Suspension Ideas and Questions

[humble sabot]

in droop

-which you still get with shorter upper control arms to a point. The amount of suspension travel also comes in.

[C09]

I find the premise of this conversation slightly odd.
I'll tell you why. As a rule the vast majority of cars with wishbone suspension have unequal lengths, and not only that i bet you'd have a bitch of a time trying to find one with longer wishbones on top (having the contact patch tuck under the car). I can't imagine a case where you'd actually want to add positive camber under roll or bump. In practice it comes out to a matter of degrees. The primary objective is to help to keep the tyre within its optimum camber range to maximise grip. F1 cars and some others often have a noticeable amount of negative camber at rest, especially on the front.

to respond to two other things:
I've noticed the same thing in f1, sometimes it looks very much like there is a real taper to the tyres, the outside sidewall being taller. I'm not certain if this is an optical illusion or the actual state of things. I'll try and find a pic.

and the other: f1 uses fairly the longest arms they can, the longer the arm the less change in angle.

I've got a lot to think about. Another thing I'd like to know about is if there are different ways to make the wheels turn: the geometry of the steering and how many different ways engineers can make the inner wheel turn more than the outer(in a turn) and the amount of difference. Also, what is the tightest practical turning radius for f1? What about the fore/aft placement of the axis where the axle/front wheel assembly turns?

I'm just full of questions here. Please teach me. F1 is so interesting to me.
Carbon fiber, aluminum, science, amazing statistics, you know how it goes.

[marcush.]

I think you are talking about caster and caster trail here ?
(shopping cart analogy)

[C09]

I think you are talking about caster and caster trail here ?
(shopping cart analogy)

I dunno what I'm talking about, at least not the terminology of it. I would post some drawings, but it's not easy figuring this url stuff out. Do inform me of anything I'm wrong about.

[Jersey Tom]

Picking up a copy of Tune to Win would really be a good starting point

[Caito]

Concerning camber in turning.

There's a "rule" that says: Don't you ever let your camber become positive.


But, why wouldn't you let your inner wheel get positive? Wouldnt that produce a higher lateral force?

Or at least keep it in 0(since a negative value would produce a force(camber thrust) opposing your turn)


Thanks!

bye

[marcush.]

in circletrack (oval racing )positive inside camber is used.

[riff_raff]

marcush,

Oval track suspension set-ups are an anomaly. Oval track cars also use tire stagger (or at least they did a few years ago).

I haven't seen a modern F1 double wishbone suspension set-up, but many, many years ago when I worked in racing, the double wishbone suspensions were designed to give about 1/4deg of camber gain for each inch of bump travel. And as I recall, they never had positive camber, even in full droop.

riff_raff

[marcush.]

marcush,

Oval track suspension set-ups are an anomaly. Oval track cars also use tire stagger (or at least they did a few years ago).

I haven't seen a modern F1 double wishbone suspension set-up, but many, many years ago when I worked in racing, the double wishbone suspensions were designed to give about 1/4deg of camber gain for each inch of bump travel. And as I recall, they never had positive camber, even in full droop.

riff_raff

sure.
Talking f1 you will not see much suspension travel anyways.and looking at the angling of the wishbones relative to the track surface it is obvious that neither camber gains nor track variation(scrub)over suspension is very high on their agenda.

[Jersey Tom]

marcush,

Oval track suspension set-ups are an anomaly.

Not the word I would use.

[mep]

marcush,

Oval track suspension set-ups are an anomaly. Oval track cars also use tire stagger (or at least they did a few years ago).

I haven't seen a modern F1 double wishbone suspension set-up, but many, many years ago when I worked in racing, the double wishbone suspensions were designed to give about 1/4deg of camber gain for each inch of bump travel. And as I recall, they never had positive camber, even in full droop.

riff_raff

I expect thats because of the high negative chamber they run. A higher negative chamber on your loaded outside tyre just brings more than a positive one on your unloaded inside tyre. When you have around 4deg negative chamber (static) you just don't get the inside tyre positive during roll.

[C09]

Thank you Riff Raff and Mep. I still don't clearly understand, but after a bit of thinking, I'll make sense of it.

Little off topic, but is Forza Motorsprt 3 a good way to learn about how to tune a car? About how accurate are the tuning options in game compared to real life?Thanx.

[RacingManiac]

I find the premise of this conversation slightly odd.
I'll tell you why. As a rule the vast majority of cars with wishbone suspension have unequal lengths, and not only that i bet you'd have a bitch of a time trying to find one with longer wishbones on top (having the contact patch tuck under the car). I can't imagine a case where you'd actually want to add positive camber under roll or bump. In practice it comes out to a matter of degrees. The primary objective is to help to keep the tyre within its optimum camber range to maximise grip. F1 cars and some others often have a noticeable amount of negative camber at rest, especially on the front.

to respond to two other things:
I've noticed the same thing in f1, sometimes it looks very much like there is a real taper to the tyres, the outside sidewall being taller. I'm not certain if this is an optical illusion or the actual state of things. I'll try and find a pic.

and the other: f1 uses fairly the longest arms they can, the longer the arm the less change in angle.

I've got a lot to think about. Another thing I'd like to know about is if there are different ways to make the wheels turn: the geometry of the steering and how many different ways engineers can make the inner wheel turn more than the outer(in a turn) and the amount of difference. Also, what is the tightest practical turning radius for f1? What about the fore/aft placement of the axis where the axle/front wheel assembly turns?

I'm just full of questions here. Please teach me. F1 is so interesting to me.
Carbon fiber, aluminum, science, amazing statistics, you know how it goes.

Like JT said, pick up a copy of Tune to Win, most of those are covered quite extensively to gain an understanding of it, without going full depth into the really math-y stuff...

As far as different rate of steering between inside and outside wheel, look up Ackermann....And there is a positive and anti version of it. And which to use again that depends on tire characteristic....

[C09]

Is Tune to win a forum discussion here or a book? I've looked for it, even in the off topic forums, I can't find it.

[747heavy]

it´s a book

http://www.carrollsmith.com/books/tune2win.html