On Sun, 18 May 1997 19:05:52 -0400 Bob Gaughan <gaughan@highway1.com>
writes:
>Any optimum way of shifting into a non-synchro first gear on a '61 MGA
1600 without grinding up a pound and a half each time?
>From a standstill, shift into 2nd to stop all the whirling bits in the
gearbox, then shift into 1st. Downshifting on the fly is a different
story.
Doing it right takes a little practice and a lot of finesse. Do not try
this from any other gear but 2nd.
a.) Read engine speed on tach, or listen carefully to note the
engine speed.
b.) Depress clutch.
c.) Shift to neutral.
d.) Release clutch.
e.) Blip throttle to speed the engine up to about twice the
original speed.
f.) Depress clutch.
g.) HAM FIST IT INTO 1ST GEAR.
This is called "double clutching" because of steps b and f.
If you have the engine speed right it makes no difference if you do it
quick or slowly, it works great either way. But, if the engine speed is
not exactly right, doing it slowly will get you a lot of gnashing noises,
and doing this repeatedly will eventually grind down the gear teeth. It
is important to use a heavy hand and deliberate motion to get it fully
into gear on the first try so you don't grind the teeth. This is not for
the faint of heart, and if you're the least bit queasy about it, don't do
it.
For a gearbox in good condition, these gearboxes are pretty tough, and so
long as you have the clutch fully depressed, you can bang it without
breaking it. The lay gear, input shaft and clutch disk do not have a lot
of inertia compared to the weight of the car pushing the wheels and prop
shaft, so the little bits can change speed quickly when you bang it into
gear. For a gearbox in old, worn, or unknown condition, I wouldn't try
it.
Now if you have absolutely no respect for the gearbox, you can skip steps
"a" through "e", and it still works. Considering the extra stress this
puts on the parts, I wouldn't make a daily habit out of it. I only do it
on weekends when I'm autocrossing. But then. I have completely
refurbished the gearbox, and I know this one is in good condition.
I did however waste a clutch today in Peoria. I haven't pulled it apart
yet, but I think the pressure plate took a hike. Makes rattling noises,
and depressing the pedal does not disengage the clutch. The clutch disk,
release bearing, and release arm bushing were all new a few weeks ago,
and I still have pedal pressure over the full travel of the pedal, it
just doesn't release. My first guess is that the pressure ring that the
release bearing pushes against has disassociated itself from the rest of
the pressure plate. My second guess is that the friction lining of the
disk has broken loose and doubled up the thickness. Anyone care to take
a position in the lottery before I pull the engine?
Incidentally, I drove it home (135 miles) with no clutch, not as hard as
you might think. From a standstill, turn engine off, shift into 1st,
depress throttle half way, engage starter, and you're off. Take it to
about 2000 to 3000 rpm, lift throttle to about 1/4 position so the engine
slows down gradually as you gently but deliberately "lean on" the 2nd
gear synchronizer. When the engine speed is right it drops right into
2nd gear without a fuss. If your 2nd gear synchronizer is bad, you will
have to estimate the correct engine speed and HAM FIST IT INTO 2ND, just
like any non-syncro gear. Repeat the process for other gears.
Downshifting without a clutch definitely requires all steps a through g
except b and f. Let the throttle up to about 1/4 position to remove the
torque from the drive train, shift to neutral, throttle engine up to the
appropriate speed, lean on the syncro, and it slips in when the engine
speed is right. Otherwise, with a bad syncro, you will have to HAM FIST
IT AGAIN. When you come to a red traffic light, you either turn off the
engine or kill it with the brakes.
Barney Gaylord -- Naperville, Illinois
1958 MGA with an attitude,
225,000 miles,
25 race dates a year,
and still no missing teeth in the gearbox.
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