Double Clutching in Simracing

Double Clutching.png


Hard, but rewarding.


Double clutching is without a doubt a very popular driving technique, one that is still being used nowadays in particular situations or circumstances, like truck driving or when a cars’ synchros are completely or very badly worn out.

Nevertheless, what is it exactly about? Well, basically, it allows you to shift (downshift mostly) very smoothly in case of absence of synchromeshes in the gearbox. To go a little bit more into detail, let us go with a practical example: let’s say that (with a manual transmission obviously) you want to go down from third into second. Double clutching means that the first thing you want to do is pressing the clutch, which will allow the engine to rotate at its own speed while the clutch and the transmission will have matching speeds, faster than the engines’. You now move your gear selector from third to neutral. This will let the clutch and the transmission to now also rotate at different speeds. You then release the clutch, meaning that the engine and the clutch will now be coupled back together and rotate at a same speed. What is happening at this point is that you have synchronised the clutch and the engine and disengaged your previous gear, but the transmission (and so the gear you need to move in) will still be rotating at a faster speed than those two. Therefore, you blip the throttle, while you may or may not be holding the brake depending on the circumstances of why you are downshifting, and so you will get the engine and the clutch to rotate at a higher speed, very much near the one of the transmission. At this point, you can then quickly engage back your clutch and move your selector from third to second, providing this way a smooth and synchronised downshift, and thus completing the process.

Why double clutching is not very frequently used while upshifting is because when you are actually going into a higher gear, it means that your engine is already going at a speed that virtually matches the next gear. Therefore, they are already pretty much in sync.

With synchromeshes though, this process is basically unnecessary. You just have to heel and toe to provide a smooth downshift, given that the car doesn’t feature an auto-blip system in which case blipping is useless too, and the synchros will match the speed of the gear you have selected with your engine.

So why should we bother with double clutching in sim-racing? Well actually, just for more realism and immersion. While the heel and toe technique can suffice with road cars, unless we are talking about cars from the Veteran or Vintage era, it is definitely not accurate for sportscars and single seaters up to the early nineties. These cars featured dog-rings, rather than synchromeshes, and while this particular kind of setup, called a “Dog Box”, could allow you to shift without even working the clutch pedal, it was only in case of necessity that it was operated this way. Mark Donohue recalls an episode of his racing career when he had to work up a sweat to learn how to drive not double clutching a Ferrari 250 LM, which he was sharing with Walt Hansgen, only to find out, truth be told, that rev-matching was easier than he feared.

Here is an excerpt[1]:

Walt drove the first two-hour stretch. When it was my turn, he came in and told me that the clutch linkage was out. It wasn’t possible to disengage the clutch at any time. I thought, “Oh ****! Now what?” He must have seen the panicked look on my face, because he got right to work explaining how to drive without a clutch. I could get going by using the starter with the car in gear. From then on I had to shift by matching engine rpms with the throttle. To upshift, I put pressure on the lever while still at full throttle, then let up on the throttle for just an instant, and it would slip into the next gear. The three-four shift was a little harder, because I had to move the lever laterally in the gate and match engine rpms better. Downshifting was somewhat like double-clutching without the clutch, with a little blip in neutral.

Racing drivers used to use this technique while competing and, in fact, those who still teach nowadays the racing technique to amateur drivers suggest learning and mastering the double clutching technique. While the use of it is, in truth, mostly useless today thanks as we said to synchromeshes, except in very particular cases as noted in the opening of the article, it is a testament to the importance it has had in the history of the motorsport. Even in a movie like “Grand Prix”, it can be clearly seen that all drivers (remember that while the film featured actors as main characters it was actually professional drivers who worked as stunts) are practising it.


And since sim-racing is the safest way to learn new driving techniques, because errors and mistakes won’t result in a fatal breakdown of your daily car, why not take the chance to try it just to learn something new, which as always in life may or may not also come useful down the line. As a plus, it would let you get closer to experiencing what racing drivers of the golden era and recent past had to endure inside a racecar for hours, sometimes even days!

Like what you see here at RaceDepartment? Don't forget to like, subscribe and follow us on social media!

 
Notes:
[1] Mark Donohue with Paul van Valkenburgh, The Unfair Advantage, Massachussets-USA, Bentley Publishers, 2000, p. 35.
 
Petrolhead and sim enthusiast, passionate since the cradle about cars, motorsports and simracing. I read a lot, and I love to share what I learned with others!

Shaun Clarke

1000RPM
Premium
Nov 20, 2014
1,912
3,322
45
Double Clutching or Granny Shifting LOL
 
  • Like
Reactions: Dr. Death

Jason Mullin

500RPM
Mar 3, 2018
761
876
I'm a truck driver here in the states and have been double clutching for years. It's quite easy in a big rig as everything is happening so slow matching engine rev with road speed.
Much more intense in racing everything is happening so fast, I need much more practice before it becomes an afterthought as it is when I drive my Semi.
 

