Quicker upshifts with SRM off?

optiontrader · 11-19-2010, 11:39 PM

I never felt the need to turn off SRM (note: NOT VDC!

) , but decided to do so when I was driving home from work.

I noticed the rpms don't "hang" as long as when SRM is engaged while upshifting. It seemed easier to snick off faster gear changes.

Before, with SRM on, there was a long enough pause that I could take a sip of coffee while accelerating from a stoplight.

Anyone else notice this? Or am I a victim of psycho-somatic button pressing in a Z?

kenchan · 11-20-2010, 08:20 AM

Made no difference for me on or off...

6spd · 11-20-2010, 09:25 AM

yeah, the timing is all driver. SRM or not, my shifts never have any time in between sip coffee!

shadow2k · 11-20-2010, 09:53 AM

You'd only want your RPM's to drop if you were driving slow. And if you were driving slow, there was no need to rev them up that high in the previous gear, you should have shifted sooner.

SRM keeps the RPM's high on upshifts so that you are kept in the powerband. Being in the powerband means more power quicker...as opposed to waiting for the RPM's to drop, and then having to bring them back up.

What you are doing makes no sense to me.

ZedZed · 11-20-2010, 10:25 AM

No difference for upshift.

Mt Tam I am · 11-20-2010, 11:17 AM

Quote:

Originally Posted by optiontrader

I never felt the need to turn off SRM (note: NOT VDC!

) , but decided to do so when I was driving home from work.

I noticed the rpms don't "hang" as long as when SRM is engaged while upshifting. It seemed easier to snick off faster gear changes.

Before, with SRM on, there was a long enough pause that I could take a sip of coffee while accelerating from a stoplight.

Anyone else notice this? Or am I a victim of psycho-somatic button pressing in a Z?

Victim and perpetrator.

the_student · 11-20-2010, 02:07 PM

Quote:

Originally Posted by optiontrader

I never felt the need to turn off SRM (note: NOT VDC!

) , but decided to do so when I was driving home from work.

I noticed the rpms don't "hang" as long as when SRM is engaged while upshifting. It seemed easier to snick off faster gear changes.

Before, with SRM on, there was a long enough pause that I could take a sip of coffee while accelerating from a stoplight.

Anyone else notice this? Or am I a victim of psycho-somatic button pressing in a Z?

I know what you mean. But, I think what you felt about faster gear changes may be related to the timing of getting back on the gas pedal when you shift after the gear change. When I drive with SRM off for a while and then turn it back on, I have to get on the gas pedal a little later to get the same smooth shift otherwise it feels like i slip the clutch a bit or it gets jerky.

So it makes sense that you do feel the RPMs hang and its related to the timing issue again. With SRM on, as the revs decrease, it slows down (just before the correct RPM) and stops at the specific rpm you need for the next gear. With SRM off, the revs would just continue to drop and won't have to slow down and stop, and instead of the SRM controlling the RPM, you as the driver would have to match the revs for the upshift. So you have to get on the gas a little bit earlier, which makes you feel like you can get those faster shifts.

I hope I make sense and hopefully I've articulated what I'm thinking correctly.

Anyway, the timing isn't as vast as you make it out to be. It's more like a fraction of a second. Unless, you are just letting the revs stay on the RPM for the next gear without engaging it...haha and that is definitely not recommended.

spearfish25 · 11-20-2010, 03:38 PM

SRM just holds the RPM at the next higher gear's appropriate level during upshifts.

Shift speed is entirely up to your right hand. That's what she said.

NiZZZmo370 · 11-20-2010, 06:52 PM

Quote:

Originally Posted by the_student

I know what you mean. But, I think what you felt about faster gear changes may be related to the timing of getting back on the gas pedal when you shift after the gear change. When I drive with SRM off for a while and then turn it back on, I have to get on the gas pedal a little later to get the same smooth shift otherwise it feels like i slip the clutch a bit or it gets jerky.

