Double Clutch AND Heel Toe

[Cthulhu]

I just took a Skip Barber course in the 4-speed formula cars and it was freakin' heaven! I already put a down payment on the next course (3 day course) and after that, I plan on taking the 2 day advanced course and doing some lapping.

I can double clutch fine, and I can heel toe fine, but haven't been doing them together. Should I be?

I've got a 135i now and miss my Lotus so bad... I find that if I attempt to double clutch heel toe on the 135i, the engine rev after a blip is very unpredictable and laggy. I either over rev or under rev. I double clutch if I'm upshifting above 4,000 RPM or downshifting to a gear above 4,000 RPM, and it works fine if I give the throttle a blip by flooring it quickly. I heel toe frequently and smoothly with no issues. I only have issues when I'm trying to bring the revs very quickly so that I can double clutch as I heel toe.

I don't know if I'm doing it too fast, need practice, or if it's the throttle response of the TT engine on my car, but it's driving me crazy! I've been mismatching revs lately trying to do this, and it's frustrating the hell out of me.

I'm thinking about practicing double clutching without blipping at WOT, since I can't get my foot to go WOT easily when heel toeing.

Anyone do these two things together? Is it necessary? Any suggestions?

[viacondotti]

Originally Posted by Cthulhu

I just took a Skip Barber course in the 4-speed formula cars and it was freakin' heaven! I already put a down payment on the next course (3 day course) and after that, I plan on taking the 2 day advanced course and doing some lapping.

I can double clutch fine, and I can heel toe fine, but haven't been doing them together. Should I be?

I've got a 135i now and miss my Lotus so bad... I find that if I attempt to double clutch heel toe on the 135i, the engine rev after a blip is very unpredictable and laggy. I either over rev or under rev. I double clutch if I'm upshifting above 4,000 RPM or downshifting to a gear above 4,000 RPM, and it works fine if I give the throttle a blip by flooring it quickly. I heel toe frequently and smoothly with no issues. I only have issues when I'm trying to bring the revs very quickly so that I can double clutch as I heel toe.

I don't know if I'm doing it too fast, need practice, or if it's the throttle response of the TT engine on my car, but it's driving me crazy! I've been mismatching revs lately trying to do this, and it's frustrating the hell out of me.

I'm thinking about practicing double clutching without blipping at WOT, since I can't get my foot to go WOT easily when heel toeing.

Anyone do these two things together? Is it necessary? Any suggestions?

I can't offer advice on your main question, though I've seen it done up close (by Mark Starr) and it's a complicated bit of coordination that must take a lot of practice. It also lengthens the shift time.

On rev matching, though, precise blipping is a lot easier if your engine has good throttle response and the engine revs freely. The Elise engine in pretty good in this respect. Porsche engines are even better in my experience. The engine in my 2001 Audi TT (1.8 turbo) on the other hand makes precise blipping fairly difficult.

[mopho]

Why would you want to double clutch, that is what synchromesh is for?

[Vexige]

From what I remember, you don't have to use clutch at all on this gearboxes Just to engage 1st.

[Cthulhu]

To reduce synchro wear

The real reason is because it gives me something to do. I drive about 90 miles a day, although too much of it is in traffic. I figure that if I can improve track techniques, the mileage won't be in vain.

viacondotti, your 1.8TT comment makes me feel a little better . The weird thing is that I could do both (although I needed more practice) on my 5 speed, cable throttle saturn.

[Cthulhu]

Originally Posted by Vexige

From what I remember, you don't have to use clutch at all on this gearboxes Just to engage 1st.

That is true of most gearboxes, but come on... You have to rev match so exactly to get in it gear, and have to hold the revs constant as you throw it in gear, or you grind. The clutch is a safety net. It would save time though...

[khamai]

I'm kinda with Morgan here, dbl-clutching isn't really needed with good synchros. But then a good dbl-clutch is easier on the synchros and can be alot smoother and faster.

Same rules apply for any heel-toe shift, pedal placement and engine/gearbox responsiveness are needed.

What's the pedal placement (brake/throttle) like in the 135i?

