Folks,
It is my experience that a normal unmodified
Tiger has understeer with no power applied to the rear.
Remember that tires have a more or less constant grip.
If one normilized this grip value to "1" and proceeded around
a corner ( without applying power) than you would have the
maximum laterial acceleration capability. If you hit the
power enough to spin the tire, then the laterial acceleration
would be close to zero and you would spin out on a turn
as there would be nothing left for laterial acceleration.
If you apply power to 50% of the tires's grip capability
then the laterial acceleration capability is also around
50%. Simple vector forces.
So assuming that you are going around the corner
and hit the gas hard, you may experience "power oversteer"
because you wasted your laterial acceleration or grip with
forward acceleration while your undriven front tires were
working as normal.
The set up of the Tiger also counts. I added a rear
sway bar to my Tiger once in hopes of getting better
autocross times. I tested the setup and had three consecitive
360 or more degree spins. The rear sway bar makes the rear
end stiffer and you get more oversteer. Maybe because you
can put more power down? I took the bar off the same day!
Now have an 1 1/8" sway bar up front that keeps the Tiger
flat in the corners. ( Also quickly wears out ball joints).
Another way to get oversteer is to put bias tires
on the rear and radials on the front. Bias snow tires are
excellent for doing 360 degrees when you make a slow turn.
So are old hard and wide B series bias tires.
Put more grip on the rear(wider,softer tires) if you have
oversteer problems. Also soften up the rear to reduce oversteer.
A soft rear end is not necessarly the thing to do if you are
autocrossing. You need to set up for maximum grip period!
Autocross setups normally have a bit of oversteer.
James Barrett Tiger II 351C and others
|