Changing gear without the clutch..
Discussion
This is something i got very pissed off with today. I was in my car with my mum today, and she was driving. At one point in the journey, she changed gear without pushing in the clutch, and as a result the gearbox made a very nasty sound :S When i proceeded to have a go at her, she told me that it is possible to change gear without using the clutch!! Now to me, this didnt sound too healthy for the car. Can anyone back me up here, or am i in the wrong??
It is possible, been in the car with my dad when the clutch went, he managed to get it home. Although you can't stop, which can be difficult. It doesn't do any harm if you do it properly. Obviously taking it out of gear is the easy bit, you then have to match the revs when it's out of gear to the revs it will be when you put it in the new gear, so that it joins seamlessly. Useful thing to know how to do.
However, if the noise you heard from the gearbox was a grinding noise, and the change was very jerky, then it wasn't done correctly, and she's grinding the gearbox, not recommended.\
However, I can't see the point in doing this when you have a perfectly good working clutch right there.
However, if the noise you heard from the gearbox was a grinding noise, and the change was very jerky, then it wasn't done correctly, and she's grinding the gearbox, not recommended.\
However, I can't see the point in doing this when you have a perfectly good working clutch right there.
Edited by CorsaScott on Friday 13th June 23:05
CorsaScott said:
It is possible, been in the car with my dad when the clutch went, he managed to get it home. Although you can't stop, which can be difficult.
Changing gear smoothly without a clutch is not a problem, nor is stopping and starting - a skilled driver can do this and show you how to move off from a stand with the ENGINE RUNNING and no clutch, go up through the box and down again to a stop. Done properly it will not damage the gearbox and arguably saves clutch wear. - For those puzzling how you initially move away, trust me it can be done and no, it does not involve cranking the starter motor in first gear although that does work. Skilled bikers amongst us will know that clutchless gear changing is pretty standard on the move but the trick that you can use to move off in a car does not work with bikes - now there is a clue ! Edited by CorsaScott on Friday 13th June 23:05
Edited by Jules2477 on Saturday 14th June 01:59
Edited by Jules2477 on Saturday 14th June 02:13
Edited by Jules2477 on Saturday 14th June 02:16
Jules2477 said:
Changing gear smoothly without a clutch is not a problem, nor is stopping and starting - a skilled driver can do this and show you how to move off from a stand with the ENGINE RUNNING and no clutch, go up through the box and down again to a stop. Done properly it will not damage the gearbox and arguably saves clutch wear. - For those puzzling how you initially move away, trust me it can be done and no, it does not involve cranking the starter motor in first gear although that does work. Skilled bikers amongst us will know that clutchless gear changing is pretty standard on the move but the trick that you can use to move off in a car does not work with bikes - now there is a clue !
Doesn't work in Morris Minors either
I think the starter motor method is somewhat less damaging though...A clutchless gear change should be smooth and silent... if it isn't it's just put bits of swarf inside the gearbox... and it should go in just as easily as a normal one, with no extra force, otherwise you've again got it wrong and are using the synchros to get it right, only under load, causing heavy wear.
How easy is it... depends on how good you are at rev matching... it's basically the same principle as double-declutching but with sufficient accuracy on the rev-matching stage in neutral that you don't need the clutch to get it in again. Depends on the box as well. Some cars are easier than others. Bike boxes it's such a doddle you can find yourself doing it by accident, just forgetting to use the clutch.
For a car it's pretty much of a party trick, it's useful when your clutch cable breaks but generally you'll get a faster change by using the clutch.
Ramming it in so it graunches because you can't be arsed to use the clutch is just silly... potentially dangerous too... if you break off bits of metal inside the box which then jam it up and irretrievably lock the driven wheels things could get interesting.
Pigeon said:
Jules2477 said:
Changing gear smoothly without a clutch is not a problem, nor is stopping and starting - a skilled driver can do this and show you how to move off from a stand with the ENGINE RUNNING and no clutch, go up through the box and down again to a stop. Done properly it will not damage the gearbox and arguably saves clutch wear. - For those puzzling how you initially move away, trust me it can be done and no, it does not involve cranking the starter motor in first gear although that does work. Skilled bikers amongst us will know that clutchless gear changing is pretty standard on the move but the trick that you can use to move off in a car does not work with bikes - now there is a clue !
