Heel-and-toe downshifting multiple gears; skip or row?

[Nomes]

Hi guys

I am fairly happy with the process of heel-and-toe downshifting and am now using it routinely. There is one thing that I have read conflicting views on and was hoping you guys may be able to give clearer information on. When downshifting multiple gears (e.g. 4th to 2nd), is it better to do so as one motion or better to blip down into 3rd and then again into 2nd?

Just to provide a bit of context to my question, I understand that if you are really going for it (e.g. on a racetrack) and are almost at redline in 4th, downshifting into 2nd in one go is very risky in terms of damage to engine or locking up wheels, and so it makes sense to row down to 2nd via 3rd. My question pertains more to on-road driving where you may be in the middle of the rev range in 4th, and then want to change down into 2nd. In that situation, I would currently use a fairly large blip of the throttle in the latter part of the braking zone and go into 2nd. Is there any potential problem with this? I also have a stretch of dual-carriageway nearby which is punctuated by a well-sighted roundabout, and I usually need to get from 6th (at 70mph) to 2nd (around 20mph). In this situation I blip down into 4th and then into 2nd. Would anyone advocate rowing down through each gear here?

Thanks in advance

[Toltec]

Depends somewhat on the gearing and gearbox. If the revs drop too low in 6th before you can take 2nd you will need to take an intermediate gear, 3rd for example. Some gearboxes are happier about large block changes than others.

Not being a driving God sometimes I do a comfort change into the gear one higher than the one I end up needing.

[7db]

Just a note -- you may find it easier to do the blipping in the early part of braking when you are firmest on the pedal (ie once you've smoothly got into the brakes, get the change in while in firm braking. Much harder to modulate everything later on in the braking as you are starting to taper off to avoid locking up etc.

I personally do 'em all on the way down. It sounds better, and frankly, I need the practice.
Here's someone good doing the whole box at the end of the straight at Sebring
https://youtu.be/-UjnbIuJNuI?t=51s

[CrutyRammers]

I do both; depends on the car and the box and how easy it is to block change. I don't think it matters beyond what you are comfortable with. In your example I'd probably go 6-3-2 rather than 6-4-2, I think purely because I find going 6-4 or 4-2 to be a more awkward movement than going in a single direction.
A good H&T shift down 3 gears is one of driving's great pleasures, so sometimes I'll go through all of the gears I can, "just because".

[alicrozier]

On the road I'd normally go through all the gears for smoothness (and fun) unless there was a good reason not to...

On track there are sometimes good reasons. I posted this recently in the trackday forum:

alicrozier said:

In my rwd car the brake bias is not adjustable but you can use technique to get around that somewhat.
In the wet you don't get the same weight transfer to the front of the car so ideally need more braking at the rear. To achieve that I'll go down through each gear 4-3-2 changing optimally early (so the lower gear comes in at high revs) - this is to maximise engine braking at the rear. Same car and corner in the dry I would go 4 straight to 2 and change later (lower revs) as the front is doing most of the braking and the rear is really light - and any more braking can make it unstable and I wan't to minimise time with the clutch disengaged.

http://www.pistonheads.com/gassing/topic.asp?h=0&f=18&t=1651541

[nw942]

I have just started practicing H&T.

When doing H&T (say third to second) when do you actually engage second gear:

1. Do you do it straight-away i.e. de-selecting third and engaging second in one movement.
2. De-select third, and apply slight pressure at the top of the second gear gate. As the falling revs match the speed of the gearbox it should slot in a little easier. This option 'seemed' to have a nicer engagement.

As I type this I'm thinking that option 2 is preferred and that the moment the gear engages is your trigger to release the clutch?

I may be getting away with 1 as a) I would normally be going fairly slow in lower gears, and b) the clutch delay valve may be smoothing things out for me?

[plenty]

With practice it's easy to modulate the amount of throttle and therefore revs you give when blipping...large blip for block downchange, smaller one for one gear down.

[davepoth]

nw942 said:

I have just started practicing H&T.

When doing H&T (say third to second) when do you actually engage second gear:

1. Do you do it straight-away i.e. de-selecting third and engaging second in one movement.
2. De-select third, and apply slight pressure at the top of the second gear gate. As the falling revs match the speed of the gearbox it should slot in a little easier. This option 'seemed' to have a nicer engagement.

As I type this I'm thinking that option 2 is preferred and that the moment the gear engages is your trigger to release the clutch?

I may be getting away with 1 as a) I would normally be going fairly slow in lower gears, and b) the clutch delay valve may be smoothing things out for me?

Don't do 2. 2 will cause extra wear on the synchros, which is the opposite of what you're aiming for.

I think it's useful to wind the clock back even further to the days of double declutching, as the full process helped me to understand what was going on.

When doing a double declutched H'n'T downshift the process is like this:

1. Depress clutch.
2. Shift to Neutral
3. Release clutch
4. Depress clutch
5. Rev match
6. Shift to next gear
7. Release clutch

Nobody's expecting you to double clutch - if you have a CDV it's likely to be almost impossible to do properly anyway. But from the above process you can see the point at which the rev match is supposed to take place - just before you move the gearstick from Neutral into the next gear. You have to make having the gearstick in neutral a very brief but distinct phase in the shift for it to work properly.

