Do i have to rev match when down shifting gears?

[Rope-Pusher]

^ What Cow Mooed + When coasting with the clutch disengaged, the input shaft is spinning at a given speed for whatever gear is engaged.
If you know you will be coming to a stop, you can just shift into neutral and the input shaft will spin down to a stop. While stopped, you can shift into whatever gear you want to start out in with no wear to the synchronizers.
F U know that U want 2 coast down 2 a lower speed and then drive off N a lower gear at that speed, U might hold the clutch disengaged while U shift down thru each gear until U get 2 the gear U want 2 resume driving in. This will spread the synchronization wear-n-tear among more synchronizers, as each downshift gear engagement will raise the speed F the input shaft bit by bit. F N U Hold the clutch depressed and downshift directly from say 5th gear ("Fifth gear" - there, I said it) to 2nd gear, then the 2nd gear synchro will be responsible 4 raising the input shaft speed by the entire difference N rpm between 5th and 2nd. F N ewer 2nd gear synchro was already worn some, this might result N clash.

[tankinbeans]

I usually double clutch it when I want to skip a gear. Ever since I watched the video of the dude in the big rig double clucthing and thinking of "neutral" as the rev-matching gear, as per somebody's suggestion (I can't remember who off the top of my head), I've found double clutching fun. I botch it every now and again, but I don't worry about it. As for lights, depending on my mood I'll coast in gear up to the light, or if I have reason to believe the light will change I will double clutch into the gear which will give me the most power so I can continue on my way.

[kayubassist]

^ What Cow Mooed + When coasting with the clutch disengaged, the input shaft is spinning at a given speed for whatever gear is engaged.
If you know you will be coming to a stop, you can just shift into neutral and the input shaft will spin down to a stop. While stopped, you can shift into whatever gear you want to start out in with no wear to the synchronizers.
F U know that U want 2 coast down 2 a lower speed and then drive off N a lower gear at that speed, U might hold the clutch disengaged while U shift down thru each gear until U get 2 the gear U want 2 resume driving in. This will spread the synchronization wear-n-tear among more synchronizers, as each downshift gear engagement will raise the speed F the input shaft bit by bit. F N U Hold the clutch depressed and downshift directly from say 5th gear ("Fifth gear" - there, I said it) to 2nd gear, then the 2nd gear synchro will be responsible 4 raising the input shaft speed by the entire difference N rpm between 5th and 2nd. F N ewer 2nd gear synchro was already worn some, this might result N clash.

you are giving us some good information but the way you write (I think you are doing it on purpose) is not very effective at sending your message across. I stopped reading as soon as you said F U know.

[tankinbeans]

^ What Cow Mooed + When coasting with the clutch disengaged, the input shaft is spinning at a given speed for whatever gear is engaged.
If you know you will be coming to a stop, you can just shift into neutral and the input shaft will spin down to a stop. While stopped, you can shift into whatever gear you want to start out in with no wear to the synchronizers.
F U know that U want 2 coast down 2 a lower speed and then drive off N a lower gear at that speed, U might hold the clutch disengaged while U shift down thru each gear until U get 2 the gear U want 2 resume driving in. This will spread the synchronization wear-n-tear among more synchronizers, as each downshift gear engagement will raise the speed F the input shaft bit by bit. F N U Hold the clutch depressed and downshift directly from say 5th gear ("Fifth gear" - there, I said it) to 2nd gear, then the 2nd gear synchro will be responsible 4 raising the input shaft speed by the entire difference N rpm between 5th and 2nd. F N ewer 2nd gear synchro was already worn some, this might result N clash.

you are giving us some good information but the way you write (I think you are doing it on purpose) is not very effective at sending your message across. I stopped reading as soon as you said F U know.

It's just him. I personally find it funny because it catches me off guard and I go back and re-read it.

[Reverence]

^ What Cow Mooed + When coasting with the clutch disengaged, the input shaft is spinning at a given speed for whatever gear is engaged.
If you know you will be coming to a stop, you can just shift into neutral and the input shaft will spin down to a stop. While stopped, you can shift into whatever gear you want to start out in with no wear to the synchronizers.
F U know that U want 2 coast down 2 a lower speed and then drive off N a lower gear at that speed, U might hold the clutch disengaged while U shift down thru each gear until U get 2 the gear U want 2 resume driving in. This will spread the synchronization wear-n-tear among more synchronizers, as each downshift gear engagement will raise the speed F the input shaft bit by bit. F N U Hold the clutch depressed and downshift directly from say 5th gear ("Fifth gear" - there, I said it) to 2nd gear, then the 2nd gear synchro will be responsible 4 raising the input shaft speed by the entire difference N rpm between 5th and 2nd. F N ewer 2nd gear synchro was already worn some, this might result N clash.

you are giving us some good information but the way you write (I think you are doing it on purpose) is not very effective at sending your message across. I stopped reading as soon as you said F U know.

