If I translated it right, they are not understandable or what? I heard that ride height does not effect downforce at all. So, it's only for adjusting car higher on rally, so chasis don't bump on tires (or tyres, however you want).
Why is it incomprehensible? Whilst it's not a realistic way of changing the ride height (in which you'd measure the actual ride height, not the ride height reduction from an arbitrary 'standard ride height'), it still works. Increasing the number by 1 will lower the car by 1.
If you want stiffer suspension, you change the Newtons value. If you want a chance in ride height you change the ride height value. Reducing the hardness by a factor of 10 doesn't mean you need a factor of 10 higher ride height.
The trick to using ride height reduction is to look at the "inclination" in the suspension view in the pits. It is a number that represents something... Choose a preferable height then look at the inclination number. When you adjust the hardness make sure you adjust the ride height reduction so that number is the same after all your changes. If you do this you will keep the actual height the same when you change the hardness.
To sum up, if you keep the inclination number the same, then you will also keep the height the same.
I agree with that, however to be exact about it you need an exact reference from which to readjust to.
Some scenario of spring setup (w/o using VHPA):
I want to adjust just the front spring rate, but I also don't want to change my front ride height.
I could just eyeball it and get it close, but a slightly raised or lowered front will effect the performance apart from just making the spring stiffer.
The best reference would be the ground, but in the pits you can't get an exact ride height.
The only exact measurement for a reference is the inclination.
What exactly is inclination measuring anyway, and in what units?
Inclination adds positive camber to both front wheels as the steering angle increases. Likewise, caster adds negative camber to the outside front and positive camber to the inside front as steering angle increases.
How can you possibly not understand how this works? Haven't you experimented with it? Haven't you played with it in the garage and seen how the slider affects the ride height and motion range?
You are perhaps confused by the wording of the slider. Internally it sets a ride height offset, but it is labelled as "ride height reduction", as that is the purpose of being able to adjust the offset. So a higher offset gives a higher ride height, it sounds like you expect a higher reduction value to lower the car.
It could be worded more clearly but as Forbin suggests, it only takes seconds to see which way round the slider works.
The Newton is a measure of force. The force on the spring is dependent upon A) the vehicle's mass and B) acceleration (often gravity). In other words, you have no control over this.
What do you mean by deflection? The sag at rest (difference in travel between full extension and loaded)? Or the usable suspension travel (difference between loaded at rest and bottomed out)?
For someone who wants to approach this scientifically, you don't seem to know much about the science behind it.
For a 5000 N load to compress a spring by 50 mm, the spring must have a stiffness of 100 N/mm (or 100 kN/m). This is totally independent of ride height unless your suspension travel range is less than 50m m. If it is less than 50 mm, you will bottom out the 100 N/mm spring before you get to 50mm.
How did you determine that the load is 5000 N in the first place?
Maybe he should go to the French forum and ask there.
It is unreasonable to expect a response in French when English is the primary language on this forum. David 09 seems very well aware of this.
It's less than ideal, I'll give you that, but it's not very hard to understand. Zero ride height reduction gives you maximum suspension travel, max ride height reduction gives you zero suspension travel. Stiffer springs don't sag as much as soft, and also don't use as much travel, so more ride height reduction is useful.
In the real world, ride height is adjusted by adding an offset to the travel, often by changing the length of the suspension linkage. In this case, suspension travel remains the same. However, if the travel is long, this can result in contact between the wheel and body. Spring preload can help prevent this to some extent.
No, it is not. But you have to think about what you are doing, it's not natural.
I have no experience of setupping real race cars, but form what I've heard it's not so different compared to RC cars. Atleast the principals are the same. For an example if the rear of my RC car keeps bottoming out I could do two things. 1: Raise the ride height. 2: Put on stiffer springs.
To do the first one I'd add more pretension. NOT reduce the ride height reduction.
The second one would raise the rear because the stiffer springs wouldn't compress as much as the softer ones and I'd reduce the pretension to get the same ride height. NOT put on more reduction.
So in my mind the way it's in LFS is backwards compared to real life. Atleast real RC life.
Preload/pretension is not intended to be a ride height adjustment. It's merely a suspension force offset. This means that the minimum force required to compress the suspension is greater (increasing compression force results in 0 compression up to a certain point) and it also increases the maximum force the suspension is able to generate at full compression before bottoming. There's often a fine balance between using a softer spring with more preload, giving up some travel on rebound, and using a stiffer spring with less preload, regaining some of that rebound travel.
The change in ride height is merely a side effect.
So, it's only for adjusting car higher on rally, so chasis don't bump on tires (or tyres, however you want).