Part-clutch part-throttle in F1

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
marcush.
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Joined: 09 Mar 2004, 16:55

Re: Part-clutch part-throttle in F1

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the clutch always is in a slip situation whenin use ,even if it is only microslip.
The problem with Carbon and many other clutch materials is the characteristic of the friction coefficient with increasing speed deltas ,in a nutshell as the rpm drops the clutch bites harder ....so the natural reaction of the operator reducing the rpm is counterproductive as it leads to a stallsituation.

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raymondu999
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Joined: 04 Feb 2010, 07:31

Re: Part-clutch part-throttle in F1

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SectorOne wrote:
raymondu999 wrote:I don't "stand" on part throttle/clutch, I use it to transition between braking and getaway.
Everyone does this so i´m confused what you actually do different then the rest of us,
Often we have traffic jams with cars moving 1m at a burst, but with pauses of several seconds in between - at that point it just gets too troublesome to brake at all.
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SectorOne
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Joined: 26 May 2013, 09:51

Re: Part-clutch part-throttle in F1

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So when it´s an uphill section to the red light you will slip the clutch in order to not move backwards instead of using the brakes.
I think i understood it fully now.
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marcush.
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Joined: 09 Mar 2004, 16:55

Re: Part-clutch part-throttle in F1

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this is called a hillhold btw and is a normal test for a transmission be it automatic or manual .I cannot go deeper into it unfortunatelly but it is one of the severe tests any clutch(not the individual part that is going into a car ) and transmission has to go through for approval.Needless to say there are time limits for the clutch to survive such an abuse.
One needs to acknowledge it´s not just the clutch linings but also throwoutbearing and of course the axial bearing of the engine which is held under load for which it is not really designed.. so it certainly is better to avoid such practise....
for the newer cars the hillhold assist does apply the brakes automatically when a creep backwards situation is detected so you do not need the handbrake for the take off .
additionally the automated boxes of todays help with selecting the right parameters for a smooth creep from standstill -or should i say should help? anyways .... and it can be adjusted :
http://www.stemei.de/pages/coding/vw-ca ... l-hold.php

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raymondu999
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Joined: 04 Feb 2010, 07:31

Re: Part-clutch part-throttle in F1

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SectorOne wrote:So when it´s an uphill section to the red light you will slip the clutch in order to not move backwards instead of using the brakes.
I think i understood it fully now.
Not necessarily to the red light, but to the traffic congestion is another possibility.
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SectorOne
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Joined: 26 May 2013, 09:51

Re: Part-clutch part-throttle in F1

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raymondu999 wrote:Not necessarily to the red light, but to the traffic congestion is another possibility.
Ok but i think this is normal if the road is flat. Sounds like your average congestion.
It´s quite different from the first post though which got me confused.
In a manual car, when I drive up a slope, if I need to stop at the slope, I will feather the throttle and clutch to a point on part-throttle and part-clutch until the car is at a standstill without using brakes.
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riff_raff
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Joined: 24 Dec 2004, 10:18

Re: Part-clutch part-throttle in F1

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Kiril Varbanov wrote:....Otherwise, I agree with what riff_raff says. The tiny carbon fiber disks can take about 900 degrees, but they are easily overheated in slip conditions due to the great friction.
While it is true that 13K revs are a ballpark number, I think you can afford a bit more if you have had a fresh one.....
In simple terms, the heat load absorbed by a slipping clutch is the equivalent amount of power lost from friction. The power converted into heat in the clutch disks can be roughly calculated from the relative rpm differential between the sliding clutch disks times the amount of torque being applied at the clutch input where slippage occurs, divided by the appropriate shaft HP constant. Convert that HP into thermal energy, and then calculate the temperature rise that thermal energy input produces in the carbon clutch disk mass. If the heat input to the 1.0kg mass of carbon clutch disks from slippage produces a temperature rise in the carbon disks beyond what they can safely handle structurally, then there is likely a problem.

In reality, with regards to thermal overload of a carbon clutch, things are a bit more complex. Due to relatively poor heat transfer properties thru the thickness of carbon clutch materials, the temperature right at the disk surface where the slippage occurs can be significantly higher than the rest of the clutch disk body. Carbon clutch disk materials can begin to rapidly degrade from oxidation at temperatures in excess of 1800degF.
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