Can someone explain why "heel & toe"

[Tidybuoy]

Considering I been driving a Porsche for at least 20 years, this may be a dumb question. What is the purpose of heel & toe?

I recently watched a video on the new Porsches, specifically on a European 911 Targa that still had a manual transmission and the driver was commenting that the transmission had an auto "Blip" feature that revved the engine during shift changes which eliminated the heel & toe need. (BTW, he also commented that this in no way compensated for the worthless 450lbs extra weight of the new targa system).

1) I've always wondered why racers revv during shift changes

2) I've always thought this was something needed specifically on turbos where you wanted to keep the turbo spooled up during a shift change but I'm not sure how needed this is for a N/A engine.

Can anyone give me a simple explanation - just for my own education.

[OldSpool87]

The "blip" that heel toe creates is an attempt to match engine and transmission speeds. If you don't blip, you get that lurch forward which upsets the balance of the car. In a perfect heel toe downshift you feel nothing and it feels wonderful. So, as the car is being slowed with part of your foot on the brake the other part of the foot hits the accelerator (blip) while nearly simultaneously, but not quite, the clutch is let out.

[SOAZ]

Originally Posted by Tidybuoy

Considering I been driving a Porsche for at least 20 years, this may be a dumb question. What is the purpose of heel & toe?

I recently watched a video on the new Porsches, specifically on a European 911 Targa that still had a manual transmission and the driver was commenting that the transmission had an auto "Blip" feature that revved the engine during shift changes which eliminated the heel & toe need. (BTW, he also commented that this in no way compensated for the worthless 450lbs extra weight of the new targa system).

1) I've always wondered why racers revv during shift changes

2) I've always thought this was something needed specifically on turbos where you wanted to keep the turbo spooled up during a shift change but I'm not sure how needed this is for a N/A engine.

Can anyone give me a simple explanation - just for my own education.

If you have a motorcycle handy shift down through the gears quickly and the rear tire will chirp. A bit dangerous, but it happens.
When you do that in your car you are not only effectively encouraging the rear tires to break traction, but you are being very hard on the gear box too. By blipping the throttle you are trying to match engine speed to where it will be once you let out the clutch.
Thereby smoothing the entire process for the transmission and grip of the tires. If you are on the limit, not doing this will cause you to spin out and possibly crash. If you are in traffic, it's still nicer on your transmission and it's fun practice.

The 911 is one son of a ***** to Heel Toe. I can heel toe a Landcruiser more easily!
However, I still, always blip the throttle when down shifting. I love my car.

[darrin]

Heel/toe rev matching is done on downshifts to match revs prior to shifting into the lower gear. On a track, you want to brake as late as possible out of a straight and simultaneously downshift so that you're back in the powerband coming out of the turn. Doing this simultaneously (breaking, rev matching and depressing clutch) would require 3 feet, so one combines the braking and rev matching with one foot.

If done in conjunction with "double clutching" (depress clutch, take car out of gear, rev match and then engage clutch and put back in gear), this will save wear on synchros. Otherwise, heel and toeing simply assures that the drivetrain doesn't need to absorb the shock of bringing the engine up to speed.

[kyngfish]

I think that blip is pretty much not very noticeable, and most people do it fairly automatically. I only ever really "hear" it for a downshift, when you're trying to downshift for acceleration, not because you're reducing speed.

But I've actually been wondering some of this myself. I've driven a stick since I learned to drive, but I've always wondered if I do it optimally.

[Driven97]

Simple answer is it's hitting all three pedals at once, but the throttle only as much as needed.



I tend to prefer to use the right side side of my right foot rather than my heel, assuming the pedals are close enough.

It's a really difficult art to master, but very useful at 10/10ths. I suck at it.

[RAW911]

+1 on darrin's last paragraph.

When teaching my granddaughter to drive the 911, I had her shift between 1st, 2nd and 3rd while maintaining the same speed. By double clutching, if done right, you should not feel any jerking or a change in vehicle speed, only the sound of the engine.

