I'd like to know how they differ from any street car. Also I saw on Daily F1 that Stewart was working on a 'contractive' (contraction ?) suspension, already used by Ferrari and Mc Laren. What's that and how do they differ from the other F1 ones ?
I think they are plenty of knowledgeable people out there to clarify these questions.
It seems that each team is working on it's own suspension, I guess they take an important role in the car behaviour.
F1 suspensions questions...
Started by
Chris
, Aug 19 1999 17:08
8 replies to this topic
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#2
IndyIan
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Posted 20 August 1999 - 02:41
Chris,
I think one thing that most F1 suspensions have in common is the double A arm design or wishbones. A lot of road cars these days use macpherson struts except honda, I know the civic, accord, and prelude use double A arms and those cars have a reputation for good handling and supple rides.
I have never heard of contractive suspension but if I had to guess I would say the the springs are stretched instead of compressed as the wheel travels up although I don't know waht the advantage of that would be.
I think one thing that most F1 suspensions have in common is the double A arm design or wishbones. A lot of road cars these days use macpherson struts except honda, I know the civic, accord, and prelude use double A arms and those cars have a reputation for good handling and supple rides.
I have never heard of contractive suspension but if I had to guess I would say the the springs are stretched instead of compressed as the wheel travels up although I don't know waht the advantage of that would be.
#3
SlowDrivr
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Posted 20 August 1999 - 03:19
There's a description of contractive suspension in one of the other F1 sites, but I can't find it right now.
As I remember it, it was a significant enhancement to the conventional double wishbone they use now.
Because of downforce the car tends to want to bottom out at high speeds. To prevent this stiff springs are required, so stiff that grip may be comprised in slow bumpy corners (or over kerbs) where a less stiff spring would be better. The trick contractive design allows is (I think) it allows the roll stiffness to be less when there's less downforce which improves grip in low/medium speed corners.
As I remember it, it was a significant enhancement to the conventional double wishbone they use now.
Because of downforce the car tends to want to bottom out at high speeds. To prevent this stiff springs are required, so stiff that grip may be comprised in slow bumpy corners (or over kerbs) where a less stiff spring would be better. The trick contractive design allows is (I think) it allows the roll stiffness to be less when there's less downforce which improves grip in low/medium speed corners.
#4
Frank R. Champs
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Posted 20 August 1999 - 10:11
Hi,
The main difference between F1 suspensions and a sporty road car's is that while the springs and shocks are placed in between or in the proximity of the suspension arms on the road car, F1 cars run pushrods which transfer suspension motion to the springs and shocks which are mounted centrally in the chassis. The pushrods act on rocker arms which act upon the shocks and springs. Also, while coil springs were most commonly used in the past, and on road cars as well, torsion bar springs are gaining a lot of popluarity, because they seem to take up less room.
Regarding the link to the site describing the contractive (reactive) suspension, here it is:
http://206.108.60.18...ve/reactive.htm
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Frankie
The main difference between F1 suspensions and a sporty road car's is that while the springs and shocks are placed in between or in the proximity of the suspension arms on the road car, F1 cars run pushrods which transfer suspension motion to the springs and shocks which are mounted centrally in the chassis. The pushrods act on rocker arms which act upon the shocks and springs. Also, while coil springs were most commonly used in the past, and on road cars as well, torsion bar springs are gaining a lot of popluarity, because they seem to take up less room.
Regarding the link to the site describing the contractive (reactive) suspension, here it is:
http://206.108.60.18...ve/reactive.htm
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Frankie
#5
Chris
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Posted 20 August 1999 - 20:48
Thanks all.
(I must go to the dictionary know to figure out the translation to the equivalent in French...)
(I must go to the dictionary know to figure out the translation to the equivalent in French...)
#6
SlowDrivr
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Posted 21 August 1999 - 02:04
Frank-
What do you mean by torsion bar spring? That sounds different than a conventional anti-roll bar.
What do you mean by torsion bar spring? That sounds different than a conventional anti-roll bar.
#7
PDA
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Posted 21 August 1999 - 11:37
Torsion bar:
As you know, with a coil spring, pressure is applied to the end of the coil, the spring compresses, resisting cornering or road irregularities. What actually happens is that the rod which is used to creat the spring is twisted about its longitudinal axis as the spring compresses.
