On Tue, 21 Nov 1995, MACEDONIA wrote:
> Just by the fact that I'm asking this question you can tell that I've never
> driven a car with a non-synchro gearbox before. What is the "heel and toe"
> technique? I probably should know this because I'm restoring a 1966 Mark I
>MGB.
> But, since its pretty much stripped down to the shell, I figured I have plenty
> of time to find out!
You don't REALLY need to know this, because only 1st is unsynch-ed
(right?), so as long as you only engage 1st at standstill, you are OK.
H&T refers to a technique used while downshifting. When you downshift,
your engine suddenly has to spin faster, just like when you downshift on
your bicycle, you have to pedal faster.
Now consider the gears inside your transmission. Say you are downshifting
from 3rd to 2nd because a curve is coming up. Before you shift, your 3rd
gear is spinning at the same speed as the gear connected to the engine,
because the two gears are engaged. Now you press the clutch, take it out
of gear and try to engage 2nd. Since 2nd is "shorter", it spins
faster. For the "engine gear" to mesh with 2nd, it has to speed up to
that same speed.
Here is where the synchro comes in. The synchro is like a small clutch
that when you engage 2nd, smoothly grabs the "engine gear" and spins
it up to the right speed so it can mesh with 2nd.
(this is not really correct, but it serves the purpose here...)
Alternatively, you could press the clutch, take it out of gear (to
neutral), and rev the engine to exactly the right speed, so that the
gears mesh quietly. Pretty tough, that's why it is somewhat of an art to
drive a car with no synchros at all.
H&T then, is used before curves, when the driver has to brake and
downshift at the same time. He uses the toe to press the brake and the
heel to press the gas to rev the engine to the right speed.
Many LBC drivers use H&T, for 3 reasons:
1) It sounds impressive and pampers the synchros.
2) They are going really hot into a corner and want to shift as fast
as possible while feeling like Stirling Moss.
3) They have a worn transmission with a shot synchro (mostly 2nd, since
that one gets used most.
Two more points:
You could use this to shift into 1st while still moving, but the time you
would spend practicing this might take its toll on your gears.
When upshifting w/o synchro, you take it out of gear and wait until the
motor has slowed to the same speed as 3rd gear, before engaging it. With
a little practice all this can be figured out.
Also: while you are practicing the technique outlined in 2), remember
that your clutch is designed to transmit high torque one way, and not
necessaryly the other way. So if you are going into the corner at 5000rpm
in 3rd and after downshifting depend on your engine for a lot of braking,
your clutch might spontaneously combust. (been there, done that, with
italian sportscar though...I can explain why this happens, if you are
interested). H&T helps this too.
P.S. It DOES sound good and is in the spirit of LBC driving :)
Ulix
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