[Dannyxz]

Do you (1) clutch in -> (2) blip throttle -> (3) select gear -> (4) slowly release clutch

Or do you (1) clutch in -> (2) select gear -> blip throttle -> (4) slowly release clutch

Or do you (1) clutch in -> (2) simultaneously blip throttle and select gear as soon as the clutch is in -> (3) slowly release clutch

Are you even supposed to slowly release the clutch, or try to get engage as quickly and smoothly as possible?

Thanks

[Sportstick]

1) clutch in -> 2) shift to neutral portion of gate -> 3) release clutch and blip throttle -> 3) clutch in -> 4) shift to desired lower gear -> 5) release clutch smoothly but quickly enough before revs drop.

Generally know as “double clutching”. If done well, no strain on synchros and very smooth downshift outcome. Gear shift falls into place like a hot knife through “butta”!

[overcoil]

The only time I intentionally slowly release clutch is from a dead stop or accelerating on snow or ice. And even in the summer when the engine is cold I shift early ( short shift ) and release clutch as I’m gradually adding throttle.

As for blipping throttle, I’ve never or don’t really know the experience of engines that hold onto revs. I do heel and toe and my best heel and toes on my 235 is left side of ball of foot on brake and right side of foot on gas. With the 235 it feels so good.

[delvec03]

Originally Posted by Sportstick

1) clutch in -> 2) shift to neutral portion of gate -> 3) release clutch and blip throttle -> 3) clutch in -> 4) shift to desired lower gear -> 5) release clutch smoothly but quickly enough before revs drop.

Generally know as “double clutching”. If done well, no strain on synchros and very smooth downshift outcome. Gear shift falls into place like a hot knife through “butta”!

I never understood why you would releases the clutch, rev, only to put it back in again. the engine is disengaged in neutral and with the clutch in. what's the difference?

[Sportstick]

Originally Posted by delvec03

I never understood why you would releases the clutch, rev, only to put it back in again. the engine is disengaged in neutral and with the clutch in. what's the difference?

Better written than I could provide:

https://www.roadandtrack.com/car-culture/a11646461/what-is-double-clutching-and-how-does-it-work/

[MarkDemma]

Originally Posted by delvec03

I never understood why you would releases the clutch, rev, only to put it back in again. the engine is disengaged in neutral and with the clutch in. what's the difference?

You don't. No modern car since the 70s should need this.

[overcoil]

Originally Posted by MarkDemma

You don't. No modern car since the 70s should need this.

maybe I'm just wrong or not comprehending.

But if you down shift and don't let the revs drop you'll get a rpm spike when you let up in the lower gear.
If your driving at high rpm at high speed and don't have the time to let both speed and rpm drop before needing to get in the optimal gear for a turn of pass then - then blipping the throttle or braking and blipping the throttle while downshifting is the only way safely to downshift.

[Sportstick]

Originally Posted by MarkDemma

You don't. No modern car since the 70s should need this.

It is not a matter of need, just as even having a MT is no longer such either with high performing ATs available. Double-clutching is a skill, if well-executed, that rewards the driver for their ability, and also provides a far smoother dowshift than the synchros can accomplish. No one needs to be a good dancer either, but the ability to coordinate, move, and achieve is pleasing in all aspects.

[CE750Jockey]

Originally Posted by Sportstick

It is not a matter of need, just as even having a MT is no longer such either with high performing ATs available. Double-clutching is a skill, if well-executed, that rewards the driver for their ability, and also provides a far smoother dowshift than the synchros can accomplish. No one needs to be a good dancer either, but the ability to coordinate, move, and achieve is pleasing in all aspects.

Well put, my friend.

[MarkDemma]

Originally Posted by Sportstick

It is not a matter of need, just as even having a MT is no longer such either with high performing ATs available. Double-clutching is a skill, if well-executed, that rewards the driver for their ability, and also provides a far smoother dowshift than the synchros can accomplish. No one needs to be a good dancer either, but the ability to coordinate, move, and achieve is pleasing in all aspects.

I get that folks do it because they find it fun to do, or did it back in the day, but I'd challenge that double clutching has any effect at all on a modern manual at all, especially one with rev matching.

I remember way back in the late 80s when I'd gotten a Mercury Capri 5.0. Remember those? Was the Mercury version of the Mustang GT but with more glass in the back. (the bubble back) I remember letting my dad take it for a spin and it had been so long since he'd driven a manual, he double clutched out of habit. What on earth are you doing, I asked. And he explained that before synchro-mesh you HAD to double clutch to sync it up to shift, but mentioned that if you were really good you could use the accelerator pedal to bring the revs up to match by ear (or this new thing called a tachometer). So I messed around with it a bit and found that I could shift with the clutch out if I got the revs perfect.

