I agree with MrElussive
Double clutching is for old cars that don't have synchros.
Besides, stepping on the clutch, putting the stick into neutral, stepping on the clutch again and putting it back into gear can be achieved by just stepping on clutch, blipping the throttle, shifting into lower gear and releasing the clutch. What the point of double clutching ? - to rev the engine in neutral? it can easily be done while the clutch is depressed. This is just an extra step that complicates the rev-matching process.

<font color=orange>Atco Meet</font color=orange>

 

<blockquote><font class="small">In reply to:</font><hr>


I've played around with it a few times. I think the biggest problem is that you aren't braking hard enough that you can easily reach the gas pedal. To execute heel/toe, you really need to be on the brakes. If you aren't braking that hard, there's no need to heel/toe. Just my observation. Please correct me if I'm wrong.

gunga

<hr></blockquote>

My thoughts exactly! The harder I brake the easier it becomes, at least for me. I have performed it at low speeds as well, but its not as smooth and the car jerks.



2003 G35 Sedan 6MT
14.13 @ 99.55

 

I have the nissan drilled pedals and I can brake with the ball of my foot and catch the gas pedal with the right side. No need to twist my foot like I've seen in some clips.

Maybe I just have big feet.

2003 G35 Coupe 6MT/Black/Graphite/15% tint/6 wire GroundingGear™

 

Thanks for all the replies.. Seems I had the thing wrong... I was thinking heel on brake and toe on throttle since I would have thought I would get better accuracy with my toe on the blip portion of HT. I guess I can try my toe on the brake and heel on the gas.

I have this one turn that goes into the street that I live on from the main road. The turning lane is really short and I'm usually goin 50mph on the main road and then I have like 50-70ft in the turning lane before I have to turn into the side street. So I've been pushing in the clutch while braking and then I quickly blip while I'm putting the gear into second and then I'm back on the brake as I let go of the clutch to rev match before the turn. Alot to do in about 50-70ft. Sometimes I mistime and I just leave the clutch in and just hold the brakes and turn in, but getting that HT done right and rev matching for the acceleration out of the turn feels great!

Thanks for the tips. I'll give it a try next time. BTW, I've been driving stick for 2 months now.. LOL



<font color=red>Shibal G-Thang</font color=red>
<font color=blue>'04 TB 6MT Graphite: Aero Pkg, Premium</font color=blue>

 

I disagree with both MrElussive and Speedoholic regarding double cluthing is a thing of the past. The technique you guys refer to as rev-matching is double clutching. I have a synchro mesh tranny that I do the DC technique all the time. My original clutch lasted up to 120k before I replaced it. And this is because of the DC technique. You save the ware and tare on the clutch by rev matching when downshifting through your gears. Everyone has his or her own technique when racing in a circuit. DC or RM techniques apply very well in these conditions. It takes a lot of practice to master this technique. Anyone who says they got it down in day is lying. Even the most seasoned racing veteran took a few weeks or races before he/she can get the timing right.

With the likes of BMW, Maseratti, Porsche, etc. introducing paddle shifter or SMG type tranny in their cars. Perhaps the DC or RM technique will be a thing of the past, but right now it's here to stay.



<font color=blue>04 CB COUPE / WILLOW / PREM PACK</font color=blue>

 

I have the same thoughts as MrElussive when it comes to the real necessity of disengaging/engaging the clutch twice. I still don't understand why you can't just disengage, do all the rev matching/braking, and then let the clutch re-engage.

It seems to me that you'd be saving stress on the clutch by doing this. Yes, you are keeping the clutch depressed longer, but if this is supposed to happen in less than a second, the difference of time it spends depressed is minimal. And, D/E the clutch twice is just gonna cause more wear and tear on the throwout bearing, etc.

2003.5 G35 Coupe 6MT Black/Willow
- Texas Tech Mechanical Engineering - Texas Tech Advanced Vehicle Engineering -

 

If you are unsure of foot placement and not sure if you'll be able to execute it while driving, practice it with your car parked. Practice pressing the brake with the ball of your foot then sliding out the heel part and pressing on the accelerator. I've somewhat got the HT down...just don't find a use for it in daily driving. Only when I take it hard(which is once in a while), do I find it necessary to HT. However, I sometimes do it when I'm bored while exiting the freeway on the off-ramp.

