10 replies to this topic

[Sisyphus]

For the past few years, the upper front suspension arms in head-on photos of F1 cars have looked peculiar to me. 

 

Traditionally, the inboard top front suspension arm pivot would be closer to the ground than the outboard top pivot.  This causes camber to go more negative on the loaded outboard side as the chassis rolls and thus give the tires more grip.

 

But the photos I've seen the last few years, particularly with Mercedes and Red Bull (but I think probably with all of them) that the inboard pivot seems to be higher than the outboard pivot which will cause the camber to become more positive.

 

Can someone explain what is going on?  Is this an optical illusion--I think flexures are now used instead of rod ends but I don't see why that would change what the tire wants?

 

Thanks.

[gruntguru]

An image illustrating your point would help.

 

Angle of the top arm in front view is only half the picture. It is actually the angle between top and bottom arms that determines camber change at a given "instant". Extend the line passing through the top arm spherical joint centres until it meets the equivalent line for the lower arm. If the intersection lies outside the track, the camber is increasing (towards positive) in bump. If inside the track camber will go negative.

 

Obviously the intersection point may move when the suspension travels more than an infinitesimal amount.

[Bloggsworth]

There's naff all travel in modern F1 suspension, normal rules about roll centre hight, camber change and changes in track width have gone out of the window. IIRC, back in the 50s to 70s, the front roll centre used to be below the rear, roll centre height was tightly controlled in order to maintain neutral balance, too low at the front relative to the rear = oversteer etc. Geometrically, the three controllable elements, camber, roll centre and track, only two of which can be wholly satisfied at any one time, do their bit. Nowadays aerodynamics mostly control the roadholding/balance equation, and the rear suspension maintains traction, while the engineers work some magic with springs and dampers to overcome the incredibly high front roll centre which which appears to put it above the CofG. and ought to make the front want to lean into the corners like a power boat! This is a result of the need to keep the suspension arms out of the critical airstream - I've probably read this all wrong and, hopefully, the real engineers on this forum will put me straight...

 

 

Sorry, can't help correcting my grammar and punctuation.

Edited by Bloggsworth, 22 November 2024 - 23:25.

[Thekirkshop]

F1 truism: It doesn't matter how bad your kinematics are if you don't let it move.

[Greg Locock]

Colin Chapman: Any suspension, no matter how poorly designed, can be made to work reasonably well if you just stop it from moving

[Magoo]

Colin Chapman: Any suspension, no matter how poorly designed, can be made to work reasonably well if you just stop it from moving

 

I love that quote. 

[Greg Locock]

I occasionally remind myself of it when reading some of the FSAE posts. Their aero cars have 25mm of travel by regulation, and then fit stiff springs to keep the aero perfect. Quite what the tires make of all this i don't know

[Magoo]

The version of the Chapman quote I know, which may well be incorrect, is "Any suspension will work if you don't let it." 

[Greg Locock]

That's how I remember it, but the one I used came from a quotes website. I expect he said it more than once.

[Bloggsworth]

The version of the Chapman quote I know, which may well be incorrect, is "Any suspension will work if you don't let it." 

He clearly forgot that when the Lotus 30 came along...

[Nathan]

Aerodynamics, in particular where to locate the bottom arms to the chassis (then dictating the top).  If you look at late 90/early 00's cars you see many had a 'single keel' to make the connection, over the year F1 worked to get rid of the keel.