Setup on a wet track

[LogicPro]

I have looked for answers on this topic, but I haven't found really an explanation for this...

Before the start of a GP2 race (I think it was 4 or 5 years ago, but I don't think it's a relevant data) it started to rain and the cars were already on the grid ready for the warm-up lap. The mechanics then started to work on the setup on the cars, in order to adjust it to wet conditions.
In particular, former F1 driver Ivan Capelli (now commenting F1 races), pointed out that the mechanics were removing the torsion bars on the front suspensions in order to give more grip in wet conditions. Why were they doing that?
I am almost sure he said torsion bars and not anti-roll bars (which may be adjusted too, in case of wet track), while I'm not so sure that they actually removed the torsion bars and not substitued; maybe he said "removing" without specifying that they would fit softer bars...

[silente]

I am italian too and, i can tell you, although Capelli is not bad, they say a lot of b....t

What you tipically do, in a single seater, when it's raining (and the track is significantly wet) is to increase ride heights (to avoid the car to be lifted by the water) and to reduce camber, to increase the draining effect of tyre cuts.

Some engineers sometimes also remove ANTI ROLL BARS. the idea is that a soft rolling car is more predictable, although they often don't even know how the Total Lateral Load Transfer Distribution is changing when doing so.
Some of them only remove the rear anti roll bar, to increase traction, but it is also not always ideal.

In anycase they could not completely remove the Torsion Bars, otherwise the car (if you exclude the effect of third springs, at least) would fall on the floor!

They could opt for softer ones, to again help mechanical grip. Since the car experiences smaller accelerations, you anyway could be in a position to choose a "softer" suppor for body movements, since the external forces are smaller.

Wether they really help to increase mechanical grip this way or not is another story.

[Lycoming]

ARBs are usually torsion springs, so they are still torsion bars if that's the case. If you don't have a heave spring, removing the side springs means your car will sit on the ground.

[thisisatest]

... and to reduce camber, to increase the draining effect of tyre cuts.

im not so sure that's accurate. a heavily cambered tire would be quite resistant to hydroplaning, with what is essentially a narrower footprint. i believe they would reduce camber because with reduced traction comes reduced cornering loads, so there is less force to lean the car over and deform the tire, etc. so less camber is needed. i believe raising the ride height is to accommodate the softer springing. softer springing would not be to "increase traction", as wouldnt you always want to increase traction? it's to slow the reactions of the car, making it easier to drive, if ultimately lowering its potential performance slightly.

[silente]

im not so sure that's accurate. a heavily cambered tire would be quite resistant to hydroplaning, with what is essentially a narrower footprint. i believe they would reduce camber because with reduced traction comes reduced cornering loads, so there is less force to lean the car over and deform the tire, etc. so less camber is needed. i believe raising the ride height is to accommodate the softer springing. softer springing would not be to "increase traction", as wouldnt you always want to increase traction? it's to slow the reactions of the car, making it easier to drive, if ultimately lowering its potential performance slightly.

how would a high cambered tire use its cuts to take out water from the contact patch (let's say in braking, for example) ?

Anyway, i never said i agree with those who change spring stiffness to adapt a car to rain conditions...

And when you go with something like 17 mm static ride height, i can tell you could have big problems with heavy rain because the car could behave more like a boat...this is the first reason you normally increase ride height, at least in my experience. This is not at all a consequence of the softer springing, sometimes you do that also if you don't change the spring stiffness.

[thisisatest]

A cambered tire, mainly up front (and having an f1-type car in mind) would not be relying on the channels to evacuate the water. running, say, 3degrees camber puts much less of the tire on the road, with a pressure concentration on the inside shoulder. One could draw similarities to motorcycle tires. It's a bit of a reach, but you get where I'm coming from.
I'm not saying one would definitely focus on doing this, I'm just saying that the reason for straightening up the tire is not for better water evacuation.

[LogicPro]

i believe raising the ride height is to accommodate the softer springing. softer springing would not be to "increase traction", as wouldnt you always want to increase traction? it's to slow the reactions of the car, making it easier to drive, if ultimately lowering its potential performance slightly.

In fact I was thinking the same. So softer springs (and also softer anti-roll bars) don't increase traction in both dry and wet conditions, right?
I understand that if a driver can feel the car even with a stiff setup, then he may go faster than with the same car with a soft setup on a wet track. So it's a matter of making the driver feel the grip, while loosing the least possible performances due to a softer setup...

