what is this heel-toe stuff?
Discussion
nervous said:
oy, say happy birthday to the old gits you lot! this may well be his last post...
a kindly thought, gratefully received. am now officially too old to buy a 911 without relentless mid-life crisis ribbing, which is sad.
and since I currently have a sore heel (and am having to wear the sort of orthopaedic insole usually reserved for geriatrics and dwarves), I think I'll leave this heel-toe stuff until the spring
weltmeister said:
Only asked as blipping the throttle surely defeats the purpose of synchromesh ?
I have never used H&T as I brake really hard initially and get off the brakes entirely at which point sufficient speed is scrubbed off before needing the correct gear for accelerating through the turn.
You still use the sychromesh when heal and toeing (you need to double declutch to not wear that). Heal and toe matches the revs to the gear as you go down the box, so if you are geared to be 2000rpm higher in the rev band if you drop a gear, you are blipping the engine so that it will be at the required 2000rpm more as you release the clutch in the lower gear.
You don't really need heal and toe on the road unless you are really pressing on. Tends to be more useful with very hard and late braking where you are dropping down to the correct gear for the corner exit whilst on the brakes. You also get the advantage of extra engine braking which will give you more rear brake bias. Manufacturers setup the brake balance so that you can't lock up the rears with engine braking (unless you engage a lower gear and the revs aren't matched!) so you aren't getting all the cars braking ability without it.
weltmeister said:
Only asked as blipping the throttle surely defeats the purpose of synchromesh ?
I have never used H&T as I brake really hard initially and get off the brakes entirely at which point sufficient speed is scrubbed off before needing the correct gear for accelerating through the turn.
Indeed. At low revs a modern transmission will soak up anything, but in a high revving car, you get a better change and it hurts the transmission less if you give it a blip. Easy to heel n toe in a Porsche as the brakes are so controllable, not so in an Audi. I'd do a brake and blip on that, get the braking done then give it a blip when changing down. Get nearly the same effect and it's much easier.
The only time I've locked the wheels on a car changing down was in my old '75 Magnum on 165 tyres.
Mind you, Sherpa vans, Dolly Sprints, Granada's ...... old shit basically.
The gearbox syncro lets you get the car into gear with your foot on the clutch without crunching the gears. The reason for heal & toe is to stop the rear wheels locking up as they drive the engine up to speed. Think about when you bump start a car you push the car along in gear with your foot on the clutch. As you drop the clutch the wheels skid for a tiny bit as they start to drive the engine.
If you are braking late and actually turning a bit whilst doing your down-change that little lock up, (and remember the rear of the car is light anyway because you`re braking), will cause the back of the car to oversteer and put you in a spin.
We have discussed heal & toe before on the forum & I`m not sure it`s that relevant for road driving as it sort of implies you might be pushing on harder than public road conditions allow.
For the track it`s a very relevant skill to learn, especially in a 911.
Henry
911virgin.com top people to buy used Porsches from !!
>> Edited by henry-f on Thursday 8th December 18:32
If you are braking late and actually turning a bit whilst doing your down-change that little lock up, (and remember the rear of the car is light anyway because you`re braking), will cause the back of the car to oversteer and put you in a spin.
We have discussed heal & toe before on the forum & I`m not sure it`s that relevant for road driving as it sort of implies you might be pushing on harder than public road conditions allow.
For the track it`s a very relevant skill to learn, especially in a 911.
Henry
911virgin.com top people to buy used Porsches from !!
>> Edited by henry-f on Thursday 8th December 18:32
workshy fop said:
I used to do all that H&T ,..left foot braking....pendulum effect when Porsche`s were real mens cars..........................then i got a F1 360...
So it does it all for you?
Good question , actually it ( F1 trans ) does go a long way in assisting . H&T teaches a good discipline if you can master it.
Using the F 1 transmission in a 360 circumnavigates H&T leaving the driver to focus more on trottle, braking and steering input. In "sport " mode at high revs aproaching corners where ultimate concentration is needed , the computer "heels & toes" for you.
My post was tongue in cheek but what the hey I`m feeling lucid
With respect to my electronic friends, H&T not intended to allow for a smoother change or to prevent the driven wheels from locking, although those are side benefits. On a circuit, its primary purpose is to save time.
If you're going quickly but need to slow, at that slower speed the optimal gear may be lower than the one you're in. Often the maximum engine speed will not accomodate the new lower gear until the car is going more slowly, so you have to brake before downshifting. If you wait until the braking is finished and then take your foot off the brake and do the downchange, during the phase when you are changing gear the car is just coasting. Normally you would want always to be either on the throttle or on the brakes.
H&T allows you to get the gearchange done during the period when you're off the throttle anyhow, but while you're doing something else that has got to be done.
You would not normally H&T on public roads because saving a fraction of a second on a downchange doesn't matter. Also, as folks have observed, it is more difficult to H&T if you're only slightly pushing on the brake pedal.
H&T does have a place on public roads if, say, you are caught out and find yourself going downhill in too high a gear. In that situation if you were to downshift as normal, when the clutch was in the car would pick up speed. If you apply the brakes during the downchange it's easier to keep things in control.
