Damper and spring suspension settings.

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varley16
varley16
0
Joined: 18 Apr 2010, 17:11

Damper and spring suspension settings.

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Hello im new to these forums, i have a technical background with road vehicles. and always been a fan of formula 1. So now i want to learn everything about the sport.

one question i have is if a track has more left hand bends to right hand bends, how would the stiffness of the front suspension vary from side to side?

thanks

Jersey Tom
Jersey Tom
166
Joined: 29 May 2006, 20:49
Location: Huntersville, NC

Re: Damper and spring suspension settings.

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Depends on which corner(s) are going to be most influential on overall lap time, if it's high- or low-speed, etc.

Good starting point would be understanding oval track setup. The question really becomes.. how far toward an oval track setup do you migrate from a perfectly symmetric road course setup.
Grip is a four letter word. All opinions are my own and not those of current or previous employers.

DaveW
DaveW
239
Joined: 14 Apr 2009, 12:27

Re: Damper and spring suspension settings.

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Jersey Tom wrote:Good starting point would be understanding oval track setup. The question really becomes.. how far toward an oval track setup do you migrate from a perfectly symmetric road course setup.
An "oval" set-up starts with tyres having different properties (pressures & cambers, at least) on each corner of the vehicle, recognizing that each is subjected to very different loads. A symmetrical suspension set-up just would not "work" in that case. Understanding and optimizing an asymmetrical suspension set-up is a complex task & is, I suppose, one good reason for not going there unless it is absolutely necessary.

So far as I am aware, asymmetrical suspension set-ups are almost unknown outside the USA, with the possible exception of minor camber adjustments, largely because "oval" circuits are almost unknown.

Belatti
Belatti
33
Joined: 10 Jul 2007, 21:48
Location: Argentina

Re: Damper and spring suspension settings.

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The problem with asymetrical setup on a road track is braking and accelerating out of corners, a thing that doesnt happen in ovals (OK, maybe at Martinsville, but the slightly banked track helps you right? :) ).

Generally, the 99% of the drivers expect the car to stay straight when braking. The other 1% are extraordinary alien trailbrakers :lol:

I have tried some things in sport cars, including tilted right height (with some inevitable static weight bias) and the tenths gained here were even with the tenths loosed there, with an asymetrical and not desirable tyre wear.
"You need great passion, because everything you do with great pleasure, you do well." -Juan Manuel Fangio

"I have no idols. I admire work, dedication and competence." -Ayrton Senna

Jersey Tom
Jersey Tom
166
Joined: 29 May 2006, 20:49
Location: Huntersville, NC

Re: Damper and spring suspension settings.

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Braking / accel out of corners happens at the following tracks in NASCAR:

Fontana
Las Vegas
Atlanta
Bristol
Martinsville
Phoenix
Texas
Richmond
Darlington
Dover
Charlotte
Pocono
Michigan
Loudon
Chicago
Indianapolis
Kansas
Homestead.

(Not just Martinsville).

In any event.. there are plenty of options for an asymmetric setup, beyond kinematics. Air pressure, sure. Static cross and left side weight for sure... asymmetric toe... springs... ARB gaps, etc.

Certainly very relevant on road courses.. Lime Rock in the US is the best example. F1 engineers must be very familiar with it as well given that the chassis' themselves have been designed without symmetry.
Grip is a four letter word. All opinions are my own and not those of current or previous employers.

Belatti
Belatti
33
Joined: 10 Jul 2007, 21:48
Location: Argentina

Re: Damper and spring suspension settings.

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Yeah, those 200 to 60 mph stops at Indy and NASCAR oval races are hard, dont they?
"You need great passion, because everything you do with great pleasure, you do well." -Juan Manuel Fangio

"I have no idols. I admire work, dedication and competence." -Ayrton Senna

Jersey Tom
Jersey Tom
166
Joined: 29 May 2006, 20:49
Location: Huntersville, NC

Re: Damper and spring suspension settings.

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Keeping control of a 1590kg racecar under the brakes with minimal downforce is a challenge no matter what speed.
Grip is a four letter word. All opinions are my own and not those of current or previous employers.

marcush.
marcush.
159
Joined: 09 Mar 2004, 16:55

Re: Damper and spring suspension settings.

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there are tracks where you really need to go asymmetric ,as an example short circuit in Hockenheim ,where a symmetric setup will just kill your front left in no time.
As there is only one significant lefthander on that track and this is the banked Sachskurve it really makes sense to optise the car for the righthand corners there.

DaveW
DaveW
239
Joined: 14 Apr 2009, 12:27

Re: Damper and spring suspension settings.

