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Old 20th December 2004, 16:10   #16
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when i was talking about F1 cars - I meant to say that F1 cars use this principle (whether it is actually being done by computers or humans is not the issue!).

Why did the F1 cars do away with the clutch if it wasn't going to help them going faster? The point here is that clutch use requires more time! When u say that the computers in the F1 cars do everything, what exactly do they do - think about that! All the computers do is change the revs of the engine, so that the gear slots in without the use of the clutch - This is what i think! Haven;t done any reading on this yet. but i intend to do some this week.

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Old 20th December 2004, 16:23   #17
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clutchless downshifting in bikes is not efficient as there is no neutral gear after every gear (like in cars).

Keep in mind that it is possible - I myself had tried it out in my cbr600.

clutchless downshifting should only be tried in low gear AND low speed as the bike tends to surge forward during the blip!
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Old 20th December 2004, 16:36   #18
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Hey SG, I don't think the cars do away with the clutch. A clutch (of some sort) is needed to transfer power from the engine to the gearbox. For example, the Ferrari F1 system in their street cars still use clutches.
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Old 20th December 2004, 16:51   #19
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Quote:
Originally Posted by rtech
the Ferrari F1 system in their street cars still use clutches.
True, however the `box manages to do most of its shifts so quickly because of revvmatching. ie i believe the clutch is not even used on most shifts....

cya
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Old 20th December 2004, 18:13   #20
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from howstuffworks.com:

Clutches are useful in devices with two rotating shafts. In these devices, one of the shafts is typically driven by a motor or pulley, and the other shaft is driving another device. In a drill, for instance, one shaft is driven by a motor and the other is driving a drill chuck. The clutch connects the two shafts so that they can either be locked together and spin at the same speed, or be decoupled and spin at different speeds.

In a car, you need a clutch because the engine spins all the time and the car wheels don't. In order for a car to stop without killing the engine, the wheels need to be disconnected from the engine somehow. The clutch allows us to smoothly engage a spinning engine to a non-spinning transmission by controlling the slippage between them. To understand how a clutch works, it helps to know a little bit about friction.
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Old 20th December 2004, 18:39   #21
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Bottom Line : You have to use the clutch when shifting. Clutchless shifting has no special purpose.

Shan2nu
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Old 20th December 2004, 18:45   #22
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that statement is not right!

clutchless upshifting is used by almost all bikers on the road and surely all bike riders on the racetrack!

clutchless shifting in cars is also used in racing. I have spoken to many racers in Chennai who use it! I have also seen them do it! They only use it for downshifting though! As it saves them time!
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Old 20th December 2004, 20:24   #23
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Quote:
clutchless shifting in cars is also used in racing. I have spoken to many racers in Chennai who use it! I have also seen them do it! They only use it for downshifting though! As it saves them time!
Racers in Chennai?? I've seen GT champs use the clutch on every ocassion. Show me one professional video where you can see the driver try clutchless shifting.

What time are you planing to save, a pro driver will change gears within 0.3 of a sec. That is pretty much the time it'll take one to move the gear stick from one gear to another.

I ain't saying it's not possible, maybe it is, but is it useful? Not enuf to make a diff.

Shan2nu

Last edited by Shan2nu : 20th December 2004 at 20:28.
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Old 20th December 2004, 21:46   #24
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shn2, a lot of it also depends on the type of gearbox the car has. As I mentioned, most of the lower racing formula's still use H pattern "dog" boxes which have no syncromesh. This includes the FISSME cars of chennai and the formula fords and F2000's I raced. Here a clutch is useless when you are shifting up through the box at racing speeds. Its a lot quicker and smoother without depressing the clutch. Quite a few drivers downshift without the clutch too in these cars. I did that occasionally, but personally prefered the clutch while downshifting. However, that was a matter of preference.

On road cars and on the street though, its a lot easier and safer for the box to use the clutch. Also, a quick shift using the clutch would be almost the same anyways, and you are sure to get in in gear!

On a bike though, clutchless upshifting is more the rule than novelty, as its really the only way to ride fast while not unsettling the bike.

Rt
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Old 20th December 2004, 22:04   #25
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Thumbs up is clutchless gearshifting the way to go?!

I'm not too good in this, but this is what I know

Gear changing time is very crucial in a race or for that matter, times in 0-60 and 0-100. If you do not shift gears in less time or at right rpms, your timings will suffer.

