Choppy Upshifts/Manual Questions

bakerjal · Nov 21, 2017

Hello all,

I'm sure my biggest problem here is that I'm just really inexperienced with a manual car, but I've got some questions regarding not just driving a stick shift, but doing so in this car specifically.

First of all, I'm getting some really choppy upshifts. Is this just because of the infamous rev hang? Do I just wait for the revs to drop slowly? How do I know what RPMs I need to be at when moving up a gear?

I've noticed that, for me, at least, 1st to 2nd is usually the roughest (and also the one I wanna figure out the most since I need to shift to 2nd so quickly). But I get it any time I'm giving it a little more oomph than normal before upshifting.

Secondly, what's the timing of a rev match supposed to be? Hit the throttle just before the clutch bites? Right as it bites? Before I even start letting the clutch up? Also, again, how do I know what RPMs I need to be at for the next gear?

Lastly, how should I approach stopping? My mother taught me how to drive a manual initially, but that was last night after about 20 years of not driving one. SO, I wanna hear from you guys. Should I be downshifting through each gear? Or can I just hold the clutch in and use the brake?

Please guide me and my novice ways. I'd like to not wear out tires/brakes/clutch more than I need too.

thatwhiteSi · Nov 21, 2017

From a stop I blip the gas before letting off the clutch then get back on the gas once the clutch engages. If I am shifting up a gear I kind of do the same thing. It's hard to explain, but it is the exact same bullshit feeling shifting I had with my 8th gen. I believe it is due to the drive by wire throttle. (controlled electronically). I always felt there is some delay or lag in the throttle response with this crap. The rev hang doesn't help either. Something you just have to get used to I guess.

As far as downshifting, I barely ever downshift. If am bored and doing a little spirited driving I'll downshift. Around town I generally just clutch in and brake to a stop.

bakerjal · Nov 21, 2017

thatwhiteSi said:
From a stop I blip the gas before letting off the clutch then get back on the gas once the clutch engages. If I am shifting up a gear I kind of do the same thing. It's hard to explain, but it is the exact same bullshit feeling shifting I had with my 8th gen. I believe it is due to the drive by wire throttle. (controlled electronically). I always felt there is some delay or lag in the throttle response with this crap. The rev hang doesn't help either. Something you just have to get used to I guess.

As far as downshifting, I barely ever downshift. If am bored and doing a little spirited driving I'll downshift. Around town I generally just clutch in and brake to a stop.

So when you upshift, you give it gas right as the clutch engages?

Phylanx · Nov 21, 2017

In order to eliminate or decrease the choppiness when shifting, you need to learn to rev match properly. When upshifting, you need to wait for the rpms to drop to the appropriate level before engaging the clutch. When downshifting, you'll need to blip the throttle before engaging the clutch. Yes, the rev hang means you need to wait a little longer before engaging the clutch as well when upshifting.

To know what proper rpm you need to be at when rev matching, you need to understand gear ratios. Gear ratio is the number of teeth essentially between the driven gear / driving gear.

These are the Si gear ratios.
Gear Ratios: 1st: 3.643, 2nd: 2.080, 3rd: 1.361, 4th: 1.024, 5th: 0.830, 6th: 0.686, Reverse: 3.673, Final Drive Ratio: 4.105

So in first gear, for every 3.643 turns of the driven gear, you'll get one turn of the driving gear. This is accomplished in second gear with only 2.080 turns. You'll notice that the drop in gear ratio is the largest between first and second gear. This translates into the largest drop in rpms when upshifting from first to second when maintaining the same vehicle speed.

Doing some math, say you are at 3000 rpms in first gear. Say we want to solve for x to see what rpms we need to be in at second gear.

3000 rpm / 3.643 = x rpm / 2.080

(3000 rpm * 2.080) = 3.643 x rpm

6240 = 3.643 x

x = 1712.87

For stopping, there's nothing wrong with downshifting to brake, so long as you rev match properly to smooth out the jerkiness. Same goes for skipping gears. I find myself using second mostly to engine brake and clutch in / shift to neutral once the speed drops down to about 5-10 mph.

bakerjal · Nov 21, 2017

Phylanx said:
In order to eliminate or decrease the choppiness when shifting, you need to learn to rev match properly. When upshifting, you need to wait for the rpms to drop to the appropriate level before engaging the clutch. When downshifting, you'll need to blip the throttle before engaging the clutch. Yes, the rev hang means you need to wait a little longer before engaging the clutch as well when upshifting.

To know what proper rpm you need to be at when rev matching, you need to understand gear ratios. Gear ratio is the number of teeth essentially between the driven gear / driving gear.

These are the Si gear ratios.
Gear Ratios: 1st: 3.643, 2nd: 2.080, 3rd: 1.361, 4th: 1.024, 5th: 0.830, 6th: 0.686, Reverse: 3.673, Final Drive Ratio: 4.105

So in first gear, for every 3.643 turns of the driven gear, you'll get one turn of the driving gear. This is accomplished in second gear with only 2.080 turns. You'll notice that the drop in gear ratio is the largest between first and second gear. This translates into the largest drop in rpms when upshifting from first to second when maintaining the same vehicle speed.

Doing some math, say you are at 3000 rpms in first gear. Say we want to solve for x to see what rpms we need to be in at second gear.

3000 rpm / 3.643 = x rpm / 2.080

(3000 rpm * 2.080) = 3.643 x rpm

6240 = 3.643 x

x = 1712.87

For stopping, there's nothing wrong with downshifting to brake, so long as you rev match properly to smooth out the jerkiness. Same goes for skipping gears. I find myself using second mostly to engine brake and clutch in / shift to neutral once the speed drops down to about 5-10 mph.

