RE: sometimes when i downshift to second gear..i hear a crunch

["Nick Koleszar" <npk@domain.elided>]

When going down a gear, take these steps:

1. disengage the clutch (put the pedal down)
2. put the transmission into neutral
3. engage the clutch (let the pedal up)
4. blip the throttle (give it a little bit of gas)
5. repeat step 1
6. put the transmission into the next gear
7. repeat step 3

if you've done it properly, the engine and gearbox revs should be matched
nicely and the gears should easily engage. if you haven't done it properly,
at step 7, the engine revs will suddenly go up or down or at step 6, you
will hear unhappy noises from the gearbox Many people skip step 3 when
double-clutching. This fails to perform the single most important step and
makes the whole sequence almost pointless (but not quite, if you see the
sequence on normal shifting, below).

When going up through the gears, you can do the same thing but skip step 4.

Of course, if you're braking whilst doing this on the way down the gears,
your right foot ends up having to do 2 jobs, braking and blipping the
throttle so you then will learn how to "heel and toe". further, unless
you're driving a car from about 1965 or earlier with poor brakes and a dog
box, you should not be using the gearbox to slow the car, all downchanges
should be occuring without affecting the car's speed or stability.

All of this takes lots of practice to get right and, as I said, will
increase your fuel consumption because every time you go down a gear, you
are blipping the throttle. In normal driving, to be honest, you shouldn't
need to double-clutch in a normal car. Even an Alfa. I developed the habit
many years ago when my only sports car was a 1974 VW Minibus in which you
couldn't find any gears at all if you didn't double-clutch and I've been
unable to kick the habit since.

Correct normal gear shifts should be like this:

1. clutch in
2. gear shift from one gear to neutral
3. slight pause
4. clutch in
5. gear shift from neutral to next gear.

if you do this instead:

1. clutch in
2. jam gear shift quickly from gear to next gear

you may hear crunching noises. every car has its own rhythm. with many FWD
Japanese cars, the gearboxes are very slick and you can get away with pretty
hamfisted driving but with most cars, especially as they age, you have to
develop the correct rhythm for the car and when changing gears, feel the
transmission find its correct way.

It's early on Sunday and I had a small party last night, so apologies if I
have typed any of the above incorrectly and, if you follow my instructions,
you are still all on your own and don't blame me if you mess it up and break
something. Braking something, however, is not quite so bad! Do your own
research and be happy that you know everything you need to know before
attempting any of this. These are trained professionals, don't try this at
home, folks. Kids, your parents put it together. Drive it like you stole it.
etc.....

nk
  -----Original Message-----
  From: MRAXLROZE@domain.elided [mailto:MRAXLROZE@domain.elided]
  Sent: 02 February 2003 03:25
  To: npk@domain.elided
  Subject: Re: sometimes when i downshift to second gear..i hear a crunch


  how do you double clutch?
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