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Old 06-26-2003, 10:57 AM   #1 (permalink)
Riiiiight........
 
clutchless shifting

has anyone tried shifting gears in a manual without using the clutch??

I found that if i let off the gas while in third, I can pop the gear into neutral, and occasionally pop it into fourth without using the clutch.

Its also possible to do this from first to second, but it occasionally grinds.

Anyway, I think its bad for the transmission if done wrongly, so kids, please don't try this at home....
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Old 06-26-2003, 11:32 AM   #2 (permalink)
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HAHA ya i've done it, not on purpose though, hehe


i wanna see how long that tranny lasts

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Old 06-26-2003, 11:33 AM   #3 (permalink)
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Racecar drivers do it all the time... the noise is something. I think they have special transmissions though.
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Old 06-26-2003, 11:41 AM   #4 (permalink)
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I can't do it, but it's perfectly safe for your car. All you have to do is match wheel speed and RPMs and then shift. That's all you use the clutch for, really. I know several people that can and have done it for me.
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Old 06-26-2003, 12:18 PM   #5 (permalink)
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You should be able to pop from any gear into neutral. It's a safety feature to disengage the drive train at any given time. After you hit neutral you can give it some gas to speed up the RPM's and match the next gear. Don't know if it hurst the car or not when you get that aweful grinding noise though.
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Old 06-26-2003, 02:45 PM   #6 (permalink)
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Yeah, if it grinds...that's bad.
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Old 06-26-2003, 03:41 PM   #7 (permalink)
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Quote:
Originally posted by hrdwareguy
You should be able to pop from any gear into neutral. It's a safety feature to disengage the drive train at any given time. After you hit neutral you can give it some gas to speed up the RPM's and match the next gear. Don't know if it hurst the car or not when you get that aweful grinding noise though.
At almost any time... try popping it into neutral with a load on the tranny, it's damn near impossible on my '85 Yota 4x4 with a 22R (only 96 HP ).

Anyways, I'd be scared to shift without the clutch. There is a clutch there for a reason....
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Old 06-26-2003, 04:24 PM   #8 (permalink)
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Yup. That reason is take off. It's the only time you absolutely need it.
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Old 06-26-2003, 06:08 PM   #9 (permalink)
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typically on the street I will always use my clutch. When I am out at the track I almost never, except when launching, will I use my clutch OR if I am cross gate shifting. As metioned as long as you match RPM's you're fine. Its something that takes some getting use to but - practice makes perfect. My tranny has 11k - all racing miles and my synco's are working just as good as the day the tranny was new.

If you don't belive me, ask Caroll Smith LOL
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Old 06-26-2003, 07:34 PM   #10 (permalink)
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Spyder_Venom: I guess what I don't get is why it's quicker to match the revs than to use the clutch. It seems like it'd take longer for the engine to climb down in rpm than it would to disengage the clutch and do it that way. I used to have a little Alfetta that I shifted without the clutch. Granted, It's not race engine, but it seemd like it took longer to rev-match than to just blast through it with the clutch.
Also, what about open throttle shifting? Would it be more beneficial (not to the clutch i'm sure ) to shift that way instead of rev-matching? I think they do that in Le Mans. I haven't ever raced on a track so please correct me if I'm mistaken.
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Old 06-26-2003, 07:35 PM   #11 (permalink)
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'93 Saturn, for background information. I tend to only do it when I don't feel like shifting particularly quickly, as it takes a moment for the revs to drop down to speed for an upshift. I use the clutch for downshifts unless I'm feeling nutty.

Here's a question: In my car, during clutchless shifting, there are points across the rev range at which the car will slide easily out of gear. Between those points, I have to really yank the bastard into neutral. An idiot-proofing measure, or a result of the physics of the driveline?
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Old 06-26-2003, 09:13 PM   #12 (permalink)
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I do it all the time in a junky pizza delivery car, mostly out of laziness, and never for any kind of speed or performance. As long as everything is in sync it's perfectly safe and easy if you shift when you're supposed to.
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Old 06-26-2003, 09:53 PM   #13 (permalink)
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A bunch of friends do it all the time on the track. I don't spend enough time driving a stick to be comfortable doing it without the clutch.

