The use of the clutch and double-[de]clutching in historic racecars discussion

Google Docs about double-clutching


There is a lot of information that is not necessarily accurate floating around about the clutch pedal. In racing sims using the gmotor2 engine, it's used to get off the line then forgotten about for the rest of the session in the ubiquitous autoclutch sim racing culture that currently pervades our hobby. The clutch-slip used on the Howstons heralds a new era for sim racing with rFactor2. Now shifting has become a skill and the new driveline model in the pipeline is going to bring us that much closer to simulating driving a race car.

The information on shifting a racecar is sparse, misunderstood and hard to find. To complicate matters, each racing driver has a different technique for shifting and each era of racing requires a slightly different technique. Modern cars dog boxes have better designs, better materials and area lot more reliable than was available in the 1950's when Piero Taruffi wrote The Technique of Motor Racing. In my document, I quote Niki Lauda who used double de-clutching to shift down but crashed up through the gears. Bob Bondurant and Skip Barber recommend Double-clutch downshifting. On upshifts it is not used as much, but on downshifts it is. In endurance racing the double-clutch has to be used to preserve the gearbox for the race. It can also be used to preserve the gearbox if the team has limited budget or if the series rules limits gearboxes used in a season. In a sprint race one-off with a big-budget team, all bets are off and the fastest method is used. But double-clutching is used on downshifts if the box has to last.

 

This is an interesting read, thanks for that Guy! I have been double-clutch downshifting in my cars/trucks since I started driving, my dad taught me how to do it. Even though my truck doesn't require it (I think), I still do it...just a thing he ingrained into my brain I guess. Sim-racing is a totally different story though, considering I don't yet have a set of pedals that even has a clutch. So, with sim racing, I just use auto-clutch out of necessity.

That leads me to a question about clutching in rF2. Since I don't have a clutch pedal to find out, how does the clutch actually 'work' in rF2? Is it completely digital, as in 'engaged' or 'disengaged'? Or, is it analog like a real clutch with friction points, etc? Basically, would I get a more realistic experience by using a pedal with variable movement, rather than using an on/off button? Or would a digital on/off button on my wheel give me the same exact experience (albeit with the hand instead of foot)?

 

Not entirely right at all in the black and white sense you paint, and this is part of the problem. There are too many cars, too many techniques to understand easily, too many techniques.
What I'm saying is it's exceptionally difficult to say if someone had a gear failure because of wear, or because they did something silly, or simple part failure that happens regardless. The Lotus 49 comes to mind, a car that had a gearbox made of glass. Or were Clark and Hill just incompetent shifters? It's not black and white at all, on any car. Yes, the instructors will want you to double clutch - that is why they are instructors. They want to teach you the most perfectly flawless way and technical way, though that isn't the only way ever to be used.

Even on "historic" cars it's not always used, some guys just shift at a lower RPM. Some HnT more deliberately. Double clutching is a "old world" technique, I bet in reality you find those drivers who use double clutching simply do it because A) it causes no harm to anything, infact it prevents the possibility for damage and B) they've been doing it since forever. Even then you will find that drivers didn't always double clutch, even in the same race. It's most commonly used in large braking zones when skipping gears where you have a large difference in speeds to go through.

Double clutching a paddle shifted semi automatic car like a GT3 car is not just slow, it provides zero benefit - there is a reason the gearbox doesn't work like that. Just to throw that out there and make that clear from the start.

The same goes for pretty much any car with a lever operated sequential dogbox as well such as a V8SC. For every driver you see in the V8s using the clutch on downshifts, you'll probably find another who doesn't. A large portion of those drivers are using the clutch on downshifts just to help smooth things out / make rev matching more forgiving with their high power + high torque cars that will wheel hop with ease (something AFAIK rF2 doesn't have). Watch some pedal cams from the NASCAR guys on road courses - some clutch on downshifts, some never clutch, and then there was Kasey Kahne who was clutching on upshifts but not downshifts.

Not a single one of them were double clutching, because the technique itself is not required anymore. Infact, I'll throw this article in here. Say they are selling gearboxes and it should be taken with a grain of salt sure, but what is said is indeed truth in the regards that modern boxes should be shifted fast and crisply - the exact opposite of slow and deliberately. Just in case any of you guys like to run sequential cars with a H pattern...
http://www.hewland.com/svga/advice.html

But yes, if you want maximum longevity and less POTENTIAL for damage it's a good idea to double clutch in historic cars with boxes made of weaker materials, particularly when the speed differential is large, which is something you will with cars that have fewer gears. Not only that it is also much easier to get right as it is a slower technique to help keep the rear end of the car from becoming unsettled. I say potential, because it is just that, potential. As with most things, if it has more steps it's probably slower but more idiot proof.

Tool bag - it's good to have a large one, never know what you will see.

 

You should really read my doc before commenting on it. I address all that. This is mostly aimed toward historic cars, not modern ones.


I changed the thread title to clear this up

 

I did read your doc. It's written in a very black and white manner. Your title was also very nonspecific in regards to what you were talking about specifically, I figured I'd throw more information in there to clear things up. Especially seeing how people like to run everything as a "ye olde classic" H pattern, where if they were mislead to try and double clutch they would really just be doing things... backwards.

It's like the LFB v RFB argument. One guy telling you to RFB and a fast guy saying that he RFB doesn't mean that the only way you can use the pedal is with your right foot. The only time you can't LFB is when the car literally forbids it - if you catch my drift here.

 

Please explain how I make this black-and-white so I can tweak it to explain myself better. I am only writing what the real race car drivers have written in their own words in the books I have scanned.