A torsion bar spring is an uncoiled length of metal bar. The suspension arm is clamped to it and the other end of the bar is ridgidly attached to the chassis/body of the car. As the suspension arm rises, it twists the bar, giving the springing effect.
Some people (engineers) claim that one can getter better control over the springing by using torsion bars. the main reason for not using them, and using coils springs instead, is that torsion bars tend to be long and difficult to place in the car, whereas coil springs are easily accomodated.
The original Volkswagen Beetle had torsion bar suspension, so they are not by any means a new invention. I'm not sure without looking it up, but I think that the prewar Auto Union GP race cars had them. An early use in the more modern era in F1 was the Lotus 72, but there may well have been others before that.
As you know, with a coil spring, pressure is applied to the end of the coil, the spring compresses, resisting cornering or road irregularities. What actually happens is that the rod which is used to creat the spring is twisted about its longitudinal axis as the spring compresses.
A torsion bar spring is an uncoiled length of metal bar. The suspension arm is clamped to it and the other end of the bar is ridgidly attached to the chassis/body of the car. As the suspension arm rises, it twists the bar, giving the springing effect.
Some people (engineers) claim that one can getter better control over the springing by using torsion bars. the main reason for not using them, and using coils springs instead, is that torsion bars tend to be long and difficult to place in the car, whereas coil springs are easily accomodated.
The original Volkswagen Beetle had torsion bar suspension, so they are not by any means a new invention. I'm not sure without looking it up, but I think that the prewar Auto Union GP race cars had them. An early use in the more modern era in F1 was the Lotus 72, but there may well have been others before that.
#8
Frank R. Champs
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Posted 21 August 1999 - 11:53
PDA,
Correct about the torsion bars, however, I meant that they are becoming more popular in F1. Also, they are arranged within the chassis in a very clever manner...
First of all, since the springing of an F1 car is quite stiff, the torsion bars can be a lot shorter than those on a road car. Secondly, they are used as the axes for the rockers, which transfer motion from the pushrods to the dampers. As the rockers move, they flex the bars. In this way, the bars can be conveniently mounted, taking up less room than a coil spring.
If you noticed the horns on top of the nose of the williams and stewart cars in 98, those were for clearnace of the torsion bars.
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Frankie
Correct about the torsion bars, however, I meant that they are becoming more popular in F1. Also, they are arranged within the chassis in a very clever manner...
First of all, since the springing of an F1 car is quite stiff, the torsion bars can be a lot shorter than those on a road car. Secondly, they are used as the axes for the rockers, which transfer motion from the pushrods to the dampers. As the rockers move, they flex the bars. In this way, the bars can be conveniently mounted, taking up less room than a coil spring.
If you noticed the horns on top of the nose of the williams and stewart cars in 98, those were for clearnace of the torsion bars.
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Frankie
#9
tak
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Posted 31 August 1999 - 11:07
On a more fundamental front, a road car suspension is meant to create a comfortable ride (even in a sports car). On a modern race car, the suspensions primary mission is to hold the chassis at the optimum attitude to the road so the aerodynamics work!
While a road car might have 6" of suspension travel, I think F1 cars have less than 2" of travel. A typical road car has a wheel spring rate of around 150 to 250 lbs/in of travel. That is it takes around 200 lbs to push a car wheel up 1". An F1 car has a wheel spring rate of aroung 1000 to 2000 lbs/in--Very very stiff. That's why the ride hight doesn't change much from when the car is going 30mph around Casino Hairpin and weighs 1200 lbs vs 200 mph down the Silverstone straight where the car weighs 2500 lbs or more.
F1 cars (almost any car that makes downforce) have no droop travel--that is the weight of the car does not compress the springs (or twist the torsion springs!) Only when the car is dynamically loaded does the suspension move.
While a road car might have 6" of suspension travel, I think F1 cars have less than 2" of travel. A typical road car has a wheel spring rate of around 150 to 250 lbs/in of travel. That is it takes around 200 lbs to push a car wheel up 1". An F1 car has a wheel spring rate of aroung 1000 to 2000 lbs/in--Very very stiff. That's why the ride hight doesn't change much from when the car is going 30mph around Casino Hairpin and weighs 1200 lbs vs 200 mph down the Silverstone straight where the car weighs 2500 lbs or more.
F1 cars (almost any car that makes downforce) have no droop travel--that is the weight of the car does not compress the springs (or twist the torsion springs!) Only when the car is dynamically loaded does the suspension move.
