F1 PITSTOPS EXPLAINED
What is regarded as a good pitstop these days?
For a standard tyre change, a team should aim to be averaging 2.5 seconds. The important thing is consistency. It is no good doing one stop at 2.2 seconds and three others at 2.9. The best stops this year have been around that lower target, although there is always a little discrepancy between the times shown on the TV and the numbers the teams work with.
Why are pitstops so much faster these days?
Until refuelling was banned, there wasn’t much emphasis on the tyre-change aspect of a pitstop. Since refuelling took anything from six seconds upwards, there was plenty of time to change the tyres. It was hard to speed up the refuelling because the flow rate of fuel was regulated, so the only time that could be shaved off came from a clean connect and a rapid disconnect of the fuel hose when the fuel flow stopped.
What are the secrets of a good pitstop?
Having good equipment, lots of discipline, and practising over and over again until the process becomes second nature. That said, it is impossible to recreate the nervous tension of waiting for a car to arrive at the pitstop area, knowing that the actions of a few seconds can put your driver out with an improved situation, or conversely lose that hard-won track position.
How do teams practice and how often?
There are two training regimes, those done at the factory and those done during a race weekend. At the factory, regular practice is organised in a special area that replicates the pitlane area where a stop is made. A dummy car will be used, which will have all the latest hub details so the crew can train in a realistic mode. The car may rely on human power to propel it into the pitstop area, although some teams use low-power engines to provide the drive. In addition to this, teams have various rigs for practising aspects of the pitstop and to check and calibrate their equipment.
Do you practise for unusual events, or is it better just to deal with these as they occur?
There are many scenarios that differ from the routine single-car pitstop and all of these have to be practised because although they may occur infrequently, they can still make the difference between achieving a good finishing position and losing it. The most frequent non-standard stop is a nose change. This can be quite tricky to perform, since the nose assembly is both heavy and unwieldy. Often these tend to occur on the first lap when the pit crew have just run back from the grid and are still in the process of readying the equipment. Even so, we would hope to be changing the nose and all four wheels in well under ten seconds.
What about the equipment used in pitstops – is that being developed all the time?
The engineering behind pitstops is both detailed and sophisticated. All F1 teams use wheel guns developed by Italian company Paoli, but they will often strip and modify these to their own exacting requirements, attempting to improve the gas flow that runs through them. Indeed, until it was banned, many teams used helium rather than compressed air to drive the guns in the search for improved performance. The detail design of the hub and wheel nut is also fundamental to a good pitstop, with most current designs using a very coarse pitch but a very ‘loose’ thread. The nut itself, and the socket that engages it, are multi-drive devices rather than the traditional hexagonal nut, so the socket can engage with the nut first time.
How do the lights on the pitstop gantry work?
Time was when the driver looked solely to the lollipop man. The lollipop man controlled the pitstop, and when he was satisfied that all work had been properly completed, he would lift the ‘lollipop’ to allow the driver to launch. These days we could not accept the multiple sequential human reaction times involved in such a process, and so a system of lights is used. The driver holds the car in first gear with the clutch pulled. The men with the wheel guns will have followed the car in and will be engaging the nut before the car comes to a halt. With the wheel nuts captive in the wheel, the process of loosening the nut also starts to pull the wheel off. One mechanic removes this wheel as another one positions the new wheel. During this time the gun man will have reversed his gun and will follow the wheel on to tighten it, a process that takes just half a second. As soon as the wheel is tight he hits a button on his gun. When the computer detects two ‘tight’ signals, it automatically drops the jack. Once it detects that both jacks have been dropped, it changes the lights to green to allow the driver to launch.
It sounds like expensive equipment.
It is. Each wheel gun costs around £3,000 and there are two at each wheel station (plus extras for the garage itself and for use on the grid). The sockets cost £1,000 and a complex auto-release swivelling front jack will cost many tens of thousands of pounds. Even the wheel nuts cost over £300 and around 24 are made new for each race, so, as ever, the search for speed does not come cheap.
What of the human element: how do you go about transforming a mechanic into a wheel-change guru?
A pitstop mechanic primarily needs to be strong and fit. The wheel guns weigh 3.5kg and produce a torque of over 3,000ft/lbs, so just handling these devices requires a certain degree of athleticism. Couple that with the nimbleness needed if the car stops slightly awry and you can see that the human performance element is all-important. At Williams we employ a qualified osteopath to train our crew in the search for perfection.
Practice, consistency and having the strength to operate the heavy wheel guns are key to getting pitstops right
Pat Symonds explains