I promise his knot dewing it on purpose.

[Shadow]

you are giving us some good information but the way you write (I think you are doing it on purpose) is not very effective at sending your message across. I stopped reading as soon as you said F U know.

Eye think heez just trying to be sofa king funny all the time.

^^^^ My pathetic attempt to emulate Rope ^^^^

[six]

you are giving us some good information but the way you write (I think you are doing it on purpose) is not very effective at sending your message across. I stopped reading as soon as you said F U know.

Eye think heez just sofa king funny all the time.

^^^^ My pathetic attempt to emulate Rope ^^^^

Fickset

[Bawked]

Let out the clutch very slowly. Living in Hong Kong, I frequently ride mini buses with sticks. Unlike the crusty old drivers, them young'uns drove as if they never had been taught to rev match.

That's not something you'd want to do very often. By doing that, you're basically using your clutch to absorb (for lack of a better word) the engine RPM. A simple throttle blip is a much better idea.

This is something i've been wanting to clear up for years!

Actually....... it's fine to do so

The total energy dissipated during a shift only depends on the difference in rotation velocities and the inertia's of the respective systems. The rate of heat generation depends on time, therefore dropping the clutch means the time to dissipate the heat is almost nil. Slipping the clutch for a longer time will result in slower heat dissipation, which means in laymans terms that the temperature of the clutch will be lower, as the heat can conduct away.

Ideally though due to rev matching the difference in rotational velocities is nill or close to and it doesn't matter

[Shadow]

Let out the clutch very slowly. Living in Hong Kong, I frequently ride mini buses with sticks. Unlike the crusty old drivers, them young'uns drove as if they never had been taught to rev match.

That's not something you'd want to do very often. By doing that, you're basically using your clutch to absorb (for lack of a better word) the engine RPM. A simple throttle blip is a much better idea.

This is something i've been wanting to clear up for years!

Actually....... it's fine to do so

The total energy dissipated during a shift only depends on the difference in rotation velocities and the inertia's of the respective systems. The rate of heat generation depends on time, therefore dropping the clutch means the time to dissipate the heat is almost nil. Slipping the clutch for a longer time will result in slower heat dissipation, which means in laymans terms that the temperature of the clutch will be lower, as the heat can conduct away.

Ideally though due to rev matching the difference in rotational velocities is nill or close to and it doesn't matter

I'm not debating the length of time that one lets the clutch out in such a situation....I'm simply saying that using the clutch to "absorb" engine RPM while downshifting will cause unnecessary wear that can be avoided with a simple blip of the throttle (rev match). Seasoned drivers do it all the time and it's second nature to them.

[pmacutay]

It's interesting: I actually find myself rowing down through the gears while staying clutched-in the whole way through.

It's usually when I'm coming up to a line of cars at a light that just turned green. I don't know when exactly the car will start moving in front of me, so I don't know what gear I'm going to want to be in, so I keep the clutch pressed in and go down to 4th, 3rd, 2nd as I'm braking. If the car starts pulling away, I'm already in the gear I want to be in, so all I have to do is blip a bit and let up the clutch and I'm seamlessly in gear.

However, if the gear I want to be in is known, like for a 2nd gear turn, I'll usually DCHT 5-3 and then 3-2.

So it's basically about adapting to unknown situations.

[Reverence]

This is something i've been wanting to clear up for years!

Actually....... it's fine to do so

The total energy dissipated during a shift only depends on the difference in rotation velocities and the inertia's of the respective systems. The rate of heat generation depends on time, therefore dropping the clutch means the time to dissipate the heat is almost nil. Slipping the clutch for a longer time will result in slower heat dissipation, which means in laymans terms that the temperature of the clutch will be lower, as the heat can conduct away.

Ideally though due to rev matching the difference in rotational velocities is nill or close to and it doesn't matter

I am surprised his bovine holiness or his pushing ropiness did not react to your above conclusions.
-"dropping the clutch means the time to dissipate the heat is almost nil": you mean the temperature at the clutch would be very high? well not really. Before the clutch starts dissipating the heat, it has to transform the energy into heat, and it can only do so by friction, i.e. slipping the clutch for a period of time. If there is not enough time for friction to occur, the clutch cannot transform this energy into heat, it goes instead into work done in giving a sudden acceleration or deceleration to the car, or a shift shock.

-"Slipping the clutch for a longer time results in slower heat dissipation, which means temperature of the clutch will be lower": I don't know about the "slower heat dissipation", but you certainly get more heat generated the longer you slip the clutch, which means the temperature at the clutch will be higher the longer you slip.

The higher the rpm difference, the more energy is required to align the rpms, meaning more shock or more heat is produced, depending on how long you slip the clutch.

I agree that when one gets familiar with rev-matching, which ever way one chooses to release the clutch has very little impact on usage to the car as a whole.