rec.autos.simulators

Silverstone was always a killer at Abbey, every single lap....Finally
able to nail it properly, lap time drop by 4 (!!!!) seconds to 1:30.9.
All down to the confidence my own setup allows.

I found that shock absorber tuning made a huge difference to the turn-
in characteristics of the car, I've got it down very nicely. Nunnini's
theories on ride height vs. spring rate worked very well, as did
setting the spring rates to the exact weight distribution of the car.
However, it would be interesting to be able to adjust the damper rates
in smaller increments. If the weight dist. - spring rate theory is
valid (which it is) then as the weight is transferred when entering a
corner would also require a 38%/62% (Lotus) damping rate, with some
small adjustments to get a nice turn in or oversteer.

I tried something as best I could with such coarse adjustment, which
was alright, but an exact 38/62 rate would be very interesting. If
this was possible using the setup editing tools...

I have also found that my style tends to leave the rear tyres
generally hotter than either fronts, generally because I tend to
always hang the back out and use a bit too much throttle. Is this a
common situation for others? I know that the cars are tail-happy, but
I have read often about the outside front consistently overheating
being a big problem for most. My setup generally yields 180-200 on the
inside front, 200-220 outside front, and 210-230 on the rears.

Any other setup development thoughts or experiences?

Rafe Mc

For example:  If the rear has a 100 lb/in spring rate and a 50 lb/in
arb rate, the total rate resisting suspension compression due to
lateral weight transfer for the rear is 150 lb/in.  Now, if the front
has a 62 lb/in spring rate I need an 88 lb/in arb rate so that the
front end has the same total 150 lb/in roll rate as the rear.  Makes
for a nicely balanced car IMHO.

I have wondered the same as you how the car would behave if the damping
rates could be adjusted to the weight distribution percentages (i.e.
61% of range rear bump damping vs. 39% of range front bump damping).
Maybe the gentleman who made the setup editor that enabled us to change
the spring rates in 1 lb increments would be kind enough to enable us
to adjust the damper settings in 0.1 step increments vs. the 1 step
increments we currently have.

-Chris-

Grant.

-Chris-

Sent via Deja.com http://www.deja.com/
Before you buy.

He has actually updated his site recently, and renounced his earlier
theories on arb settings. He now suggests that you set the front arb
to obtain the right grip, temp and camber to work, and then use the
rear to get your own preference for over/understeer. I was trying to
follow this, but couldn't really get what he was trying to say! I just
set the front to reduce the body roll nicely, then balanced the car
with the rear.

Interesting idea, I'll have to try it out.
I feel that it would be a great way to fine tune the handling of the
car. It's just too coarse by adjusting in 20% increments. However, in
reality such fine adjustments were not possible, that is why the
settings are so coarse. But if Chapman was designing his Lotus for a
specific set of damping rates, he would be able to get exactly what he
wanted. So why shouldn't we??

What kind of toe in/out settings do you use? Currently using -0.075
deg on the front, which gives a nice turn in and grip, but makes the
car a bit twitchier. I know that more toe out would be faster, but
that makes the setup difficult and uncomfortable - so I actually go
slower and less consistently.

Rafe Mc

I'll probably end up with different settings in another month, though.
One of the things I really like about GPL is the ability to play
with the setups.  I end up with a different setup philosophy about
every two months or so. :)

-Chris-

Sent via Deja.com http://www.deja.com/
Before you buy.

Doesn't sound like the best way to balance a car's handling - by
compensating for the power oversteer by dialling in more understeer.
The reason the 60 deg diff is so oversteery is because the outside
rear locks too easily when power is transferred from the slipping
inside rear. You don't get that gradual transfer of torque via the
clutches that you do with an 85 deg diff. Just seems to be
compensating for a lack of rear end grip with reducing the front end
grip.

I always found it so difficult to be consistent with the lower angle
diffs - yourself? I guess I'm too heavy with the throttle to be able
to control a more locked diff - I usually use an 85/45 with 5 clutches
in the Lotus.

Rafe Mc

 <snip>

I agree. I spent piles of time trying to get a 60 power-side ramp to
work well. I was actually getting some decent response in training
but the Eagle was too much of a handfull during the pressure of a race.

I'm currently settling in on 85/45 with 5 clutches as my sweet spot.

<snip>

I change my philosophy every other lap  :-)  but I think I've reached
a more stable phase. I am more comfortable (and faster) with my
current setups than ever before (a 1:27.48 freak lap at Monza
the other day <vbg> ). Some of the more experienced drivers
might chuckle at my setups but they suit my style, for now anyway.

My current obsession is massive amounts of toe-out at the front
and major amounts of toe-in at the rear (eg. -0.500F, +0.475R
at Zandvoort). It doesn't seem to slow me down at all and it
provides a lot of grip.

