Why do we shift the way we do?

[oohhh yeah]

Hello, long time no talk.

I have been driving manual for a while now, on cars and bikes. I can be very smooth if I want to. I've always wondered...why do we shift the way we do? We shift like a see saw. When one side of the see saw goes up, the other side goes down. When clutch/gas goes in, the other goes out. Now, my question is, wouldn't that be slipping the clutch? I understand the necessity when starting at a standstill. The clutch needs to be slipped so the engine doesn't stall. But what about when the car is already moving? From 2nd to 3rd, 3rd to 4th, 4th to 5th, it is all shifting see saw style, unless you're out for a grandma cruise. If you're out driving like a grandma, the brake and clutch wouldn't be directly proportionate, as the gas wouldn't be continued to be depressed as the clutch pedal is released all the way. Wouldn't getting on the gas before the clutch is fully engaged be slipping the clutch (but this doesn't make sense...since I don't hear or smell the clutch slipping). Sorry if I confused any of you. Another way to put it, if you up shift and engage the clutch without any throttle at all, would that be less slippage to the clutch?

Is it because the slip is so minimal that it doesn't matter?

OR, is it because there is NO slip, because the amount of throttle is proportionate to how much engaged the clutch is?

This has been bugging me for quite a while

 

[Blackbird.]

Hello, long time no talk.

I have been driving manual for a while now, on cars and bikes. I can be very smooth if I want to. I've always wondered...why do we shift the way we do? We shift like a see saw. When one side of the see saw goes up, the other side goes down. When clutch/gas goes in, the other goes out. Now, my question is, wouldn't that be slipping the clutch? I understand the necessity when starting at a standstill. The clutch needs to be slipped so the engine doesn't stall. But what about when the car is already moving? From 2nd to 3rd, 3rd to 4th, 4th to 5th, it is all shifting see saw style, unless you're out for a grandma cruise. If you're out driving like a grandma, the brake and clutch wouldn't be directly proportionate, as the gas wouldn't be continued to be depressed as the clutch pedal is released all the way. Wouldn't getting on the gas before the clutch is fully engaged be slipping the clutch (but this doesn't make sense...since I don't hear or smell the clutch slipping). Sorry if I confused any of you. Another way to put it, if you up shift and engage the clutch without any throttle at all, would that be less slippage to the clutch?

Is it because the slip is so minimal that it doesn't matter?

OR, is it because there is NO slip, because the amount of throttle is proportionate to how much engaged the clutch is?

This has been bugging me for quite a while

You have far too much time to think about this...

 

[GT Pro]

All I can think about after seeing this thread's title is Nissan's 'Shift the Way you Move' campaign...

 

[Kievit]

There dousn't have to be slip when up or down shifting, but there usually is because the input and output shaft rotate at different speeds. Only a small amount though, so the clutch dousn't heat up a lot and therefore you can't smell the clutch "burning".

When you shift, release the clutch and press the gas pedal there is no slip after the input and output shafts have matched eachothers speed. The clutch dousn't have to be fully (de)pressed, it just means there is less pressure on the clutch and that it is easier to slip.

.. atleast when normal driving. As you can also shift without using the clutch and if you drive like a hooligan, burn the clutch without touching it.

Dous that answer anything?

 

[homeforsummer]

If you'd like to know why shifting is a smooth, fluid action between clutch and shifter, treat the clutch like an on/off switch next time you change gear at normal speeds. Your drivetrain and your passengers will thank you for not doing it that way again...

Either way, you shouldn't really be slipping the clutch as you change gear - it should be a smooth transition between clutch and throttle. Since the throttle is generally closed when you shift, any slipping of the clutch probably means you're pushing the throttle too early before you've finished shifting.

 

[Bopop4]

There is always going to be some clutch slip, if you do it in the way you're describing then there will be slightly more, but not enough to damage the clutch in normal driving.

 

[oohhh yeah]

There is always going to be some clutch slip, if you do it in the way you're describing then there will be slightly more, but not enough to damage the clutch in normal driving.

Everyone drives with the clutch and gas like a see saw. I know there will always be some clutch slip, but, I'm wondering why there isn't more with the see saw technique. We are applying gas before the clutch is fully engaged. Wouldn't that be more slip? Or is it because there is no slip, because it is proportional?

