Geo & Aero - Where to start with a track day Ultima
Discussion
The next order of business is the setup.
I'm looking for some help with a base line suspention geometry and aero settings for my track day Ulitma
Configuration
Tires:
Dry - Dunlop Racing Slicks
Wet - Kuomo V70
Weight:
Not yet weighted but a good guess I think would be around 950kg.
Aero:
Front Splitter (just making one so suggestion on length would be helpful)
Rear wing - Standard (it's set to max at the moment so any suggestion there would also be good)
Underbody - None at this time
I'm looking for some help with a base line suspention geometry and aero settings for my track day Ulitma
Configuration
Tires:
Dry - Dunlop Racing Slicks
Wet - Kuomo V70
Weight:
Not yet weighted but a good guess I think would be around 950kg.
Aero:
Front Splitter (just making one so suggestion on length would be helpful)
Rear wing - Standard (it's set to max at the moment so any suggestion there would also be good)
Underbody - None at this time
tony,
first you need the technical data of the tires.
they give you the camber and the toe,..
then the ride height is important,....which dampers you have?
do you run rollbars,....
let me know.
Gottfried
www.grasser-racing.com
first you need the technical data of the tires.
they give you the camber and the toe,..
then the ride height is important,....which dampers you have?
do you run rollbars,....
let me know.
Gottfried
www.grasser-racing.com
Very nice reply, but for the amateur not very effective. I will try to explain, based on my experiences.
Basicly ridehight depends on how much suspension travel you have, eg, need for the track. How is your drivingstyle, driving neatly, or do you take the curbs full. So if you want to keep your Ultima sidepods in one piece, don't go too low.
Frontsplitter the length is important up to a certain length, beyond that it doesn't matter. How much? try with thin plywood to make an adjustable one. This is also the fun you can have on a trackday.
Basically the toe at the rear should better be left as they are, since they have a huge impact on midengined cars, and most of the times not for the better.
You want to have maximum tirepatch in contact with the road in corners obviously, you want to have minimum tirepatch contact on straights, because more is drag. So the track decides what you need in camber.
Toe settings on the front mainly make the car to put it simple more agressive in attacking corners, but less stable in straight line.
How to measure things? Look at the scrubbing pattern on the tires, and measure the tire temperature across the tire.
Here you can also play with the tire pressure to balance things out.
This is what you want: even temperature distribution means longer tirelife, maybe not the maximum grip. So if you get it, more camber less contact to distibute weight to, so higher temperature on the inside patch, more scrubbing of the tire. same for toe settings.
If you have more camber also some second corner phase ie roll will improve, but braking before cornerphase one (weightdistribution) will suffer due to less tirepatch for braking.
As you see it's a balance act, not easy to say you will need this to be good all the times.
Suspension travel on the front is mainly dedicted by the braking. You never want to bottom out under braking. bottoming out due to uneven surfaces make the ride rough and jumpy and thereofr scary.
The roll bars mainly influence oversteer and understeer to put it simple. Softer rear rollbars or stiffer front means more understeer. (Generally what you make softer creates more grip to that element.
If you get all of this, look for the 4 corner phases on the web, if you want to get into the matter deeper.
A world will open on weightdistribution rear to front, left to right, diagonal in different cornerstages which can be influenced with bound and rebound settings of the dampers. Now I asume you only have slowspeed adjustment on the dampers.
Rear wing settings, to be honest they start to kick in beyond 80mph beyond 100mph they become effectively. So driving on a mickeymouse track they only hold you up. On highspeed tracks with lots of highspeed corners, you want lots of rearwing. slow corners and a lot of highspeed straights, you don't need too much rear wing.
Do you really want to leran your car, get a good datarecorder with springtravel measurement, gps, brakepressure etc. and you can spend the whole week after the trackday anoying your friends in the pub with the data you collected.
)
Basicly ridehight depends on how much suspension travel you have, eg, need for the track. How is your drivingstyle, driving neatly, or do you take the curbs full. So if you want to keep your Ultima sidepods in one piece, don't go too low.
Frontsplitter the length is important up to a certain length, beyond that it doesn't matter. How much? try with thin plywood to make an adjustable one. This is also the fun you can have on a trackday.
Basically the toe at the rear should better be left as they are, since they have a huge impact on midengined cars, and most of the times not for the better.
You want to have maximum tirepatch in contact with the road in corners obviously, you want to have minimum tirepatch contact on straights, because more is drag. So the track decides what you need in camber.
Toe settings on the front mainly make the car to put it simple more agressive in attacking corners, but less stable in straight line.
How to measure things? Look at the scrubbing pattern on the tires, and measure the tire temperature across the tire.
Here you can also play with the tire pressure to balance things out.
This is what you want: even temperature distribution means longer tirelife, maybe not the maximum grip. So if you get it, more camber less contact to distibute weight to, so higher temperature on the inside patch, more scrubbing of the tire. same for toe settings.
If you have more camber also some second corner phase ie roll will improve, but braking before cornerphase one (weightdistribution) will suffer due to less tirepatch for braking.
As you see it's a balance act, not easy to say you will need this to be good all the times.
Suspension travel on the front is mainly dedicted by the braking. You never want to bottom out under braking. bottoming out due to uneven surfaces make the ride rough and jumpy and thereofr scary.
The roll bars mainly influence oversteer and understeer to put it simple. Softer rear rollbars or stiffer front means more understeer. (Generally what you make softer creates more grip to that element.
If you get all of this, look for the 4 corner phases on the web, if you want to get into the matter deeper.
