stiffness will change, depending on whether you make one thing stiffer or the opposite, make something softer.

Dampers are a bit special but take the anti roll bars:
Front softer or rear stiffer will both lead to less understeer, or more oversteer. You see, opposite here too. Less understeer is the same like more oversteer!

Now a softer front arb will make the steering wobble more, until a point where you won't be able to control the car mid corner because it's just too soft!
In that case you stiffen the rear anti roll bar instead.
Now a stiffer rear anti roll bar gives you:
- less traction when accelerating
- more stability under braking and slightly turning.

Examples:
If you understeer during the second left/right at Imola in sector 1 you soften the front anti roll bar.
If you lose the rear while braking at the downhill double right in sector 2, you stiffen the rear anti roll bar instead.

Hope that makes sense

In general a stiff car is easier to drive but has less overall grip and traction.
A soft car will have more overall grip and traction but will be more difficult to drive.

 

[Mr Deap]

point of beginning

Deceleration force before the apex(grip on entry):
-Brake
-Lift off
-steer over the limit(it's slower but help to find the maximum steering input by feel)

Acceleration force after the apexgrip for exit)
-Throttle... Throttle more late if you have trouble with losing grip

If you drive holding the line symmetrically, holding the pattern, you can adjust by feel & understand the car behavior better. On some car you basically have to hold the brake at 100% until mid entry on high speed corner. I often use the term bomb dive with the brake & retain the best you can do with retaining some brake pressure until the apex & use the steering input in delay to force the turn in. Controlled understeer is a skillset in sim racing.

Use the speedometer as a reference as deceleration force & acceleration force. Also, the game punish you really hard in cornering efficiency if you get acceleration force before the apex on the ideal racing line.

The cars are balanced for a flat surface. The common change is readjust the natural frequency, wing & match the damper/arb. The change is often by ratio which result the need to mess with every setting just to increase or reduce roll to optimize the car cornering speed, straight line or complience. It's pretty much about having the same car behavior while changing everything to get better car. If it's not matched, it's broken.

It's the reason to drive default.

The change in oversteer/understeer change doesn't promote anything in particular in my opinion.

Again toe on default is optimal & I only recommend default or close to neutral. If you have problem with oversteer on throttle, you simply need to reduce the front toe closer to neutral as it get less sync & less reactive to steering input, but at the cost of reduced cornering speed.

 

[PhilS13]

In this thread, there is decent advice from someone and there is pure poop from the other.

Unfortunately, a beginner has no way to find which one is poop and which one is good.

Thank you, poop maker.

 

[alain martin]

hey guys,
I need a lot of help with braking some cars just spiral out of control when I start braking. how do I fix this issue?

 

[Mr Deap]

hey guys,
I need a lot of help with braking some cars just spiral out of control when I start braking. how do I fix this issue?

What's important is to understand the suspension geometry.

When the car spin out under braking, the contact patch is greatly reduced for the cornering at the rear from decompression from the toe/camber change due to the suspension geometry design.

So the question is...
-if the toe increase or decrease from the suspension decompression
-if the camber increase or decrease from the suspension decompression

In a nutshell, you want the tires ideal slip angle to follow the racing line(both rear wheel travel a different path). Also remember that the sway bar make the pair of suspension to compress & also decompress when leaning which result different toe/camber value from the suspension geometry.

The ideal camber value is based on the load sensitivity of the tire to match the front grip.

You can use more aggressive front damping to slow down the toe/camber change from the suspension geometry, since it's based by force added to it. Although it will screw up the front maximum cornering capacity.

Could also be caused by the rear not dropping down fast enough to touch the road which can be remedy by increasing the rear spring rate, but it may be possible to reduce the damping value to match the compression/decompression from the default value while cornering.

If the rear tires overheating(or higher than front) is due to too aggressive rear brake. this lead to more front grip than the rear which result oversteer.

There's also the differential that doesn't match the speed of the wheel is traveling resulting uneven grip on both side(when cornering the inside should heat a tad bit less). Although you can play with this setting to gain better traction by obtaining ideal tire temp depending of the situation.

More rear downforce, but can reduce higher top speed..

There's also the possibility of the get good value, but have no footage whatsoever...