 

[homeforsummer]

Everyone drives with the clutch and gas like a see saw. I know there will always be some clutch slip, but, I'm wondering why there isn't more with the see saw technique. We are applying gas before the clutch is fully engaged. Wouldn't that be more slip? Or is it because there is no slip, because it is proportional?

It depends how much gas you're applying. Ideally you're looking for a balance, pressing the gas just as the clutch engages again and you have drive. There'll be a tiny bit of slip, but really minimal.

It's something that comes naturally with practice though. You get used to the biting point of the clutch in most cars and find the ideal combination of clutch and gas for smooth gearchanges.

It's not really a case of "why isn't there more slip?", because if there is more slip then you're not using the right fluid motion for that particular car.

 

[SpartanG]

You have far too much time to think about this...

Seems to me like you're on the wrong site.

 

[MSTER232]

All I can think about after seeing this thread's title is Nissan's 'Shift the Way you Move' campaign...

What this guy said. And that is what Nissan obviously want so you can't get their name out of your head and you end up buying their cars 👍 .

 

[Bopop4]

It depends how much gas you're applying. Ideally you're looking for a balance, pressing the gas just as the clutch engages again and you have drive. There'll be a tiny bit of slip, but really minimal.

It's something that comes naturally with practice though. You get used to the biting point of the clutch in most cars and find the ideal combination of clutch and gas for smooth gearchanges.

It's not really a case of "why isn't there more slip?", because if there is more slip then you're not using the right fluid motion for that particular car.

That. Unless you are doing it so slowly that the revs come up then the extra slip won't be noticeable.

 

[oohhh yeah]

It's something that comes naturally with practice though. You get used to the biting point of the clutch in most cars and find the ideal combination of clutch and gas for smooth gearchanges.

I am already used to it, on cars and bikes. I still can't figure out the science behind it. Another aspect to the question: the see saw technique would be more slip than up shifting without any use of the gas at all (assuming the timing is correct). Correct?

 

[Kylehnat]

If you're perfect at matching revs on every shift, there will be no slippage. You can dump the clutch, and there will be no herky-jerky motion from the car. If you're driving like a sane person, and you slip a little bit during shifts, no big deal. The revs are low enough so you won't torch the clutch. Street clutches can handle this for 100,000+ miles.

 

[Grayfox]

All I can think about after seeing this thread's title is Nissan's 'Shift the Way you Move' campaign...

Same.

 

[oohhh yeah]

If you're perfect at matching revs on every shift, there will be no slippage. You can dump the clutch, and there will be no herky-jerky motion from the car. If you're driving like a sane person, and you slip a little bit during shifts, no big deal. The revs are low enough so you won't torch the clutch. Street clutches can handle this for 100,000+ miles.

Makes sense. But, is there more slippage from the see saw technique? When we shift, while we are releasing the gas pedal we are pressing the clutch pedal. And when we are pressing the clutch pedal, we are releasing the gas pedal. The gas is still pressed when the clutch pedal is not fully released. This means there is slip right? Or is there none because the gas and clutch is proportional? I still can't figure this out.

Let's say you are a robot and can time everything perfectly. If you match the revs perfectly BUT you are giving it a lot of gas, there would be no jolt from the drive-train right? Would this be hard on anything? If so, what and how?

 

[homeforsummer]

The gas is still pressed when the clutch pedal is not fully released.

Key word here: pedal.

The clutch pedal's travel is far greater than the small amount of travel during the clutch biting point. You could drive around all day with the clutch semi-depressed if the biting point was further down, because drive would still be engaged.

 

[oohhh yeah]

Key word here: pedal.

The clutch pedal's travel is far greater than the small amount of travel during the clutch biting point. You could drive around all day with the clutch semi-depressed if the biting point was further down, because drive would still be engaged.

But still, the clutch is not an on and off when it gets to a certain point. This is why riding the clutch is bad.

 

[Bopop4]

Yes, but he is saying that near the end of the see saw motion the clutch is hooked up anyways.

 

[homeforsummer]

Yes, but he is saying that near the end of the see saw motion the clutch is hooked up anyways.

This. And the biting point of the clutch is only a small proportion of the length of the pedal's travel.

It's still not great to ride the clutch, but in terms of changing gear there's only a very brief moment when the clutch is passing between engaged and disengaged and the throttle is being applied.