RE: Bumps, Suspension, Etc.

["Albaugh, Neil" <albaugh_neil@ti.com>]

Dave;

This is very valuable data; thanks for sharing it.

Your data acquisition system is probably sensitive enough to see
periodic suspension movement due to small imbalance forces from the
wheel/tire/rotor/hub assembly. Its frequency varies with speed.

Regards, Neil    Tucson, AZ



-----Original Message-----
From: owner-land-speed@autox.team.net
[mailto:owner-land-speed@autox.team.net] On Behalf Of Dave Dahlgren
Sent: Sunday, September 05, 2004 4:29 AM
To: land-speed@autox.team.net
Subject: RE: Bumps, Suspension, Etc.

"I have worked with the data quite a bit and tell you the following with
a
few reservations. The first one being we have to find a way to log this
data
both as down force and travel in inches. this will unfortunately for the
short term require using 8 channels rather than 4. The reason being that
the
response curve in both down force and travel is not linear and is
subject to
using only 6 data points to make it linear. Not ideal but better than a
straight line. Second is that the initial down force calibrations were
done
with a couple of assumptions that proved incorrect. The largest one
being we
were looking for lift and had more data points in the lift range than
the
down force range or at least they are over a wider range. What we got
was
down force over the entire run rather than lift so all the lift data
points
in the calibration were wasted.

In places other than a gear change or other major input into the car the
travel is small at Bonneville. Approximately 0.10 inches as an average
but
the car does move down with increased lift from the down force. So the
movement is superimposed on a curve that is progressively showing more
down
force with the same chassis/wheel movement. There is some periodic
movement
in the suspension That is fairly regular but does move up in frequency
with
speed. I would suspect it is the natural frequency of the suspension or
shocks and is somewhat different front to rear which would further
support
this thought as the rear suspension is much heavier....."


Dave Dahlgren