Manual gearbox nerdism maxed out!

"Tentacle, Dutchman, drives French" (Tentacle) 11/19/2014 at 07:11 • Filed to: None

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Ok, so I have a modern car, with a proper synchomesh gearbox. Also, I don't particulaly race my little 92 horse turbodiesel. I don't need to do any boutique stuff when doing the Three Pedal Dance. Yet, having said all that, this morning I pretty much geeked out when I performed a flawless double clutched blipped heel-and-toe rev-matched downshift!

Wait, a what?

Get off the throttle

Apply brakes (and keep applied untill fully completing gear change)

Turn in for the corner

Clutch in

Pull out of gear into neutral

Clutch out

Blip throttle to sync gearbox

Clutch in

Put into lower gear

Blip throttle again to rev match

Clutch out

Ease of brake pedal

Hello apex!

Apply throttle

Steer out

Yeah, all that while taking a flowing 90 degree left turn. It's a rhythmic coordinated sequence which takes, between the first clutch in and last clutch out, about a second, or perhaps a little bit more.

And most of it is utterly unnecessairy.

Yet, having said that, being elaborate like this means that moving the gearshift is buttery smooth and light (the synchro mesh doesn't have to do its thing so there is no added resistance in the throw) and the transition from driving, braking-while-downshifting and back to driving is completely continuous.

Yes of course I was grinning like a maniac because I executed it perfectly!

In other news, also this morning: I've hit the ton (in kilometers, not miles)

bob and john > Tentacle, Dutchman, drives French 11/19/2014 at 07:13

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what car is this? that dash screams saab to me, but i know its not....

thebigbossyboss > Tentacle, Dutchman, drives French 11/19/2014 at 07:22

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Well done. what do you drive?

Tentacle, Dutchman, drives French > bob and john 11/19/2014 at 07:29

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Citroën C4, the 2011 model.

Tentacle, Dutchman, drives French > thebigbossyboss 11/19/2014 at 07:39

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A 2011 Citroën C4

thebigbossyboss > Tentacle, Dutchman, drives French 11/19/2014 at 08:03

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Nice. In Canada Citroens are very rare. I see one or two per year only.

OPPOsaurus WRX > Tentacle, Dutchman, drives French 11/19/2014 at 08:13

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i've been getting better at the whole manual hing but still havnt really gotten into the heel toe stuff. Whats the point of reving when your out of gear? wouldn;t reving before you let off the clutch in gear be doing the same thing?

BATC42 > Tentacle, Dutchman, drives French 11/19/2014 at 08:47

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How are the pedals placed in the C4 ? In my Xsara the brake pedal is forward from the other two. So heel & toe is quite hard to do.

Tentacle, Dutchman, drives French > BATC42 11/19/2014 at 09:22

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I don't technically heek-and-toe, I side-flip. So the ball of my right foot touches the right side of the brake pedal while the outside of my right foot can hit the throttle if I twist my foot. It only works with normal width shoes, my Puma Speed Cats are too narrow for this.

Side-flipping works in a Xsara too, I had a Xsara Coupé VTR phase II before this.

twochevrons > Tentacle, Dutchman, drives French 11/19/2014 at 09:39

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I've never managed to get it while heel-toeing, but that buttery-smooth feeling when you perfectly rev-match a downshift. Best damn thing in the world.

Also, yay Citroëns. I have very fond memories of a Xantia that I used to own, an my father's BX GTI 16v. The valve-controlled brakes on those were far too sensitive for me to dare try to heel-toe in them (there's only about 1cm of pedal travel), but they were both great to drive.

Tentacle, Dutchman, drives French > OPPOsaurus WRX 11/19/2014 at 09:42

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First, you can forget double clutching on a synchronised gearbox. You don't need to do it. I tried it to experience what it would be like to drive a car with a gearbox without synchro meshes. Curiosity, nothing else.

As for heel-and-toeing (side-flipping), that takes the jolt out of a downshift, it's nothing more than rev-matching/blipping the throttle on a downshift, it's just that you do so while braking.

OPPOsaurus WRX > Tentacle, Dutchman, drives French 11/19/2014 at 09:49

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whats the difference between a sync gear box and a non sync gear box? which would the WRX (not STI) have? I revmatch on down shifts but I only blip once.

Tentacle, Dutchman, drives French > OPPOsaurus WRX 11/19/2014 at 09:58

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Most manual cars from the 1960s on have a synchromesh gearbox.

If your oldtimer has a gearbox that's not synchronised, then you need to double clutch/exactly rev-match every gearchange.

In modern times, rev-matching is entirely optional. It's smoother for sure, but not required.

biturboism, the cult > Tentacle, Dutchman, drives French 06/02/2015 at 11:30

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Sorry to dig an old thread form the grave, but I’m curious how you dealt with going from a sporty Xsara to a comfy family hatch like the C4. My father’s C4 II 115HDI is a very nice cruiser indeed, but I have to say this comfort makes any mountain road quite boring to drive (when doing reasonable family-friendly speeds). Also, the brakes are typical Citroen push-button over-assisted monsters that make me uncomfortable to brake with confidence out of fear of disturbing my passengers (by snapping their necks).

My second point is that I applaud you that you successfully did rev-matching with that engine. I’m used to cable-throttled TU engines and going into the HDI I had the cumulative lag of the throttle map, throttle body and general dieselness, so after 10 attempts of looking like a complete dork in front of my dad I gave up.

Cheers!

Tentacle, Dutchman, drives French > biturboism, the cult 06/02/2015 at 16:59

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Going from a Xsara Coupé VTR to a C4 II 92 HDI was quite a change, and then it wasn’t that big of a change. Yes, some 15 HP down, but 80 Nm more. NA vs small turbodiesel. 1150 (because of the LPG conversion) vs 1180 kg. Both 1.6L 4-bangers, though the diesel is only 8 valve.

But in day-to-day driving, with a commute distance of almost 50 km mostly on highway, there is little difference between the two in terms of handling. I guess that comes down to the fact that there is little use for sportyness on a commute like that. Of course the difference between NA petrol and turbodiesel is massive.

As for your second point, the TU5JP4 engine in the Xsara VTR Phase II is throttle-by-wire, just like the DV 6D oil burner I have now, so I didn’t notice any difference on blipping. It may have helped that I blip every downshift (without double clutch antics) so the rhythm is embedded in muscle memory now, it doesn’t take conscious thought.

biturboism, the cult > Tentacle, Dutchman, drives French 06/02/2015 at 19:41

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I had no idea the C4II was that light! Do you have an intercooler? Because the 1.4 HDI doesn’t :)

As for the throttle blip, do you manage to precisely bring the revs up to the correct amount? To me that is very difficult, and even after plenty of practice I more or less end up stabbing the throttle and hoping for the best. Needless to say, sometimes it’s worse than no rev-match at all...

Tentacle, Dutchman, drives French > biturboism, the cult 06/03/2015 at 04:04

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See

http://www.peugeot-citroen-moteurs.fr/cache/docs_pub… for the tech specs.

As far as blipping goes, it’s not about dosage, it’s about timing. So it’s about exactly when you jab the throttle, in relation to when you let out the clutch. The clutch can take some mis-match in revs through friction.