'03 G35c DG/G 6mt, full options

 

glennp_1999,

I didn't say rev-matching is a thing of the past. I'm just wondering as to why would you depress the clutch, put it into neutral, release the clutch, rev the engine, depress the clutch back, put it into lower gear, and finally release the clutch (double-clutching), where you can accomplish the above by just depressing the clutch, downshift, blip the throttle, and release the clutch (rev-match). Both accomplish the same exact thing (bring the engine to the proper RPM to match a lower gear). Rev-matching accomplishes the same thing with one less step.

my $0.02

<font color=orange>Atco Meet</font color=orange>

 

Double clutching on the track? Are you crazy? In the time it takes you to DC, the car you are chasing will have already HT'd (once) and will now be at speed in the corner pulling away while you are taking the extra time to save wear and tear on your tranny. The fastest DC-er is still takes twice as long to get their car in the corner gear than the fastest standard HT-er. I don't know anyone who DCs on the track. Watch the vids, they have pedal cameras on every car. Nobody DCs on R/L turn tracks.

Sure, your MT may last a bit longer, but the other guy will make faster lap times.


Black/Willow 03.5 6MT, Premium, Navi, Aero, SAT
350Z Nismo CAI

 

i thot double clutching is when you're on a gear and wanna go faster, u tap the clutch twice to burn out on that gear.

 

To Speedholic,

Double-clutching was developed originally because transmissions did not have synchros. I think we all agree to that, but it is still a good technique to use if you don't want to wear out your synchros prematurely (not to mention clutch).

By releasing the clutch in neutral, you speed-match the gear pairs between the input shaft and the output shaft by way of the idler gear-set. Big-rig transmissions require this technique going up or down! Advanced truck drivers don't even use the clutch once they get moving.

By the way, I'd rather replace a clutch than worn-out synchros if it comes down to it!

To the newbie above,
"heel-n-toeing", is a misnomer in use now. "Back in the day" the pedals were arranged such that you actually had to use your heel and toes to affect this technique. Now, you simply rock your right foot to the side to blip the throttle while covering the brake.

 

This is why double clutching is "necessary" (umm, you can always just downshift....): rev-matching the engine is only half the story. For simplicity's sake, we can imagine the drive train as three components: the engine, the gear box, and the output shaft. (Please don't explain to me that's not an accurate picture.) Revving the engine while "engaged" in neutral ensures that the gear box component gets revved up too.

Yes, synchros help downshifting, but without DC (i.e. simply revving up while depressing the clutch) two things happen: 1) more wear & stress is put on the synchros & collar gears, and 2) you still get slowed down a little even though your engine is revved up. For those of you who skip the actual double clutching part, you should have noticed that downshifting is never 100% smooth, and this is why. Yes, double-clucthing when done well gives you a 100% smooth downshift.

Now, some of you have pointed out it is quicker to H&T without DC than with. So let's talk in a racing perspective: you're missing the point. DC is done under braking conditions. And if you're braking enough to warrant a downshift, you'd be braking for a much longer time than needed to do DCs. So, if you're entering a turn braking and it's taking 2 seconds, who's gonna exit the turn faster - the guy who only rev-matched his engine, or the guy who revved both his engine and gearbox? Not to mention, when you're on the limit of traction, any small jerky movements (such as downshifting without full DC) could nudge you into loss of traction.

For those who want to pick up DC, I advise practicing without braking first. Just cruise on 4th at 35mph and try DCing into 3rd. Once you get the hang of that, HT & DC come relatively easily.

For more information, here are a few links I found on google:
http://www.driversedge.com/dblcltch.htm
http://www.triumphspitfire.com/healtoe.html
http://auto.howstuffworks.com/transmission6.htm

Happy Double Clutching!

http://www.imagestation.com/member/?name=bsoo

 

Shader7, please see my previous post about timing. As for the videos you watched, what race cars were they? Most modern race cars now have hydraulic or electric-solenoidal sequential manual shift, in which case they indeed don't need to do the full DC. (Then again, they don't need the clutch at all when upshifting.) Mechanically, the full DC is still accomplished.

I must point out though I'm not entirely up-to-date on what they're doing with race cars. I'm somewhat down to earth, I mean, street


http://www.imagestation.com/member/?name=bsoo

 

bsoo.............AMEN!!!!!............AMEN!!!!!... ........AMEN!!!!!!

You hit the nail on the head with that explanation.

H/T or DC is all about timing........... eyes, hand and feet all have to be in sync. Believe me you do one thing wrong and you can feel the car jerk or miss a gear.
Practice makes perfect the example of downshifting from 4th to 3rd on a stright line is best til you get it down. Then you can hit freeway connectors or off/on ramp when trying this technique.




<font color=blue>04 CB COUPE / WILLOW / PREM PACK</font color=blue>