General Setup of the FR 3.5

[jego]

Just recently I found that ISI states that the default setup of the car is more or less what you would expect the car to be setup in real life.
Also I found that they provide an easier setup. Both those however are completely different to the ones that get posted here.

David's and especially Martin's setups are super soft. Everything regarding the springs is at the lowest setting and also the car height is very low.

I am no expert at all but from what I have read such a setup should actually behave very unstable, as high downforce in fast sectors would push the car very low and once slowing down the springs would open up making the car feel and react very different.

Am I misunderstanding something here?
Also how is your approach towards making a setup?
I am using a 21 step guide made for GTR2.

 

[MOOOOOOOOOSCHT]

Sry, no time for a comprehensive answer, but here are some statements:

The softer the suspension the more grip you have, but like you wrote, the harder the handling can be.
Also the lower the car the better the handling, but the possibility to touch the track is higher, and then you have a really bad handling (e.g. on curbs, ...).

I`m also no expert, but I think it is the best way to find out how the car reacts for your own.
Try to take a default setup and change the setup step by step and look how it feels.
This and read all setup guides you find, then you will find you way.

Basicly I understand the background of the settings.
And the result of the changes are often how I wanted to modify the handling of the car.
But also often then I`m not faster
So my secret procedure to create a setup is often trail&error

Also an important point is that the setup has to fit to the driver respectively to the driving style.
E.g. I never ever was able to do a PB with a setup from David, but we all know, he`s damn fast, and so they can`t be bad setups ...
... or the setups are bad and he`s a much much more faster driver ... hopefully not

And finally: a setup is always a compromise

I hope I was able to help you

Cyas
Martin

 

[MOOOOOOOOOSCHT]

... and I use this very useful PlugIn from our Cosimo
Martin

 

[jego]

Yea thanks for your input. I guess it just comes with experience to know how to do this properly.
My main problem is probably sticking with small changes. I often catch me thinking, well this one corner has too much oversteer and I end up changing 3 settings at once to see if this fixes anything

 

[April Dillon]

Suspension

I'm gonna go ahead and spoil something for you... Open wheel car suspension sucks, always. And it's as simple as that. The best open wheel suspension in this day and age is actually just the least terrible. It's pretty much always a compromise between suspension and aero where the suspension ends up much lower on the priorities list.

Have you ever heard about how harder suspension is worse for handling, and ideally you want it as soft as can be in all cars? Open wheel cars basically live in the 'too hard' region of that scale all the time. You'll find there's more change in suspension behaviour from tire pressure changes than with suspension rate changes. So when following setup guides on the internet, try applying the advice they give for springs to tire pressures. Too high or too low and you lose out, but small adjustments following those principles are very helpful.

Also, remember how I said aerodynamics ends up being higher priority than suspension? For every suspension & tire pressure setup, there is a sweet spot in the ride heights. So just try raising/lowering the front or rear (separately) and see what happens. You'll know when you find the sweet spot because much faster lap times will come with barely any effort as a driver.

Differential

This is the most style dependent part of the setup IMO. So if you ever have trouble using someone else's setup, this should be the first thing you look at. It's probably the single biggest part of controlling the understeer-oversteer scale of handling in a setup in relation to throttle input. So when we all think a car should oversteer/understeer more/less in reaction to what's happening with the throttle? We look at the diff.

It's worth remembering that not all cars lift their inside driven wheel enough that an open diff will spin all its power away on there. Pretty much all single seat race cars built after 1980 are like that. I think people would be surprised how well a modern open wheel car can drive with an open diff. Having a limited slip diff in cars like this is much less urgent, though it's still preferable. Hence they all do it.

Goal #1 of the diff is to maximise the engine torque output to the wheels so that you use all of the longitudinal grip. Too much locking, and the inside wheel spins too fast, causing wear. Too little locking, and the inside does nothing and you limit yourself to the longitudinal grip of the outside wheel only (this also causes insane oversteer when accelerating). Again, there's a sweet spot here which gives optimal corner exits, and deviating too much from it won't do any good. This is what the 'power' setting is in the FR35.

The 'coast' setting is the same thing, but when we have negative torque going into the wheels... Such as engine braking. And this is probably the most important part of driver comfort of all. If you want more stability at initial turn-in, more coast-side locking will probably do it. If you want more rapid initial turn-in, less coast-side locking will help. And reducing the 'brake map' setting in the setup will make these characteristics more pronounced.