So it makes sense that you do feel the RPMs hang and its related to the timing issue again. With SRM on, as the revs decrease, it slows down (just before the correct RPM) and stops at the specific rpm you need for the next gear. With SRM off, the revs would just continue to drop and won't have to slow down and stop, and instead of the SRM controlling the RPM, you as the driver would have to match the revs for the upshift. So you have to get on the gas a little bit earlier, which makes you feel like you can get those faster shifts.

I hope I make sense and hopefully I've articulated what I'm thinking correctly.

Anyway, the timing isn't as vast as you make it out to be. It's more like a fraction of a second. Unless, you are just letting the revs stay on the RPM for the next gear without engaging it...haha and that is definitely not recommended.

travisjb · 11-20-2010, 09:00 PM

suggest OP try lifting throttle split sec sooner during up-shifts - most likely there's a timing issue here and higher rpms between shifts is a result of being on throttle too long

also, the stock flywheel is dual-mass... if you really can't stand the momentum of the motor, you can swap out for a single mass and solve it

optiontrader · 11-20-2010, 11:19 PM

Thanks for the replies everyone.

Quote:

Originally Posted by the_student

I know what you mean. But, I think what you felt about faster gear changes may be related to the timing of getting back on the gas pedal when you shift after the gear change. When I drive with SRM off for a while and then turn it back on, I have to get on the gas pedal a little later to get the same smooth shift otherwise it feels like i slip the clutch a bit or it gets jerky.

So it makes sense that you do feel the RPMs hang and its related to the timing issue again. With SRM on, as the revs decrease, it slows down (just before the correct RPM) and stops at the specific rpm you need for the next gear. With SRM off, the revs would just continue to drop and won't have to slow down and stop, and instead of the SRM controlling the RPM, you as the driver would have to match the revs for the upshift. So you have to get on the gas a little bit earlier, which makes you feel like you can get those faster shifts.

I hope I make sense and hopefully I've articulated what I'm thinking correctly.

Anyway, the timing isn't as vast as you make it out to be. It's more like a fraction of a second. Unless, you are just letting the revs stay on the RPM for the next gear without engaging it...haha and that is definitely not recommended.

This is EXACTLY what I'm experiencing - rep for you. It feels like SRM, when it's matching the revs at lower rpms for the higher gear, SLOWS down the needle drop. It's something I got used to, but with SRM disengaged, shifting is MUCH smoother.

The "hang" at the lower gear seems shorter, but again, I could be smoking sumthin.

I can shift VERY quickly, but I feel like the "holding back" I need to do is much less with SRM off than with it engaged. Guess I'm not used to the rpms settling in at the next gear shift range instead of dropping like a rock to idle.

I may go back to heel/toe shifting...

travisjb · 11-20-2010, 11:58 PM

here read this

syncro rev match

optiontrader · 11-22-2010, 07:54 PM

Yup - you're right on. While I don't feel a throttle "blip" when I clutch in, I definitely notice the "rpm hold".

I've switched SRM back on (call me lazy - I love not having to exercise my leg to heel/toe in SoCal traffic [on a track, that'd be another thing]), and the "hold" is definitely there.

I'll get used to it (I know, I can hear you all: "suck it up!"

).

Cheers, and enjoy the drive!

rmorrow · 11-24-2010, 03:24 PM

Optiontrader,
I really have not noticed quicker upshifts with SRM off, but I have definitely noticed smoother shifts with it off, especially from 1st to 2nd. There is a recent thread on this issue, with others noticing smoother shifts with SRM off/VDC off/SRM and VDC off. I drive with SRM off most of the time now, because I feel that the shifts are smoother.