But on a motorcycle I can do it. For some reason it's a lot easier for me to match engine and tire speed so that I can shift easily on the bike.
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Old 06-26-2003, 10:22 PM   #14 (permalink)
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my dads clutch went out on him once and he drove like that for a lil while till he was able to get it fixed... he was pretty good at it...
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Old 06-27-2003, 05:55 AM   #15 (permalink)
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Quote:
Originally posted by deathbygaetano
Spyder_Venom: I guess what I don't get is why it's quicker to match the revs than to use the clutch. It seems like it'd take longer for the engine to climb down in rpm than it would to disengage the clutch and do it that way. I used to have a little Alfetta that I shifted without the clutch. Granted, It's not race engine, but it seemd like it took longer to rev-match than to just blast through it with the clutch.
Also, what about open throttle shifting? Would it be more beneficial (not to the clutch i'm sure ) to shift that way instead of rev-matching? I think they do that in Le Mans. I haven't ever raced on a track so please correct me if I'm mistaken.
For down shifting its not a matter of all out speed, and since the motor is already being pulled down by the slowing of the car a quick blip of the throttle (while still hard on the brakes) is all it takes. During down shifting I will sometimes do a cross gate shift from 3-2 but its a little uncomfortable for me, still. While upshifting its very natural. I don't need to make a effort to match revs. All I need to do is back off a hair and it will slide right into the next gear with out missing a beat.

The reason this is faster is 1. you don't loose as many revs while the clutch is out, you also don't get the shock to the drive line when you let the clutch back out. 2 Loosing revs can be kind of kept by blipping the throttle, but as I said, its hard on the drive line - the other major advantage and not to be confused with #1 is gear transfer times, how long it takes you to go from WOT in gear 1-2. If you do it right it will go in to gear just as fast as if you used the clutch but you don't loose the time with engauging and dis-engauging the clutch.

In road racing there is this big deal over if you should heal-toe and use the clutch or use the newer left foot, clutchless shifting technique - personally I use both... it all depends on the track. At BIR (my local track) I have gotten to the point that I will never heal-toe there becuase of its size you never have any 5-1 or 5-2 down shifts. At a track like Pocono I would just throw the damn clutch in after the L O N G strieght going into the tunnel turn (back when they ran it the "normal way" LOL) and throw it into 2.

People talk about using the engine rev's to pull down the speed of a car.. This is dangerous but it does have its plus sides *IF your car is not equiped with a brake bias controller. What engine braking does in a RWD car is slow down the rear wheels in addition to what the brakes are. On most production cars running non stock tires (by that I mean DOT slicks, other high performance tire) the front end will be way out of balance with the rear. Even though your rear brakes do 20-30% of the braking of the car, in some cases they have concluded becuase the car was mis-proportioned it was doing less than 3%. The dynamics of a car will be the ultimate ruler of just how much it can take but still, a differnce of 27% braking capacity is huge. How if you have a bias controller you can adjust that and get it to the treashold of the vechical. The reason I would do this is simple, when downshifting you have a great chance of down shifting too soon and over revving the motor. No rev limiter can prevent this and results are catastrofic. Another reason to have a bias controller is by evenly setting up braking they will run cooler. You will find that brake fade is far less noticalbe when the car is leveled off.

Sorry for the long ramble about this, hopefully some of it made sense. I know a missed a lot but I'm trying to not write a book on the TFP
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Old 06-27-2003, 11:40 AM   #16 (permalink)
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spyder is the guru ... my 2 cents are not needed ... besides I don't own a manuel at this time
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Old 06-27-2003, 03:41 PM   #17 (permalink)
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I still don't get it... I just can't jam my tranny into gear when the clutch is out. I guess I am just an idiot .
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Old 06-27-2003, 04:42 PM   #18 (permalink)
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On an upshift, it is MUCH faster to use the clutch. Racing, and the like...use the clutch on a normal transmission. Racing trans' with straight cut gears are a different story. When downshifting, it CAN be faster to not use the clutch. Although, if you're in that big of a hurry to stop, that's what the brakes are for.
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Old 06-28-2003, 04:56 PM   #19 (permalink)
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GOING UP

Shifting without the clutch will result in minimal drive loss. If speed is your issue, this is what you need. However, most people are insufficiently sensitive/skillful to time this action correctly. Therefore we have the clutch.

