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Clutchless shifting

To: mgs@Autox.Team.Net
Subject: Clutchless shifting
From: DANMAS@aol.com
Date: Mon, 19 May 1997 15:46:50 -0400 (EDT)
Fellow Listers:

Many years ago, I drove a large Mack dump truck for a living. At that time, I
was not the giant of a man that I am now. I stood 5' 6", and weighed 112
pounds (I'm still 5' 6", but I've added a few pounds. OK, a lot of pounds).
In order to drive that beast, I had to learn to double clutch. Perhaps a
brief description of what takes place during this manuever would be helpful
for those new to it.

When you are travelling along at a steady speed, or accelerating, the gears
on the input shaft are DRIVING the gears on the output shaft. The teeth on
the input gears are applying pressure to the output gear teeth. When you lift
off the throttle, and use the engine to slow the car, the gears on the input
shaft are now being DRIVEN by the gears on the output shaft. Now, the teeth
on the output gears are applying pressure to the teeth on the input gears.
During the transition between these two conditions, there is a period at
which no pressure is being aplied by or to either set of gears, and they are
rotating at the same speed. At this time, only the slightest force is
required to slip the transmission into neutral.

Once in neutral, the output shaft continues to rotate at the same speed as
before (at least until the car slows down). The input shaft is rotating at
engine speed. If you now rev the engine up to where the engine RPM nearly
matches the RPM it *WOULD BE* turning if it were in already in the lower
gear, the two shafts will now be turning at almost the same speed. Since they
are turning at the nearly the same speed, there would be very minimal
pressure applied to the gear teeth if the gears were to be meshed again.
Since it is impossible to exactly match the speeds, if you lightly press the
gearshift lever, the two gears will rotate till the teeth are in mesh, and
the transmission will readily slip into gear with no damage. 

Of course, shifting up is the reverse of the above. You let the engine speed
drop till it matches the speed it will be at when in the higher gear.

With a little practice, except for starting from a stop, the clutch becomes
redundant. I don't recommend this method, but if you are having clutch
problems, or transmission problems, it can be a lifesaver. Combining this
technique, with the use of the clutch, significantly reduces the strain on
drive train components.

Given my druthers, I'd druther drive an LBC!

Dan Masters,
Alcoa, TN

'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
                    www.sky.net/~boballen/mg/Masters/
'74 MGBGT---3000mile/year driver, original condition
'68 MGBGT---organ donor for the '74


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