Thanks all for the answers; maybe Ivan Capelli was simply saying "remove" while they actually changed the torsion bars or they were removing the anti-roll bars and he called it torsion bar... removing torsion bars doesn't make sense indeed

[trinidefender]

Well I know the wet and intermediate tyres have a larger rolling diameter than the dry tyres. Can't remember the exact numbers so if anybody here knows them. Allows teams to make quick wet setup changes during the pits because they know by how much the ride height is changed just by changing the tyres and makes less work on the suspension to be done.

Of course the siping is relied upon to drain the water in the tyres. Why do you think the tread pattern is asymmetrical. To put the correct amount of siping where it is most needed and more rubber on the outside of the tyre where the camber causes it to be less loaded up

[LogicPro]

Well I know the wet and intermediate tyres have a larger rolling diameter than the dry tyres. Can't remember the exact numbers so if anybody here knows them. Allows teams to make quick wet setup changes during the pits because they know by how much the ride height is changed just by changing the tyres and makes less work on the suspension to be done.

Of course the siping is relied upon to drain the water in the tyres. Why do you think the tread pattern is asymmetrical. To put the correct amount of siping where it is most needed and more rubber on the outside of the tyre where the camber causes it to be less loaded up

The intermediate tyre has symmetrical tread, while the wet tyre isn't symmetrical... however I don't know if this is due to the camber angle or other reasons such as to remove water more efficiently...



As for the ride height, if I'm not mistaken, the rolling radius of the intermediate tyre is 5 mm larger than the slick tyre, while the wet tyre radius is 9 mm larger than the slick one.

[trinidefender]

Well look at the siping on the wet tyre. The finer, more numerous sipes are placed toward the inside of the tyre where the load is the highest to make sure there is always a chennel for water to flow away while further out on the tyre where there is less load the siping is further spaced out the each block of rubber is larger to generate more grip on the corners(assuming the tyre doesn't hydroplane)

[olefud]

Generally, a rain tire works better with a higher loading to squeeze water out and get the tire in better contact with the road. Raising the CG is one way of transferring more load to the outside tires.

Softer springs keep the tire in better constant contact with the road surface so the sipes can do their job. Hard springs tend to allow the tire to intermittently get on top of the water which establishes a hydrodynamic support that is difficult to undo, i.e. hydroplaning.

[marcush.]

in wet conditions you got less grip ,in all directions ,so with that in mind your cornering forces are lower ,and the car will simply not be able to use all the camber you have dialled in ,resulting in less than ideal temperature spread across the tread.With this you already have cut a compromise in terms of braking and acceleration -as the neg cambers will rob you at least of some tyre footprint ..so if you know it´s going to be wet on sunday you have all reason to think again if the increase tyre diameter is all that´s needed to be competitive..

[marcush.]

we see teams not even replacing damaged front wings after accident damage during a race so it seems unlikely you would see a team prepared to make mechanical changes worth a few tenths per lap and invest minutes to perform those changes...it just does not add up .
The non change of front wings does amaze me though..as the loss in tyre endurance due to balance shift should outweigh the time loss to change the front wing easily.

[GitanesBlondes]

What you tipically do, in a single seater, when it's raining (and the track is significantly wet) is to increase ride heights (to avoid the car to be lifted by the water) and to reduce camber, to increase the draining effect of tyre cuts.

Raising the ride height is one of the simplest, but most important things one can do in a single-seater in the wet.

That was one of the things that had Williams done this at Donington in 1993, they likely could have had a chance to win the race. Since they kept the dry setup, they wound up having to deal with hydroplaning due to how far away the chassis was from the ground...something like 15mm if I remember correctly.

[thisisatest]

The non change of front wings does amaze me though..as the loss in tyre endurance due to balance shift should outweigh the time loss to change the front wing easily.

I have a theory that a damaged endplate does not hurt balance that much these days, as the endplate works a lot to get air smoothly around the front wheel to be used by the rear wing. A damaged endplate hurts front downforce, but also affects rear downforce to a degree. Overall downforce is reduced, and probably some aero efficiency. Who knows, maybe that side's radiator runs hotter too.
It probably also depends on the track and the driver. Upsetting downforce and balance could hurt your lap time much more on some tracks than others, and very good drivers (aren't they all?) are quite adaptable to the circumstances.