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Any thoughts on the new MB dual axis steering?


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#1 mariner

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Posted 21 February 2020 - 09:37

As I (maybe) understand it the objective is to remove toe in down the straights to, I assume, increase speed.

 

Clever idea I think , it seems the driver has to do it manually , I would guess the loads are not too high butt that depends on the mechanical ratios used etc.

 

I presume there is some sort of safety lock to keep it engaged either way. ?

 

If the driver just pushes and pulls is he just shoving the whole rack in and out on sliders or is it some other mechanism - probably far more complex being F1!



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#2 Wuzak

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Posted 21 February 2020 - 11:20

My first thought is that it is changing the suspension geometry, and therefore is illegal.

 

But Mercedes seem to have taken the view, shared by the FIA, that it is a steering system and thus does not fall foul of the regulations.

 

However, since the system is activated on the straight it's not actually steering, and the suspension geometry is altered I would argue that it is illegal.

 

The biggest argument must, surely, be about the safety of the system. Moving the steering wheel/column in and out must increase the risk of failure of the steering.


Edited by Wuzak, 21 February 2020 - 11:21.


#3 DogEarred

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Posted 21 February 2020 - 13:37

A zero toe in setting will diminish the straight line stability.

Whether to a significant extent, I do not know.

There is also the case of cars bunched and overtaking at the end of the straights.
In the heat of the moment, the shift back to toe in/out may be missed & the turn in will be affected.

A possible dangerous situation.

#4 DogEarred

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Posted 21 February 2020 - 13:42

Also, there will be the issue of the change in temperature profile across the tread.

That needs to be taken into account.

#5 DogEarred

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Posted 21 February 2020 - 13:44

The mechanics of it all should present no difficulties.

There are other systems on the car that are more complex.

#6 DogEarred

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Posted 21 February 2020 - 14:00

My first thought is that it is changing the suspension geometry, and therefore is illegal.
 
But Mercedes seem to have taken the view, shared by the FIA, that it is a steering system and thus does not fall foul of the regulations.
 
However, since the system is activated on the straight it's not actually steering, and the suspension geometry is altered I would argue that it is illegal.
 
The biggest argument must, surely, be about the safety of the system. Moving the steering wheel/column in and out must increase the risk of failure of the steering.



Although the FIA technical department has some very good people, your post reinforces the point that the FIA is poor at writing rules and judging by the number of 'requests for clarity' that to and fro between the teams before and during the season.

It's all retro legislation.

On a slightly different point, some generic clarifications are issued to all teams, whereas some specific ones, such as the DAS, can be confidential.

The wording of these decisions is along the lines of 'It is the opinion of the Technical Committee that 'such and such' enquiry is in breach/ complies with 'such and such' a rule.

It does not actually ban anything but leaves it in no doubt of the result of any investigation/protest.

#7 SJ Lambert

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Posted 21 February 2020 - 21:30

As I (maybe) understand it the objective is to remove toe in down the straights to, I assume, increase speed.
 
Clever idea I think , it seems the driver has to do it manually , I would guess the loads are not too high butt that depends on the mechanical ratios used etc.
 
I presume there is some sort of safety lock to keep it engaged either way. ?
 
If the driver just pushes and pulls is he just shoving the whole rack in and out on sliders or is it some other mechanism - probably far more complex being F1!




Aren’t they reducing/removing toe out on the straights and restoring it in corners?

#8 Fat Boy

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Posted 23 February 2020 - 19:06

Aren’t they reducing/removing toe out on the straights and restoring it in corners?

Yes. I can't see how it's possibly legal and, for sure, it will be declared illegal. It's a misdirection play. They're likely doing other stuff which is dodgy, but well hidden. This is dodgy and on display. It'll get disallowed, but whatever their other thing is will be unobserved and allowed.



#9 mariner

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Posted 24 February 2020 - 09:11

I don't think you can ban it under the CURRENT rules.  It changes toe in/out,. many, many suspensions have toe in/out change with movement so the argument has to lie with the driver doing it. The problem there is the driver has to be able to move the steering wheel so unless it says somewhere "not in or out" that's legal tool. I can see it would be illegal if power assisted but MB kept away from that.

 

As an historic note the Lotus 64 4WD F1 car had a truly weird steering linkage to get past the drive shafts and the steering wheel on that car moved in and out noticeably.

 

If I understand it the FIA will ban the MB device for 2021. I think that is a bit sad as MB have tried to be innovative away from Aero and without huge extra cost so why does even this have to be banned?

 

You could argue MB crushes everybody with its money but in this case  they tried to be better race designers.



#10 Charlieman

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Posted 24 February 2020 - 11:33

On the positive side, when the drivers make a mistake and leave the toe out setting in the straight ahead position, we'll get to see how much difference it makes.



#11 7MGTEsup

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Posted 24 February 2020 - 16:21

On the positive side, when the drivers make a mistake and leave the toe out setting in the straight ahead position, we'll get to see how much difference it makes.