Apologies for the pedantry.
>> Edited by flemke on Thursday 8th December 19:29
If you're going quickly but need to slow, at that slower speed the optimal gear may be lower than the one you're in. Often the maximum engine speed will not accomodate the new lower gear until the car is going more slowly, so you have to brake before downshifting. If you wait until the braking is finished and then take your foot off the brake and do the downchange, during the phase when you are changing gear the car is just coasting. Normally you would want always to be either on the throttle or on the brakes.
H&T allows you to get the gearchange done during the period when you're off the throttle anyhow, but while you're doing something else that has got to be done.
You would not normally H&T on public roads because saving a fraction of a second on a downchange doesn't matter. Also, as folks have observed, it is more difficult to H&T if you're only slightly pushing on the brake pedal.
H&T does have a place on public roads if, say, you are caught out and find yourself going downhill in too high a gear. In that situation if you were to downshift as normal, when the clutch was in the car would pick up speed. If you apply the brakes during the downchange it's easier to keep things in control.
Apologies for the pedantry.
>> Edited by flemke on Thursday 8th December 19:29
Nice way to explain it! 
On tarmac you can go from 5th to 2nd and use the braking time to blip the throttle in neutral with the clutch up, helps syncro, also keeps the car dead stable and looks cool to your mates.
On gravel - the opposite cos by ramming it into gear and bringing the clutch up will help the backend come around without needing the handbrake (RWD car of course) sometimes this can just give you extra momentum rather than using the handbrake
Anyway on gravel your legs are bouncing all over the place and your are lucky to find the brake pedal never mind neatly place your foot over half the pedal.
On the road waste of time and confuses pedestrians
On gravel - the opposite cos by ramming it into gear and bringing the clutch up will help the backend come around without needing the handbrake (RWD car of course) sometimes this can just give you extra momentum rather than using the handbrake
Anyway on gravel your legs are bouncing all over the place and your are lucky to find the brake pedal never mind neatly place your foot over half the pedal.
On the road waste of time and confuses pedestrians
porsche4life said:
On tarmac you can go from 5th to 2nd and use the braking time to blip the throttle in neutral with the clutch up, helps syncro, also keeps the car dead stable and looks cool to your mates.
On gravel - the opposite cos by ramming it into gear and bringing the clutch up will help the backend come around without needing the handbrake (RWD car of course) sometimes this can just give you extra momentum rather than using the handbrake
Anyway on gravel your legs are bouncing all over the place and your are lucky to find the brake pedal never mind neatly place your foot over half the pedal.
On the road waste of time and confuses pedestrians
H&T can be very handy on gravel (more important with big power though, just watch in-car footage of Rohrl, Blomquist etc in the Grp B cars. simply amazing footwork). I've never had trouble finding the brake pedal or H&Ting on gravel, and it can be quite useful for maintaining the attitude of the car if you need to drop a gear when you already have the angle you want, and don't want to change it.(in the same way that not using it can help swing the tail out if you need to)
its definitely not vital on the road unless you're pressing on pretty quickly, but the way I see it, if you dont practise it while driving on the road then you won't be very good at it when you do need it.
GravelBen said:
its definitely not vital on the road unless you're pressing on pretty quickly, but the way I see it, if you dont practise it while driving on the road then you won't be very good at it when you do need it.
My thinking too, which is why I do it a lot on the road myself. Only gently though as I then don't have to scream up to junctions and it's harder and requires more sensitivity anyway.
flemke said:
With respect to my electronic friends, H&T not intended to allow for a smoother change or to prevent the driven wheels from locking, although those are side benefits. On a circuit, its primary purpose is to save time.
If you're going quickly but need to slow........
I disagree with this and ignorance might cause someone to bend their car on a trackday.
ABS brakes are great - I know true racing drivers don`t use them and you can all out brake the ABS with cadence braking just like the heroes you all are, but for us mortals I love the ABS in my GT3 cup car. At Zolder this year in the wet it was the dogs bollox. 5 heavy braking zones, some downhill, some cornering, some both ! It`s not infallable and a couple of sideways moments will testify to that, but it is good. On dry trackdays you probably won`t be wearing my slick tyres and so with less grip the ABS will be your friend and allow you to brake accurately in the same place each lap.
There is however a problem. ABS won`t stop the wheels from locking up if you use the engine to brake which is exactly what you`re doing by not balancing engine revs and car speed on a downchange. So be careful. Old Hall at Oulton Park where the RS day is planned as per the top post of this forum is a perfect corner for getting into trouble. You`re braking hard, it`s a bit bumpy and you could easily need to turn in a bit as you`re still braking, especially if you`ve overcooked the speed a little on entry. You dump the clutch on your downchange and asta la vista baby you`ll be paying Mr in-field barrier a visit as the back end locks up and swings round.
I also wouldn`t advocate a jump from 5th to 2nd in one go, you`ll be out of gear for a long time and will have to be bloody handy feading the gear in when the time comes. Pay all the gears a visit on the downchange. Helps keep the car flatter, the engine revs balanced and everything nice & rosy !
Happy driving - Henry
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