Double Clutching
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 TR, 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.
Heal and Toe
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
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