PHYSICS Bumpstop telemetry in the setup screen

@Aristotelis

I was wondering if you can confirm my understanding of the spring rate, bumpstop gap and bumpstop rate.

If I soften spring rate, is the general approach should be increase bumpstop gap and stiffen bumpstop rate and the opposite, if I use a stiffer spring rate, lower bumpstop gap and soften bumpstop rate to achieve a similar result in suspension compression? I know that there can be a little bit of fine tuning with the bumpstop gap and the bumpstop rate but I'm just trying to understand the general relationship

 

@Aristotelis

Why you don't answer the questions of Leprekaun?

His questions are justified and not everyone is a setup genius.

 

From my point of view, if you are softening the front/rear springs, then I'd be thinking about what to do with the bumpstops to try to ensure that the maximum amount the suspension compresses (as-in how low the front/rear ride height gets) stays the same as it was before I softened the springs. Or perhaps that is what you mean and we are both saying the same thing but in a different way.

In that context, if I softened the front/rear springs, I'd be concerned about the front/rear getting so low where it will either stall the splitter/diffuser, bottom out on the track in a compression, or touch a kerb I was wanting to run over, so I'd be trying to use the bumptstops to limit the travel. If the spring is softer it will have taken less energy out the car for a the same distance of travel, so I'd want the car to either hit the bumpstop earlier (lower the bumpstop range) and/or for when it hits it for it to hit something harder (increase the bumpstop stiffness), or likely both.

How much to decrease the range, and how much to increase the stiffness is the tricky part. I don't believe the telemetry output from ACC gives the actual ride height, so its all about feel for that. As a rough guess if I went down a click on springs from a setup I felt was nice already, I'd probably go 20% lower on the bumpstop range, and 50% higher on the bumpstop stiffness, but I could be wildly off with that.

@Aristotelis If I'm wrong with this, I'd love to know it, or if you have any tips for working things out from the telemetry I'd be very interested.

 

My understanding is that the bump stop gap defines the damper stroke you would like to achieve (limiting it), so it is dedicated to the lower threshold of your ride height you want to achieve to preserve your aero effectiveness.

The bump stop rate defines how stiff the bumpstop is, to keep the lower threshold ride height as close as possible to the desired value. But if it is to stiff the car will have harsh reactions, if it is too soft you'll have temporary less aero effectiveness untill the damper goes back to defined position as it will compress more.

So if it is linked somehow to your wheelrate settings, it is still independant.

When you adjust the wheelrates your damper stroke isn't affected in ACC (it was in AC and you had to re do the geometry) when you soften or stiffen the wheelrate what you change is the amount of suspension travel so at a constant vertical charge you change the time spent on the bump stop.

If you want to delay when you'll hit the bump stop you need to increase damper settings.

As a sumary:
- Wheelrate defines the amount of travel.
- Dampers defines the speed of travel.
- Bump stop further limits the travel depending on bump stop rate (it acts as a additional spring) and it starts impacting the travel when it hits the bump stop (defined range)

 

@seb 6th gear
"As a sumary:
- Wheelrate defines the amount of travel.
- Dampers defines the speed of travel.
- Bump stop further limits the travel depending on bump stop rate (it acts as a additional spring) and it starts impacting the travel when it hits the bump stop (defined range)"

Your summary is exactly the needed message. It is also important to see some pictures in internet how these springs, bumpstops, dampers looked like in GT3 cars. Then it will be easier to understand the whole concept.

 

You can look at suspension manufacturer's websites to get further details like
https://www.kwsuspensions.co.uk/technology/coilovers

 

If I understand correctly, bumpstop range has nothing to do with the physical size of the bumpstop itself.

Increasing the bumpstop range effectively makes the bumpstop physically smaller and that is what increases the range.

Have I got this correct?

Also, a more general question for you experts if you don't mind... How important is it to get involved in this part of the setup when compared to all of the other sections? Is it more of a final adjustment that's way down the pecking order when you faster guys are making a setup or one of the go to fundamentals?