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Jersey Tom wrote:F1 engineers must be very familiar with it as well given that the chassis' themselves have been designed without symmetry.
It is true that a vehicle with an offset c.g. might benefit from an asymmetrical suspension set-up, but the easier (& arguably better) solution is to minimize the c.g. offset. I have yet to see an F1 vehicle, or any other open wheeler outside the US, with an offset c.g, built-in "wedge", or any other observable intentional asymmetry.

I have seen road course set-ups with deliberate asymmetry in US open wheelers, but that tends to be a fall-out from other decisions (e.g. spring selections that can't be "balanced" with bars). The result is rarely a quick vehicle (quicker, perhaps, but not quick).

The primary reasons for maintaining vehicle symmetry are to decouple vertical & lateral responses (a "coupled" vehicle will, for example, change lateral balance when it is subjected to symmetrical inputs), & to maintain a consistent balance through both left & right-handed corners. It is not easy to maintain decoupled response when the vehicle &/or its suspension set-up are asymmetrical.

p.s. Marcus: How, precisely, do you modify vehicle set-up to improve the FL tyre life at Hockenheim?
Last edited by DaveW on 19 Apr 2010, 09:14, edited 1 time in total.

marcush.
marcush.
159
Joined: 09 Mar 2004, 16:55

Re: Damper and spring suspension settings.

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placement of ballast ideallly... :mrgreen:

DaveW
DaveW
239
Joined: 14 Apr 2009, 12:27

Re: Damper and spring suspension settings.

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marcush. wrote:placement of ballast ideallly... :mrgreen:
Good answer, but that is likely to "cost" overall performance unless the suspension set-up is also asymmetrical. What cost? I had a customer last year with a vehicle having an offset c.g. We worked on "success ballast" placement to minimize c.g. offset. He found that installing success ballast actually improved lap times for his vehicle/driver....

Thruxton (UK) is another track that "kills" left side tyres. The solution is bespoke tyres for the circuit, rather than asymmetrical set-ups.

marcush.
marcush.
159
Joined: 09 Mar 2004, 16:55

Re: Damper and spring suspension settings.

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DaveW wrote:
marcush. wrote:placement of ballast ideallly... :mrgreen:
Good answer, but that is likely to "cost" overall performance unless the suspension set-up is also asymmetrical. What cost? I had a customer last year with a vehicle having an offset c.g. We worked on "success ballast" placement to minimize c.g. offset. He found that installing success ballast actually improved lap times for his vehicle/driver....

Thruxton (UK) is another track that "kills" left side tyres. The solution is bespoke tyres for the circuit, rather than asymmetrical set-ups.
to help the front tyres I resorted to maximum possible lf negative camber but very view rf camber there.
I also had the option of using a bit of stagger with the tyres as in my race series we had bias ply tyres and I found considerable differences in inflated tyre diameter ...
but honestly speaking shaving (reducing tread thickness when new )the tyres was an even better choice to make them survive...

speaking of ballast placement ...this is in fact a phenomenom also apparent with the Lotus Elise and its derivates .The better distribution and more front bias helps quite a bit.

DaveW
DaveW
239
Joined: 14 Apr 2009, 12:27

Re: Damper and spring suspension settings.

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Cambers & pressures good (within reason), but are likely to require suspension changes. Tyre mods. ingenious....

Elise's I have tested had c.g. positions that were too far aft for the tyres. Moving ballast forward would definitely help to work the tyres more evenly. I guess traction (loss of) would be the limiting factor.

ubrben
ubrben
29
Joined: 28 Feb 2009, 22:31

Re: Damper and spring suspension settings.

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I'm probably closer to Tom on this. If you look at circuits like Paul Ricard, Lime Rock, Road America, Road Atlanta, Monza, all can warrent having harder tyres on the left-hand side of the car.

Agreed that you rarely see asymmetric springs or dampers, but toe, camber and tyres (pressure and specification) is normal. Running cross weight at places like Long Beach also makes sense because two of the best passing opportunities are braking into 90 degree left handers so some more LF corner weight is useful.

Ben

Belatti
Belatti
33
Joined: 10 Jul 2007, 21:48
Location: Argentina

Re: Damper and spring suspension settings.

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Jersey Tom wrote:Keeping control of a 1590kg racecar under the brakes with minimal downforce is a challenge no matter what speed.
No doubt about that. Just meant that usually in ovals there arent 4 or 5 sec brakings where you have to keep the car straight, unless there is an accident.

An ex Indy driver told me that in fast ovals the first brake pedal pump does nothing to stop the car due to the precharged that keeps the brake pads far from the rotors, to minimize fricion looses. So I guess that NASCAR does the same.

Also an ex Indy team manager told me that asymetric setup was not used out of ovals.

Im just basing on comments here, nothing to take for granted.
"You need great passion, because everything you do with great pleasure, you do well." -Juan Manuel Fangio

"I have no idols. I admire work, dedication and competence." -Ayrton Senna