Please test my theory to achieve smooth shifts.

StevenGregory

Member
First Name
Steve
Joined
Dec 16, 2019
Threads
1
Messages
29
Reaction score
26
Location
Illinois
Vehicle(s)
2017 Civic Si
Country flag
To validate my comments: I once drove a 3.8 L E-type Jag from Chesterfield, IN back to Indianapolis, where I worked on it for the friend that owned it, WITH NO CLUTCH (the slave cylinder had blown). It was a matter of putting the car in 2nd gear with the engine off, hitting the starter to move the car up to speed where the engine fired, backing off the throttle to un-load the gears, timing the next up-shift so the gears were moving synchronously, and so on. On a downshift, back off the throttle, pull into neutral, bring the revs up to match the gear speeds. then pull into the lower gear. To stop, back off the throttle, pull into neutral, turn off the ignition, brake to a stop and re-start the whole process.

Having said all of this, the problem with every Civic Si I've driven (including my own): 1. a clutch so light as to be numb, 2. throttle hang which keeps the revs up for way too long when shifting causing a "jerk" when you release the clutch in the next gear. In "sport" mode, my Hondata flash gizzy eliminates this problem. In normal mode, it is still a problem. The solution, slow down the shifts long enough for the RPMs to drop down where they should be.

If you haven't guessed, I'm an old fart who cut my teeth on manual transmissions.
Sponsored

 

jacobzl

Senior Member
Joined
Aug 26, 2019
Threads
8
Messages
76
Reaction score
22
Location
Beverly Hills, CA
Vehicle(s)
2019 Civic Si
Country flag
mine shifts amazingly, ‘19 with almost 5k, i think it’s one of the smoothest manual transmissions ever made and possibly the easiest to drive, ever.... the transmission is one of the selling points on this car IMO
 

xcivicx

Senior Member
Joined
Jan 14, 2016
Threads
69
Messages
933
Reaction score
490
Location
whycanogaparkofcourse.
Vehicle(s)
19 SI coupe in black
Country flag
i have actually shifted with out the clutch, on mine, just to see if i could, and yes you can, wasn't that hard and it went smooth.
iv'e heard back in the 60's this i how the top drag racers did it--that is in cars with 4 speeds.
edit: but not off the line
 

jacobzl

Senior Member
Joined
Aug 26, 2019
Threads
8
Messages
76
Reaction score
22
Location
Beverly Hills, CA
Vehicle(s)
2019 Civic Si
Country flag
i have actually shifted with out the clutch, on mine, just to see if i could, and yes you can, wasn't that hard and it went smooth.
iv'e heard back in the 60's this i how the top drag racers did it--that is in cars with 4 speeds.
yeah my friend used to do that in his 8th gen lol, have to have the synchros at the perfect spot or something idr
 
OP
OP

COOL COUPE

Senior Member
Joined
May 2, 2017
Threads
47
Messages
516
Reaction score
321
Location
South Carolina
Vehicle(s)
2019 Civic SI coupe (red) Skunk 2 shift knob BOV Spacer Plate (red) K&N Panel Filter Dual Muffler Delete
Country flag
If I put the clutch to the floor and HOLD IT THERE ... Shift ... Then move my left foot upward I did achieve markedly better shifts. This is a very awkward motion for me ... So it is a combo of sequence of events that is the difference of a buttery shift vs chrunch chrunch ...
 


First Name
James
Joined
Sep 8, 2019
Threads
2
Messages
15
Reaction score
5
Location
Kansas City, Missouri
Vehicle(s)
2019 Honda Civic Type R
Vehicle Showcase
1
Country flag
I have a 2019 Type R. I also release the clutch in a fluid motion rather than all at once. I figured this was just the way it should be done. If you just let your foot off the clutch all at once you're going to get a nasty jerk due to the drivetrain / engine speed differences. In that scenario, something has to give if the connection is solid between the fly wheel and the clutch plate. Letting off the clutch in a smooth motion puts the duty of speed matching on the frictional plates, as there will be a gradient of friction from light to solid as it becomes further engaged... and of course you want to ensure that the revs are very close to your target before doing this so that the rev matching isn't being done purely by the frictional plate (otherwise prepare to buy a new clutch very soon).

I figured this would be the case with any manual car in existence, but maybe I am wrong.
 