Drive in both 2nd & 3rd at a certain mph; note the rpm at each speed; when in 3rd, put in clutch, rev to the rpm it was in 2nd and it should drop right into gear. Then try the same method using 1st and 2nd.

A little practice and Bob's your Uncle!

[McLovin]

Heel and toe is super easy to learn, *if* the pedals are set up properly for it.

I have an old BMW that has the gas and brake pedals in perfect position for heel and toe. In that car, I heel and toe every downshift. I do it automatically now, without thinking about it.

It's fun when you hit it just right and have a super smooth corner entry downshift. Technically, it's a little easier on the drivetrain, I suppose, too.

Air cooled 911s, I think, have some pedal adjustability, but I don't think there's enough to get it really perfectly "right." The gas pedal is usually way too low. At least in my car it is.

I've seen lots of aftermarket gas pedals available, with adjustability. Those seem designed mostly to make heel and toe easier.

Once you learn it, you can do it in any car, even with poorly set up pedals. But it's not as fun or easy.

[scarceller]

I'll try explaining mechanically what the objective is.

If you ever try shifting from 2nd to 3rd with no clutch at all you learn that to get it out of 2nd you need to match engine speed precisely with wheel speed. You put a tiny bit of pressure on the shift lever towards neutral and the minute the engine speed matches the wheel speed magically the gear lever comes out of 2nd and into neutral. It's that speed match up between the engine and wheels your looking for.

OK, so now onto the next harder part: now that we are in neutral we want to slide into 3rd but without using the clutch. What needs to be done here is to precisely anticipate the engine speed needed to match the wheel speed for 3rd gear. Once that engine speed matches the wheel speed the 3rd gear engagement can now be done. I shift my 5 speed VW Passat this way often with no ill harm.

So in the heel toe approach it's mainly used for down shifting in an attempt to get engine speed at or slightly above the target RPM for the lower gear we are shifting into.

You may better understand the concept by understanding double clutching as seen here:
https://www.youtube.com/watch?v=zy0BfG_CG2Y
The explanation starts around the 6 minute mark. The vid is long but he does a decent job at explaining it.

[Neilnaz]

I think the answers above have failed to explain the whole reason for 'heel and toe'. 'Heel and Toe' is generally used to down-change gear whilst slowing for a corner in order that you are in the right gear to accelerate out of that corner. You want to be in the right gear and at the right speed to enter the corner, hit the apex and accelerate out/through the corner.

You lose precious time changing gear or braking and not doing these things at the same time. 'Heel and Toe' enables you to slow and change gear at the same time.

Firstly the 'heel' is used to blip the throttle to enable rev-matching during a change down in gears (for the same speed the engine needs to rev higher to have a smooth down change)

Secondly the 'toe' is used to simultaneously apply the brakes

I have always rev matched by blipping the throttle on down-changes in order to sympathetically change gear but I have yet to master the 'heel and toe' method. This is one of the things I am going to concentrate on to learn correctly.

Cheers, Neil

[Bob Kontak]

Originally Posted by Neilnaz

You lose precious time changing gear or braking and not doing these things at the same time. 'Heel and Toe' enables you to slow and change gear at the same time.

Is there any slowing meant to be performed by a lower gear while you are braking to the turn in point?

If you are in fourth and you want to come out of the turn in second, do you utilize third gear on the way down to 2nd to scrub any speed off?

[scarceller]

Just blipping the throttle gets the engine to speed in anticipation of the lower gear. But the main shaft in the tranny is still spinning to slow compared to the intermediate shaft that's directly connected to the wheels. So when you blip the throttle you get the engine speed closer to the wheel speed for that lower gear.

But you still have the main shaft in the tranny sort of spinning in limbo, it's not connected to either the motor or the wheels if the clutch is in. So the heel toe helps align engine mass rotational speed with the wheel speed for the down shift and the engine has the grand majority of mass so it really helps. But the main shaft still remains at a lower speed and will be brought up to speed on the engagement of the clutch.