F1 cars do have clutches, but they are mostly used during the start of the race and in the pits. They are not used during the race. They only have to engage the gear lever like a push of a button, and the gear is shifted in hundredths of a second. Since there is no synchromesh, the electronics of the car must match the engine speed with the gearbox speed and then engage the gear in that small period of time. Synchromesh is a feature that allows you to upshift and downshift a manual transmission without grinding gears.

Now logically speaking in F1, this type of clutchless shifting saves a lot of time. If the driver were to engage clutch and then shift gear, there would be those crucial miliseconds which can make him "winner" or "loser". So why not do the same with road cars. Why not change without clutch so that I can get those milisecond advantages? NO!

It won't make a difference because the layout of a road car gearbox is much different than in F1 cars. F1 cars have sequential gearboxes, and there is no synchromesh and the electronics do the synchronization of the engine speed and gearbox speed. In normal road cars, you have a synchromesh transmission. If you do not use your clutch during shifting, your synchromesh and gears are going to wear-out. The gears literally grind and you will need to replace your gearbox sonner. And for all you know, you won't get any timing advantage, since the engine speeds and gearbox speeds are not matched.

Someone please correct me if I'm wrong.
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Old 20th December 2004, 22:05   #26
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oh sorry rtech, didn't see your post...started typing my post at 9:45 board time, and was searching for the right words to explain what I thought it was. now after seeing your post, I'm glad that I wasn't all that wrong...

Last edited by Gordon : 20th December 2004 at 22:09.
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Old 20th December 2004, 22:20   #27
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Quote:
Originally Posted by Shan2nu
Bottom Line : You have to use the clutch when shifting. Clutchless shifting has no special purpose.

Shan2nu

hey shan,
Od had carried an article which said that clutchless operation if done properly can improve the life of ur clutch plate.
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Old 21st December 2004, 11:04   #28
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Yo bikerSG have a look at:
http://www.formula1.com/insight/tech...fo/11/467.html and
http://www.formula1.com/insight/tech...fo/11/645.html
you will get a good idea of how the clutch and gearbox work in a formula1 car.
Regards
Pranav Jairam
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Old 21st December 2004, 11:38   #29
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Gordon,
U have said that in normal road cars, u wont have any timing advantage as the engine speed and gear speed is not matched. thats why u need to blip! once u get both speeds to match (with practice) u dont really need the clutch!

I have checked a copule of sites on the net and found some stuff on clutchless shifts. check out aussieracingcars.com.au -
How are gears changed?
The sequential gearbox is connected to a super tourer style quick shift lever mounted up close to the steering wheel. Click back to change up, click forward to change down. Gears are changed lightening fast as quick as you can lift and re depress the throttle.

How do I know what gear I am in?
The carbon fibre dash binnacle houses a unique illuminated digital gear position read out indicator that displays each gear number and neutral.

Do the cars have reverse gear?
The cars are fitted with a reverse gear system fitted on the rear axle which is engaged Electrically.

Why is the clutch pedal offset?
The clutch is only used to start and stop. When driving gear changes are made simply by lifting off the throttle and click the next gear. Gears are selected in milliseconds (like super tourer and F1).

I am not saying that clutchless shifting is always faster! I myself cant get it right when driving fast! But I am not a racer! The racers also dont do it always! But I have seen them do it! Like rtech said - it depends on the type of gearbox! Maybe it does! I dont know!

My thinking is - if it works for F1 cars, it has to save time. Look at dragsters! All the top class dragsters have clutchless transmissions. In a 10 sec car, clutchless changes save .10 seconds. This is not me guessing. This is from the drag sites. Look them up urself!

(from proshift.co.uk) Graham Hill & Rod Stead, Westfield XTR2 race car drivers:

“We approached ProShift with the idea of fitting one of their push button gearshifts to our Westfield XTR2 race car used in the JCC 100 mile race series, they accepted the challenge and engineered a really professional solution !”

“We found in back to back tests that the ProShift saved us 1.4 seconds a lap at the Snetterton race circuit. We found a great benefit in being able to change up the box seamlessly at full throttle without using the clutch just by the push of a button. Downshifts are also much quicker than manually, the added bonus is that the standard gearlever is retained!

We made a winning race debut recently in our new ProShift equipped race care at Donnington, setting the fastest lap in class. The benefits of being able to make full throttle clutchless gearshifts without letting go of the steering wheel are immeasurable. We wouldn’t hesitate to recommend the ProShift to anyone”.
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Old 21st December 2004, 11:43   #30
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hey pranav,
i couldnt find much info on the sites u sent me!
SG
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