 

I wonder if the longitudinal g's when hitting the brakes in enough to put it back into its nominal position? Or if it has some sort of loading that the driver has to pull quite hard towards himself to activate it and the action of turning the wheel is enough to pull it back into the nominal position?


Edited by 7MGTEsup, 24 February 2020 - 16:22.


#12 Fat Boy

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Posted 24 February 2020 - 20:06

My guess is that it simply moves the steering rack longitudinally in the chassis with the help of a linear motor.



#13 Wuzak

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Posted 25 February 2020 - 03:22

I don't think you can ban it under the CURRENT rules.  It changes toe in/out,. many, many suspensions have toe in/out change with movement so the argument has to lie with the driver doing it. The problem there is the driver has to be able to move the steering wheel so unless it says somewhere "not in or out" that's legal tool. I can see it would be illegal if power assisted but MB kept away from that.

 

It depends if you see the toe setting as being a suspension geometry issue or a steering issue.

 

If it is the latter, then there is little to say that it is illegal.

 

If it is the former, the rules specifically state that the suspension geometry cannot be altered by the driver, and can only be done so in the pits.

 

The argument that has been given so far is that the mechanism is part of the steering system.

 

But what if they changed the toe angle of the rear suspension? That would clearly be illegal.



#14 gruntguru

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Posted 25 February 2020 - 04:06

The initial thought is that this device is there to permit zero toe on straights and particularly under braking.

What if toe settings are a compromise - they would like to run more in the corners but have to reduce it to avoid issues on the straights. This device gives them the freedom to set cornering toe to any value they want (in addition to what can be done with Ackerman alone).



#15 Fat Boy

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Posted 25 February 2020 - 16:47

Toe settings are very much a compromise (as is just about everything). I've ran toes all over the place. I've found the response/grip differences to be very tire (as opposed to car) dependent. Interestingly enough, I've never been able to see a straight-away speed difference by increasing or decreasing the toe setting. For any of the cars I've dealt with, it's just below the noise floor of the data collection. Logically, it has to matter, but the influence in the corners is significantly more important.



#16 Lukin

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Posted 26 February 2020 - 04:27

Toe settings are very much a compromise (as is just about everything). I've ran toes all over the place. I've found the response/grip differences to be very tire (as opposed to car) dependent. Interestingly enough, I've never been able to see a straight-away speed difference by increasing or decreasing the toe setting. For any of the cars I've dealt with, it's just below the noise floor of the data collection. Logically, it has to matter, but the influence in the corners is significantly more important.

 

Yep! I've had cars sit down with 3 times the setup toe come back due to wheel contact and no noticeable speed difference to before the hit or to a teammate.

 

Whats thoughts on front toe under brakes? Had two drivers think I was a total dunce for not knowing toe out helps reduce front locking. They were right (toe out helped and I am a dunce).

 

Other than that example it's only really effected the car when you turn the wheel. Generally found front toe somewhat insensitive (you can use it for a pseudo ackerman almost?). Rear toe is quite powerful.



#17 gruntguru

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Posted 26 February 2020 - 04:47

I wonder if tyre wear in the straights is an issue with lots of toe.



#18 Fat Boy

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Posted 26 February 2020 - 20:31

Yep! I've had cars sit down with 3 times the setup toe come back due to wheel contact and no noticeable speed difference to before the hit or to a teammate.

 

Whats thoughts on front toe under brakes? Had two drivers think I was a total dunce for not knowing toe out helps reduce front locking. They were right (toe out helped and I am a dunce).

 

Other than that example it's only really effected the car when you turn the wheel. Generally found front toe somewhat insensitive (you can use it for a pseudo ackerman almost?). Rear toe is quite powerful.

Lukin Lives!

 

I've honestly never found toe to be an issue on brakes except that 'too much' (whatever that happens to be) causes the front end to follow pavement camber excessively. I don't have any toe setting universals. Some cars I run toe-out or toe-in on the front. It depends on the tire. The rear is *usually* toe-in, but, at times, I've used toe-out successfully, too.

 

Like you, I find rear toe to be a much more powerful tool than the front setting.



#19 Fat Boy

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Posted 26 February 2020 - 20:31

I wonder if tyre wear in the straights is an issue with lots of toe.

I've never found that, but I've also never worked with F1 chewing-gum tires.



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#20 Dmitriy_Guller

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Posted 28 February 2020 - 00:50

To me it seems very clearly to be a steering system.  Imagine that instead of a steering wheel you have two joysticks, one to control the left wheel, and one to control the right wheel.  DAS is basically taking that concept, and just realigns the two degrees of freedom to ease the demands on the driver to keep the two steering inputs in proper balance at all times.



#21 gruntguru

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Posted 28 February 2020 - 22:52

That is a perfectly reasonable argument. Unfortunately (as McLaren discovered) we cant allow the driver to brake the left and right sides independently so the same reasoning will probably be applied to the steering.



