# HDV file: damper/spring location

Discussion in 'Car Modding' started by Gumball, Sep 30, 2019.

1. ### GumballRegistered

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Hi all,
Ive studied Skipbarber's pushrod's spindle, body, inboard and outboard explanations and i think i understand about the coordinates relative to the rigid bodies but am wondering about their placement within the car.
from what i see from Spkipbarber's hdv file is that the rear spring damper is almost horizontal with the chassis of which length of spring/damper to be 29 mm.

PushrodSpindle=(-0.12,-0.14,-0.05) // spring/damper connection to spindle or axle (relative to wheel center)
PushrodBody=(-0.413, 0.1100455,-0.05) // spring/damper connection to body (relative to wheel center)

where as isi's NSX. the Push rod body is 2m vertical as seen below:

PushrodSpindle=(0.02,-0.12,0)
PushrodBody=(0.02,2,0)

Would like to understand:
1. why the discrepancy of the spring/damper locations between the cars, in particular the nsx's pushrod body position at 2m seems so wrong but works well in game.
2. Am im guessing what each function does correctly? or am i missing something here? im wondering as well, being the spring damper locations having mechanical properties, how come this parameter is not within ptool?

Last edited: Oct 1, 2019
2. ### BerndRegistered

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From the values of the skip barber, that you have posted, the pushrod has another length.
PushrodSpindle=(-0.12,-0.14,-0.05)
PushrodBody=(-0.413, 0.1100455,-0.05)
When i only take the height values -0.14 and 0.11, i get a length of around 25 cm, not 29 mm.
I would say that the important part, that affects the physics, is the travel, not the overall length of the pushrods.
As you say, the nsx values are really strange.

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3. ### GumballRegistered

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So i assume that if the mount points for the coilover is not as important, the mechanical effect of the arms affecting the coilovers are not calculated for ?

4. ### EmeryRegistered

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Believe you can choose to use wheel rate or spring rate depending on value of AdjustSuspRates=

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5. ### BerndRegistered

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English is not my native language, so i am not sure what you mean with "the mechanical effect of the arms affecting the coilovers".
What mechanical effect do you mean?

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6. ### GumballRegistered

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Hi Bernd,
what i meant by 'mechanical effect' is how the geometric position of the pivot points and location of the damper/spring mounts working together will effect the loads, like different positions within a lever.

7. ### BerndRegistered

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I don't know if the Motec or any other plugins can help to find it out.
If not, an exact answer can only be given by the S397 physics team, i guess.

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8. ### RastasRegistered

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Is made in the same way the Brabham,from dev guide: By placing the pushrods as upright as possible, around on the kingpin axis, we ensure minimal change in motion ratios or wheel rates.

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9. ### BerndRegistered

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But 2 m length?

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10. ### RastasRegistered

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Im not a pro hehe

11. ### GumballRegistered

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yes and the front is 1.6m in length. im sure there is some variable in the .hdv to make this work.. but i cant find it

12. ### BerndRegistered

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As said before, i think that the length don't matters at all or at least not so much (even if most women won't agree ).
I still guess the travel is the important value and maybe the angle, defined by its mounting points, too.
A S397 physics developer could answer that easily.

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