So... final thought... I'm habitually in the middle, I single-clutch upshift and dbl-clutch downshift with synchro gearboxes. On upshifts the layshaft in the gearbox naturally slows when you engage the clutch. So, rev-matching is much easier. But, on downshifts the layshaft needs to be sped up, so manually speeding it up with the clutch out and a blip on the throttle helps and makes rev-matching easier.

All of this goes out the window with straight gears and a non-synchro box, as in many race cars. What were you driving at Skippy? Were you in their Formula cars with a non-synchro transaxle?

Cheers,
Kiyoshi

[Cthulhu]

I believe they're synchronized but with straight cut gears. I had to rock the car a little or rev a little to get the teeth lined up so I could shift, but they said double clutching wasn't mandatory. If you don't have syncrhos, you need to double clutch in addition to rev matching, or you grind, right?

The pedal placement on the 135i is one of the reasons I bought the car, it's set up nicely for heel toe. Now that I'm really driving the car, the gas might be a little low, so I may buy an aluminum pedal cover kit, and use only the gas pedal one.

I just took a drive (lunchtime is fun) and paid very careful attention to the throttle response on the 135i, and have concluded that it is sucky. The brakes are quite touchy and the throttle does nothing until it takes off at a certain point. There is also throttle lag, possibly due to the TT. Rev matching is easy if I don't blip. I can also rev match if I WOT blip, but not part throttle blip.

I wish I had a cheap, NA, non-synchro car to drive around all day...

[spf4000]

^Probably more to do with the way they map their drive by wire settings. I've seen reviews of the 135i where they complain about the throttle response as well.

[kaz]

I HnT double clutch downshift in both my cars when going down into 2nd or 1st gear...I definitely do it on my Subie all the time as the more complicated 4wd box likes the extra help even on the synchros. It's just habit now sometimes going down into 3rd, but all the time going down into 2nd and 1st gear.

[tomrev]

The Skippy formula cars used to have Hewland Mk-9's in them; dog ring, straight cut gears. Use the clutch to launch, and put your left foot on the dead pedal for the session. What changes the gears on a Hewland are the dogs on the ring gear, so the faster the shift, the less likely for the dogs to whack into each other. Double de-clutching just adds time to the shift, and wears out the clutch, dogs and gears faster, so most formula guys do quick, clutchless upshifts, and coming down, will do a quick blip in neutral to match rev's with the lower gear, allowing the dogs to line up easily, and away you go. I see no reason to double clutch on upshifts with any type of box, especially a syncro one. Just don't over-speed the shift; let the syncro's have a second to get the next gear spinning, same on down shifts, where a blip will help match the gear and engine speeds to ease the syncro work. I never use a WOT for a down shift, simply a little stab at the throttle to rev the engine just enough to bring the engine speed up to meet the lower gear's speed. Enjoy!

[Icedog_16]

I don't think it's an issue of throttle response or pedal setup; you just need to practice. I have no problems in my 335i. The flywheel's not quite as light as the Elise's, so it doesn't blip as quickly as you're used to and you'll have to adjust. So, like I said, practice.

[Cthulhu]

Originally Posted by tomrev

The Skippy formula cars used to have Hewland Mk-9's in them; dog ring, straight cut gears. Use the clutch to launch, and put your left foot on the dead pedal for the session. What changes the gears on a Hewland are the dogs on the ring gear, so the faster the shift, the less likely for the dogs to whack into each other. Double de-clutching just adds time to the shift, and wears out the clutch, dogs and gears faster, so most formula guys do quick, clutchless upshifts, and coming down, will do a quick blip in neutral to match rev's with the lower gear, allowing the dogs to line up easily, and away you go. I see no reason to double clutch on upshifts with any type of box, especially a syncro one. Just don't over-speed the shift; let the syncro's have a second to get the next gear spinning, same on down shifts, where a blip will help match the gear and engine speeds to ease the syncro work. I never use a WOT for a down shift, simply a little stab at the throttle to rev the engine just enough to bring the engine speed up to meet the lower gear's speed. Enjoy!

I read that the 3 day school I'm saving up for puts an emphasis on Heel Toe/Double Clutch. I'm probably stupid to practice both on the 135i after owning it for only 2 weeks (it's broken in w/ 2 oil changes at ~2K miles), but I freakin' nailed a DCHT downshift on the off ramp just now, so I'm happy! I figured that it wasn't needed if you rev match and go easy on the synchros, but if I do a really hard heel toe, I might as well double clutch as well.

