412 virtues

[lansdownplace]

Hi Kevin, I started with my own experience on the relative
difference, but as 'why' was asked I thought I should go off and
check for myself.

I have now managed to lay my hands on some facts and figures on this
handling issue, which do explain my thesis.

The 412 S1 has 32% more torsional rigidity than the 411 although the
beam rigidity is the same, The 412 S2 has the bars at the top of the
windows connecting the A and B pillars and other chassis modifications
so the torsional rigidity rises to 45% more than the 411 with 25%
stiffening in beam rigidity. The effect of this is to make the car
respond more readily to steering input as it maintains the alignment
of the the suspension better, reduces the oscillating effect of
flexion in the chassis. It explains why it hunkers down in corners
more readily.

The other data to hand now is that the center of gravity is 8 mm lower
in the 412 than the 411, which I thought sounded small, but the effect
is magnified because the center of gravity on a 411 is 80mm above the
roll axis, whereas it is 72mm on the 412 ( and lower again on the
Beaufighter).That represents a 10% improvement in the roll couple
ratio which does make a difference to the balance of the car. In a
perfect world the center of gravity would sit on the roll axis, but
there you are.

Some other interesting technical stuff I picked up is that the
Blenheim is three times stiffer than the 411 and the Blenheim had the
highest torsional rigidity of any passenger car up until '98. It is
stiffer than the McLaren F1. The reason is that the chassis is further
reinforced, but the body skeleton acts as a monocoque in it's own
right, but in addition the panels are rigidly fixed to the skeleton
and provide further stiffness an they they are thicker than normal.

Anyway, yes we are free to disagree, but I am happy in my own mind
that I understand the reasons behind the claims for the 412 handling
and having observed them in the wild I am going to take by 412 out for
a bit of a thrashing this afternoon!

regards

Paul