[DeTomaso] some rough numbers re need formula for springs needed-- was shocks for ORR

Sat Oct 13 19:24:43 EDT 2007

First off I had no bump stops on hill/dip "take-off". The shaft mounted bump stops and the heavier rated springs (750 vs 700) would have helped on 'landing'  where I got 'full-compression at speed.

  Secondly if you look at photos of my Pantera at speed on my web site you'll see the Pantera is siting pretty low. On 2-3 full compression hits at speeds I'll assume I was above 155 mph I got enough full compression of the existing springs to crack the ABS side skirts and ABS sitting on bottom of front air dam. That's not a problem...the ABS was installed with a plan that it would be expendable on any hard hits where I got airborne. 

  I got some rear tire sidewall 'burn' on full compression hits but the rear fenders were rolled so the tires were not damaged. ;-]>   

  Some Good news -  there was; 
  No body damage
  No suspension or chassis damage
  And the Pantera stayed straight and true on take off AND landing!

  md
  pantdino at aol.com wrote:
    Thought I'd run some numbers to see how much one would have to increase spring force if my velocity squared theory is correct:

Since for some reason my equation didn't show properly before, I'll try to show this one differently:

Since kinetic energy increases as the square of the velocity, it seems to me that if you know that a set of springs is adequate at a certain velocity, you can calculate how stiff they would have to be to still be OK at a higher velocity.

(V2 squared / V1 squared)   x    spring force which is adequate at V1 =  spring force which is adequate at V2

using this formula, if 700 lbs is adequate at 150mph, then you would have to have 796 lb springs at 160.

At 170 you'd need 899lb springs.

Back solving for what speed 750lb springs are good for yields 155mph.

The multipliers are actually simple:

to go from 150mph to 160, multiply the spring strength by 1.1377
to go from 150mph to 170, multiply the spring strength by 1.284

So if a 750 spring is needed at 150 you'd need 963 lbs at 170.  Anyone know what NASCAR cars run?

Dennis, what exactly are you trying to prevent, the bodywork from hitting the ground or the suspension from hitting the bump stops?

Jim

-----Original Message-----
From: Mark McWhinney <msm at portata.com>
To: 'Jason Eaton' <jason.eaton at gmail.com>
Cc: 'Mad Dog Antenucci' <teampantera at yahoo.com>; detomaso at realbig.com; JJD1010 at aol.com
Sent: Thu, 11 Oct 2007 9:30 pm
Subject: Re: [DeTomaso] need formula for springs needed-- was shocks for ORR

I am running 750 lbs springs and doing so without seats.  I have driven to
  LV.  No problem.

  You're all slackers.

  Unsubscribe me.

  :)

  -----Original Message-----
  From: Jason Eaton [mailto:jason.eaton at gmail.com] 
  Sent: Thursday, October 11, 2007 9:13 PM
  To: Mark McWhinney
  Cc: Mad Dog Antenucci; JJD1010 at aol.com; detomaso at realbig.com
  Subject: Re: [DeTomaso] need formula for springs needed-- was shocks for ORR

  I would say that the ride is too rough for the street. Grandma lost
  her false teeth and dad hurt his back riding in my car :)

  Maybe i'm just getting old.

  On 10/11/07, Mark McWhinney <msm at portata.com> wrote:
  > A 750 lbs load will compress a 750 lbs spring 1.00 inch.
  > A 750 lbs load will compress a 700 lbs spring 1.07 inch.
  >
  > How good is your butt-o-meter?
  >
  >
  > -----Original Message-----
  > From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com]
  On
  > Behalf Of Mad Dog Antenucci
  > Sent: Thursday, October 11, 2007 1:10 PM
  > To: JJD1010 at aol.com
  > Cc: detomaso at realbig.com
  > Subject: Re: [DeTomaso] need formula for springs needed-- was shocks for
  ORR
  >
  > Jeff,
  >  I'm not a racer and its not a race car! ;-]>
  >  Seriously, excellent idea....no one has mentioned that before. Anyone
  > noticed a discernable handling change on the street (positive or negative)
  > going from 700 to 750 rear springs?
  >
  >  Dawg
  >
  > JJD1010 at aol.com wrote:
  >  Racers have different equipment and settings depending on the track. Why
  > not
  > get a second set of springs and shocks to use at Silver state? All you'd
  > have to do is align it.
  >
  > Jeff
  > 6559
  >
  >
  >
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