Doesn't work in Morris Minors either I think the starter motor method is somewhat less damaging though...A clutchless gear change should be smooth and silent... if it isn't it's just put bits of swarf inside the gearbox... and it should go in just as easily as a normal one, with no extra force, otherwise you've again got it wrong and are using the synchros to get it right, only under load, causing heavy wear.
How easy is it... depends on how good you are at rev matching... it's basically the same principle as double-declutching but with sufficient accuracy on the rev-matching stage in neutral that you don't need the clutch to get it in again. Depends on the box as well. Some cars are easier than others. Bike boxes it's such a doddle you can find yourself doing it by accident, just forgetting to use the clutch.
For a car it's pretty much of a party trick, it's useful when your clutch cable breaks but generally you'll get a faster change by using the clutch.
Ramming it in so it graunches because you can't be arsed to use the clutch is just silly... potentially dangerous too... if you break off bits of metal inside the box which then jam it up and irretrievably lock the driven wheels things could get interesting.
but ye i didnt think it was reali worth trying to do it when using the clutch is absolutely no effort at all! seeing as it would probably cause more damage to my carJules2477 said:
a skilled driver can ... show you how to move off from a stand with the ENGINE RUNNING and no clutch, ... Done properly it will not damage the gearbox and arguably saves clutch wear.
Can you explain how you move off from standstill with the engine running without using the clutch and without damaging the gearbox? I assume you do mean in a manual not an auto!GreenV8S said:
Jules2477 said:
a skilled driver can ... show you how to move off from a stand with the ENGINE RUNNING and no clutch, ... Done properly it will not damage the gearbox and arguably saves clutch wear.
Can you explain how you move off from standstill with the engine running without using the clutch and without damaging the gearbox? I assume you do mean in a manual not an auto!I DO NOT RECOMEND THIS AS NORMAL DRIVING PRACTICE as it can cause undue wear on the synchro cones but the odd one off will do little harm as modern manufacturing makes these parts pretty damn tough. Besides the way some people abuse gearboxes makes this far less damaging than their normal driving technique. It is also not suitable for a fast get away ! - The syncho is actually a type of clutch which engages and matches the cog speeds exactly before they mesh hence this is what enables you to change gear without a horrible gnashing sound. (It is the bit that is missing in crash gearboxes which is why you can only change gear by manual rev matching)) It follows that if you move the gear lever towards first gear until you feel resistance, that resistance is the synchro cone. On a level road, maintain the pressure to the gear lever with the engine on tick over and you will find that the car will gain speed (slowly). As soon as the road speed matches the gear speed it will drop in. In other words the synchro has acted like slipping the clutch to move off. From there on it is a case of careful rev matching to go up and down the box. Another important point with clutchless changes is that you should also rev match the engine to take the car out of gear, i.e to stop, so the cogs themselves are not under pressure from either power or overrun. If you dont you will find the gears are locked in mesh and the undue ammount of force to shift them can cause damage. In short the whole operation requires finess but done correctly the gears will slip in and out with nothing more than than normal effort on the gear lever or risk of damage.
I can see a few bets being placed and won on the pulling away bit !
A quick point with rev matching is that it should always be done with a synchro box as good practice to minimise wear on the gearbox, clutch and associated drive train. Unfortunately the vast majority of drivers don't think to blip or sustain change down, relying on technology to do it for them, and without a thought for what is actually going on or the eventual impact on their pocket.
Edited by Jules2477 on Saturday 14th June 21:24
Edited by Jules2477 on Saturday 14th June 21:33
Edited by Jules2477 on Saturday 14th June 21:44
GreenV8S said:
Jules2477 said:
The last bit saving clutch wear was meant to be a bit tongue in cheek but ....
OK I'll bite: you mean you are serious about the part about starting it on the synchro? 
