[gbhgbh]

To followup on the last basic car question, I have a question about upshifting. In the last thread, there were several articles suggesting to use double clutching along with heal and toeing to maintain a smooth transition and balance while downshifting. So my question is, is there a similar technique for a smooth transition while upshifting? Also, is gradually letting out the clutch (taking about a couple of seconds) to get a smooth transition, bad technique?

[Don Pickett]

Originally Posted by gbhgbh

To followup on the last basic car question, I have a question about upshifting. In the last thread, there were several articles suggesting to use double clutching along with heal and toeing to maintain a smooth transition and balance while downshifting. So my question is, is there a similar technique for a smooth transition while upshifting? Also, is gradually letting out the clutch (taking about a couple of seconds) to get a smooth transition, bad technique?

I'm not sure what you mean my "smooth transition". Unless you're taking ages to shift the drop in revs should barely be noticeable. If you get really good you don't even need to use the clutch.

[Sandakt]

Are you racing your car? A manual transmission nowadays has syncros so you don't have to "heel-toe" and "double-clutch". Just press in the clutch, let off the gas, shift, and continue driving.

[Diggory Laycock]

You haven't needed to double de-clutch since about the 60's.

[Goldfinger]

Originally Posted by Don Pickett

If you get really good you don't even need to use the clutch.

Yeah well don't do this, this is about the worst thing you can do to your gearbox.

Are you racing your car? A manual transmission nowadays has syncros so you don't have to "heel-toe" and "double-clutch". Just press in the clutch, let off the gas, shift, and continue driving.

Not true, if you do this you will still feel a little shock.

What you need to do is touch the accelerator just a bit before letting down the clutch again. And for extra smoothness you can put down the clutch slower than normal. You need the experiment what's best with your car, they all differ a bit.
And double de-clutching is indeed BS.

[analogika]

Originally Posted by Goldfinger

What you need to do is touch the accelerator just a bit before letting down the clutch again. And for extra smoothness you can put down the clutch slower than normal. You need the experiment what's best with your car, they all differ a bit.

I have a question here, seeing as my van went into the shop for a new clutch today. The new clutch and installation would have cost me probably over €2000 at a regular garage (since the entire engine has to ripped out to get at the gearbox - go figure), though it should be good for another 200 000 km AT LEAST once it's done now...but still, out of long-term financial interest:

Is releasing the clutch slowly harder on the clutch in normal use, resulting in faster deterioration than fast release, or is it more a function of getting the engine up to the right rev using the accelerator?

I'd think that careful rev-matching and fast release are probably ideal, but since my "common sense" may be off, I ask...

[Goldfinger]

Your common sense is dead on AFAIK. The most important part is getting your revs up a bit. When you rev a bit up you can release the clutch pretty quickly. I guess your van is a diesel ? (was it Mercedes or VW you had ?) A diesel doesn't lose revs as quick as a petrol engine so you shouldn't need to rev up too much. Anyway those diesel vans, especially Mercedes, are tanks. So don't worry too much about them lasting because they will outlast you.

[analogika]

Originally Posted by Goldfinger

Your common sense is dead on AFAIK. The most important part is getting your revs up a bit. When you rev a bit up you can release the clutch pretty quickly. I guess your van is a diesel ? (was it Mercedes or VW you had ?) A diesel doesn't lose revs as quick as a petrol engine so you shouldn't need to rev up too much. Anyway those diesel vans, especially Mercedes, are tanks. So don't worry too much about them lasting because they will outlast you.

VW T4-generation (1997), 1.9L turbodiesel.

I was considering a Mercedes MB100 before I got this one, but, although it's a tank and the engine will probably outlive cockroaches on this planet, its rear brakes simply don't work (known fact), nor does heating, and, most importantly, the gearbox is complete ****. The Vitos have the same gear box problems (they're from the same plant in Vitoria, Spain as the MB100 was) and, while nice vans, are *completely* out of my price range.

[gbhgbh]

The essence of my original question was whether I should let out the clutch quickly, or let it out slowly to avoid a lurch or jerk, and thus have a smooth transition while shifting.

To give some background, I've never been taught how to drive a manual transmission. My brother took his car in to be repaired and was given a manual transmission car as a loaner until his car was fixed, so I was learning on that without any instruction. The biggest problem I had was getting the car going from a complete stop without the car jerking. I eventually learned to slowly let out the clutch while applying the gas. I assumed that I should do this between all gears in order to smoothly shift, that is, without having the car jerk from one gear to another. I guess this would be slipping the clutch. At the time (and at the time I originally posted), I didn't know much about rev matching.

So at this point, I assume it's necessary to slip the clutch to get the car going from a complete stop. But in the other gears, my question is, should I let the clutch out quickly (less than a second), or let it out slowly (2 to 3 seconds) to ensure there is no jerk--in each case while attempting to rev match. I ask this from the point of view of just driving around on regular streets, not racing, and ask this from the point of view of what would cause the least wear on the car.