Listen to old ladies revving the tits off an engine as they slowly blend that clutch in. Listen to any racing driver and he will be going through them almost quicker than you can distinguish.

Whether you're on a bike or a car, you will find that if you try to shift faster and faster, you are actually using less and less clutch. Eventually you're probably only tapping it. At that point you're almost ready to walk on the rice paper.

On a motorcycle clutchless shifting is essential in racing or during long wheelies. Disengage the drive during a wheelie to change gear and you'll be popping the front tyre before you know it as the bike sinks like an anvil.


Shifting without the clutch is faster, smoother, and does not actually wear it out.... ...if you can do it properly.

GOING DOWN
Here you have the problem of matching the engine speed with the speed at which the wheels are turning / the road is going past.

Obviously if you're in fifth and you want to drop it to third, you are going to have to speed the engine up a hell of a lot before you ram 3rd home. If you do shove it in, and it actually goes in, you'll experience that massive deceleration and a huge amount of noise as the wheels and engine try to figure it out (engine speeding up, wheels tending to lock up).

So you have to match the engine RPM, by double de-clutching (dip, neutral, rev, next gear) or rev pairing (dip, rev, gear).

Without rev pairing on a motorcycle with a lot of engine braking from big cylinders (like a V twin harley, Ducati etc) you will lock the back wheel up if you just smash it down, and it will be hopping around behind you. You will lose control. You better fether that clutch quickly to regain composure. As you fether it, you are effectively allowing wheels and engine to negotiate and reach a compromise.
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Old 06-29-2003, 10:56 AM   #20 (permalink)
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a clutch is mostly unneccessary for upshifting. on my motorcycle, I rarely use it to upshift.
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Old 06-30-2003, 01:24 AM   #21 (permalink)
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I drove a piece of shit VW van California to Ohio with no clutch once. Only stopped for gas and to piss a couple times. Took off with the key and starter. Stoplights sucked.
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Old 06-30-2003, 06:00 PM   #22 (permalink)
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dimbulb,

As far as simply pulling a manual gearbox out of gear when you let off the gas you should be able to shift out of gear into neatral no problem. What is happening is the at some point in time very soon after you lift the drive-line including transmission goes from transmitting power from the engine to the road to transmitting power from the road to the engine. At some point in time during this transition there is no load on the drive-line (i.e. no power is being transmitted in either direction). It should make sense that to go from one transferring power in one direction to the other there has to be an instant when power not is being transferred in either direction. At this point (or in practice very near it when the drive line is lightly loaded) you can simply move the tranny into neutral. This is because the mechanism that engages the gear is not 'held' in place by the power that is being transmitted through the tranny.

Try this: drive at a steady speed with the tranny in any gear. Rest your hand on the shifter adding only a slight pressure. Lift off the gas and the shifter (with the slight pressure you have on it) will move easily into neutral. Once you feel the shifter start to move get it into neutral. If you go really slow at that point you may wind up with a grind. It really isn't that hard. Do not ride along for long stretches pushing on the gear lever: this can result in transmission wear. Doing so for the second or two it will take for the tranny to fall into neutral shouldn't be a problem. With a little practice you will get the feel and be able to simply move the tranny into neutral at the right time without the constant pressure.

You will also find that when leaving the car in gear as you slow down transmission will slip easily slip into neutral as you reach idle speed. At the point where you slow down enough to reach what would be engine idle speed the power situation reverses again (from road to engine to engine to road) and you have a point where no power being transmitted. You'll be able to pull the gearshift into neatral.

That part is easy. Shifting back into gear from neutral (either up or down) is a little different for a normal manual tranny like you'd find on a street car. What you need to do is make the engine speed (RPM) match whatever it needs to be to the gear you are trying to engage. If you are shifting to a lower gear the engine must be turning faster than it was in the higher gear. This is accomplished by simply giving the car enough gas momentarily to create this matching condition. Blip the throttle just right and you'll be able to engage the gear you want. This takes a lot more pratice to do properly. Others have already pointed this out. If the next gear you want is a higher gear you must wait for the engine speed to slow down before you can engage the higher gear. On a street car as DE137, points out it is simply faster to use the clutch.