While double clutching results in bringing both engine and main shaft up to speed because in the double clutch scenario you slide into neutral, release the clutch and then blip throttle. Here both the engine and the main shaft come up to speed. Then you move clutch back in and select the downshift gear. But double clutching is very time expensive so heel toe is a trade off between getting the majority of the mass (engine mass) up to speed in favor of time. We trade off time for the main shaft speed.

Hope that helps.

[J-Mac]

If you are in fourth and you want to come out of the turn in second, do you utilize third gear on the way down to 2nd to scrub any speed off?[/QUOTE]

I believe that slowing down is the sole job of the brakes in the vast majority of situations. And to your question, not necessarily. If you have perfect synchros etc you could go direct to 2nd from 4th but definitely with the aid of heel toe to avoid the engine adding additional force on the driven wheels and upsetting the balance or causing momentary lock up.

[scarceller]

This guy covers both the simple heel toe and the heel toe with double clutch
https://www.youtube.com/watch?v=ucwtXkCfcbI
He does a very good explanation and demonstration of both techniques.

Very hard to master! I understand the concepts but I'm not a master

[darrin]

Originally Posted by J-Mac

If you are in fourth and you want to come out of the turn in second, do you utilize third gear on the way down to 2nd to scrub any speed off?

I believe that slowing down is the sole job of the brakes in the vast majority of situations. And to your question, not necessarily. If you have perfect synchros etc you could go direct to 2nd from 4th but definitely with the aid of heel toe to avoid the engine adding additional force on the driven wheels and upsetting the balance or causing momentary lock up.

Exactly -- My VERY MINIMAL track driving education taught me that the only real reason to downshift is to be in the sweet spot, power-wise, when coming back on throttle out of a turn. Braking in the track environment is seldom done gradually, as 1) gradual braking scrubs speed and 2) sharp braking provides effective weight transfer (loads up the front end going into a turn). Or -- put another way, since a clutch replacement is more $$ than new brake pads, it makes little economic sense to preserve brakes at the expense of your clutch when slowing down.

[Bob Kontak]

Originally Posted by J-Mac

If you are in fourth and you want to come out of the turn in second, do you utilize third gear on the way down to 2nd to scrub any speed off?

I believe that slowing down is the sole job of the brakes in the vast majority of situations. And to your question, not necessarily. If you have perfect synchros etc you could go direct to 2nd from 4th but definitely with the aid of heel toe to avoid the engine adding additional force on the driven wheels and upsetting the balance or causing momentary lock up.

Thanks guys.

Upsetting the balance/lock-up...............At my one real track event, I overheard old timers talking about new kids with monstro cars and they have yet not learned car control. These things have to fall into that category

[Neilnaz]

Bob and others, changing gear from 4th to 2nd via 3rd wouldn't be particularly useful and you should be able to go from low revs in 4th to high(ish) revs in 2nd without an dramas. I don't believe you should be slowing when in the corner itself apart from initial trail braking as you commence the turn. You want to be on the power through the corner maintaining speed modulating the throttle.

Cheers, Neil

[Bill Verburg]

Originally Posted by Neilnaz

Bob and others, changing gear from 4th to 2nd via 3rd wouldn't be particularly useful and you should be able to go from low revs in 4th to high(ish) revs in 2nd without an dramas. I don't believe you should be slowing when in the corner itself apart from initial trail braking as you commence the turn. You want to be on the power through the corner maintaining speed modulating the throttle.

Cheers, Neil

Most of the experts would disagree w/ you on that point

Not being an expert I do it all the time, you just need a bigger blip.

[Neilnaz]

Bill, I said going from 4th to 3rd to 2nd wouldn't be useful. I would advocate going from 4th to 2nd with a bigger blip as you say....

[wayner]

Watch Hurley explain it at 12:00 in to this video