Is the math you did for the RPMs needed when upshifting just the opposite for figuring out what you need to rev match at?

coopermidnight · Nov 21, 2017

The math applies for all rev matching, whether you're shifting up or down and whether you're shifting sequentially or skipping gears. Mind you, you shouldn't expect to be doing mental math every time you shift; it'll come naturally after a while

In any case, the formula can be made a bit simpler: (G2/G1) x R
(G = gear, R = RPM)

Let's say you're in 1st at 3k RPM and want to skip straight to 3rd:
(1.361/3.643) x 3000 = 1120

Or you're cruising in 6th at an easy 2k and want to downshift to pass someone with style in 4th:
(1.024/0.686) x 2000 = 2985

Now that that's out of the way, on to the rest. I always downshift for a stop/slowing down if there's time. It's personal preference, really, but I think it's good for discipline and it keeps you in the right gear if something unexpected happens. As for rev hang, the Si/EX-T/Sport are notorious for this; it does exist and it's very annoying. Without a tune, you'll have to wait a while for the RPMs to drop when upshifting.

Design · Nov 21, 2017

Shifts at WOT are pretty tough on this car due to the heavy flywheel and rev hang. RPMs simply do not drop fast enough for quick shifting. Shifting under light or moderate acceleration is similar to most other MT platforms, IMHO.

The above explanation (lengthy, but quite good) can be summed up by simply saying... wait a second (or two) between shifts before releasing the clutch pedal. Takes a bit of time & practice... but you'll get it. GL.

bakerjal · Nov 21, 2017

coopermidnight said:
The math applies for all rev matching, whether you're shifting up or down and whether you're shifting sequentially or skipping gears. Mind you, you shouldn't expect to be doing mental math every time you shift; it'll come naturally after a while

In any case, the formula can be made a bit simpler: (G2/G1) x R
(G = gear, R = RPM)

Let's say you're in 1st at 3k RPM and want to skip straight to 3rd:
(1.361/3.643) x 3000 = 1120

Or you're cruising in 6th at an easy 2k and want to downshift to pass someone with style in 4th:
(1.024/0.686) x 2000 = 2985

Now that that's out of the way, on to the rest. I always downshift for a stop/slowing down if there's time. It's personal preference, really, but I think it's good for discipline and it keeps you in the right gear if something unexpected happens. As for rev hang, the Si/EX-T/Sport are notorious for this; it does exist and it's very annoying. Without a tune, you'll have to wait a while for the RPMs to drop when upshifting.

I've considered getting a KTuner for fixing that, but as I've never used something like that, I'm worried about warrantee. I'm certainly in no position financially to be comfortable with voiding it in any way. In any case, I'll be waiting til at least the summer before I do anything like that.

Thanks for the great explanation. I've got a better idea of when do engage the gear now while I'm still getting the feel of it down.

themaincop · Nov 21, 2017

I've been slipping the clutch a little bit when going 1-2, this is just at low speeds in daily driving. Not sure if this is a bad habit to get into, it seems to be the only way I can get into 2nd smoothly without falling behind the rest of traffic.

bakerjal · Nov 21, 2017

themaincop said:
I've been slipping the clutch a little bit when going 1-2, this is just at low speeds in daily driving. Not sure if this is a bad habit to get into, it seems to be the only way I can get into 2nd smoothly without falling behind the rest of traffic.

Tonight, I've been experimenting with letting it rev higher in 1st. That way you can get up to a decent speed, then upshift. That way, your going with traffic and have the time for the revs to drop. Seems to work pretty well if you just go up to 4000 RPM in first.

The rev hang from 1st to 2nd is pretty ridiculous though.

9civic10 · Nov 21, 2017

It's just something you'll get used to and get better at as you have time in the car

tehSteve · Nov 22, 2017

OP you are overthinking it.

Just continue to drive and enjoy the car. This is my first "rev hang" vehicle and it took me about a month to smooth out 1-2 and really any other gear changes that were problematic for me. The proper timing of your shifts will automatically be learned overtime and become natural.

Every manual car you drive, you will need to make some-kind of adjustment. For example... going from my Stage4 Exedy Twin Disk & Lightweight Flywheel from my EvoX to this clutch kinda freaked me out because I couldn't feel anything. Overtime I adjusted and can feel the stiffness.

dmitri · Nov 22, 2017

bakerjal said:
Hit the throttle just before the clutch bites? Right as it bites?

I try to do it just a split-moment after it bites. A bit easier on the clutch, that way.

polished1 · Nov 22, 2017

I had the exact same experience. I thought when shifting you had to let the clutch go completely before giving it gas again, which resulted in a falling behind driving experience while waiting for revs to drop.

The concept is the exact same thing when starting from a stop, IE gas and clutch balance, but just less and less the more you move up in gears. When shifting from 1st to 2nd just give it gas as you let off the clutch, repeat quicker as you get higher in the gears. Boom, much better driving experience.

You don't need to rev it higher or anything, just gas in as clutch out and you're good, just keep in mind not to ride the clutch after 1st gear.

sesty · Nov 22, 2017

Watch your tach with one eye as you make shifts... When up shifting: If the revs drop quickly as you let out the clutch pedal... you didnt let the revs fall enough (shifting too fast). You will feel the car kind of lurch

When up shifting and the revs race up a bit when you let out the pedal, you let the refs fall too much (shifted too slow).

You will also have a rough ride if you are just dumping the clutch ( which i think might be worse on the powertrain than feathering the clutch)

Choppy Upshifts/Manual Questions

bakerjal

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thatwhiteSi

Senior Member

bakerjal

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Phylanx

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bakerjal

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coopermidnight

Senior Member

Design

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bakerjal

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themaincop

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bakerjal

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9civic10

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tehSteve

GrayBeard McGootch

dmitri

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polished1

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sesty

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