Also I am using positive cambers on the front and rear tires.
After reading G. Tifosi's comments on R. Nunnini's site
re. keeping the unloaded (inside) tire flat in the corners, I tried
positive cambers and was very pleased with the increased
grip. I'm using less positive camber now then I needed with
negative settings (0.00LF, 0.75RF, 0.00LR, 0.75RR at
Zandvoort).

I'm also using a quite stiff rear bar and a relatively soft front
bar (100F, 200R at Zandvoort) which I was reluctant to do
as the GPL guide recommended running stiffer bars in the front
versus rear. The change has really helped the mid-corner performance.

B.t.w. I run an 85/45 diff with 5 clutches on most of my setups.
I find that I can really toss the Eagle into the corners with this
setting (coupled with the setups above).

I would welcome comments.

Wow, I don't think I've ever seen a setup with that much toe-in at the
rear. What is the reason and effect of that much? It won't change the
rolling resistance in GPL, as that is one of the few things that is
not modelled.

Unusual to have zero camber on the left at Zandy. Currently using -0.5
and 0 (front), -0.5 and +0.25 rear. I get a nice even temperature
spread, good corner speed and turn in.
I don't think I'd ever be able to control the car with twice the arb
on the rear. Goes to show how much the style must suit the setup. (and
vice versa).

I've found I get the best speed and control using either 4 or 5
clutches, depending on the circuit. Confidence at throwing the Lotus
into corners is paramount with me, my setup really lets me get stuck
into it when I want to. Has a nice wide slip angle, and can get REALLY
sideways and still be caught easily. Something I tend to need....!

One thing that helped my setup was to adjust the tyre pressures to get
24-25 psi hot, something Nunnini is not in favour of. I found that I
get good grip and control at this pressure, nice even temps, etc. What
pressures do you run at when hot?

Rafe Mc

:>My current obsession is massive amounts of toe-out at the front
:>and major amounts of toe-in at the rear (eg. -0.500F, +0.475R
:>at Zandvoort). It doesn't seem to slow me down at all and it
:>provides a lot of grip.
:>
: Wow, I don't think I've ever seen a setup with that much toe-in at the
: rear. What is the reason and effect of that much? It won't change the
: rolling resistance in GPL, as that is one of the few things that is
: not modelled.

  The book that came with GPL strongly suggests that rolling
resistance IS modelled.

--
Richard G. Clegg       Only the mind is waving
    Networks and Non-Linear Dynamics Group
      Dept. of Mathematics, Uni. of York
    www:  http://manor.york.ac.uk/top.html

        I don't know how Toe is measured in GPL.  I'll just assume that (if the
car was a physical car, one that you could touch) If you took a string
and laid it across the center of the tire horizontally and parallel to
the center of the car (front to rear), the Toe would be measured as the
distance from the string to the edge of the wheel..

  |
  |a/-/     \-\
  |/ /---|---\ \
  |-     |    -
  |      |
  |      |
  |      |
   (hope this graphic displays right)

        Where "a" is is the measuring area.  The Left line is the string, then
there's the +toe tire, Then axle, then Center line of the chassis.  Then
the same thing for the Right hand side.  This is one way to measure Toe
but is it the way GPL measures and displays Toe?  If so, then a + or -
5.0 Toe would be a very bad setup.

--
=========================================
Mike Barlow
Current GPVL points Champion
=========================================

  If so, then a + or -

        I should have reread the original post.. A + or - 5.0 is a bad setup,
but a 0.5 like mentioned is ok.
--
=========================================
Mike Barlow
Current GPVL points Champion
=========================================

I'm not really an expert on the physics behind toe settings but I knew
that -'ve front toe would help the car into the turn. I wasn't really sure
how rear toe-in could help in a turn but I knew it provided stabilty.
One day I just got tired of losing grip in the corners and having the
back end slide out so I figured the more rear stability in the corner
the better. So I cranked in lots of toe-out in front and toe-in on the
rear and never looked back. Now that I have my times down a bit
I'll try backing off the toe settings and see if I pick up any straight line
speed.

Actually the zero camber tires have higher temps on the outside due to
factors other than camber. So when I go into a left turn the temps even
out, indicating that the inside tire is flat on the track.

I don't have to work too much at controlling the car. It's nice and stable,
dive under braking is not a problem, and it turns quite nicely in
mid-corner.
I think the other setup items contribute to stability and allow for a loose
front bar. I'm using R. Nunnini's table for my spring settings b.t.w.

I run 24-25 psi hot too. His tire pressure page quotes some cold pressures
(is that what you were thinking of ?) but recommends 24-25 psi hot.

Do you have any views on Lotus setups at all, or do you not drive it?

Mauricio.