***edit: after re-reading spyder's and others posts, I admit I don't understand exactly how clutchless upshifting can be faster on a normal street car tranny. Three possible reasons for this occur to me. First, the spacing between gears typically gets smaller and smaller in the higher gears (this is true both for road cars and race cars) so the engine speed drop needed to engage the next higher gear is less. Second, is that when shifting close to red-line or at least at high engine speeds the engine speed will slow rapidly anyway. i.e. it will take less time for the engine to fall from 6000 to 5000 RPM than it will take to fall from 3000 to 2000 RPM. Third, my guess would be that worn synchros will be less and less effective and result in easier engagment under these conditions. ***

That isn't the whole story though. DE137 is on to something about the racing transmission but he is wrong about the straight cut gears being the reason. Straight cut gears are used in racing applications mostly becuase they are strong. They are also more effecient than helical cut gears (they generate less heat). The downside is that they are noisy. Ever hear a car whine when it is in reverse? This is because reverse gears are typically straight cut gears. Helical gear run much quieter, this is the reason (I believe) they are used on street cars.

Any modern gearbox either for street or race cars are what is known as a constant-mesh gearbox. In a constant-mesh gear box each gear set (in a five speed tranny there are five gear sets - i.e there are five pairs of gears matched to eachother) is always engaged (meshing). The gear sets, how many ever there are are mounted on two adjacent shafts. When you "engage" a gear you are not meshing one gear with another; they are already meshing with eachother. What you are really doing is "engaging" one set of already meshed gears to the input shaft of the transmission thus creating a path from input shaft to output shaft. (Each of the gear set are always engaged to the output shaft - the sets that aren't engaged still rotate with the output shaft.)

In a racing gearbox this mechanism will disengage the gear very easily and quickly and is fundamentally the same operation as the street type gearbox. It is the process of engaging a gear that is different. In a racing gearbox you do not have to perform the engine speed to road speed matching. Under most circumstances you can simply jam the box into gear. This can result in the driven wheels (typically rear, but the same would apply to a front wheel drive car) that want to lock up and other braking considerations that have already been touched on in this thread. I am not that familiar with motorcycles but I believe they operate in the same fashion as a typical racing gearbox.

In a street car the gear box will incorporate synchronizers. There is a synchro associated with each gear set. They are devices which through the use of friction will not engage the gear until the input shaft and the gear (and therefore output shaft and everything connected to it) speed are roughly matched. It is due to the synchro that you have to wait for the engine speed to slow when attempting a clutchless upshift on your road car. The lack of a synchro is the reason why the motorcycle guys and easily upshift without using the clutch. It is also due to the synchros that you must match engine revs on a downshift. One point here, it is still generally a good thing to match engine speeds on a downshift on a racing box in order not to upset the whole car when the gear engages. The major difference is that it is not necessary to do so to get the gear engaged in the case of the race type gearbox.

Synchros were developed and are used in transmissions simply so the driver doesn't have to perform the engine speed/road speed matching in order to shift gears without a grind or even at all. Ever notice that you can't even engage one of the lower gears like first when the car is still moving at a high rate of speed. Ever notice the whine the gearbox can make if you try to jam the gear in under these conditions. That is the sychros doing their work. I suppose it is as much a safety consideration as anything now. We've all probably changed from fourth to third instead of fifth accidently. It is propable a good thing first is near impossible to engage at this time because people would be over-reving engines and so forth by accidently putting the car in a gear that is way to low at that moment. I'm sure we'd also have people accidently engage a low gear followed by rear wheels locking and accidents because of this too. Synchros are not used on race cars because they create lots of heat and also as pointed out slow shifting down.

I know it was a simple questions and I've written a very long answer. I enjoyed typing all this in and also wanted to make it clear that the manual gearbox on a street car and the manual box on a race car and motorcyle operate differently. That is why there are some conflicting posts above. Also, it sounds like spyder_venon must race some sort of production based car since he mentions synchros in one of his posts.

Last edited by rs8001; 06-30-2003 at 06:17 PM..
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