Double-Clutching - Stupid Question Alert

[Tekno Virus]

Took me a while to understand the difference:

When you single clutch and rev match, the synchros bring up to speed the intermediate shaft even though your input and output shafts are about the same speeds.

When you go into neutral first then rev match, the input shaft and intermediate shafts are connected and thus spinning at the same speed, in turn, spinning at the same speed as the output shaft, and that's why it's easier on the synchros.

[Justin.b]

Originally Posted by DM7

When you rev match with the transmission in neutral and with your foot off the clutch, the input shaft is connected to the engine via the clutch and spins at the same speed as the engine. The output shaft is always spinning with the wheels. If engine speed is correct (rev matched) for the gear you are selecting, the synchros will do less work as the input shaft speed should be the same as the output shaft speed.

I downshift into 1st gear a lot. I find that without double clutching, the input shaft speed is too slow with respect to the output shaft speed so the synchro simply won't mesh (unable to match the speed of the input with the output shaft). In neutral with the clutch plate engaged I rev the engine to get the input shaft spinning faster and closer to the speed of the output shaft.

I have no idea why you would be downshifting into first so much, but I believe there is no synchro on first gear because, well, you're not supposed to be using it except to get the car off the line.

In case you're thinking of downshifting into reverse when underway, I believe that gear also lacks a synchro.

-Justin

[Tcoat]

Originally Posted by Ultramaroon

I think you're so experienced that you have your timing down pat. You don't pause long enough in neutral to feel the effort required after missing that golden moment.

Try this tomorrow morning. Get going in first and intentionally pause in neutral. Then feel if it takes any extra effort to engage second. You might not notice it with such a broken-in transmission but I'm betting you'll feel at least a little difference.

Taking into consideration that I upshift at about 2500 rpm when it's cold, recovering from a missed shift is more like this:

Input shaft 2500 rpm
clutch disengaged - input shaft still spinning while in gear
neutral - input shaft grinds to a halt
clutch engaged - blip to 2500 rpm (I don't actually watch the tach)
disengage clutch - drop into second before it has a chance to spool down
keep calm and drive on

You will also feel the increased force required to disengage first if you pause after pushing the clutch. Just drag from the molasses.

Well whodathunkit. After a prolonged battle with my muscle memory developed from decades of shifting I managed to pause in neutral. Sure enough it was much harder to get into second. I expanded my trial to the Vin Diesel style of grabbing the knob and man handling it into gear in conjunction with a pause and it was freakn' near impossible to get into second (and fifth was no pleasure either) even after it was warmed up. For at least the 500th time I state I have never once had an issue so for the last year thought that everybody that complained was crazy or I just got lucky with the tranny (well that doesn't sound right at all).

That feeling when your existing driving style match's the car so perfectly you think others are crazy for complaining:

[Tcoat]

Originally Posted by Justin.b

In case you're thinking ow downshifting into reverse when underway, I believe that gear also lacks a synchro.

-Justin

If it had one before you shifted while underway it probably wouldn't after.

[MuseChaser]

Originally Posted by Tcoat

That feeling when your existing driving style match's the car so perfectly you think others are crazy for complaining:..

Yeah.. that's why I started the whole mess.. I had no idea what the problem folks were having with this transmission was, either, and couldn't figure out why double clutching was being mentioned as a solution for anything. Mine's smooth as silk, I guess 'cause I'm used to listening to the engine and and matching, and not smackin' the gearshift around.

Thanks for the discussion, Ultra and T.

Barry

[Ultramaroon]

Originally Posted by MuseChaser

Thanks for the discussion, Ultra and T.

Barry

My pleasure, gents!

[Ultramaroon]

Originally Posted by Justin.b

I have no idea why you would be downshifting into first so much, but I believe there is no synchro on first gear because, well, you're not supposed to be using it except to get the car off the line.

In case you're thinking of downshifting into reverse when underway, I believe that gear also lacks a synchro.

-Justin

First gear does have a synchro. There is also a device designed to limit engagement of said synchro until the two sides are close enough in relative speed. You can see in the exploded view of the transmission a single ball called, I think, the "limit ball." I'm guessing here, but I think that's one of the differences in the builds. Tcoat and I discussed this a while back because he can get into first pretty easily while moving. Mine? No friggin' way. If I'm doing anything faster than a casual walking speed, I have to double-clutch into first.

And before anyone says "you're not supposed to" or "just stop and then go into first," no.

[fika84]

Originally Posted by Justin.b

I have no idea why you would be downshifting into first so much, but I believe there is no synchro on first gear because, well, you're not supposed to be using it except to get the car off the line.

In case you're thinking of downshifting into reverse when underway, I believe that gear also lacks a synchro.

-Justin

I believe you sir are a not very intelligent.

[Justin.b]

Originally Posted by fika84

I believe you sir are a not very intelligent.

[Braces]

I wonder if the flappy paddle folks would be interested in the mechanics of double clutching? Probably not.

[02.ACCORD.DUDE]

Originally Posted by Braces

I wonder if the flappy paddle folks would be interested in the mechanics of double clutching? Probably not.

HEY flappy paddle folks have feelings too.

[DM7]

Originally Posted by Justin.b

I have no idea why you would be downshifting into first so much, but I believe there is no synchro on first gear because, well, you're not supposed to be using it except to get the car off the line.

In case you're thinking of downshifting into reverse when underway, I believe that gear also lacks a synchro.

-Justin

I had a look at the service manual, both first and reverse gears have synchros.

"A lot" was an exaggeration but I do downshift into 1st a few times each week. Instead of trying to accelerate in 2nd below 10mph I prefer to downshift and use higher rpms in 1st. I typically do this in parking lots and when approaching stopped traffic that is starting to get going again.

[chaoskaze]

Why are you guys downshifting into first?.....I never find the need for that unless I'm doing some gymkhana session. In Traffic maybe once in a while but those are very easy.

PS: I noticed having my digital speedo set on KM makes things really easy if I'm granny shifting. >__> It's pretty much 11km = 1st gear 22 = 2nd gear 33 etc etc to 66 @ 6th gear... from 2.2k to 1.8k rpm

[Tekno Virus]

You can shift into first if you're only moving at less than 5 mph.

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