Help with Shock Valving....
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Joined: Feb 2002
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From: Phoenix, AZ USA
Help with Shock Valving.... Before I start, please don't just tell me to "go buy someone else's set up....I would really like how to learn how to do this...
Ok...now down to business <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Here is what I'm at so far.
the car weighs 3,440 lbs (empty tank and no driver)
Weight Distribution is about 55/45
so that comes to:
Front Left = 946 lbs
Front Right = 946 lbs
Rear Left = 774 lbs
Rear Right = 774 lbs
I am thinking of using:
Front springs = 650 lbs/in
Rear springs = 175 lbs/in
(both linear)
I have been working with some formulas I dug up from old books I had
front vertical stiffness per wheel = 390 lbs/in
rear vertical stiffness per wheel = 175 lbs/in
front natural frequency = 2.00
rear natural frequency = 1.48
formula for natural frequency:
3.13 (sqrt((suspension vertical stiffness per wheel)/(sprung weight per wheel)))
now....for the shock damping (with a ratio of .45) I used the following formula:
(0.45)(2(sqrt((suspension vertical stiffness per wheel)((sprung weight per wheel)/(32.2 * 12))))
What I go, was the following:
front = 27.81 lbs/in/sec
rear = 25.15 lbs/in/sec
now...that seems all fine and dandy...but the problem is...when I convert those damponing numbers to the shock manufaturer's lbs/25 in/sec.....I get:
front = 695 lbs/25 in/sec
rear = 628 lbs/25 in/sec
that seams REALLY REALLY high.....so high that it is way outside of what is even offered (they stop at a 600# comp. / 65# reb.)
so the ultimate question is....where did I go wrong? or did I?
Any help that you can give "pointing" me in the "right" direction would be really nice.
Thanks
Chris
Ok...now down to business <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Here is what I'm at so far.
the car weighs 3,440 lbs (empty tank and no driver)
Weight Distribution is about 55/45
so that comes to:
Front Left = 946 lbs
Front Right = 946 lbs
Rear Left = 774 lbs
Rear Right = 774 lbs
I am thinking of using:
Front springs = 650 lbs/in
Rear springs = 175 lbs/in
(both linear)
I have been working with some formulas I dug up from old books I had
front vertical stiffness per wheel = 390 lbs/in
rear vertical stiffness per wheel = 175 lbs/in
front natural frequency = 2.00
rear natural frequency = 1.48
formula for natural frequency:
3.13 (sqrt((suspension vertical stiffness per wheel)/(sprung weight per wheel)))
now....for the shock damping (with a ratio of .45) I used the following formula:
(0.45)(2(sqrt((suspension vertical stiffness per wheel)((sprung weight per wheel)/(32.2 * 12))))
What I go, was the following:
front = 27.81 lbs/in/sec
rear = 25.15 lbs/in/sec
now...that seems all fine and dandy...but the problem is...when I convert those damponing numbers to the shock manufaturer's lbs/25 in/sec.....I get:
front = 695 lbs/25 in/sec
rear = 628 lbs/25 in/sec
that seams REALLY REALLY high.....so high that it is way outside of what is even offered (they stop at a 600# comp. / 65# reb.)
so the ultimate question is....where did I go wrong? or did I?
Any help that you can give "pointing" me in the "right" direction would be really nice.
Thanks
Chris
