jerk free shifts

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theholycow
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Re: jerk free shifts

Post by theholycow » Wed Apr 09, 2014 7:30 am

No load going through the transmission means there's zero acceleration and zero engine braking going on. There is zero jerk as you disengage and engage the clutch with no load, and your tachometer holds steady during each clutch pedal movement.

In practice, that means that you:

- Declutch (aka disengage the clutch aka floor the clutch pedal) either at the perfect time after getting off the accelerator pedal, or while holding the accelerator pedal at the perfect position.

- Engage the clutch (aka let up the clutch pedal aka release the clutch pedal) either while holding the accelerator pedal at the new perfect position or in the perfect moment after blipping (a quick stab and release of the accelerator pedal).

That said...keep in mind that "less wear for the clutch" as you are asking it is an inconsequential amount of wear at stake. Don't allow a worry about it to affect anything more important, including your preference for a smooth shift/clutch engagement.
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Re: jerk free shifts

Post by tennispro » Tue Sep 30, 2014 4:36 pm

FRSstyle wrote:shift faster so that when you get into second, the rpms haven't dropped to low.

ironically, you letting the clutch out slower and smoother is giving you the jerk because the revs are falling too much. watch where the rpms land when you jerk and then try to let out the clutch before the revs drop below that point when you shift to second.
Seems like one of two solution:

Shift quicker so RPMs don't fall as much and that way you should be at the desired RPM range for the next gear, or if you are holding the clutch in longer give it gas and ease the clutch out slower until the engine catches for that gear then release the clutch. The first way is obviously better. When it comes down to it, you want the RPMs to be in the correct range for the gear you're in when you let off your clutch.

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Re: jerk free shifts

Post by Ewilon1988 » Tue Jan 12, 2016 12:33 am

tankinbeans wrote:
jhg1232 wrote:thanks for all the help guys! :) another question, is it ok to let go of the clutch fast once im giving gas on clutch release ? clutch in, shift, gas+release clutch quickly or should i still slowly release the clutch?
Do whatever you need to in order to get a smooth shift. Generally, for all shifts aside from 1>2 the clutch action will be minimal. What I do is clutch in, shift, wait for a second - so the revs can drop - and let off completely on the clutch. My shifts tend to be pretty good, with the occasional jerkiness - which I can put up with.

Obviously this will depend on your specific car and how it behaves to different inputs, but you'll get to know that as you drive it more. Its personality will become more obvious and you'll learn how to work with it.
I have a 2016 wrx with really bad rev hang as well. My 1-2 shifts aren't that great so I'm looking for help and I'm going to try what you said but I have one question. When you let the revs drop then completely let off on the clutch, are you adding a bit of gas? Or just smoothly letting up the clutch as the revs fall

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Re: jerk free shifts

Post by Ewilon1988 » Tue Jan 12, 2016 12:36 am

tankinbeans wrote:
jhg1232 wrote:thanks for all the help guys! :) another question, is it ok to let go of the clutch fast once im giving gas on clutch release ? clutch in, shift, gas+release clutch quickly or should i still slowly release the clutch?
Do whatever you need to in order to get a smooth shift. Generally, for all shifts aside from 1>2 the clutch action will be minimal. What I do is clutch in, shift, wait for a second - so the revs can drop - and let off completely on the clutch. My shifts tend to be pretty good, with the occasional jerkiness - which I can put up with.

Obviously this will depend on your specific car and how it behaves to different inputs, but you'll get to know that as you drive it more. Its personality will become more obvious and you'll learn how to work with it.
I have a 2016 wrx with really bad rev hangs as well. My 1-2 shifts aren't that great so I'm looking for help and I'm going to try what you said but I have one question. When you let the revs drop then completely let off on the clutch, are you adding a bit of gas? Or just smoothly letting up the clutch as the revs fall

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Re: jerk free shifts

Post by IMBoring25 » Tue Jan 12, 2016 12:43 am

That depends on speed and gear. Any time you re-engage the clutch in gear, you ideally want the engine to already be spinning the same speed it will be once the clutch is fully engaged. If you aggressively short-shift or have a significant amount of rev-hang remaining, that might be no-throttle. Otherwise, smoothness will dictate some.

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Re: jerk free shifts

Post by Ewilon1988 » Tue Jan 12, 2016 1:04 am

For instance, I normally shift from 1-2 at about 3k-3200k rpms. They take awhile to drop to let's say 2k rpms where 2nd gear likes to be in my car. So should I just shift then let up the clutch since the rpms are already high?

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Re: jerk free shifts

Post by tankinbeans » Tue Jan 12, 2016 1:29 am

When I do it I just smoothly release once the revs have fallen appropriately. It's been awhile since I've dealt with revhang so my technique might have changed slightly. I definitely don't add any gas back though.
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Re: jerk free shifts

Post by Ewilon1988 » Tue Jan 12, 2016 2:39 am

Thank you! I'm going to practice that tomorrow and let you know how it goes.

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Re: jerk free shifts

Post by potownrob » Tue Jan 12, 2016 3:15 am

Ewilon1988 wrote:For instance, I normally shift from 1-2 at about 3k-3200k rpms. They take awhile to drop to let's say 2k rpms where 2nd gear likes to be in my car. So should I just shift then let up the clutch since the rpms are already high?
my accord is said to have rev-hang, though it seems mild to me, and i've adjusted to it more or less. what i have learned to do is to let off the gas slightly before pushing in the clutch during my upshift routine. this gives the engine/ecu time to wind down before i shift to the next gear and re-engage the clutch. an onlooker may not even notice i'm delaying things, as the delay is subtle and occurs before the actual shift. alternately, there are some downshifts, namely the 6-5 and 5-4 downshifts, where i don't usually have to add much if any gas due to the revs not dropping (and sometimes inadvertantly not coming off the gas fully - don't try this at home kids!!).
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Re: jerk free shifts

Post by Ewilon1988 » Tue Jan 12, 2016 3:40 am

When I do clutch, I am always fully off the gas before I push the clutch in, but the revs still hang fairly high.

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Re: jerk free shifts

Post by potownrob » Tue Jan 12, 2016 4:03 am

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)
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Re: jerk free shifts

Post by Reverence » Tue Jan 12, 2016 12:39 pm

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.

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Re: jerk free shifts

Post by Ewilon1988 » Tue Jan 12, 2016 3:27 pm

I'll try to drag them down by releasing the clutch and see how that works. Thanks for the responses, they're truly appreciated.

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Re: jerk free shifts

Post by Ewilon1988 » Tue Jan 12, 2016 8:13 pm

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?

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Re: jerk free shifts

Post by tankinbeans » Tue Jan 12, 2016 9:46 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?
Double clutch.

1. Disengage clutch (pedal down)
2. Shift to neutral
3. Reengage clutch (pedal up)
4. Wait a moment
5. Repeat step 1.
6. Shift to 2nd
7. Repeat step 3.
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