An update - caster angle in GT6 (not adjustable - except IMO through rake)?
Above in post #140
Ride Height Glitch Returns in GT6
I showed some pictures of camber changing with steering. IRL this would be due to caster and kingpin axis inclination. We don't know these parameters in GT6, other than (if you agree with my expt above), knowing that camber increases with steering angle and that rake can affect how this happens.
However I recently found an equation online
http://www.ft86club.com/forums/showthread.php?p=1248235 for the relationship of camber gain, caster and steering angle. It is:
camber gain = caster angle * (sin steering angle)
Note that when I use this, a negative camber gain gives a negative caster angle. Positive caster is what is generally used on cars to give more neg camber when steering, so there should probably be a minus sign in the equation i.e.
camber gain = - caster angle * (sin steering angle)
Now, with my photos above, taking the level ride height case for simplicity 0 static camber, I have neg cambers of -4.51 and -5.05 deg. For simplicity, lets just use -5 deg. I've not yet measured full lock angle on the Silvia, but I'd imagine it's ~ 45 deg (these assumptions don't affect the end caster number much - easily checkable in Excel etc)
rearranging to make caster the subject:
caster angle = - (camber gain/(sin steering angle)
caster angle = -( -5 deg / sin (45 deg))
caster angle = -( -5 deg * 0.7) =
7.07 degrees
Now, people may well be asking
i) How do you know this is correct?
ii) What about kingpin axis inclination?
iii) Even if this is true, what does it mean for GT6 tuning?
i) I don't for sure, as I didn't code GT6, but.
http://forums.nicoclub.com/s13-caster-adjustment-t506755.html IRL 7 deg caster stock... close enough.
ii) I don't know if KPI is modelled in GT6. But a guy called SiNiST3R who I believe has some history at GTP has (on other sites) mentioned things about preset caster in the game. There is mention on other sites of caster but not KPI as far as I know. So maybe KPI is not modelled?! I don't know. Just to be clear, I am not taking any sides in what seems to be a feud. I'll happily read everyone's theories and try to make my own mind up. I'm sure many of the regs here will know where to look if interested as I have seen some GTP user names on other sites too.
iii) Well what it means is that, presumably some cars gain more camber when steering than others (as not all cars have the same inbuilt caster). *IF* my method is correct it would allow someone to estimate caster by using GIMP to take camber angles when steering like I did. Then you could estimate camber gain at various different steering angles.
Depending on how you like to use camber this might help you choose initial camber settings. I have recently tried running forward rake to reduce the caster and thus gain less camber, since I think the outside front wheel is often cambered too much on very tight corners (lots of steering lock, lots of camber gain) and washes out. So I'm adding a little static camber to begin with, but trying to gain less. On shallow turn tracks with long sweepers the effect will presumably be less, but on Autumn ring, GT arena, perhaps Eiger, where you have to use more steering lock (or handbrake!) it might make a difference. I still need to test this properly.
My gut feeling is that the ride height bug gives good turn in with reverse rake due to extra caster. Perhaps there is another way? It would be interesting to see what the pros and cons are of each.
And PD, if you ever read this, if caster is indeed in your game, please give us an adjustment slider for it in an update!
Cheers,
Bread
I agree with 