[sminch]

i've always tried to rev-match a little at least, but it tends to be a bit hit and miss... gotta be better for the car, and prolly a bit of overcompensation (leading to acceleration) produces a better feel for passengers than undercompensation. after first i've tended to pretty much drop the clutch as it doesn't jerk so much as it would if you did the same downshifting, and i figure lack of jerk = lack of impact on the clutch / transmission / engine. of course, if i was driving on snow, ice, or gravel i'd be more gentle.

this is one thing i've always wondered about, however, and there was a line in the fast and the furious where mr diesel hassles the pretty boy for 'granny shifting' in their first race, which i took to mean not double-clutching, so i did wonder if i was a shameful closet granny shifter (albeit unwitting) who would never make it on the street race circuit

the shame, etc.

sminch

[Don Pickett]

Originally Posted by Goldfinger

Yeah well don't do this, this is about the worst thing you can do to your gearbox.

Actually, the worst thing you can do to your gearbox is blow the 4-3 downshift while braking into the big bend at Lime Rock. Spin city, man.

Notice I said "if you get really good". I meant it – it's the kind of thing you can do if you practice enough. If you do it well it doesn't do much of anything to your gearbox.

[Fyre4ce]

As an automotive engineer, I'll take this one:

I saw the previous thread on braking/engine braking/downshifting/etc and didn't have time to write the long reply I wanted to. But this question is much easier to answer.

No need to double-clutch on an upshift. The correct procedure, whether racing or getting groceries, is:

1) simultaneously close the throttle and depress the clutch
2) move shifter into new gate
3) simultaneously open throttle and release the clutch

The only difference between a racing shift and a street shift is the speed. Racing cars have very light flywheels so when the clutch is in, the revs fall very quickly, which actually requires a fast shift in order to be smooth. Street cars have heavy flywheels, so the revs fall slowly. I drive a Cavalier with a very heavy flywheel and when I shift, especially from high RPM, I have to sit with the clutch in for a moment or two and watch the tachometer fall to the point when I know the engine and transmission are matched. If I try to shift too fast, it shocks the hell out of the car and chirps the tires. The lower the gear, the longer I need to wait and the worse the shock is if I don't.

Mechanically, there is not a need to let the clutch out in neutral to get the shifter to go into the new gate. The input shaft needs to be slowed down for the new gear to engage but friction will naturally slow it. In a downshift, the revs are increasing so the input shaft needs to be spun up, against friction - hence the need to let the clutch out in neutral and blip.

[Athens]

Originally Posted by gbhgbh

To followup on the last basic car question, I have a question about upshifting. In the last thread, there were several articles suggesting to use double clutching along with heal and toeing to maintain a smooth transition and balance while downshifting. So my question is, is there a similar technique for a smooth transition while upshifting? Also, is gradually letting out the clutch (taking about a couple of seconds) to get a smooth transition, bad technique?

The more gradually you are letting out the clutch the smoother the ride BUT you are basically slipping the clutch and killing it slowly. I tend to slip it only from N to first, all the other gears its just a smoke action. If you want smooth upshifts, change at the right RPMS and it will be smooth. I usally prefer the power feeling so I change at 5000 RPM but when im trying to save on gas or just feel like taking it easy I change at 2200RPM and when I do it at that RPM it feels very smooth. Mind u im sure every car is different so dont take these numbers as exact numbers for your car.

[Athens]

Originally Posted by gbhgbh

The essence of my original question was whether I should let out the clutch quickly, or let it out slowly to avoid a lurch or jerk, and thus have a smooth transition while shifting.

To give some background, I've never been taught how to drive a manual transmission. My brother took his car in to be repaired and was given a manual transmission car as a loaner until his car was fixed, so I was learning on that without any instruction. The biggest problem I had was getting the car going from a complete stop without the car jerking. I eventually learned to slowly let out the clutch while applying the gas. I assumed that I should do this between all gears in order to smoothly shift, that is, without having the car jerk from one gear to another. I guess this would be slipping the clutch. At the time (and at the time I originally posted), I didn't know much about rev matching.

So at this point, I assume it's necessary to slip the clutch to get the car going from a complete stop. But in the other gears, my question is, should I let the clutch out quickly (less than a second), or let it out slowly (2 to 3 seconds) to ensure there is no jerk--in each case while attempting to rev match. I ask this from the point of view of just driving around on regular streets, not racing, and ask this from the point of view of what would cause the least wear on the car.

hehe I remmeber the early days. I had 3 ppl teaching me how to drive a standard with 3 styles. One thing to be careful cuz I made this mistake when I started getting to conforatble with it, always push the cluch in all the way when you are changing fast until you are really good at it. A couple times I grinded my gears when I wasent putting pushing the clutch in far enough while changing gears. Dont think I broke anything since it still works find but it sure sounded like it was going to break. These days I only push the clutch in about 15% when im at the right RPM for a super smooth change.

[suvsr4terrorists]

Don't do it so fast that you do smoky burnouts, don't take forever either. Shifting isn't rocket science, and I think most of you are making it way more complicated than it needs to be.

[SVass]

Having driven a shift car forever and having taught a spouse and two teenagers (both girls) to drive shift cars, I can say that as long as you are not racing any shift that does not cause a car to lurch, stumble, or otherwise misbehave is reasonable. Also, do not slip the clutch (except when starting up a steep hill) as that shortens its life. sam