I'd put double clutching in the same category. Something fun to do if you want, but there's absolutely no point to it other than it makes folks feel good. Just like modern automatics shift faster than any human can and thus autos will get better times, I'm pretty sure if you put two drivers head to head, one double clutching one regular clutch with rev match that the one not taking that extra time to release and then re-engage would come out on top.

So yeah, just like I choose a manual because I like to do it and know that it's gonna shave a 1/10 second or so off times ... double clutching isn't gonna make you any faster. I get that folks just like to do it.

[MarkDemma]

Originally Posted by ScottSinger

maybe I'm just wrong or not comprehending.

But if you down shift and don't let the revs drop you'll get a rpm spike when you let up in the lower gear.
If your driving at high rpm at high speed and don't have the time to let both speed and rpm drop before needing to get in the optimal gear for a turn of pass then - then blipping the throttle or braking and blipping the throttle while downshifting is the only way safely to downshift.

Synchromesh will equalize things out for you, but if it will wear the clutch, especially if you are doing big jumps. The auto rev match will essentially do the "blip" for you to bring your RPMs up just before a shift. I guess for upshifts hypothetically double clutching done consistently could save some clutch wear.

[Sportstick]

Originally Posted by MarkDemma

I get that folks do it because they find it fun to do

Why else do we do almost anything with our cars? Or, even have a BMW instead of a Toyota?

Originally Posted by MarkDemma

... I'd challenge that double clutching has any effect at all on a modern manual at all, especially one with rev matching.

Rev matching is modern tech taking one more step to replace the driver...but your challenge would be easily met. There is a clear effect. Anyone who has tried and succeeded at it can easily feel the difference. The shifts are smoother and easier if the driver is skilled and more folks don't yet have rev matching than do. As you also can read in this forum, some with rev matching wish to turn it off as an intrusive annoyance.

Originally Posted by MarkDemma

Something fun to do if you want, but there's absolutely no point to it other than it makes folks feel good.

The point is that it is rewarding, and it also provides far smoother downshifts. When did smoother shifting become no longer the point?

Originally Posted by MarkDemma

I'm pretty sure if you put two drivers head to head, one double clutching one regular clutch with rev match that the one not taking that extra time to release and then re-engage would come out on top.

On top of what? We're not street racing here.

Originally Posted by MarkDemma

...it's gonna shave a 1/10 second or so off times ... double clutching isn't gonna make you any faster. I get that folks just like to do it.

Who said anything about going faster? This is about skillful and smooth driving. For most who aren't on a track, do we really care about differences to the right of the decimal point getting to the next red light?

[XutvJet]

Most of my cars have been manuals since I started driving in late 1980s. I've only had one clutch wear out and have never had a trans go bad. All of my cars have been driven fairly hard with lots of hard upshifts and high rpm downshifts. Many of the cars pushed more power than stock too.

I've always rev matched on downshifts. I can double-clutch but it's not necessary plus it's very time consuming.

I find the hardest thing to do is executing a smooth multi-gear downshift like going from 6th to 3rd, 5th to 3rd, etc. With all the crap BMW has integrated into the clutch system of the 6MT, I find it DAMN hard to figure out the catch point. The self-adjusting clutch, dual mass flywheel, clutch delay valve, and clutch pedal helper springs kill any feel. It also makes for a clutch catch point that is constantly changing. It drives me nuts during normal driving, whether upshifting or downshifting.

Rarely can I get a quick multi-gear downshift executed perfectly. When driven in anger though, the 6MT is spot on. I can rip the gears. On downshifts during hard driving, you're always going to select one gear downshifts. In this instance, rev matching downshifts are very easy to execute smoothly and not mess up chassis stability.

In terms of rev matching during normal driving, I've found the following works best:

(1) clutch in -> (2) select gear -> blip throttle -> (4) slowly release clutch


During hard driving, you simply release the clutch much faster.

[Shovelman]

A while back cars and especially trucks had no synchromesh. Double clutching was needed to downshift. (spin up the intermediate shaft to mesh with the output shaft) Mistakes were scolded with a grinding noise. Later vehicles had synchromesh in all but first gear so double clutching was needed less. Since then it is just a way to reduce wear on synchros. (or if you like to do it on upshifts, it's a way to increase the wear)

Rev matching happens with the clutch in so the intermediate shaft is not involved, so no effect on the synchromesh. What it does is match engine speed to wheel speed so letting out the clutch is less of an event.

