Suspension Tuning Guide

[sucahyo]

I got some mechanic reference, I am not sure about spring rate behaviour though.
http://www.fd3s.net/suspension.html

			Basic Suspension Adjustments

Suspension			Less Understeer		More Understeer
Component			More Oversteer		Less Oversteer
___________________________________________________________________________

Front spring rate		Lighter			Heavier

Rear spring rate		Heavier			Lighter

Front anti-roll bar		Lighter, or adjust	Thicker, or adjust
				to lengthen arm		to shorten arm

Rear anti-roll bar		Heavier, or adjust	Lighter, or adjust
				to shorten arm		to lengthen arm

Weight distribution		More rearward		More forward

Front shock setting		Softer			Harder

Rear shock setting		Harder			Softer

Front camber			More negative		More positive

Rear camber			More positive		More negative

Front tire width		Wider			Narrower

Rear tire width			Narrower		Wider

Front tire pressure		Lower			Higher

Rear Tire pressure		Higher			Lower

Front track			Wider			Narrower

Rear track			Narrower		Wider

Front spoiler			Larger, or more angle	Smaller, or less angle

Rear spoiler			Smaller, or less angle	Larger, or more angle


I had this mailed to me, but don't remember from whom.

Adjustment            To Increase Understeer      To Increase Oversteer
_______________________________________________________________________
Front Tire Pressure   Decrease                    Increase
Rear Tire Pressure    Increase                    Decrease
Front Wheel Camber    More Positive               More Negative 
Rear Wheel Camber     More Negative               More Positive
Front Springs         Stiffer                     Softer
Rear Springs          Softer                      Stiffer 
Front Sway Bar        Larger (Stiffer)            Smaller (Softer) 
Rear Sway Bar         Smaller (Softer)            Larger (Stiffer)

Whenever making adjustments or changes in chassis setup make 
only one change at a time and be sure the change makes an 
improvement.  This way you can see the effect of each change on 
the car.  It is also a good idea to record these changes.

 

[sukerkin]

Could've been me, S - I recognise the table .

Similarly, I've linked to the first table in your post in the past too (in answers here and there around the web).

A couple of years ago, in a private forum {no, not that sort of private forum }, I posted up a library of links to every site that I'd found useful information on about tuning, suspension behaviour and understanding harmonic motion etc etc.

I'm wondering if a sticky here in the tunings forum, containing similar information, would be of use?

The only reason I mention it is that, by the nature of the net and peoples searching of it, the same information keeps popping up again and again and again. But it also sinks out of sight again and again and again, leading to a form of informational perpetual motion .

For me personally, the annoying thing about it is that, each time a datum resurfaces, those fresh to the discourse treat it as a whole new phenomenon and thus the depth of knowledge never increases as the examination never moves on.

Any other voices want to chip in on this? Or is it a purely personal reaction from me and the general consensus is that the 'data fountain' is the best way of delving into the black art of suspension tuning?

 

[sucahyo]

I think GTPlanet already provide a tool for that.
We can accumulate all information to this page:
https://www.gtplanet.net/guides/index.php/Gran_Turismo_4

funny, GT4 do not have tuning page

For me, this page :
https://www.gtplanet.net/guides/index.php/Gran_Turismo_2_:_Tuning_Tips

 

[sukerkin]

Ah. I'm not sure we're talking about the same thing here, S.

I mean a stickeyed resource thread with a compilation of the links to automotively useful sites that various interested parties have found over the years.

For example:

www.me.udel.edu/meeg467/Vehicles

http://hometown.aol.com/EURORALLY/Suspension1.htm

http://thundervalleyracing.com

http://catalog.com/susq/other/stuning.htm

www.ground-control.com

www.uts.com/products/cartech3.htm

www.engin.brown.edu/courses/en4/notes/Dampedvibes/Dampedvibes.html

www.e30m3performance.com/tech_articles/eff_rate/eff_rate.htm

http://forums.12hundred.com

www.miata.net/sport/Physics/phor.pdf

Also searches on the following will yield results:

“Jacob Eelkema”

“Journal of Sound and Vibration” +Suspension +system +road

“California 95616” +suspension +deflection

“Scott Gruenberg” +Damping

“Aleksander Hac” +Suspension

“eme823pr.pdf”

“Michael William Sayers”


_______________________________________________________
These were posted up by me in 2002, so some of the links, given the fluid nature of the web may no longer work or attach to information that is not longer pertinent. But it's enough to give the idea.

 

[sucahyo]

Nice link 👍, I will use this .
Maybe you can create one in GTPlanet GT4 wikipedia guide

 

[sucahyo]

Some revision to my spring tuning.
Spring is complex. There is optimum value in order to get maximum grip from spring. The easiest way to test this is in 1000m. The optimum value is different for every car. With this my tuning for spring is change.

To make the car more understeer:
move the front spring slider farther from optimum value or move the rear spring slider closer toward optimum value.
The front and rear value differences should not exceed 2 to get optimum grip, unless the optimum grip value is wide.

I also find that RCD is important factor in handling.
RCD = Roll Couple Distribution is a term used to describe the relationship of the front's roll rate to the rear's roll rate
basically car with more rear roll will be oversteer.


Good real car tuning guide link: http://www.turnfast.com/tech_handling/handling_tuningtable.shtml

 

[drifter916]

wats oversteer n understeer

 

[sucahyo]

understeer = when you think the car should be turning but it doesn't
oversteer = when you think the car turning too much