jerk free shifts

Read the FAQ and still not sure about something? Want to shift faster? Post here.
Ewilon1988
Senior Standardshifter
Posts: 101
Joined: Tue Jan 12, 2016 12:27 am
Cars: 2016 WRX 6MT

Re: jerk free shifts

Post by Ewilon1988 »

Ok, I'll try this. Thank you
Rope-Pusher
Master Standardshifter
Posts: 11607
Joined: Mon Mar 16, 2009 3:44 pm
Cars: '08 Jeep Liberty
Location: Greater Detroit Area

Re: jerk free shifts

Post by Rope-Pusher »

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!"
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"
Ewilon1988
Senior Standardshifter
Posts: 101
Joined: Tue Jan 12, 2016 12:27 am
Cars: 2016 WRX 6MT

Re: jerk free shifts

Post by Ewilon1988 »

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?
Rope-Pusher
Master Standardshifter
Posts: 11607
Joined: Mon Mar 16, 2009 3:44 pm
Cars: '08 Jeep Liberty
Location: Greater Detroit Area

Re: jerk free shifts

Post by Rope-Pusher »

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.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"
Ewilon1988
Senior Standardshifter
Posts: 101
Joined: Tue Jan 12, 2016 12:27 am
Cars: 2016 WRX 6MT

Re: jerk free shifts

Post by Ewilon1988 »

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
User avatar
potownrob
Master Standardshifter
Posts: 7833
Joined: Sun Jun 05, 2005 11:35 pm
Cars: '17 CX-5 GT
Location: Dutchess County

Re: jerk free shifts

Post by potownrob »

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.
ClutchFork wrote:...So I started carrying a stick of firewood with me and that became my parking brake.
User avatar
theholycow
Master Standardshifter
Posts: 16021
Joined: Tue Jun 24, 2008 1:36 pm
Cars: '80 Buick LeSabre 4.1 5MT
Location: Glocester, RI
Contact:

Re: jerk free shifts

Post by theholycow »

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.
1980 Buick LeSabre 4.1L 5MT

Put your car in your sig!

Learn to launch/FAQs/lugging/misused terms: meta-sig
watkins wrote:Humans have rear-biased AWD. Cows have 4WD
User avatar
potownrob
Master Standardshifter
Posts: 7833
Joined: Sun Jun 05, 2005 11:35 pm
Cars: '17 CX-5 GT
Location: Dutchess County

Re: jerk free shifts

Post by potownrob »

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.
ClutchFork wrote:...So I started carrying a stick of firewood with me and that became my parking brake.
tankinbeans
Master Standardshifter
Posts: 4029
Joined: Tue Apr 26, 2011 9:04 pm
Cars: 17 Mazda6 To, 18 Mazda3 i
Location: Shakopee, MN

Re: jerk free shifts

Post by tankinbeans »

FedEx is better. Faster delivery.
17 Mazda6 Touring
18 Mazda3 iSport
InlinePaul wrote:The driving force of new fangled features to sell more cars [is to] cater to the masses' abject laziness!
Image
Reverence
Senior Standardshifter
Posts: 264
Joined: Sat Jan 16, 2010 12:46 pm
Cars: Peugeot 307 2L
Location: Beijing, China

Re: jerk free shifts

Post by Reverence »

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
User avatar
theholycow
Master Standardshifter
Posts: 16021
Joined: Tue Jun 24, 2008 1:36 pm
Cars: '80 Buick LeSabre 4.1 5MT
Location: Glocester, RI
Contact:

Re: jerk free shifts

Post by theholycow »

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.
1980 Buick LeSabre 4.1L 5MT

Put your car in your sig!

Learn to launch/FAQs/lugging/misused terms: meta-sig
watkins wrote:Humans have rear-biased AWD. Cows have 4WD
Ewilon1988
Senior Standardshifter
Posts: 101
Joined: Tue Jan 12, 2016 12:27 am
Cars: 2016 WRX 6MT

Re: jerk free shifts

Post by Ewilon1988 »

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.
Ewilon1988
Senior Standardshifter
Posts: 101
Joined: Tue Jan 12, 2016 12:27 am
Cars: 2016 WRX 6MT

Re: jerk free shifts

Post by Ewilon1988 »

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.
tankinbeans
Master Standardshifter
Posts: 4029
Joined: Tue Apr 26, 2011 9:04 pm
Cars: 17 Mazda6 To, 18 Mazda3 i
Location: Shakopee, MN

Re: jerk free shifts

Post by tankinbeans »

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.
17 Mazda6 Touring
18 Mazda3 iSport
InlinePaul wrote:The driving force of new fangled features to sell more cars [is to] cater to the masses' abject laziness!
Image
Ewilon1988
Senior Standardshifter
Posts: 101
Joined: Tue Jan 12, 2016 12:27 am
Cars: 2016 WRX 6MT

Re: jerk free shifts

Post by Ewilon1988 »

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.
Post Reply