Earlier today the issue of traction rolling 12th scales came
up on RC Tech. Being a victim of this
lately, led me to write a long post on some of the techniques that I have
learned setting up my car in order to eliminate them from my race nights. I
thought this would make a good blog article for the week and it would help keep
building on the pan car information base located here on the site.
Often, all it takes is removing camber and/or camber gain
from your car. However this can lead to severe coning on the outside of the
tires which makes tire life shorter than it should be. So in an effort to make
the car wear tires flat in the front, these are my go to moves:
2. Softer side springs, linear springs being preferred as
they cause less lifting. This allows the pod to react a little bit slower. In
low traction conditions can make the car feel lazy, but we are talking about
high bite here and it does not seem to affect response too much as the car
already has too much.
3. Wider Track Width: Both front and rear. The wider the
car, the less lateral weight transfer and the less traction rolling you will
have. In High bite conditions, you want to run wider. An added benefit of the
wider rear is that it will put more leverage on the side springs making them
act softer.
4. More Forward shock position: This is big. I am happy I
can do this with our car. It slows down the transfer of weight to the front
tires and I can run a stiffer center spring which controls the lateral roll on
the car to keep it from rolling. It's sort of like reducing droop on a sedan.
Increases response and limits lifting, to a point. Go to stiff and the car just
turns too much on entry.
5. Longer side links.
This is also big, this allows the car to roll at a further forward position on
the chassis and it decreases leverage on the front end from the rear pod. Makes
the car flatte.
6. Longer upper
arm: The longer the upper arm, the
slower the reaction time of the front end as well as a tid bit less camber
gain. This makes the car less aggressive in the middle of the corner.
7. Less Static:
Reduces camber gain in the middle of the corner. Makes the car turn in
harder at the beginning of the corner, but mellows middle.
8. More Reactive
Caster: More reactive caster actually reduces caster in the middle of the
corner as the car rolls more. This is big because it actually reduces some
initial entry corner response and then does it further in the middle of the
corner. It is a good adjustment to use.
9. Longer wheelbase:
with our car, it moves the pivot further forward, which again gives the rear
less leverage over the front to lift it, sort of like a longer link as well.
10. Run battery in
line: Keeps more weight at the front of the chassis which makes it harder for
the car to lift.
11. Softer front springs.
The harder springs put more pressure on the carpet which creates a bigger
"wrinkle" where the tire is contacting the carpet on the track. This
slows down reaction and allows the car to roll instead of "dig in" to
the carpet. Put a stiff spring in the front of your car at our place and watch
it do some somersaults.
12. Lighter tube
fluid, again, this is sort of like softening up the pod springs, it just allows
the car to dump over and roll. I always try to get away with the lightest fluid
I can get away with without my car becoming unpredictable on our bumpy tracks.
13. Less tire sauce
in the front: I am not sure if saucing
less time is particularly effective past 5 or so minutes, however how much you
sauce is big. Using less additive in the front can dramatically
decrease your rolling over.
14. Softer front
tire: A harder tire digs into the carpet
harder which causes more rolling over. The opposite is the case with a softer
tire.
Like everything there is a curve to all settings. I think if
the grip is lower, the settings seem like they have the counter effect, this is due to the relationship of grip and
reaction forced on the car. When the grip is lower, you want to increase
response and weight transfer to dial in the car, to a point.
On a lower grip track a soft spring can both increase
steering and decrease steering, depending on the part of the corner you are
looking at tuning. Early in the corner and it turns harder, but later in the
corner it makes it push. Opposite is of a stiff spring.
When I think about it, when you are tuning on high grip vs
low grip you are tuning a different part of the corner. On lower bite, you want
the mid corner response to be higher as cars tend to be on top of the track and
need a quick response suspension to come back to center quickly and get around
the corner fast. On high bite you are trying to tame down than middle corner
response to keep the car on all 4 wheels.
Just my 2 cents. At my place, when the grip comes up and
everyone is flipping off the track, I keep on trucking and I take the approach
above.