Now that I'm shifting closer to the redline, I know all my shift points. It's really easy to to a DCHT downshift if you're aiming near the redline when you rev for the downshift.

I was attempting to DCHT downshift to ~5,000 RPM, and I was running out of time and lacking the precision. If I drive harder, it's easy.

I think I'll be good now, this car is geared to go stupidly high speeds. The Lotus was more fun for this sort of thing. . I think I'll go back to driving more gently

Icedog, do you DCHT downshift to anything below ~5,000 RPM or so, or do you only do it when you're aiming closer to the red?

[Icedog_16]

I play with it at all types of speeds around town, but it's easier the faster you're going.

[Vexige]

Originally Posted by Cthulhu

That is true of most gearboxes, but come on... You have to rev match so exactly to get in it gear, and have to hold the revs constant as you throw it in gear, or you grind. The clutch is a safety net. It would save time though...

My bad, i thought you're referring to the race gearbox, which doesn't have synchros

[fun4two]

I'm not sure I read this correctly, but you said you double clutch when you upshift? What purpose would that serve? Our trannys are matched perfectly for upshifting to the next gear from the factory (in fact all new manual cars are). Your heel and toe double clutch downshift is very important to save the life of your synchro's if your doing Lots of down shifting. Its only truely necessary when your really pushing the limits of the revs and downshifting like on a track, otherwise the synchros are perfectly capable of going 100,000+ street miles without problem. But to answer your question you asked - yes you should be heel and toe double clutching whenever and as often as you can. It will make you a faster driver on the track as well as a better driver on the street, you will have greater control over your car entering corners when you can do all the correct procedures at the same time and be in the correct gear for the exit so your focaus can remain on cornering not finding gears mid way through the corner. It takes huge amounts of practice. I will actually sit at a red light and blip the throttle with my heel while trying different foot positions on the throttle so I can a comfortable position while maintaining good brake pressure without jabbing harder on the brake. This is very important, I find that if I press the brake pedal with the middle of my right foot and twist my leg to reach the gas pedal will work the best for me to be able to blip the throttle without jabbing the brake harder especially important when braking at the limits of tire adhesion, over the past few years I have gotten smooth enough to do it at normal driving speeds without jabbing the brake pedal each time I blip the throttle I can smoothly go from 6th gear at approx 50mph to 0 shifting all the way back to 1st without the passenger feeling any gear change. When it becomes second nature you will be a safer driver also, as you won't be hunting for gears, you will already be in the next lower gear for the situation. If you continue your tracking/ or possible autoxing in your car this will become in-valuable to you as you get better at pushing the car around corners. Anyone can go straight, its the cornering speed that wins a race. Also like others have posted that our engins do rev freely making heel and toe very easy but I have to admit getting the actual heel and toe movement was very difficult for me in my elise I found the gas pedal to be way off at first, but in my STi I had no problem as the pedals were perfectly placed for H and T and the throttle was very responsive. Is there a re-flash or tune out there for your ECU, maybe the would help. I know the 07 STi's also suffered from a laggy throttle response quite frustrating I'm sure. Luckily I've only had cars with decent throttle response.

[Cthulhu]

