jerk free shifts

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Ewilon1988
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Re: jerk free shifts

Post by Ewilon1988 » Tue Jan 12, 2016 10:10 pm

Ok, I'll try this. Thank you

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Re: jerk free shifts

Post by Rope-Pusher » Tue Jan 12, 2016 11:53 pm

You do want to ease back on your acceleration prior to the shift, so that when you stab the clutch pedal and the car stops accelerating, it is not such an abrupt transition from acceleration to coast that the passenges head jerks forward and they utter the phrase "Yo Quiero Taco Bell!"
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Ewilon1988
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Re: jerk free shifts

Post by Ewilon1988 » Wed Jan 13, 2016 12:01 am

Rope-Pusher wrote:You do want to ease back on your acceleration prior to the shift, so that when you stab the clutch pedal and the car stops accelerating, it is not such an abrupt transition from acceleration to coast that the passenges head jerks forward and they utter the phrase "Yo Quiero Taco Bell!"
So you're saying before I clutch in to completely let off the gas?

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Re: jerk free shifts

Post by Rope-Pusher » Wed Jan 13, 2016 12:05 am

Ewilon1988 wrote:
Rope-Pusher wrote:You do want to ease back on your acceleration prior to the shift, so that when you stab the clutch pedal and the car stops accelerating, it is not such an abrupt transition from acceleration to coast that the passenges head jerks forward and they utter the phrase "Yo Quiero Taco Bell!"
So you're saying before I clutch in to completely let off the gas?
Yes, smoothly let off the accelerator pedal so that the car transitions from acceleration to coast just before you step on the clutch pedal to perform your upshift. If you harshly transmition from acceleration to coast, no matter how well you rev match, drag the engine rpm up or down by slipping the clutch, etc., you have already jerked your passenger around.
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Ewilon1988
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Re: jerk free shifts

Post by Ewilon1988 » Wed Jan 13, 2016 12:07 am

Rope-Pusher wrote:
Ewilon1988 wrote:
Rope-Pusher wrote:You do want to ease back on your acceleration prior to the shift, so that when you stab the clutch pedal and the car stops accelerating, it is not such an abrupt transition from acceleration to coast that the passenges head jerks forward and they utter the phrase "Yo Quiero Taco Bell!"
So you're saying before I clutch in to completely let off the gas?
Yes, smoothly let off the accelerator pedal so that the car transitions from acceleration to coast just before you step on the clutch pedal to perform your upshift. If you harshly transmition from acceleration to coast, no matter how well you rev match, drag the engine rpm up or down by slipping the clutch, etc., you have already jerked your passenger around.
I normally let off the gas fully, but I'll be more conscious of how smoothly I do it

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Re: jerk free shifts

Post by potownrob » Wed Jan 13, 2016 2:14 am

Reverence wrote:
potownrob wrote:
Ewilon1988 wrote:When I do clutch, I am always fully off the gas before I push the clutch in, but the revs still hang fairly high.
:shock: :( :cry: :oops: :o

guess that means you have to delay your clutch release :evil: :? 8)
'clutch release' It could mean disengage the clutch or release the clutch pedal, to people new to this forum.

From context, I guess you mean the former, which is what I would do too, or if bored of waiting, just drag the revs down with the clutch.
Though annoying to wait, it doesn't take too long even with the worst of rev hangs out there.
The Hyundais sold in the Chinese market have the worst of hangs, what people tend to do here is to shift and wait for the revs to start falling, then engage the clutch to catch the falling revs. It does allow for some smooth shifts.
sorry i wasn't clear there. i meant to delay the re-engagement of the clutch, as in the last part of the shift where the clutch comes up and you're in the next gear. what i had described earlier was delaying the de-clutching or pushing in/down of the clutch (aka: disengagement), by way of coming off the gas completely (foot off the gas pedal) before even starting to push in the clutch, all prior to shifting into the next gear. what you describe about waiting to re-engage the clutch is what many other SS members will recommend to the rev-hang victim. i haven't driven a hyundai or kia lately, but i sure hope they're better (the clutch AND shifter - what a bad shifter on those older models) than the older ones from the 90s.
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Re: jerk free shifts

Post by theholycow » Wed Jan 13, 2016 10:02 am

Ewilon1988 wrote:I used only the clutch today(no gas) to shift from first to second and it was still too "jerky". I shifted around 3k rpms. Any suggestions?
How jerky?

Your goal shouldn't be to be as smooth as a luxury car's automatic transmission. If you wanted that kind of a boring ride could just drive an automatic. Besides, it's physically impossible; there is an interruption in power delivery with manual transmissions that doesn't happen in automatics (which can slip one gear's clutch while engaging the other's)...the best you can do is spread it out over a loooooooong time so it's gradual, but personally I'd rather get on with accelerating/decelerating already.
tankinbeans wrote:Double clutch.
With rev hang? Might as well send all your throttle and shift inputs to your car via US Postal Service.
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potownrob
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Re: jerk free shifts

Post by potownrob » Wed Jan 13, 2016 10:54 am

theholycow wrote:
Ewilon1988 wrote:I used only the clutch today(no gas) to shift from first to second and it was still too "jerky". I shifted around 3k rpms. Any suggestions?
How jerky?