Andy-R

1000RPM
Jul 23, 2016
1,206
973
I started off double clutching the 250F in Assetto Corsa, then went online and got absolutely destroyed by people I'm normally competitive against. Once in a blue moon for a bit of fun I try it. The penalty (in AC at least) for not flat shifting is quite large let alone double clutching! It is something that could do with be addressed IMO. Auto clutch/gear systems could be made to replicate shift times that are possible using the correct technique (perhaps with some variation like a human) to make it a level playing field for all players.
 

Andy_J

I hate VR. ( ͡° ͜ʖ ͡°)
Oct 2, 2010
7,800
3,642
Double clutching was used in the old HGV's. I used to do it many many years ago driving 4 and 8 tonners in the military. Never thought it would be done in racing.
 
  • Like
Reactions: Alex72 and HazelR

The-IC

100RPM
Premium
Dec 5, 2016
108
398
Are there any games that actually have a mode/difficulty setting that punishes you for not specifically double clutching though? How do you know you're doing it correctly if nothing really happens if you do it wrong?
 

HazelR

50RPM
Jul 29, 2018
56
24
Double clutching was used in the old HGV's. I used to do it many many years ago driving 4 and 8 tonners in the military. Never thought it would be done in racing.
Oh, I remember 4-tonners, big green Bedfords with the steering wheel on the 'wrong side', no synchro on first or second. Some of the older ones lacked the requisite number of diffs too, which meant bouncing wheels off kerbs to unwind the driveshafts/propshafts when on road!

Double declutching, no power steering and chokes are things the young'uns will never get to enjoy:whistling::cool:
 

Troy Barman

500RPM
Oct 30, 2010
835
470
This isn’t something you can pratice in a game because it’s all based off feedback you get from the shifter. If unless someone makes a FFB shifter which would be interesting.
 
  • Like
Reactions: Medilloni

Mike Kadlcak

100RPM
Jul 23, 2015
195
143
43
I started off double clutching the 250F in Assetto Corsa, then went online and got absolutely destroyed by people I'm normally competitive against. Once in a blue moon for a bit of fun I try it. The penalty (in AC at least) for not flat shifting is quite large let alone double clutching! It is something that could do with be addressed IMO. Auto clutch/gear systems could be made to replicate shift times that are possible using the correct technique (perhaps with some variation like a human) to make it a level playing field for all players.
I understand that w/o flat shifting that u lose time to others. Which btw should be a blown engine penalty if u ask me. :p
But double clutching is used under braking. So as far as ur brake distance is the same u should not lose any ground there. Your feet will just be way more active under braking.
 

Andy-R

1000RPM
Jul 23, 2016
1,206
973
I understand that w/o flat shifting that u lose time to others. Which btw should be a blown engine penalty if u ask me. :p
But double clutching is used under braking. So as far as ur brake distance is the same u should not lose any ground there. Your feet will just be way more active under braking.
Now you mention it I was doing it for upshifts as well :redface: I have an excuse though I'm under 30 and I've never driven a lorry :D I think it would still slow me down a bit not being able to grab the right gear fast enough at times even if I was only using it for downshifts.
 

RobertGracie

250RPM
Jun 4, 2017
342
119
29
If I am driving IRL I tend to heel toe my car through the corners and I dont do the double de clutch routine, its slower from what I found but if I am driving economically I do sometimes do it unnaturally to let the engine revs fall back enough to slip it into gear, but thats IRL I dont do it in the simulators because well I dont have a wheel and pedals I have a controller
 

Mike Kadlcak

100RPM
Jul 23, 2015
195
143
43
I did not drive truck either. But i went to Skip Barber Racing school when i was young :) took the 3 days at VIR. Their cars there have no synchro so they teach u the double clutch way. You can feel and hear the transmission way smoother if u r doing it. If u dont it sounds broken.. works but sounds broken.

Since that day i drove my bmw every day car the same way.. it was smoother on the clutch and gears. And its an amazing training to match revs even in the bmw.
 

protonv5

500RPM
Jan 6, 2017
556
206
DC in SIM racing is utterly useless. It may be fun when driving older cars, but serves no effective purpose.
 

David Wright

1000RPM
Sep 27, 2009
1,257
877
In the context of this thread its perhaps worth noting that synchromesh gearboxes were also used on open wheelers and sports cars/prototypes. Synchro gearboxes were rare in F1 but it so happens the most commonly simulated cars had synchro gearboxes - the 67 Lotus 49 and the Lotus 25. Also for sports prototypes it was quite common to have synchro gearboxes. Porsche for example used sychro gearboxes from the 904 through to the 962. Ford used synchro gearboxes on the GT40. Ferrari also used ZF gearoboxes which had synchro on the P3 and 512 prototypes. Synchro gearboxes were the norm for touring cars and GTs during the 60s and 70s.
 
  • Like
Reactions: Davide Nativo

Mike Kadlcak

100RPM
Jul 23, 2015
195
143
43
Hard ro belive that those lotus cars had that. Synchro gearbox meant more weight in the racecar so it was never used. As its not benefical for the driver to have that or the extra weight.