 

[Blauweke]

Here's a question: what does the rear roll centre do, and how can you tell what the diffirent settinsg actually are.

 

[David Turnbull]

Heres some info I have on roll centres that I keep handy for anytime I need to change them, but tbh thats very rarely I stick to what I have had for a long time and it usually serves me well everywhere with minimal changes.

 

[Stephen Miller]

Suspension

Differential

This is the most style dependent part of the setup IMO. So if you ever have trouble using someone else's setup, this should be the first thing you look at. It's probably the single biggest part of controlling the understeer-oversteer scale of handling in a setup in relation to throttle input. So when we all think a car should oversteer/understeer more/less in reaction to what's happening with the throttle? We look at the diff.

It's worth remembering that not all cars lift their inside driven wheel enough that an open diff will spin all its power away on there. Pretty much all single seat race cars built after 1980 are like that. I think people would be surprised how well a modern open wheel car can drive with an open diff. Having a limited slip diff in cars like this is much less urgent, though it's still preferable. Hence they all do it.

Goal #1 of the diff is to maximise the engine torque output to the wheels so that you use all of the longitudinal grip. Too much locking, and the inside wheel spins too fast, causing wear. Too little locking, and the inside does nothing and you limit yourself to the longitudinal grip of the outside wheel only (this also causes insane oversteer when accelerating). Again, there's a sweet spot here which gives optimal corner exits, and deviating too much from it won't do any good. This is what the 'power' setting is in the FR35.

The 'coast' setting is the same thing, but when we have negative torque going into the wheels... Such as engine braking. And this is probably the most important part of driver comfort of all. If you want more stability at initial turn-in, more coast-side locking will probably do it. If you want more rapid initial turn-in, less coast-side locking will help. And reducing the 'brake map' setting in the setup will make these characteristics more pronounced.

Thanks for this discussion April.

This may seem like a question with an obvious answer, however, I have never found it totally clear.

One point that always has me perplexed in differential discussions, is reference to "more" power setting(or "more" coast setting) vs. "Less" power setting(or "less" coast setting). Is "more" a bigger value or a smaller value? What does "more" mean? Bigger value or bigger understeer(more rear wheel grip due to less wheel spin through the rear wheel combination)? Every once in while there are parameters where the terms "more" and "less" do not necessarily refer to a bigger or a small value depending on what you are referring too. Perhaps it is because "more" oversteer can also be thought of as "less" understeer! It has been my perception that a bigger value of "power" leads to more lockup which can lead to understeer on acceleration on corner exit. Similarly a smaller value of coast leads to more(?) lockup and oversteer on braking and turnin?

I'm not sure what "more" or "less" means in this dynamic.

Could you comment on your points above in terms what you mean by "more" and "less" relative to lockup and oversteer/understeer?

Example:

More/power = bigger/value = more/understeer = less/understeer on corner exit acceleration
Less/ power = smaller/value = less/understeer = more/oversteer on corner exit acceleration
More/coast = ?/Value = ?/oversteer = ?/understeer on corner entry
Less/coast = ?/Value = ?/oversteer = ?/understeer on corner entry

Appreciate clarification of your choice of words.

Many thanks

Stephen

 

[April Dillon]

Hey Stephen, long time no see

When I say more when talking about the diff, I mean larger numbers in the setup screen. Those larger numbers mean the driven wheels are locked together more in the situations they affect.

It usually mainfests as understeer/oversteer because of how it applies yaw forces to the car. In an extreme case where 100% of the torque goes to the RL wheel, that puts the acceleration force as far off centre from the car as possible. And it will also push to yaw the car to the right at the same time as accelerate. The more that happens, it manifests as oversteer to the driver. When you start locking the wheels together (increasing these numbers in the setup screen) it starts redirecting torque to the other wheel. So if you have 75% torque on the RL and 25% on the RR, the yaw force causing the car to oversteer has reduced because the 75% is partially cancelled out by the 25% opposite. And in a more extreme situation where the torque is split 50:50 between the rears, that acceleration force is placed directly in line with the car's CoM and there will be no yaw force at all from that (as is the case with locked diffs).

The same happens in the opposite direction when decelerating due to engine back torque, so is more pronounced when you reduce the 'brake map' number in the setup.

I don't normally like reducing setup changes down to tables of 'understeer/oversteer' scenarios, since it can transfer badly between different cars. But I guess something like this should hold true for the FR35 and other modern single seaters.