A world will open on weightdistribution rear to front, left to right, diagonal in different cornerstages which can be influenced with bound and rebound settings of the dampers. Now I asume you only have slowspeed adjustment on the dampers.
Rear wing settings, to be honest they start to kick in beyond 80mph beyond 100mph they become effectively. So driving on a mickeymouse track they only hold you up. On highspeed tracks with lots of highspeed corners, you want lots of rearwing. slow corners and a lot of highspeed straights, you don't need too much rear wing.
Do you really want to leran your car, get a good datarecorder with springtravel measurement, gps, brakepressure etc. and you can spend the whole week after the trackday anoying your friends in the pub with the data you collected.
)Edited by harry b on Friday 5th February 07:09
harry b said:
Very nice reply, but for the amateur not very effective. I will try to explain, based on my experiences.
A load of stuff that could have come from any number of books or websites
This is what you said in your first post :- "I'm an automotive contract designer, and worked on engine design and general exterior and interior prototyping and design for the major OEM"A load of stuff that could have come from any number of books or websites
Did I miss the bit where you mentioned your racing experience, comparable with Grasser's ?
Regards
No, but worked with guys who are, and it rubs off when it is your interest. Never stopped learning, and I did quite some rallysprints when I was younger. And besides that, I know acountants who know about this matter too, so it ain't a requirement to know stuff.
Also lot's of books with pro information available.
Although I realize I don't know a thing about knitting.
Also lot's of books with pro information available.
Although I realize I don't know a thing about knitting.
harry b said:
pilbeam_mp62 said:
harry b said:
Although I realize I don't know a thing about knitting.
Well, I would rather you read a couple of books and then knit me a jumper, than set-up a racing car..... Regards
Edited by harry b on Friday 5th February 08:31
Before I get interpretted wrong, let me put that I have the greatest respect for guys like Gotfried from Grasser racing, who are able to have a succesfull business in racing.
I've had long discussions with people like him.
Didn't mean to put his remark out of context. I tried to make it a bit more practical for the trackdayguys.
I know that people like Gottfried, they have their focus on racing. Can you afford to replace the sidepods every other trackday? If so you can go for a race setup, if you struggle with limited budget, be on the safeside regarding rideheight, oversteering setup etc.
Need to start talking to the misses about knitting. Needs to be said she's better at it.
I've had long discussions with people like him.
Didn't mean to put his remark out of context. I tried to make it a bit more practical for the trackdayguys.
I know that people like Gottfried, they have their focus on racing. Can you afford to replace the sidepods every other trackday? If so you can go for a race setup, if you struggle with limited budget, be on the safeside regarding rideheight, oversteering setup etc.
Need to start talking to the misses about knitting. Needs to be said she's better at it.
I dont think yours or anyone's contributions should be taken in a wrong context Harry, if posters were just a little more prepared to read carefully and fully digest information before hitting the keyboard with potentially insulting replies, they might actually grasp that further underlying information was conveyed!
I'm sure many others like myself gathered you were offering track-day orientated info rather than the full-on racer method's.
There are lots of owners here who dont have knowledge of the basics you have just pointed out and Im sure welcome the information.
Put the needles down and finish off that engine....am interested in your results (as an engine enthusiast).
To the OP, please keep us informed of your findings/progress, very interesting subject.
I'm sure many others like myself gathered you were offering track-day orientated info rather than the full-on racer method's.
There are lots of owners here who dont have knowledge of the basics you have just pointed out and Im sure welcome the information.
Put the needles down and finish off that engine....am interested in your results (as an engine enthusiast).
To the OP, please keep us informed of your findings/progress, very interesting subject.
Edited by 738 driver on Friday 5th February 20:24
Now now guy, play nice!
Really Gottfried is correct the tires are the starting point, unfortunately I don't have this data (or the car to hand).
What I was looking for was some opinions and some numbers to start with and then once I'm on the track I can go from there, I just don't want to start reinventing the wheel (pun intended).
So, does someone have some constructive numbers to work with?
Really Gottfried is correct the tires are the starting point, unfortunately I don't have this data (or the car to hand).
What I was looking for was some opinions and some numbers to start with and then once I'm on the track I can go from there, I just don't want to start reinventing the wheel (pun intended).
So, does someone have some constructive numbers to work with?
Swiss_Toni said:
....So, does someone have some constructive numbers to work with?
Factory's slick shod FXX killing run:Ride height was standard. 110mm front. 160mm rear
Front negative camber was 2.0 degrees
Rear negative camber was 1.2 degrees
Rear toe was 2mm overall
Tyre pressures hot were front 24psi rear 31psi
Dampers were all set at 40 clicks (Intrax)
Road springs were 25% stiffer which are an option
Standard Porsche G50-03 transaxle
Assuming you have factory recommended width rubber I would also second (or is it third now?) the factory track set up to be an excellent starting point, from there it is tweaking to personal preference, driving style and to particular track type/conditions.
I haven't wandered far from the initial set up, just played with rebound and rear wing angle slightly.
Julian
I haven't wandered far from the initial set up, just played with rebound and rear wing angle slightly.
Julian
Swiss_Toni said:
Thanks, that what I was looking for.
Does anyone have any thoughts on front splitter lengths and rear wing angles?
More comments on Geo would also be helpful.
IMO I wouldnt make the front splitter too long otherwise it will hit the car in front!!!!Does anyone have any thoughts on front splitter lengths and rear wing angles?
More comments on Geo would also be helpful.
Dom
Edited by V8Dom on Sunday 7th February 13:26
Edited by V8Dom on Sunday 7th February 18:19
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