Watching Formula 1 cars accelerate away from the start line at the beginning of a race raises an obvious question; do F1 cars have a clutch?
The answer, however, is not so obvious. Whilst there is a clutch in an F1 car that has to be operated by the driver, they don’t do it using their left foot. Nor do they have to do it every time they change gear.
Read on for a full insight in to when and how clutches are used in Formula 1 cars.
What does a clutch do?
Formula 1 cars have semi-automatic transmissions. As they’re not fully automatic they still need a clutch.
The clutch in a Formula 1 car sits between the engine and the gearbox. The engine produces the power and the gearbox transmits that power, through a number of different gears, to the wheels and the road.
The clutch is the component that sits between the engine and gearbox and works as a coupling between the two.
When the clutch is engaged it allows the engine’s output to be directly connected to the gearbox. Or, when it’s disengaged, the engine is no longer connected to the gearbox.
How does the clutch work?
The clutch in an F1 car is a mechanical device made up of 3 or 4 carbon plates held in a titanium basket. The basket is attached to the engine flywheel and the plates are attached to the gearbox.
When the clutch is disengaged each plate has a gap between it meaning the plates and basket can spin independently of each other.
When the clutch is engaged a large spring on the end of the basket is depressed forcing all of the plates together. Once all of the plates have come together the clutch acts as one unit meaning the engine is now connected to the gearbox.
When is an F1 car clutch used?
There a number of times during a race when the driver needs to use the clutch in their F1 car. There are also other times where the clutch is activated automatically, not by the driver.
Below is an explanation of each of these.
When the driver is sat on the starting grid with their engine running the clutch must be disengaged as the car’s wheels aren’t turning.
Before the race begins the driver has to build the engine revs to the optimal point. Once the lights go out they must quickly engage the clutch to transfer the engine’s power to the wheels and get the fastest start they can.
This is no different to driving a manual car and having the use the clutch when you come to a stop at the stop lights, and then releasing it when the lights go green.
For the same reason the clutch has to be used by the driver when they come in for a pit stop. As they come to a halt in their pit box they must disengage the clutch to prevent the engine stalling before their wheels stop spinning.
Once their incredibly fast pitstop is complete they have to quickly engage the clutch and accelerate away from their bit box as fast as possible.
F1 cars need to use the clutch to change gear, but this is all done automatically and doesn’t involve the driver.
All the driver has to do is select the next gear with a paddle behind the steering wheel. When they do the car’s electronic brain automatically disengages the clutch for a split second to allow the next gear to be selected.
Infact article 9.3.5 of the FIA’s Formula 1 technical regulations state the driver doesn’t need to use the clutch during gearshifts:
9.3.5: The amount by which the clutch is engaged must be controlled solely and directly by the driver with the exception of : a. Stall prevention. b. Gearshifts.
Do F1 cars have a clutch pedal?
Do F1 cars have a clutch? Yes. But do they have a clutch pedal? No.
Instead they have an additional paddle on the back of their steering wheel to engage and disengage the clutch.
This paddle is not a digital electrical switch, like it is for the gear change paddles. Instead it’s a mechanical paddle linked to a hydraulic oil system directly connected to the clutch.
There have been a couple of different iterations of how the F1 clutch paddles have worked over the last few years.
Dual paddle setup
For many years the drivers had two clutch paddles, one on each side of their steering wheel.
One was the ‘bite point’ clutch paddle and the other was the ‘master’ clutch paddle which controlled the amount of slip.
Both paddles would be pulled by the driver whilst sat on the start grid. Once the lights went out the bite point paddle would be released immediately to get the car moving.
Then the master clutch paddle would be slowly released to try and manage the amount of wheelspin experienced as the driver applies full throttle.
The video below shows David Coulthard explaining how the two-paddle clutch setup works at the start of a race.
Single paddle setup
Nowadays F1 drivers only have one clutch paddle on the back of their steering wheel. This combines the functions of the previous dual paddle setup in to just one.
The first half of the single paddle’s movement finds the bite point. The second half of its movement is used to manage the wheelspin as the car pulls away.
You can see the single paddle at the bottom of the Mercedes steering wheel on the images in the tweet below. It pivots on the left side of the wheel (when it’s the correct way round) but is operated by the driver’s right hand as it spans the whole width.
Why is the clutch on the steering wheel?
Since the clutch is now only used a couple of times per race it’s not as critical for it to be as ergonmically perfect as it once was.
The space down by the pedals for an F1 driver’s feet is incredibly limited. Almost all drivers brake with their left foot, and to give them more room to do so the clutch was changed from a pedal to a paddle.
When were clutch pedals last used in F1?
The last time a clutch pedal was used in a Formula 1 car was in the Forti FG01 during the 1995 season. This car had an H-pattern manual gearshifter, and was the only car on the grid that year to use that type of gearbox and clutch.
The Forti FG01 was raced by Pedro Diniz and Roberto Moreno and started the season a long way off the pace. In their first few races they regularly finished 7, 8 or 9 laps behind the leader. Their fastest lap times were sometimes as much as ten seconds off the pace as well.
The gearbox was partly to blame. Halfway through the season they upgraded to a semi-automatic box and started to see some improvements in their pace.
How much do F1 clutches weigh?
The clutch for a Formula 1 car is very, very small in comparison to a normal road car clutch.
The ZF Zachs four plate F1 clutch has a diameter of just 97mm. In comparison, the diameter of the clutch for a standard BMW 3 series is 240mm, about 2.5x larger.
Being so much smaller and using lighter materials like titanium means the F1 car clutch is a lot, lot lighter. The ZF Sachs F1 car clutch weighs just 1.2kg.
The BMW 3 series clutch weighs a hefty 6.5kg in comparison.
The drawing below is of a 2010 Caterham F1 car clutch design produced by AP Racing. This one had a diameter of 99mm.