Your goal shouldn't be to be as smooth as a luxury car's automatic transmission. If you wanted that kind of a boring ride could just drive an automatic. Besides, it's physically impossible; there is an interruption in power delivery with manual transmissions that doesn't happen in automatics (which can slip one gear's clutch while engaging the other's)...the best you can do is spread it out over a loooooooong time so it's gradual, but personally I'd rather get on with accelerating/decelerating already.
hey man, just because your Frankencar is like that doesn't mean all cars are like that; I can get butter smooth shifts all day (once warmed up) if I want to.
tankinbeans wrote:Double clutch.
With rev hang? Might as well send all your throttle and shift inputs to your car via US Postal Service.
might be overestimating his rev-hang a little. I know when I double clutch there's no rev-hang drama.
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Re: jerk free shifts

Post by tankinbeans » Wed Jan 13, 2016 11:48 am

FedEx is better. Faster delivery.
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Re: jerk free shifts

Post by Reverence » Wed Jan 13, 2016 12:14 pm

Ewilon1988 wrote:I used only the clutch today(no gas) to shift from first to second and it was still too "jerky". I shifted around 3k rpms. Any suggestions?
could you tell us exactly at what point(s) during your shifts does the jerk(s) occur? (picture, Rope)
what you've described so far about your shifting:
1) let off the gas pedal
2) clutch pedal in
3) shift
4) clutch pedal out
5) back on the gas pedal

There is potential for jerks at
-1) if you've got no rev hang (apparently not your case), as Rope pointed out, as you suddenly come out of acceleration.
-2) if your car is either accelerating (your still on the gas pedal while stabbing clutch pedal) or if your car is decelerating (your off the gas pedal, and your car decelerates due to engine braking, shouldn't be your case if you've got rev hang)
-4) if your rpms are higher (probably your case) or lower than target, or even if on target if you are not simultaneously and gradually back on the gas pedal since engine braking will be taking over upon clutch engagement
-5) if you've got throttle lag, meaning your gas pedal takes some time to respond to your input, that can spring the car forward.

there are ways to deal with all of the above

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Re: jerk free shifts

Post by theholycow » Wed Jan 13, 2016 1:17 pm

Reverence wrote:-5) if you've got throttle lag, meaning your gas pedal takes some time to respond to your input, that can spring the car forward.
...or potentially it's not severe rev hang but lag that works in both directions, in which case you could get engine braking because your input does not bring engine speed up when you expect it to.
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Ewilon1988
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Re: jerk free shifts

Post by Ewilon1988 » Wed Jan 13, 2016 2:17 pm

Reverence wrote:
Ewilon1988 wrote:I used only the clutch today(no gas) to shift from first to second and it was still too "jerky". I shifted around 3k rpms. Any suggestions?
could you tell us exactly at what point(s) during your shifts does the jerk(s) occur? (picture, Rope)
what you've described so far about your shifting:
1) let off the gas pedal
2) clutch pedal in
3) shift
4) clutch pedal out
5) back on the gas pedal

There is potential for jerks at
-1) if you've got no rev hang (apparently not your case), as Rope pointed out, as you suddenly come out of acceleration.
-2) if your car is either accelerating (your still on the gas pedal while stabbing clutch pedal) or if your car is decelerating (your off the gas pedal, and your car decelerates due to engine braking, shouldn't be your case if you've got rev hang)
-4) if your rpms are higher (probably your case) or lower than target, or even if on target if you are not simultaneously and gradually back on the gas pedal since engine braking will be taking over upon clutch engagement
-5) if you've got throttle lag, meaning your gas pedal takes some time to respond to your input, that can spring the car forward.

there are ways to deal with all of the above
the jerks occur when I'm almost to the top of my clutch when I'm letting it out.

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Re: jerk free shifts

Post by Ewilon1988 » Wed Jan 13, 2016 2:54 pm

On my way to work just now I did this:

1) let off gas
2) clutch in
3 shift 1-2
4) let up clutch semi slow(not slipping) to around the bite point(which isn't the easiest to find on this car) and then let up kinda quick.

The car didn't jerk, just dipped down like it lost power and then I accelerated.

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Re: jerk free shifts

Post by tankinbeans » Wed Jan 13, 2016 3:43 pm

Ewilon1988 wrote:On my way to work just now I did this:

1) let off gas
2) clutch in
3 shift 1-2
4) let up clutch semi slow(not slipping) to around the bite point(which isn't the easiest to find on this car) and then let up kinda quick.

The car didn't jerk, just dipped down like it lost power and then I accelerated.
Give it a bit of gas before letting up "kinda quick.". It sounds like you're dialing it in.
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Re: jerk free shifts

Post by Ewilon1988 » Wed Jan 13, 2016 4:39 pm

tankinbeans wrote:
Ewilon1988 wrote:On my way to work just now I did this:

1) let off gas
2) clutch in
3 shift 1-2
4) let up clutch semi slow(not slipping) to around the bite point(which isn't the easiest to find on this car) and then let up kinda quick.

The car didn't jerk, just dipped down like it lost power and then I accelerated.
Give it a bit of gas before letting up "kinda quick.". It sounds like you're dialing it in.
Ok, I'll try that.

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