SDAlexander8

Senior Member
First Name
Steve
Joined
Jul 11, 2019
Threads
49
Messages
2,450
Reaction score
2,090
Location
Indianapolis, IN
Vehicle(s)
17’ Si FC3, 17’ Accord 2dr V6 6MT, 22’ RL RTL-E
Country flag
I have a 2019 Type R. I also release the clutch in a fluid motion rather than all at once. I figured this was just the way it should be done. If you just let your foot off the clutch all at once you're going to get a nasty jerk due to the drivetrain / engine speed differences. In that scenario, something has to give if the connection is solid between the fly wheel and the clutch plate. Letting off the clutch in a smooth motion puts the duty of speed matching on the frictional plates, as there will be a gradient of friction from light to solid as it becomes further engaged... and of course you want to ensure that the revs are very close to your target before doing this so that the rev matching isn't being done purely by the frictional plate (otherwise prepare to buy a new clutch very soon).

I figured this would be the case with any manual car in existence, but maybe I am wrong.
This is indeed how a manual transmission works. :bs:
 

Design

Senior Member
Joined
Sep 28, 2015
Threads
28
Messages
3,329
Reaction score
2,903
Location
Southern California
Vehicle(s)
09 MS3, 17 ABM Si Sedan
Country flag
You're pretty much spot on. But per the previous comments, the idea is to find the optimal rev engagement between shifts. That in turn will limit the frictional slip required between the clutch and flywheel. Regardless, in normal shifting, the CDV should mitigate most of that (unless you're REALLY slow on your shifts/clutch release).

You will find that under partial throttle, it takes a second or two for engine revs to match the next gear. 3/4-full throttle takes a little longer, due to rev hang and flywheel inertia.
 

SDAlexander8

Senior Member
First Name
Steve
Joined
Jul 11, 2019
Threads
49
Messages
2,450
Reaction score
2,090
Location
Indianapolis, IN
Vehicle(s)
17’ Si FC3, 17’ Accord 2dr V6 6MT, 22’ RL RTL-E
Country flag
Is it not? I mean that is how I understood it. If I am wrong can you link me to some good sources or at least point out what was wrong with what I said?
There is nothing wrong with what you said. You’re doing it right.
 


Syntek

Senior Member
Joined
Jan 18, 2016
Threads
33
Messages
1,012
Reaction score
697
Location
Los Angeles, CA
Vehicle(s)
2019 PWP Civic Si Sedan
Vehicle Showcase
1
Country flag
To be honest, most videos I've seen have indicated that you should hold the clutch at the catching point for a moment then release, supposedly doing all that motion within a second. Also seen videos of the footwork that goes into it with similar motions. When I first started driving manual again with this car I kept that idea in mind and noticed that from 1-3 shifts, it's extremely jerky doing that movement. as @privilegejunkie pointed out, the one slow movement has been very helpful overall.
 

joecat66

Senior Member
First Name
joe
Joined
May 30, 2018
Threads
11
Messages
52
Reaction score
39
Location
hope valley ri 02832
Vehicle(s)
18 si coupe e38 bmw toyota fj60 triumph tr6 and 2 more
Country flag
I have tried everything under the sun to do something anything at all to improve shift smoothness ... Today I noticed something. Slow release of the clutch ... Maybe something to do with the flywheel mass ? - not sure - but put the car in first gear ... rev and pull slowly and deliberately your left foot upward about half as fast as you would normally do ... then shift to second gear. Marked improvement of the scratchy gear issue ... same for all gears. Third gets notchy as well. I have found improvement. Coincidence ... Or am I onto something of importance here?
Here is the best solution to smooth shifting this car...just dip the clutch. I shift my car using only the top 1/3rd of travel. put it in neutral and slowly push it into first as you slowly press the clutch, you will find it goes in w/the pedal just slightly dipped use this point for the rest of your shifts and things will smooth out through all gears no matter the shift point rpm. This eliminates jerky/slow/inconsistent shifts. I also rev match w/a throttle blip on downshifts.

try this slowly at first to quell you fear of grinding things...it took me awhile to figure this out but it takes the guess work out of finding the engagement point with useless/excess left foot movement

i have 2 other old school manual cars and this method would NOT work with either of them but it does w/the si
 
Last edited:
OP
OP

COOL COUPE

Senior Member
Joined
May 2, 2017
Threads
47
Messages
516
Reaction score
321
Location
South Carolina
Vehicle(s)
2019 Civic SI coupe (red) Skunk 2 shift knob BOV Spacer Plate (red) K&N Panel Filter Dual Muffler Delete
Country flag
I will try this in earnest! Thank you!
Sponsored

 


 


Top