Push rod on upright suspension - an examination

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PlatinumZealot
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Re: Push rod on upright suspension - an examination

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MtthsMlw wrote:
Tue Apr 21, 2020 1:55 pm
PlatinumZealot wrote:
Sat Feb 15, 2020 11:09 am
I think this is the W10
Image
Source
Yes. Beautiful.

An imaginary line through the pushrod roughly aligns to the end joint of the lower control arm as suspected. At least in this straight position.

The push rod is in compression. The torsional spring is trying to push it down against the weight of the car, the downforce, any force from bumps, roll bar forces... And the opposite is happening from the point of view of the wheel hub.

Scenario:

Straight line braking from high speed.. The torsional spring at the bell crank is "compressed" (really twisted in whichever direction lower the car)
The pushrod ends are in position A and B respectively. A is at the knuckle at the upright, B is at the bell crank.

Line of action of the pusrod goes is still aligned to the lower control arm joint since the steering is neutral.

The driver then steers into the corner. The upright rotates. The pushrod knuckle moves with the steer induced rotation of the upright. The line of action of the pushrod is now eccentric to the axis of rotation of the hub. The torsion bar untwists momentarily since push rod knukle at point A is moving away from it unoading it. Since all forces will try to balance themselves, all those downward forces acting on the supension will start to load up the torsion spring again almost immediately, pushing down that corner of the car to a lower ride height.
.. OG.. OG.. OG.. OG..
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godlameroso
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Re: Push rod on upright suspension - an examination

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Greg Locock wrote:
Thu Mar 05, 2020 1:52 am
15 or 20 years ago one of my coworkers designed a rubber bushing that was as stiff as a typical rose joint (at least as installed, the installation stiffness of most cars is way less than that of a rose joint), and had very little coning or torsional stiffness, originally used to reduce the side load in the shocks. A fine and useful bush which is used in several of 'my' suspension designs.
Similar to power flex bushings? Those are a hybrid poly urethane/rose joint.
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Greg Locock
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Re: Push rod on upright suspension - an examination

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No, PU bushes are quite different. Rubber bushes are typically double bonded, that is glued to the inner and outer metals. Those PU ones are lumps of plastic trapped between two metal surfaces. Each has advantages but PU is uncommon in production except for 'performance' models where the punters are given what they think they want.

PhillipM
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Re: Push rod on upright suspension - an examination

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Yeah, the vast majority of aftermarket PU bushes are terrible.

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coaster
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Re: Push rod on upright suspension - an examination

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The manor appears to be off axis negative 20mm to 25mm, when driving straight bump has no effect, at either lock bump still has little effect as you are only maybe half a degree from aligned. Imagine in top view, the german gun called luger, bullets load and lock with a toggle mechanism. When the toggle is fully extended it withstands the load of a bullet fired.
Simple.

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pierrre
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Re: Push rod on upright suspension - an examination

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Tim.Wright wrote:
Sat Feb 15, 2020 8:37 am
Yup I'd say so. The system creates a "negative" steering torque which effectively means the driver doesn't feel a centering force at the wheel like normal cars but an anti-centering force which tries to increase the steering angle by itself. The driver has to fight against this to keep the car going straight.
there is a natural inclination of caster to reduce ride height on the outer front suspension and increase on the inner wheel too during a corner just like those trick two piece push rod yet still maintain strong correction forces on the straights

i assume a casters effect on ride height is too negligible compared to those trick push rods that overwhelms a front wheels caster to straighten the car out in steering response and make the front of a car feel seesaw since those push rods override the entire suspensions suspending units.. the two, caster effect on ride height and trick push rods would even work simultaneously

wouldn't there be support from the chassis via rear suspension to assist in straight line stability or there is enough downforce at the front for this instability
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PlatinumZealot
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Re: Push rod on upright suspension - an examination

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Have you guys noticed that Ferrari and RedBull have not adopted this concept?

It might be another step to unlock more performance for them. I believe they should be allowed to upgrade the suspension for 2021 no?
.. OG.. OG.. OG.. OG..
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MtthsMlw
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Re: Push rod on upright suspension - an examination

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PlatinumZealot wrote:
Fri Jul 17, 2020 4:57 pm
Have you guys noticed that Ferrari and RedBull have not adopted this concept?

It might be another step to unlock more performance for them. I believe they should be allowed to upgrade the suspension for 2021 no?
Isn't this rather similar to Merc? Or are you referring to how it's aligned relative to e.g. the king pin axis?
I know you want a "naked" picture again, sadly there is none and I guess we won't get one this season. :(
Image

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PlatinumZealot
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Re: Push rod on upright suspension - an examination

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Sorry should have worded it better. I meant the high mounted top joint.
.. OG.. OG.. OG.. OG..
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Rodak
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Re: Push rod on upright suspension - an examination

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I think the high mounted top wishbone joint is an attempt to get better (negative) camber change on bump. The upcoming larger diameter wheels will allow better geometry for the upper wishbone; because of aerodynamic requirements the mounting points on the chassis for the wishbones are very high, resulting in the drooping angles we see now. Take a look at rear suspensions and you can see a more ideal geometry for bump camber change.

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coaster
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Re: Push rod on upright suspension - an examination

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Whoa! The Ferrari looks a good 125mm away from the king pin axis, that must be like wrestling a bull with terrible feedback.

Andi76
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Re: Push rod on upright suspension - an examination

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Made popular by Mercedes? Thats a joke isn't it? The Pushrod to Upright concept was introduced first by John Barnard and Ferrari in 1994 or 1995. Rory Byrne was the first designer in Formula 1 who really made this concept work and used it continously. 20 years ago!!! The highly sucessfull Ferraris from 2000(introduced during the season)-2004 all used that concept, as did most of their succesors. Honda copied it, as many other teams in the early 00's. So - it wasn't Mercedes who made that concept popular! It was Rory Byrne and Ferrari 20 years ago and it is a well known concept since that time!

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PlatinumZealot
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Re: Push rod on upright suspension - an examination

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Andi76 wrote:
Wed Feb 03, 2021 7:29 pm
Made popular by Mercedes? Thats a joke isn't it? The Pushrod to Upright concept was introduced first by John Barnard and Ferrari in 1994 or 1995. Rory Byrne was the first designer in Formula 1 who really made this concept work and used it continously. 20 years ago!!! The highly sucessfull Ferraris from 2000(introduced during the season)-2004 all used that concept, as did most of their succesors. Honda copied it, as many other teams in the early 00's. So - it wasn't Mercedes who made that concept popular! It was Rory Byrne and Ferrari 20 years ago and it is a well known concept since that time!
Lets see some photos to see how different it was and why Ferrari abandonned it.
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PhillipM
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Re: Push rod on upright suspension - an examination

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I mean, even in more recent times Mclaren had it when Hamilton first got on the scene - the FIA banned/restricted it.

marcush
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Re: Push rod on upright suspension - an examination

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The concept of moving away the pushrod mounting from the king pin axis
is weird as the suspension spring is unloaded when applying steering lock.
The car has more front rideheight in straight ahead steering position and actively steers darts into the corner hunting for more steering lock...
You could counter this maybe by applying significant caster and caster trail but does all this provide any useful
steering feedback to the driver at the limit?
I never drove such a car , nor have I engineered such a car (current F3 cars
of Dallara offer this feature as a setup option ),but generally a driver feels the front grip maxing out with the steering getting lighter .I imagine this concept is
destroying all this delicate feedback ...