I'm generally 5-7 seconds per lap slower than the aliens so should I be ignoring this totally and spend my time looking for more basic things? I'm thinking that I might end up making things even worse if I start delving into this area.

 

In case of 5-7s i think you dont have the car anywhere near where we need to be talking about setup. You can be within 1 or 2s with the safe and aggressive presets or even closer easily. I think for now you should be looking into finding the right braking points, the correct turn in points and the transition from brake to turning and back on the throttle. Learning to feel what the "state"of the car is in a given moment and the input it asks from you in these is way more important for now than changing anything on the setup for you.

Happy to help!

 

i agree with n1lyn.
5 seconds off is very big difference.
Default setups are already good enough to get to alien lap times (sometimes they can be little bit slower but i'm talking only 1 seconds or less)
Always go with aggressive setup so you get a no compromise car.

I use bumpstop range to get the grip in front tyres.(they allow more travel of suspension i guess)
I NEVER keep it at zero no matter the case because my driving style needs good front end grip.This is generally gives me better setup than default one but default one.

 

@EsxPaul like said by others, refine first your driving technique, it will help you to understand the car thus while interresting yourself to setup, you'll know better what to adjust. Atm you'd go blind.

So focus on two small universall setup steps :
- try to find the brake bias that suits your skill level (it's one of the most driver dependent setting I would say), on the front it will make the car more stable but somewhat understeery, rearwards it will make the car more agile but oversteery,
- adjust tyre pressures to run slicks as close as possible to 28 psi when hot, and wet arround 30 psi when hot, just count 3/4 laps to get proper temps values.

Leave the rest as default for now, maybe increase the TC by a click or two to gain trust in the car.

A very good ressource for you to look at, a playlist of a professionnal driver coach, Scott Mansel from Driver61, explaining from basic to advanced racing techniques in small and digest videos to look and look again at your pace

https://www.youtube.com/playlist?list=PLsEck2Be1veMR7YTL9tYtiep0elO0x6C0

 

Thank you all. I will definitely take heed of your advice and start again from the beginning.

At first, I thought I could be much faster because it was all in the setup and if I could just find that one magic setting, I would take seconds off of my time. All that's happened is me getting buried so deep in setup changes that I'm no faster and also no longer remember any of the various changes I made.

It turns out I was deluding myself and it really is 99% down to talent. It's a humbling experience but I'll only get better if I'm honest with myself.

Thanks again guys

 

keep practicing mate the seconds will come down

 

@Aristotelis Is this linearity a setup thing? i mean are you guys going to implement something to change the linearity?

 

How to add the bump stop telemetry in your Motec Workbook in a readable for
https://www.assettocorsa.net/forum/...ated-acc-workspace.55103/page-19#post-1116003

 

Very good question mate, after almost two years from d1, i question it to myself too..lol. Does it mean im learning how to make proper setups?
Anyway there are not many possibilities.
If it is not in mm, then any click is a portion of the gap remaining, and all portions are the evenly spaced.

Anyway such an info would be crucial to know. I really hope you can answer this @Aristotelis .
Thank you

 

You have to read that a bit differently. The range is the amount of travel until the suspension hits the bump stop. The more "bump stop range" you set up, the more travel is allowed, the more the car pitches, the closer the front gets to the ground.

That aside it would indeed be useful to have any sort of unit, yes. Until we get that its trial and error and you can definitely see the difference in motec data, but its a pain to find out.

 

Infact im gonna check with suspension travel!!! .
Why haven't i thought of that before?!
Thanks for the tip sir

Edit: travel and bumpstop combo

 

while bumpstop range is pretty clear for me,bumpstop rate is slightly confusing
aris said it is force at 10 mm compression but compression of what?
bumpstop or suspension ?

 

I guess of the bumpstop itself. its not a hard piece of metal not a point so to say, its a rubber (or whatever) that compresses and you can choose the stiffness of it. So you can put in different bump stops essentially.