91 Avant Shock Recommendations

Eric_R_Kissell at whirlpool.com Eric_R_Kissell at whirlpool.com
Fri Nov 21 12:02:00 EST 2003

Guilty as charged, Bernie.  I was lazy with my terminology.  What follows 
below is probably no better...

By 50% and 75% I am talking about the % of the 720 degrees of setting 
available by rotating the shaft of the Koni Sport (yellow) shock absorber. 
So, my descriptor of 50% suggest that I rotated the shaft 360 degrees 
(360/720 = 0.50, see how this works?) from the setting giving the minimum 
amount of damping. The setting of 75% that I want to try will be at 540 
degrees of shaft rotation (540/720 = 0.75) from the setting giving the 
minimum amount of damping. I did not actually measure the damping 
resulting from the settings so I cannot comment as to the linearity of the 
damping versus the setting. I suspect it is somewhat non-linear and that 
damping increases more rapidly for changes in the setting as the setting 
nears maximum damping. 

My assessment of being underdamped is not due to a lack of understanding 
about a "resonant spring/mass system" as you carelessly assume, though I 
have not worked specifically on a "resonant spring/mass system" in my 
current job for about 5 years. I suppose I could crank some calculations 
and measure some damping and spring rates to support my assessment, but I 
actually enjoy wrenching and testing theories too. My empirical assessment 
is that the car is underdamped because it does not settle down as fast as 
I would like once the mass of the car starts moving on the springs. 

Obviously you know more about my specific dampers and my specific 
"resonant spring/mass system" than I do.  However, I have my own 
first-hand perceptions about this particular "resonant spring/mass system" 
and IMHO it feels underdamped.  Since I am the one who has to feel the 
results of my "resonant spring/mass system" on my car each time I drive 
it, I am going to go ahead and try a setting with higher damping.

I will report back my perceptions about my "resonant spring/mass system" 
with an increased amount of damping after I make and evaluate the change 
at the "75%" setting. 

My use of "stiffness" in describing dampers is clearly unforgivable. I do 
not know what I was thinking. Please replace the words "stiff" and 
"stiffness" in the previous message with more appropriate words to 
describe  "resonant spring/mass systems" with differing damping levels 
that either desirably or undesirably dissipate energy through damping 
losses versus transmitting energy through to the mass of the car either as 
a "shock load" for the overdamped case or as decaying oscillation of the 
car's mass in the underdamped case.

Anyway, thanks for the feedback.  I will let you know if increasing 
damping improves my perception of my "resonant spring/mass system" that I 
perceive as underdamped yet you hypothesize is overdamped.

As I recall, you have Koni Reds.  Where do you have those set?


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