There's no "trigger" to release the clutch if you get it right, as the gear selector will move into the gear with no resistance. With practice you will be able to operate the clutch like an on/off switch once you're rolling, and in some cases (although I wouldn't recommend it on a car you care about!) dispense with it entirely.

Edited by davepoth on Saturday 25th February 22:59

[Solocle]

davepoth said:

Don't do 2. 2 will cause extra wear on the synchros, which is the opposite of what you're aiming for.

I think it's useful to wind the clock back even further to the days of double declutching, as the full process helped me to understand what was going on.

When doing a double declutched H'n'T downshift the process is like this:

1. Depress clutch.
2. Shift to Neutral
3. Release clutch
4. Depress clutch
5. Rev match
6. Shift to next gear
7. Release clutch

Nobody's expecting you to double clutch - if you have a CDV it's likely to be almost impossible to do properly anyway. But from the above process you can see the point at which the rev match is supposed to take place - just before you move the gearstick from Neutral into the next gear. You have to make having the gearstick in neutral a very brief but distinct phase in the shift for it to work properly.

There's no "trigger" to release the clutch if you get it right, as the gear selector will move into the gear with no resistance. With practice you will be able to operate the clutch like an on/off switch once you're rolling, and in some cases (although I wouldn't recommend it on a car you care about!) dispense with it entirely.

Edited by davepoth on Saturday 25th February 22:59

Surely you should rev match in neutral to synchronize the layshaft to the drivetrain? Rev matching with the clutch depressed is essentially a SDC with some frivolous footwork - the synchros will still have to put the layshaft at the wheel speed, because at no point do you actually spin it up.

Correct me if I'm wrong, I'm not some mechanical guru - but from my understanding, this is how it works.

Edited by Solocle on Tuesday 6th June 13:39

[brrapp]

I was brought up driving agricultural and semi agricultural vehicles with no synchromesh and therefore had to learn double declutch and heel toe changes from an early age if I wanted to drive around with any semblance of coolness. I've recently had to relearn the skills I had in my youth as I'm currently running an old 4x4 pickup with a knackered gearbox as my build project vehicle.
When you have to double declutch out of necessity, you soon learn the optimum times to change down and what you can get away with in terms of road speed/ engine speed differentials.
Yes you can change down from 5th to second, but you need a pretty big blip/stomp on the loud pedal combined with leaving it in 5th till your road speed is a lot lower than you would normally.
I'd suggest you practice clutchless downshifts to get an idea of the ideal speeds/ revs for smooth gear changes. Once you can drive around for a few hour without touching the clutch and without making teeth grinding crunches, You'll find 'normal' heel-toeing is a doddle.

[paul789]

Or you could buy this.

It's a lovely white Audi A3 with an S Tronic gearbox. As it's an Audi, all your friends, neighbours, peers and especially everybody who sees you driving will know you have 'made it'.

Also, you'll benefit from the fact it's the result of German automotive engineering perfectionism - it definitely won't go wrong.

https://usedcars.audi.co.uk/usedcar/audi/a3/a3/pet...

One life, live it.

[Solocle]

brrapp said:

I was brought up driving agricultural and semi agricultural vehicles with no synchromesh and therefore had to learn double declutch and heel toe changes from an early age if I wanted to drive around with any semblance of coolness. I've recently had to relearn the skills I had in my youth as I'm currently running an old 4x4 pickup with a knackered gearbox as my build project vehicle.
When you have to double declutch out of necessity, you soon learn the optimum times to change down and what you can get away with in terms of road speed/ engine speed differentials.
Yes you can change down from 5th to second, but you need a pretty big blip/stomp on the loud pedal combined with leaving it in 5th till your road speed is a lot lower than you would normally.
I'd suggest you practice clutchless downshifts to get an idea of the ideal speeds/ revs for smooth gear changes. Once you can drive around for a few hour without touching the clutch and without making teeth grinding crunches, You'll find 'normal' heel-toeing is a doddle.

I don't want to run the risk of grinding. I'm still teaching myself H&T, not doing DDC at the moment. But I've pulled off perfect matches a few times now. Boy do those feel good.

[paua]

Steps 4 & 5 (above ) are in the wrong order. Cheers

[Jambo85]

paua said:

Steps 4 & 5 (above ) are in the wrong order. Cheers

Agreed. There are a few other comments throughout this thread showing considerable lack of understanding of what the clutch does...

Also clutchless gear changes with a gearbox with synchros are also not advisable as the synchros will make you think you're better at it than you actually are, while you're putting increased stress on them.

[paua]

I have a single mass flywheel - I double de-clutch down shifts, also when braking (h&t). It is a lot smoother than just blipping to rev match with the left pedal still on the floor, which brings the engine up to speed, but not the trans.