 

I agree with Empty box. Many drivers still use regular single clutch presses, but true double clutching, like I said before, is a thing barely required after around maybe the 60s or so, as long as they used the regular single clutch press that has been good enough 95% of the time rather than having to use double clutching.

I think I hear guys in huge semi trucks still double clutching.

 

Reliability is your bread and butter.

Road Ranger and Spicer transmissions in trucks are a art form to drive and notorious for spitting out teeth and drivers . p

Many truck drivers have died missing a gear.

 

In a truck the first motion shaft and clutch disc are very heavy and have a lot of momentum/inertia. Even with a synchro box the synchros would have to work quite hard and double declutching relieves much of the load on them.

 

guys, very interesting discussion for me. I kindly ask Spinelli and Empty box to provide some kind of examples like Guy did. It would enrich the topic. I understand that it is not so easy to dig through your memories and remember where it was seen and heard, but I would really appreciate such effort.

 

Don't want to get off topic.

My dad used to carry a spare layshaft and clusters in oiled rag and box under his seat.

That taught respect your equipment I bet.

Unlike today a truck did not drive past without stopping to help or a cuppa and a yarn.........

View attachment 10551


On topic always liked the Netkar gearbox.

 

Great stuff. Havent had this interesting topic on these forums in months. I really hope that rF2 gets a realistic clutch model, that just would be pure awesomeness.

 

I have been watching racing for 14 years, all kinds. In the 20,000 (not literally) onboard videos I have ever seen, maybe 6 of them had people doing double clutching, the rest were just normal clutching (obviously with rev matching on downshifts), or no clutching (obviously with revmatching on downshifts), or a mixture of both (many times clutchless on up but still using the clutch on downshifts).

And I can assure you 99% of the F2, F3, F-This, F-That, videos I have seen In my life were using no synchros. The F1600's I drove used no synchros, the few different F2000s I drove had no synchros, the 450ish hp prototype style car I did a 2 day test in had no synchros. You clutch once per gear change, not twice, and you make sure you blip on down shifts, and you better get that damn blip correct or your rear end is going to be getting all wild on you especially when you're really starting to approach the limit area under braking. Some people were doing clutchless downshifts too, blipping while passing neutral (similar to how we do it in sims when using no auto-clutch and no auto-blip, while not owning/using a clutch pedal), but it is risky business. Clutchless on the upshifts is much easier and less risky than clutchless downshifts. As long as you match the revs correctly the gear will go in beautifully. With the racing clutches, flywheels and non-synchro gears you can do everything so fast (if you match revs) bang, bang, bang, gear to gear to gear, but its much more un-forgiving if you don't get it correct. It's also harder to shift nicely while just cruising around at low revs, low throttle, but in racing conditions non-synchros (with proper revmatching) are so much faster.

 

With my Fanatec pedals it feels like the real thing. So real that when I first turned autoclutch off, I stopped the car's engine (the Brabham's, but the Corvette's seems to me even more demanding) several times while shifting in the first gear and accelerating the car... just like I did long time ago when I learnt to drive a real car. I would not want to drive street cars in a sim without clutch anymore

 

How about players who don't have clutch pedal?

 

Another contribution from Graham Hill from early 1966 - Graham Hill Grand Prix Racing Book. This is from a section where he compares racing an F1 car with an ordinary road car.

I would also point out that some F1 cars did have synchromesh gearboxes, such as the Lotus 25, 33 and 49, and the Cooper T81. And synchromesh gearboxes were used in many sports cars/prototypes such as the GT40 and the Porsche endurance racing cars in the 60s and 70s.

 

I wish that Hill explained HOW he actually shifted, that'd be interesting to know.

There is no doubt that cars CAN be shifted without the clutch. There is no doubt that drivers have different techniques. Comparing road cars and big trucks to racing cars is of little use- race cars have race car gearboxes. But going through my books I have (I went through all of them and this is all I could find) the overwhelming majority use double clutching up through the 1990's. To me, the most convincing argument is that a 3 time F1 world champion clearly explains exactly what he does when he shifts. He was also a sportscar champion.

I'm not considering modern cars. This discussion is about historical race cars and old gear boxes. Technology has largely obviated the need to double-clutch.

 

Personally I want the option for rF2 to accurately as possible simulate the historic drivelines that existed prior to the advent of semi-automatic transmissions. The consenous seems to be that the historic transmissions were for the most part dog boxes, unsynchronized, and that some technique of rev matching was required. I wasn't there so I can only rely on what's reported by others. As I mentioned in the other thread I did find a discussion on this topic in the Nostalgia Forum at Autosport. The Nostalgia forum serves posters whose passion is auto racing history. Many of the posres claim to have raced in the lower formula during the 60-70 time period. I believe the consenous there was the most common method was doubleclutch on downshifts and clutchless upshifts though some said this method was not universal. For what its worth in the movie GranPrix the drivers are shown double clutching.

AT any rate the current Howstons require rev matching by throttle lift on up shifts. I would like the missed upshifts to also be accompanied by the sound of grinding gears I think.
SW

 

Nice document Guy, very appreciated, thanks!

 

In sim racing I've always done it a somewhat naughty way (perhaps?). I push in the clutch pedal and then rev the engine as I'm going from (for example) 3rd to N to 2nd. But the clutch doesn't come out while I'm in N, so it's essencially a straight shift from 3rd to 2nd doing the blip while the clutch pedal is down. I honestly have no idea if this is at all valid in the real world but it works in sim racing.

In my real car the pedals are positioned badly for this, It feels almost impossible to be able to brake and blip the throttle at the same time, though it's easy with my G27 pedals.