11-19-2010, 11:39 PM	#1 (permalink)
optiontrader Track Member Join Date: Jul 2010 Location: Smog Hell, SoCal Posts: 595 Drives: 40th Rep Power: 16	Quicker upshifts with SRM off? I never felt the need to turn off SRM (note: NOT VDC! ) , but decided to do so when I was driving home from work. I noticed the rpms don't "hang" as long as when SRM is engaged while upshifting. It seemed easier to snick off faster gear changes. Before, with SRM on, there was a long enough pause that I could take a sip of coffee while accelerating from a stoplight. Anyone else notice this? Or am I a victim of psycho-somatic button pressing in a Z? __________________ 40th Anniversary Z - 3M Paint Protection Film, CA Legal Tint! (70/40)

11-20-2010, 09:25 AM	#3 (permalink)
6spd A True Z Fanatic Join Date: Aug 2009 Location: South Florida Posts: 3,001 Drives: Q50RS Rep Power: 25	yeah, the timing is all driver. SRM or not, my shifts never have any time in between sip coffee! __________________ -Jay- jonathanjamesphotographer.com

11-20-2010, 03:38 PM	#8 (permalink)
spearfish25 A True Z Fanatic Join Date: Mar 2009 Location: Naples, FL Posts: 4,117 Drives: to work Rep Power: 1856	SRM just holds the RPM at the next higher gear's appropriate level during upshifts. Shift speed is entirely up to your right hand. That's what she said. __________________ 2013 Cadillac V-Wagon, RIP Z

11-20-2010, 09:00 PM	#10 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 188	suggest OP try lifting throttle split sec sooner during up-shifts - most likely there's a timing issue here and higher rpms between shifts is a result of being on throttle too long also, the stock flywheel is dual-mass... if you really can't stand the momentum of the motor, you can swap out for a single mass and solve it __________________ 2009 370Z #104 For Sale

11-20-2010, 11:58 PM	#12 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 188	here read this syncro rev match __________________ 2009 370Z #104 For Sale

11-20-2010, 08:20 AM	#2 (permalink)
kenchan A True Z Fanatic Join Date: Aug 2009 Location: N/A Posts: 76,801 Drives: N/A Rep Power: 141521	Made no difference for me on or off...

11-20-2010, 09:53 AM	#4 (permalink)
shadow2k Base Member Join Date: Jul 2009 Location: Overland Park, Kansas Posts: 143 Drives: 09 PG 370z 6MT Rep Power: 16	You'd only want your RPM's to drop if you were driving slow. And if you were driving slow, there was no need to rev them up that high in the previous gear, you should have shifted sooner. SRM keeps the RPM's high on upshifts so that you are kept in the powerband. Being in the powerband means more power quicker...as opposed to waiting for the RPM's to drop, and then having to bring them back up. What you are doing makes no sense to me.

11-20-2010, 10:25 AM	#5 (permalink)
ZedZed Base Member Join Date: Mar 2010 Location: Belgium, Brussels Posts: 237 Drives: nothing Rep Power: 15	No difference for upshift.

11-22-2010, 07:54 PM	#13 (permalink)
optiontrader Track Member Join Date: Jul 2010 Location: Smog Hell, SoCal Posts: 595 Drives: 40th Rep Power: 16	Yup - you're right on. While I don't feel a throttle "blip" when I clutch in, I definitely notice the "rpm hold". I've switched SRM back on (call me lazy - I love not having to exercise my leg to heel/toe in SoCal traffic [on a track, that'd be another thing]), and the "hold" is definitely there. I'll get used to it (I know, I can hear you all: "suck it up!" ). Cheers, and enjoy the drive! __________________ 40th Anniversary Z - 3M Paint Protection Film, CA Legal Tint! (70/40)

11-24-2010, 03:24 PM	#14 (permalink)
rmorrow Base Member Join Date: Jun 2010 Location: Houston Posts: 79 Drives: 2010 370z Sports MT Rep Power: 15	Optiontrader, I really have not noticed quicker upshifts with SRM off, but I have definitely noticed smoother shifts with it off, especially from 1st to 2nd. There is a recent thread on this issue, with others noticing smoother shifts with SRM off/VDC off/SRM and VDC off. I drive with SRM off most of the time now, because I feel that the shifts are smoother.

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