Originally Posted by fun4two

I'm not sure I read this correctly, but you said you double clutch when you upshift? What purpose would that serve? Our trannys are matched perfectly for upshifting to the next gear from the factory (in fact all new manual cars are). Your heel and toe double clutch downshift is very important to save the life of your synchro's if your doing Lots of down shifting. Its only truely necessary when your really pushing the limits of the revs and downshifting like on a track, otherwise the synchros are perfectly capable of going 100,000+ street miles without problem. But to answer your question you asked - yes you should be heel and toe double clutching whenever and as often as you can. It will make you a faster driver on the track as well as a better driver on the street, you will have greater control over your car entering corners when you can do all the correct procedures at the same time and be in the correct gear for the exit so your focaus can remain on cornering not finding gears mid way through the corner. It takes huge amounts of practice. I will actually sit at a red light and blip the throttle with my heel while trying different foot positions on the throttle so I can a comfortable position while maintaining good brake pressure without jabbing harder on the brake. This is very important, I find that if I press the brake pedal with the middle of my right foot and twist my leg to reach the gas pedal will work the best for me to be able to blip the throttle without jabbing the brake harder especially important when braking at the limits of tire adhesion, over the past few years I have gotten smooth enough to do it at normal driving speeds without jabbing the brake pedal each time I blip the throttle I can smoothly go from 6th gear at approx 50mph to 0 shifting all the way back to 1st without the passenger feeling any gear change. When it becomes second nature you will be a safer driver also, as you won't be hunting for gears, you will already be in the next lower gear for the situation. If you continue your tracking/ or possible autoxing in your car this will become in-valuable to you as you get better at pushing the car around corners. Anyone can go straight, its the cornering speed that wins a race. Also like others have posted that our engins do rev freely making heel and toe very easy but I have to admit getting the actual heel and toe movement was very difficult for me in my elise I found the gas pedal to be way off at first, but in my STi I had no problem as the pedals were perfectly placed for H and T and the throttle was very responsive. Is there a re-flash or tune out there for your ECU, maybe the would help. I know the 07 STi's also suffered from a laggy throttle response quite frustrating I'm sure. Luckily I've only had cars with decent throttle response.

Great post

I can heel toe from 50 to 0 without missing a gear in the 135i, but if I tried to do that while double clutching, I'm pretty sure I'd run out of time. The super touchy 6 piston calipers don't help. Changing my map to one with more low end boost helped improve throttle response (it will trip hidden codes, but I can clear them with software or a redundant scan tool).

It sounds like you actually use your heel and toe (well, ball of your foot), I'll have to try that out. Where do you keep your heel? At the bottom, or at the middle of the gas? If it's at the middle, does that mean your foot is kind of floating in midair while heel toeing?

From your post, it sounds like it is possible to DCHT downshift through every gear all the time if you're good enough. It seems like you guys all agree that double clutching isn't necessary on upshifts. So, with some added confidence that I'm not learning the wrong things, I will practice-practice-practice until my car sounds like it has paddle shifters.

I just have to perfect it by the time my 50K mile warranty runs out.

I'm all excited now! Can't wait till lunch.
You guys are infinitely better than bimmerpost...

[catapult]

You need to slow things down. Think of your track time as an opportunity to practise these things. As you get better you'll be able to do it faster. To begin with, as you're approaching your corner shift into neutral well before you hit your turn in and then heel n toe and downshift at the appropriate time. It will become more natural and fluid in surprisingly little time.

[ads_green]

There is abolutely no need to double clutch on these cars with synchromesh.

The are ways to trash a synchro without double clutching -
The most common is to force the gearchange too quickly and not giving the synchro enough time to do its job. The other is not fully disengaging the clutch when shifting.

In fact, you stand more chance of trashing or wearing them faster with double de clutching. Mostly down to the fact that most people are rubbish at it and end up with working against the synchros. If you can double declutch on a downshift perfectly everytime them sure, you may gain some reduced wear but it only takes a couple really bad ones and you'll be even with the people who don't double clutch but shift smoothly.

As above - zero need to double declutch on an upshift even on a straight cut dog box. Should be able to do that with a little lift of the throttle. Although remember that the toyota box has a retainer mech to hold the gear in place so trying to shift without fully unloading the transmission will just wear/stretch the shifter cables making gearchanges more and more sloppy.

Race dog boxes generally have the edges and corners filed off the engagement rings so you don't have to be as accurate to get the gear to lock in place.

Now - if you want to be really flash (and if you end up in a hedge it's not my fault) what you should really try is "double declutch with heel n toe combined with left foot braking".
It's like tapdancing on the pedals but very satisfying. To be honest even then I generally find on track dont need to double clutch - just adds an extra step where you can screw up.

[Cthulhu]

Originally Posted by catapult

You need to slow things down. Think of your track time as an opportunity to practise these things. As you get better you'll be able to do it faster. To begin with, as you're approaching your corner shift into neutral well before you hit your turn in and then heel n toe and downshift at the appropriate time. It will become more natural and fluid in surprisingly little time.

Good idea! That simplifies things for now

Now - if you want to be really flash (and if you end up in a hedge it's not my fault) what you should really try is "double declutch with heel n toe combined with left foot braking".

*cries*