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Dynamic toe legal in F1? (McLaren MC33)


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#1 MatsNorway

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Posted 24 February 2018 - 12:48

This picture got me thinking, is dynamic toe legal in F1?

28238688_2054174774610636_66854257523158

 

https://www.formula1...ng_systems.html

https://www.fia.com/...on/category/110

 

Looking at it, it seems there is no ban on that in F1.

 

Page 58 in technical regulations states

 

10.1.2 Any suspension system fitted to the front wheels must be so arranged that its response results only from changes in load applied to the front wheels.
10.1.3 Any suspension system fitted to the rear wheels must be so arranged that its response results only from changes in load applied to the rear wheels.

 

and

 

10.2.1 With the steering wheel fixed, the position of each wheel centre and the orientation of its rotation axis must be completely and uniquely defined by a function of its principally vertical suspension travel, save only for the effects of reasonable compliance which does not intentionally provide further degrees of freedom.

 

10.2.2 Any powered device which is capable of altering the configuration or affecting the performance of any part of any suspension system is forbidden.

 

Here is a explanation for one way to do it. There is also different effects if the link is longer/shorter than the other wishbones

 

JUAOKbn.jpg


Edited by MatsNorway, 24 February 2018 - 12:51.


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#2 MatsNorway

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Posted 24 February 2018 - 12:53

I do not fully understand 10.2.1.

 

Can anyone explain that one.


Edited by MatsNorway, 24 February 2018 - 12:58.


#3 Bloggsworth

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Posted 24 February 2018 - 14:19

Good luck in outlawing bump-steer...



#4 Greg Locock

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Posted 24 February 2018 - 18:05

The gotcha is "save only for the effects of reasonable compliance which does not intentionally provide further degrees of freedom", which will give you toe in response to traction and braking. Those are tunable parameters in a normal car and quite important. There's also lateral compliance steer, of course. and toe/Mz.



#5 MatsNorway

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Posted 25 February 2018 - 10:15

Can you address the question more directly. Some "slop" in the suspension being manipulated i guess is reasonable but beyond that i did not fully understand.



#6 kikiturbo2

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Posted 26 February 2018 - 00:21

I do not fully understand 10.2.1.

 

Can anyone explain that one.

quite simple really...

 

Bump steer is allowed

some limited geometry chenge as a result of suspension components bending under cornering/braking/accelerating forces is allowed.... I say this is grey area as to what is reasonable.. Is a rubber bush with different siffness in various axis reasonable (as used on road cars)? Or do they have calculated compliance in suspension arms..?



#7 Greg Locock

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Posted 26 February 2018 - 01:22

Subframe stiffness is fairly important in road cars for n'th degree of steering. If you haven't got a direct compression member between the two main suspension bushes then you'd better have some sharp structures guys around.



#8 MatsNorway

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Posted 26 February 2018 - 16:21

Surely dynamic toe does not go as bump steer...



#9 V8 Fireworks

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Posted 26 February 2018 - 16:49

Subframe stiffness is fairly important in road cars for n'th degree of steering. If you haven't got a direct compression member between the two main suspension bushes then you'd better have some sharp structures guys around.

 

In that case do uppper strut braces make any difference?  I note they are commonly fitted to many production cars, even non-sports models.

 

hyundai-i30n-boot-space.jpg?itok=XOwdXbB


Edited by V8 Fireworks, 26 February 2018 - 16:49.


#10 Greg Locock

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Posted 26 February 2018 - 19:53

They certainly do make a difference, although I doubt they affect the steering directly.  Mazda used to tie the interior of their cars together with taut strings, and then observe which went slack, or snapped, as they drove over rough surfaces.

 

Mainly they improve the installation stiffness of the shock absorbers.



#11 RogerGraham

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Posted 27 February 2018 - 04:10

Mazda used to tie the interior of their cars together with taut strings, and then observe which went slack, or snapped, as they drove over rough surfaces.

 

Ha.  Such a nice, simple idea.



#12 Nathan

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Posted 08 March 2018 - 17:32

They certainly do make a difference, although I doubt they affect the steering directly.  Mazda used to tie the interior of their cars together with taut strings, and then observe which went slack, or snapped, as they drove over rough surfaces.

 

Mainly they improve the installation stiffness of the shock absorbers.

 

I understand benefit to the shocks being the case for the upper bars, but would these lower bars benefit steering via stiffening the subframe?

 

F823.jpg



#13 Greg Locock

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Posted 09 March 2018 - 18:44

I'm tempted to say yes that should help steering feel. But... the main forces when cornering are parallel (as opposed to opposing), that is, the left wheel and the right wheel are both being pushed to the inside of the corner by the road. So a brace across the car is really not doing a great deal. What you really need is a structural belly pan, or preferably triangular reinforcement back to the firewall.



#14 Nathan

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Posted 09 March 2018 - 23:49

Very interesting.  Thanks Greg!!