If you are serious and think this is not damaging to the gearbox I think you are dead wrong.
Edited by Jules2477 on Sunday 15th June 01:24
Edited by Jules2477 on Sunday 15th June 02:06
Edited by Jules2477 on Sunday 15th June 02:10
Edited by Jules2477 on Sunday 15th June 06:35
Jules2477 said:
If you actually think about how much power is being delivered on tick over and how easy it is to manually push a car on a level road, the forces are very low. Now compare that with the forces exerted by drivers who up or down change at speed without rev matching all the time and you might think differently - How many times have you been in a car and literally heard the synchros screaming on each change, and then felt the bang every time they let the clutch back out.
I have actually thought about it and no, I don't think differently.Clearly you have some understanding of how the transmission works but you seem to have no concept of the amount of damage involved with some of the techniques you are describing. Using the synchros to move the car is extremely damaging to the gearbox. I can't think of a single occasion when I've heard the synchros screaming but if you think that rev matching avoids stress on the synchros I would say you are mistaken.
Your suggestion that clutchless gear changes save wear and tear on the clutch is just silly. The main clutch is a big heavy friction clutch that can take plenty of abuse, and it has to because every time you pull away from standstill it gets huge amounts of heat dumped into it. The wear and tear from normal gear changes are utterly trivial in comparison. Clutchless gearchanges are harmless if done perfectly, the less perfect you are the more damage they do and even a moderately well executed one can cause very high wear. Unless you are one of the few people in the world who can do them perfectly every single time it would be extremely foolish to do them on a vehicle that you cared about, outside of an emergency where the alternative is being stranded.
The synchro hubs are teeny weeny little clutches designed to absorb the inertia of a small gear cluster. To apply the sort of torque necessary to get the vehicle rolling, and then maintain that torque long enough for the vehicle to get up to the several mph corresponding to tickover speed in first gear is hugely overloading the synchro. It may not fail the first time you do it, or even the tenth, but you are causing severe wear and will reduce the life expectancy accordingly.
Frankly if you have even the slightest pretext of having any mechanical sympathy you should hang your head in shame for doing that or recommending that others do it.
GreenV8S said:
Jules2477 said:
If you actually think about how much power is being delivered on tick over and how easy it is to manually push a car on a level road, the forces are very low. Now compare that with the forces exerted by drivers who up or down change at speed without rev matching all the time and you might think differently - How many times have you been in a car and literally heard the synchros screaming on each change, and then felt the bang every time they let the clutch back out.
I have actually thought about it and no, I don't think differently.Clearly you have some understanding of how the transmission works but you seem to have no concept of the amount of damage involved with some of the techniques you are describing. Using the synchros to move the car is extremely damaging to the gearbox. I can't think of a single occasion when I've heard the synchros screaming but if you think that rev matching avoids stress on the synchros I would say you are mistaken.
Your suggestion that clutchless gear changes save wear and tear on the clutch is just silly. The main clutch is a big heavy friction clutch that can take plenty of abuse, and it has to because every time you pull away from standstill it gets huge amounts of heat dumped into it. The wear and tear from normal gear changes are utterly trivial in comparison. Clutchless gearchanges are harmless if done perfectly, the less perfect you are the more damage they do and even a moderately well executed one can cause very high wear. Unless you are one of the few people in the world who can do them perfectly every single time it would be extremely foolish to do them on a vehicle that you cared about, outside of an emergency where the alternative is being stranded.
The synchro hubs are teeny weeny little clutches designed to absorb the inertia of a small gear cluster. To apply the sort of torque necessary to get the vehicle rolling, and then maintain that torque long enough for the vehicle to get up to the several mph corresponding to tickover speed in first gear is hugely overloading the synchro. It may not fail the first time you do it, or even the tenth, but you are causing severe wear and will reduce the life expectancy accordingly.
Frankly if you have even the slightest pretext of having any mechanical sympathy you should hang your head in shame for doing that or recommending that others do it.
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Edited by Jules2477 on Sunday 15th June 17:50
Edited by Jules2477 on Sunday 15th June 17:55
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