If car understeers when accelerating, try a smaller power side diff number
If car oversteers when accelerating, try a larger power side diff number
If car understeers when decelerating, try a smaller coast side diff number
If car oversteers when decelerating, try a larger coast side diff number
If the changes above seem to do nothing, use a much lower preload number and try again
If car understeers everywhere, try a lower preload number
If car is not progressive and 'snappy' when responding to pedal inputs, try a much lower preload number
If there are rapid yaw actions during uneven/irregular loading and forces (like running on rumble strips), try a higher preload number

(As you can see, I like the theory that preload should be as low as possible in the FR35 I'm usually way below the default on preload in my setups for this car)

Note that I've said accelerating/decelerating instead of entry/exit. In corners where you're accelerating from entry to exit, coast side is irrelevant (IE Dunlop @ Suzuka) and it's all about the power side. Inversely, in corners where you're decelerating all the way through, coast side is the only one we're interested in.

 

[Stephen Miller]

Thanks April

Your summary helps, I was just trying to confirm the adjustment direction.

cheers

 

[Raymond van Soest]

Hi all, sorry for bumping this old thread but is contains some good information. Besides, I have a question regarding packers. From what I've read, packers should only be used as a last resort to keep the car from bottoming out. Also, when you ride on the packers while cornering, this should feel like your spring is infinitely stiff and should cause a sudden loss of grip.

I set up a sheet on motec with suspension positions, lateral forces and ride heights to prevent riding on the packers while cornering, but this wasn't quick at all as I had to set the ride heights quite high. Then I used Martins setup with fairly high packers which was very stable, but according to my understanding should hit the packers while cornering and reducing suspension movement.

Is this a flaw on the fr 3.5, or do I just dont understand it correct?

 

[Blauweke]

Hey Raymond,
Good to see you're trying to understand how the car works.
The thing is, even when you're completely driving on the packers, you're still driving on your tires. Wich, since we all put it at the lowest pressure, also acts as a spring.
But yeah, i've noticed that there's not much change in handling when you're driving on the packers. Maybe this is because there's only one or two wheels whose suspension is actually on the packer in a corner.

 

[MOOOOOOOOOSCHT]

For the Barcelona setup I posted, I used at first a setup with rear packers I think around 18-20, then I set it lower to 10, when I remember right. Then the car reacts quite different.
With higher packers I always lost the rear in corner 7, felt like the packers are in action ... like the springs are invite stiff ...
... on this bumpy track

 

[Raymond van Soest]

Ah yes that makes sense, thanks! The reason we are able to run on the softest pressure, is that the tire model isn't correct/complete am I right? Tire pressures don't seem to affect centre tire temps anyways

 

[Blauweke]

Yeah, lowest tyre pressures seems to be common sense in rfactor 2. We used to be able to run 90 Kpa but they changed it to 106 a while ago.

 

[Andrew Hollom]

Since I hadn't driven this car before joining the league, I've been trying to get to know it and develop some baseline setups. While looking into it, I did some reading about roll centres, and in the process created a graph that maps out their characteristics. In case anyone would find this useful, I have uploaded it in PDF format. If anyone would like the Excel spreadsheet, then just ask.

 

[Rob Swindells]

I have tested the High Downforce / default setup at Singapore this morning.

• I determined the fuel for 20 minutes + 1 lap to be 29L
• I set tyre pressures to lowest: 106 psi (as per rF2 standard operating procedure!)
• I set ride heights to lowest (because lower CoG = quicker

My best 5 laps is 9:26.117 (average lap 1:53.223 / best lap 1:52.013) How is my pace?

 

[Raymond van Soest]

Check out http://prestogp.liveracers.com/Live/ for the fastest lap times on the server. These were probably quali modes though. Make sure the car is not botomming out because that will make you lose a lot of time, so ride height as low as possible without bottoming out.

 

[patchedupdemon]

In motec it says I’m -0.10mm in the front end at the highest speed places,yet I hear no scraping.

Do we know where the ride height measurements are taken from within motec, isn’t it the undertray or a place on the chassis or suspension.

Wish I could hear the car bottoming out, it would save a lot of time looking in motec

 

[Blauweke]

You can't always hear the car bottoming out. If the ride height is negative then you are definetely bottoming.

You can set minimum ride heights and use packers to stop the car from bottoming. You want to prevent the suspension from going on the packers in the corners. On straights it is fine.