Question -- What, really, is double clutching, and how do I learn it?

[sjs]

Originally posted by Andrie Hartanto:
From Drive to Win by Carroll Smith:
"Many authors (or maybe translators) who should know better recommend double clutching in the racing car - I'll be damned if I know why." (2-43) Chapter 6.

Taking nothing away from Carroll Smith, I've never heard that he was the final word in all things driving. Even though the book is very highly respected overall, as is he, that doesn't mean that every opinion is fact or every word gospel. Besides that, there is a key term in the quote you provided, "racing car". Does anyone out there own one? OK, I do, but that's not the general discussion here. We drive street cars, sometimes on the track, and some of us put more miles on them every year than any race car sees in it's existence, and we have transmissions with syncros and without straight-cut gears, and we aren't inclined to rebuild them once or twice a season, and, and, and...


Hey Andrie, you changed/added to the quote even while I was responding! Is that fair?

[This message has been edited by sjs (edited 30 August 2001).]

 

[Andrie Hartanto]

sjs,

He actually went into more details, I just took a short quote. I went back and edit my previous post to give a bit more info.

I don't think he has final word on that, however, given the credibility between him, u and Danny Sullivan, I think I take them both

 

[sjs]

OK, you have a stock 5-speed. You are in third gear at ~110 when you need to break for the next turn. You know that you want to be doing 65 at the turn-in point and will then feed in throttle slightly to the apex but not really gaining significant speed yet. You apex at 65 - 67 and start rolling on the throttle toward the track-out point, following which is a long straight. What gear are you in, and when?

The NSX has a broad enough power band that you might be in third the whole time, but I probably dropped down to second before the turn-in, which means I did so at something over 65. I'd rather not ask the second gear syncro on my street car to do that very often. I may slightly increase clutch wear and may go slightly slower than if I didn't double clutch, but my syncros will take less wear, period. Will that add up to enough to matter over the years? Perhaps, perhaps not, but I'll bet Sullivan hasn't put 100k miles on anything he had to pay for. And by the way, I seem to recall that he isn't exactly known for being easy on the equipment.

 

[nsxtasy]

My answer doesn't do anything for the "double clutch or not" debate, but...

you have a stock 5-speed. You are in third gear at ~110 when you need to break for the next turn. You know that you want to be doing 65 at the turn-in point and will then feed in throttle slightly to the apex but not really gaining significant speed yet. You apex at 65 - 67 and start rolling on the throttle toward the track-out point, following which is a long straight. What gear are you in, and when?

Actually, I'm going to be hard on the throttle as I approach the apex. I'm probably going to be doing 80 or so as I approach the track-out point. Which means I'm going to leave it in third, rather than downshifting to second.

My rule of thumb is that, if I'm going to need to upshift again by the time I reach the track-out point, I would rather leave it in the higher gear. This is because (a) I don't care as much about needing the lower gear to accelerate through the turn as I do when the car is going straight, which it will be doing at the track out point; (b) I don't want to give up the half-second or so of acceleration that I would be sacrificing during the upshift; and (c) I wouldn't want to be upsetting the balance of the car before reaching the track-out point, while the car is still turning.

If I had to slow down more than that, so that I would be doing 65 mph at the track-out point, THEN I would downshift to second.

[This message has been edited by nsxtasy (edited 30 August 2001).]

 

[hejo]

Originally posted by sjs:
OK, you have a stock 5-speed. You are in third gear at ~110 when you need to break for the next turn. You know that you want to be doing 65 at the turn-in point and will then feed in throttle slightly to the apex but not really gaining significant speed yet. You apex at 65 - 67 and start rolling on the throttle toward the track-out point, following which is a long straight. What gear are you in, and when?

The NSX has a broad enough power band that you might be in third the whole time, but I probably dropped down to second before the turn-in, which means I did so at something over 65. I'd rather not ask the second gear syncro on my street car to do that very often. I may slightly increase clutch wear and may go slightly slower than if I didn't double clutch, but my syncros will take less wear, period. Will that add up to enough to matter over the years? Perhaps, perhaps not, but I'll bet Sullivan hasn't put 100k miles on anything he had to pay for. And by the way, I seem to recall that he isn't exactly known for being easy on the equipment.

All this toe-heel, grab my left *&^$, pull my nose, is making my head hurt. That's why I drive a SportShifter

BTW I'm in 2nd at about 4500 rpm.



[This message has been edited by hejo (edited 30 August 2001).]

 

[rquintero]

Ahh, this thread should just die. I've held my tongue on it for a while. Seems like folks are more interested in impressing themselves rather than answering the topic questions.

And since I'm one of them too, my opinion is that, exempting the turn-in to apex stage at the most, one is either balls-out accelerating or balls-out braking.

Else wait for the parade lap and don't get your panties up in a bunch. What is this "coasting" not to upshit crap.

I was, however, truly interested in the H&T / turn-in discussion.

Oh well, flame away FWIW. Or lets switch to safer topics such as politics, police ethics or how repainting exotic cars increases their value...<g>

 

[sjs]

nsxtasy, you changed the scenario! I was stating what speeds were possible based on the shape of the corner, so you actually landed out in the corn field. Wouldn't it be nice if they were all so agreeable as yours? I didn't need to shift until past the track-out and therefore had no problems. By using second I got the best pull out of the corner, at the start of the long straight I described. And that speed paid dividends the full length of the straight. Sometimes acceleration coming out of the corner is worth a lot more than the time to downshift coming in.

As for always WOT or hard on the brakes, it's a myth. Sounds cool, but isn't fast. You have a certain amount of grip from your tires. Slightly simplified, any used in cornering isn't available for acceleration, and vice-versa. Corners come in all shapes, so if you are ALWAYS at full throttle before the apex, or even before the track-out point, then you are too slow through SOME of those corners. Or, your car has no power, or you are in too high of a gear to use the power, and therefore aren't really accelerating much and will pay for it all the way to the next braking point.

BTW, I thought this thread was dead and buried more than a week ago.

 

[nsxtasy]

nsxtasy, you changed the scenario!

Moi?

I was stating what speeds were possible based on the shape of the corner, so you actually landed out in the corn field. Wouldn't it be nice if they were all so agreeable as yours?

You talk about getting on the throttle approaching the track-out point, but I'm not sure why. You should ALWAYS be able to get on the throttle as you approach the apex of the turn. That's what the apex is all about; you always have an increasing radius after the apex, so you can be accelerating as you approach that point.

 

[sjs]

Originally posted by nsxtasy:
You talk about getting on the throttle approaching the track-out point, but I'm not sure why. You should ALWAYS be able to get on the throttle as you approach the apex of the turn. That's what the apex is all about; you always have an increasing radius after the apex, so you can be accelerating as you approach that point.

Poor choice of words perhaps, I meant that as I pass the apex, which is the same thing as approaching the track-out. I also said that I'm feeding it throttle lightly before then, but not "hard on the throttle" before the apex as you said. Point is, if you can stand on it approaching the apex then you probably came in too slow, and if you can stand on it at the apex or slightly before, then you may be on the wrong line or too slow, particularly with a high HP car.