#22 jeremy durward

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Posted 03 March 2020 - 11:00

What about the implications to front rideheight? My understanding is that F1 cars run an offset pushrod mount on the upright to roll the car into corners (roll them flat once the tyre and suspension movement comes into play. Would this system not raise the front end of the car down the straights giving a lower wing angle and maybe affecting the floor as well? 



#23 desmo

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Posted 03 March 2020 - 15:03

Isn't that the primary idea? I'd think the potential upsides would be greater than tuning the Ackerman for each corner.



#24 Charlieman

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Posted 03 March 2020 - 17:47

What about the implications to front rideheight? My understanding is that F1 cars run an offset pushrod mount on the upright to roll the car into corners (roll them flat once the tyre and suspension movement comes into play. Would this system not raise the front end of the car down the straights giving a lower wing angle and maybe affecting the floor as well? 

I am trying to work out how a steering component interacts with suspension. In traditional design, steering effects are eliminated from suspension by aligning the line of inboard linkages with the steering vertical pivot.

 

Horrid description. Easier to show on paper.

 

I think that once you need a long explanation, you've shown that you are disguising a lie.



#25 Fat Boy

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Posted 03 March 2020 - 18:41

I am trying to work out how a steering component interacts with suspension. In traditional design, steering effects are eliminated from suspension by aligning the line of inboard linkages with the steering vertical pivot.

 

Horrid description. Easier to show on paper.

 

I think that once you need a long explanation, you've shown that you are disguising a lie.

Maybe, some ****'s just complicated.

 

The outboard end of the pushrod is not connected to the lower wishbone; it's connected directly to the upright. If the pushrod connection is not located perfectly on the steering axis of rotation (and it's likely not), then it will influence ride height as the steering is turned.



#26 desmo

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Posted 03 March 2020 - 19:26

In F1, that thing that looks like it's to get more mechanical grip? It's probably just sneaky aero by other means. Can't one get a lot of the pitch control benefits by just having a lot less rebound damping than the rear in the front third damper?



#27 Charlieman

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Posted 03 March 2020 - 19:40

In F1, that thing that looks like it's to get more mechanical grip? It's probably just sneaky aero by other means. Can't one get a lot of the pitch control benefits by just having a lot less rebound damping than the rear in the front third damper?

No. Actual function is an inverse of techno b*ll*cks. 



#28 gruntguru

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Posted 03 March 2020 - 21:47

Difficult to see this system changing toe to the extent that ride height changes significantly. Surely plus or minus a couple of degrees would be the limit?



#29 Fat Boy

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Posted 04 March 2020 - 02:45

Difficult to see this system changing toe to the extent that ride height changes significantly. Surely plus or minus a couple of degrees would be the limit?

Ya, I have to agree. I don't know how much they're moving the steering, but you'd have to have a hell of a pushrod offset to make much of a ride difference.



#30 Fat Boy

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Posted 04 March 2020 - 02:48

In F1, that thing that looks like it's to get more mechanical grip? It's probably just sneaky aero by other means. Can't one get a lot of the pitch control benefits by just having a lot less rebound damping than the rear in the front third damper?

Your second sentence makes the most sense. The first seems reasonable. The last one....no.



#31 desmo

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Posted 04 March 2020 - 15:06

My reasoning: Braking, pitch, then corner, the braking induced pitch is slow to rebound due to the higher rebound in the front third damper and you get DF benefit of the now Red Bull-type pitch in the corner. Then by the next straight the pitch has neutralized giving lower aero drag. Does anyone in other series besides F1 use a high static pitch set-up like Red Bull have?

 

Anyway, the consensus here seems to be that there is unlikely to be much potential laptime benefit to be got through letting the driver fiddle with the toe/Ackerman.



#32 Fat Boy

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Posted 05 March 2020 - 00:16

My reasoning: Braking, pitch, then corner, the braking induced pitch is slow to rebound due to the higher rebound in the front third damper and you get DF benefit of the now Red Bull-type pitch in the corner. Then by the next straight the pitch has neutralized giving lower aero drag. Does anyone in other series besides F1 use a high static pitch set-up like Red Bull have?

 

Anyway, the consensus here seems to be that there is unlikely to be much potential laptime benefit to be got through letting the driver fiddle with the toe/Ackerman.

 

I understand what you're saying with your first bit, but it doesn't really work that way. What Red Bull is doing is very specific to their car. The other cars which tend to carry a noticeable amount of rake is NASCAR Cup cars. In both situations, you're dealing with cars which were created around this concept.

 

I'm going to push back a little on the 'unlikely to be much' comment. It's very likely I don't entirely understand what they're doing or what the toe sensitivity is on those cars with those tires. I personally haven't found a situation where I thought adjusting toe in this manner would be a big benefit, but that doesn't mean it's not.