[albertw]

Originally Posted by Shovelman

A while back cars and especially trucks had no synchromesh. Double clutching was needed to downshift. (spin up the intermediate shaft to mesh with the output shaft) Mistakes were scolded with a grinding noise. Later vehicles had synchromesh in all but first gear so double clutching was needed less. Since then it is just a way to reduce wear on synchros. (or if you like to do it on upshifts, it's a way to increase the wear)

Rev matching happens with the clutch in so the intermediate shaft is not involved, so no effect on the synchromesh. What it does is match engine speed to wheel speed so letting out the clutch is less of an event.

This is my understanding, but unfortunately it is based on magazine articles and internet discussions. It would be great if someone would post a link to a diagram of a transmission that illustrates conclusively that this is the correct explanation for why double clutching does nothing mechanically useful.

[rainfall]

I've driven manual cars for 18 years now. I do simply

(1) clutch in -> (2) blip throttle -> (3) select gear -> (4) slowly release clutch

The thing is: if you feel the car breaking too much as you release clutch, you probably need to blip more next time.

Hundreds of thousands of miles on the clock among 4 manual cars and no problem at all.

[Sportstick]

Originally Posted by rainfall

I've driven manual cars for 18 years now. I do simply

(1) clutch in -> (2) blip throttle -> (3) select gear -> (4) slowly release clutch

The thing is: if you feel the car breaking too much as you release clutch, you probably need to blip more next time.

Hundreds of thousands of miles on the clock among 4 manual cars and no problem at all.

Just wondering why you wouldn't reverse steps 2 and 3 in your sequence to have the revs higher when you need them...blipping after you selected the lower gear? Or, are you actually doing 2 and 3 simultaneously?

[dradernh]

Originally Posted by Sportstick

Just wondering why you wouldn't reverse steps 2 and 3 in your sequence to have the revs higher when you need them...blipping after you selected the lower gear? Or, are you actually doing 2 and 3 simultaneously?

The transmission goes into the lower gear more easily when the revs are at the ideal speed during the shift. The two don't take place simultaneously, but they do take place almost simultaneously (i.e., the shift begins (more or less) just before the revs reach their peak).

This matters more when the revs are higher. An example would be when you're shifting from 3rd to 2nd and the engine is going to be turning over at 6,000 RPM after the shift is completed.

My 2¢, as always.

[XutvJet]

A few of my personal notes and discoveries:

1) Getting a smooth single rev match downshift is damn easy. (1) clutch in -> (2) blip throttle ~500rpms -> (3) quickly select gear -> (4) release clutch

2) Executing a smooth 1-2 upshift is hard on the M235 (can't speak for the 4 banger and M240 cars). I've found that revving 1st out to 3,500rpms and then shifting makes a huge difference. Shifting at an earlier rpm makes it difficult execute a smooth upshift.

3) Someone of the 3/4 series just discovered that the $70 slave cylinder from the later model 6 cylinder turbo E90 series cars will work on the F series cars (including M235/M240). This is HUGE because the E90 slave cylinder doesn't have the dreaded clutch delay valve. That means much better clutch modulation and feel. That mod is high on my list.

[Mandwer]

Even though my 230i has auto-rev matching, I still move my foot to blip the throttle out of habit.

The issue i've had when driving most modern MT cars isn't the clutch release speeds, its the reluctancy to to rev-match (engine just isn't responsive when you blip)

[Maynard]

This is a great time-machine thread, takes me back to my 240Z days. I can't imagine the added complexity of dual-mass, CDV, and all the helper springs. For me, the most use I got out of double clutching and heel/toe was the satisfaction (and not spinning the car when braking hard into a turn); I think my sports/athletic friends call it 'being in the zone' and it helped make legal-speed driving worthwhile. Only real car people even know what it is, so you never get noticed like you would for learning how to do a burnout (there was one time when being the only person around who could drive a non-synchro truck earned me an inside track on some serious speed parts/advice).

And as a tech note, double-clutching is a little harder on the clutch, but much easier on the synchros (more expensive than a new clutch); I DK about the new hardware, but when I was doing this it was just a very light brush for that midshift clutch, just enough to get the gears up to speed. And if you aren't double clutching it doesn't really matter about order of the blip-x-shift, you do them simultaneously - if the clutch is in then the gears are separated and the goal is being rev-matched when you release, else you'll shock the back wheels and driveline (much more expensive than a new clutch).