Hi!
In Formula 1 the cars have really long wish bones, because of the very narrow nose.
In all other racing, say LMP, the cars have very short wishbones, because of the wide chassis.
So the suspension is decided by the chassis layout.
But is it much of a drawback in terms of engineering to have long wishbones ? Does it matter ?
The only way to close a stupid question is to give a smart answer
theres a lot more to this than chassis width....and track change in bump to consider.
This is just one hint why some cars run their tyres hotter than others.
Think about installation stiffness,track, inclination ,etc when changing length of 1 or both wishbomes on each side ,the can of worms you are likely to open does not correlate to the simple question you asked....as we see every other weekend.
Its all a big melting pot really. A theoretical ideal has the rotation centres of the suspension as approaching infinity so the wheel travels solely in the vertical plane with no horizontal or camber shift - but that might prove a bit tricky for overtaking. Depending on designed-for body roll and spring rate (and unequal wishbone geommetry if that floats yer boat) to maintain the contact patch at a given speed on a given bend, a change in camber with the suspension compression may improve things depending on how rigidly you plan to run things. Short top wishbones could give the effect of amplifying camber with greater suspension compression. Oh, and watch out for bump-steer as well. Disclaimer - dicking around with the suspension on your car (or anyone elses for that matter) to try this is NOT recommended.
When designed properly, the arms of a "wishbone" in a double A-arm suspension are primarily tension/compression members. The greater length/section modulus characteristics of a long wishbone tube are not so critical in tension, but in compression it will be much more likely to buckle.
As others have noted, longer effective link lengths tend to produce less camber change and less roll center movement for a given vertical travel at the wheel.
"Q: How do you make a small fortune in racing?
A: Start with a large one!"
F1 wishbones use flexures as chassis attachments, rather than the ball / rose joints / hinges that we are used to seeing on most other cars as suspension / chassis attachments. So from a structural perspective an F1 wishbone is more like a cantilever in bending than a pin-jointed structure, which is how most suspension members are analysed. This means that a longer wishbone will be less stiff than a shorter one. Given the very small suspension travel of an F1 car, this change in stiffness would have to be accounted for in the suspension modelling.
Yes, the inboard suspension attachments are now typically flexures, as opposed to bearing elements, but that does not significantly change the loading the A-arm itself experiences. The "legs" of the A-arms must still be primarily tension/compression members, since that type of structure would not otherwise be able to withstand the suspension loads. The only bending moments the A-arm should experience are due to the ball joint friction or flexure bending resistance at the pivot points.
As for stiffness of the suspension members, consistency and repeatability from one chassis set-up, or set of parts, to the next is much more important. With an F1 chassis (or any chassis running race tires), most of the suspension travel occurs in the tire sidewall and not in the actual mechanical links of the suspension. So having super stiff suspension members does not provide a whole lot of tangible benefits.
The only exception would be the spring/dampener pushrod. Even though a pullrod would have less aero drag and would be lighter, pushrods are used because the slender pullrod is very limited in the amount of rebound force/dampening it can transmit back to the dampener unit or roll bar.
"Q: How do you make a small fortune in racing?
A: Start with a large one!"
