First of all let's deal with the
"double declutching " issue. This is really only
the British term for 'double clutching' and
makes reference in some way I suppose, to the
fact that it is usually a downshifting maneuver
in disengaging the clutch. The first stage in a
full 'heel and toe' gear change is the simple
use of double clutching. On its own this is a
fairly simple little dance of the toes and it
goes like this:
1. You are driving along in your MG or
whatever in third gear for example, approaching
a corner and preparing to shift to second. You
brake with the left edge of the ball of your
right foot as usual.
2. Depressing the clutch with your left foot
the shift lever passes through neutral as this
happens you release the clutch pedal out again
half way, thus setting the mechanics of the
clutch assembly in motion again.
3. Then fully depress the clutch to complete
your shift into second.
That my friends is a double declutching. It
might sound odd in print but is quite simple in
action. Practice it in the driveway, with the
engine off so you don't hit anything. The aim is
to keep the engine and the clutch plates turning
at the same speed for the moment when they
engage themselves. Your car will thank you
especially if you have an older vehicle that
lacks effective synchromesh.
The
next step is a true "Heel and Toe". Naturally it
goes without saying that this does not really
involve your heel and toe! The name is just to
make it harder to understand! (Actually it stems
from a rather odd set up in the old Ferraris
where the clutch and the brake pedals were
switched-but that's another matter.) The
technique involves combining the double clutch
method with a second technique that keeps the
engine RPM at a level to match the next gear to
be engaged.
Everyone has had the experience of changing
down into a lower gear and having the engine
forced into screaming high revolutions. The
other thing that happens is that the weight of
the car suddenly shifts forward due to the
'engine braking effect'. If you happen to be
going into a corner this can be enough to
lighten the rear end and send the tail out on a
visit to the front end! Here's where the heel
and toe technique comes in. Unless you have a
third leg you have to brake and 'blip' the gas
with your right foot. The tricky part is timing
it all right and keeping the brake pressure
steady while you do the 'blipping'. A note of
warning here. If you practice this in your
driveway as I suggested for double clutching,
some of the newer cars will flood as a result of
the gas pedal movement (yes! even without the
engine running). So if this happens just go off
and have a cup of tea and let things settle for
a while before heading off to try it in motion.
Here we go:
1. Begin the downshift as before, using the
left edge of the right foot to brake. Depress
the clutch and shift into neutral.
2. Now, as you're half releasing the clutch,
swing (or rock) the right edge and heel of your
brake foot over onto the gas pedal and squeeze
it gently to bring up the engine RPM. With
experience you'll get to know how much is
enough.
3. Then depress the clutch and complete the
shift into second. The plates should have been
spinning from your double clutching and the
engine RPM, which dropped while you were
shifting, was brought back up to the level
needed by the next gear ratio. Everything just
slipped together without a murmur, and there was
no forward weight shift or unwanted acceleration
of the car. Swing your right foot fully on to
the gas, and you're off down the straight.
Confused? I was too, and I "sort of know" how
to do it. Actually the brain is not capable of
doing this at all-the method has to leave the
area of your brain and become a fluid physical
skill. You drive along and your hands and feet
do it all, without you really being aware of it;
it's a great technique to master!
-Thanks Chris Ball, Technical Editor,
Toronto Triumph Club