[DeTomaso] need formula for springs needed-- was shocks for ORR

Art Stephens artstephens at charter.net
Wed Oct 10 12:12:04 EDT 2007 

Dawg,
     I've seen that bootay of yours and I know those springs are crying for 
mercy!  Why don't you just go straight to the 1500 pounders and get it over 
with?  :-)))))

Art



----- Original Message ----- 
From: "Mad Dog Antenucci" <teampantera at yahoo.com>
To: <pantdino at aol.com>; <jason.eaton at gmail.com>
Sent: Wednesday, October 10, 2007 7:52 AM
Subject: Re: [DeTomaso] need formula for springs needed-- was shocks for ORR


> Fellow Slacker! ;-]>
>
>  I think you, Jason and others are all right on with your spring concern 
> comments.....all the supporting feedback from mfg's and unlimited drivers 
> is forget replacing the shocks and just make an incremental increase to 
> the springs to the back end where I had a problem or full compression.  I 
> currently am running 400 lb fronts and 700 lb rears.....I may have to 
> consider raising the back end up a half inch or so too but hate doing that 
> since the car handles so well at every other ORR and at speed be it in 
> straights or corners of canyon road I am reluctant to make big changes.
>
>  I'm not sure what my speed was at when I hit the first dips but its at 
> the end of a long straight...I could  have been 150 but was probably 
> closer to 160......so right now I am going with a 750 on rears and adding 
> a poly shaft stop on top shock shaft for added protection....if that 
> doesn't work I will give up the donuts, macaroons and beer. ;-]>
>
>  thanks for your comments.
>
>  Dawg
>
> pantdino at aol.com wrote:
>
> Dennis and Jason,
>
> I freely admit that my opinion comes from a total slacker regarding ORR, 
> but I wonder if stiffer shocks is the right way to go. My understanding is 
> that it is not the shock's job to prevent excessive spring compression--  
> if that is happening, the spring is too soft. The shock's job is to dampen 
> the spring's natural tendency to continue to let the car bounce up and 
> down once it is disturbed. Indeed, the Brits call them "dampers" because 
> that's what they actually do.
>
> At the risk of boring you to tears, I had an Alfa that was "undersprung", 
> that is, the springs were too soft.? Despite Konis set on full hard so 
> expansion joints rattled my teeth, the car would still "porpoise" when 
> going thru depressions at intersections for water to drain away. The car 
> was "undersprung and overdamped."? In contrast, my MGB was "oversprung and 
> underdamped".? It would also rattle my teeth over expansion joints but 
> never porpoised. However, the ride was "bouncy," where you could feel the 
> car oscillating up and down more than it should after hitting a bump.? So 
> its dampers were not preventing the car from bouncing along in its 
> springs.
>
> What spring rates are you and Jason running??? I have no real world 
> experience at this, but if Jason doesn't bottom out at 150mph, that gives 
> you an idea of what spring rate is necessary to contain a certain amount 
> of kinetic energy. Basically a car encountering a change in road shape is 
> being forced to change its course from straight ahead in the vertical 
> plane to a different trajectory. Inertia wants to keep it going straight, 
> and the springs have to transmit force to prevent it from burrowing into 
> the asphalt.?
>
> It seems to me that since Kinetic Energy=1/2 Mass x? (V squared), you 
> could get an idea of what spring force would be necessary to keep the same 
> mass from bottoming at a different speed.? I'm afraid my physics is too 
> rusty to give you the formula, but spring strength is measured in pounds, 
> which is a measure of force, mass x acceleration.? The springs have to 
> accelerate the car away from the road. If they are not strong enough, they 
> bottom out and the whole car becomes unsprung weight. So the spring has to 
> have enough strength to not bottom out under this extreme load.?
>
> Again, I don't have the equations for you, but I suspect everything will 
> drop out of the them and you'll be left with the velocity squared factor--  
> if the car is going twice as fast the springs will have to be 4 times as 
> firm to prevent bottoming.?
>
> Meaning you'd be looking at something like:
>
> Jason's spring rate x??? Dennis' speed squared
>
>
> ?????????????????????????? Jason's speed squared??? =? spring rate needed 
> to prevent Jason's car from bottoming at Dennis' speed.? If Dennis' car 
> weights more or less than Jason's, you would correct by a simple 
> proportion, as the M is not squared in the formula.
>
> However, I think this also assumes that the springs in the two cars are 
> the same length and will crush the same distance before they bind, etc, 
> etc. But it should provide a ballpark estimate, I would think.?
>
> Jack and the other people who really know and don't just make slacker 
> guesses like me??
>
>
> Jim Oddie
>
>
> -----Original Message-----
>
>
>
> From: Jason Eaton
> To: Mad Dog Antenucci
> Cc: detomaso at realbig.com
> Sent: Tue, 9 Oct 2007 6:22 pm
> Subject: Re: [DeTomaso] Bigger-Better-Heavy Duty Shocks for Silver State 
> WOOPS - No Slacker Content
>
>
>
>
>
>
>
>
>
>
> You can reduce the unsprung weight by cutting back on the beer and donuts!
>
> We didnt have any problems with compression, but were only going 150
> though there. Also I'm pretty sure we are running higher rate spring
> then yours. lets compare notes.
>
> On 9/25/07, Mad Dog Antenucci wrote:
>> Off Roaders & JORN IN NORWAY:
>>
>> Bilstein and Aldan were wrong.....rebuilding the shocks for the Pantera 
>> with
> 25% more compression and rebound was not enough to stop full compression 
> at the
> dips (at WOT) at Silver State in the Pantera....you couldn't have pulled a
> greased string out of my backside on the hardest hit so its back to the 
> drawing
> board.;-]>
>>
>> In the last ORR I had another great run....engine although it had too 
>> much
> compression ;-]> ran great....the Pantera is handling better then it ever
> has.....but hitting full compression broke the ABS side skirts and bottom 
> of
> the air dam in the dips. Shock mounts and chassis all look good and the 
> Pantera
> stayed straight and true on full compression so no handling problem. Te 
> ABS was
> meant to provide some added hi-speed stability which it did until it broke 
> ;-]>
> but the ABS was also meant tobe the 'sacraficial lamb' which it also did 
> but
> bottom line I still got full compression in dips above 145 mph
>>
>> So, as part of this winter's projects (MORE engine compression) ;-]> I 
>> need
> some customized shocks with added compression to handle these dips (aka 
> WOOPS).
> I don't think there are any plans in 2008 to regrade the course dips so 
> the
> challenge is to build shocks around the course conditions.
>>
>> No Col. I still can't afford those high tech $5 grand computerized units 
>> but
> a couple people I spoke too suggested adding a stop on top of springs to
> eliminate the 'full compression'.... the negative to that suggestion is 
> others
> have suggested it could also cause wheel hop 'at speed' on full 
> compression
> which could lead to loss of control and an off road 4x4 excursion. ;-]> So 
> goal
> is to STOP full compression.
>>
>> If YOU have a contact name of anyone you have personally dealed with on
> customized shocks for off-road conditions send it to me. I gotta figure 
> those
> guys who are running offroad at 150 mph can help where roundy-rounders 
> can't.
>>
>> JORN, SEND ME contact infor on the VIKINGS that ran 200 MPH last week.
>>
>> MD
>>
>>
>> Mad Dawg Antenucci
>> Team Pantera Racing
>> The 1st & still the only vintage race team in open road racing
>> www.teampanteraracing.com
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> Mad Dawg Antenucci
> Team Pantera Racing
>  The 1st & still the only vintage race team in open road racing
> www.teampanteraracing.com
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