Most manual transmissions - four speeds, although five speeds work the
same way - (stock - I've never rebuilt "racing" transmissions or
transmissions with oil pumps), the oil is dispersed by "splashing".
The oil in the bottom of the trans case is splashed around by the
gears on the counter shaft spinning through the gear oil.
Whenever the engine is running and the clutch is engaged (out, turning
the trans), the input shaft turns the counter shaft (which in turn
rotates all the output shaft gears - they are free to spin on the
output shaft).
Which gear is selected depends upon which output shaft gear is locked
to the output shaft (only one can be locked at a time - the others
just rotate about the shaft when not selected). The gears are locked
to the output shaft by a moving slider (I can't remember it's proper
name and it varies from repair manual to repair manual anyways). This
slider is splined to the output shaft, and when it engages a
gear, the slider (and consequently the output shaft) is made to turn
at the same speed as the gear, which is turned by the counter shaft
gear, which is turned by the input shaft, which is turned by the
engine. By the way, the moving slider usually carries the sychro
rings, which allow the speed difference between the slider and gear to
be sychronized smoothly - but that's another long article... Note
that fourth gear is just a special case where the input shaft is locked to
the output shaft and all the output shaft gears are disengaged (from
the output shaft - not the counter shaft).
Time for ASCII art (tm) of only the third and fourth gears of a
transmassion:
4 D 3 Where:
---
|\|> --- A = input shaft from engin/clutch
|\|> <||> <|\| 2nd & 1st B = counter shaft
|\|> <||> <|\| gears go C = output shaft to drive (prop) shaft
|\|> <||> <|\| here... 4 = fourth gear - part of A
A ======|\|> =<||>=<|\|======= C D = slider/ whatever (can't remember
|\|> <||> <|\| proper name) - splined to & slides
|\|> <||> <|\| on C. engages gear 3 or 4 to lock
|\|> <||> <|\| speed of output shaft C to gear.
|\|> --- 3 = third gear - freely rotates on output
--- |/| shaft C.
|/| |/| E & F = gears on counter shaft B - may be
|/| |/| integral part of B (i.e. Lotus) or
|/| |/| splined & replaceable (i.e. TR4)
B |/|=========|/|
|/| |/|
oil ---------------------
level E F
The result of all this is that when the engine is turning (clutch
engaged), the counter shaft is turning and splashing around oil, and
all is well (lubricated). When the car is towed in neutral, ONLY the
output shaft is turning, the gears on the output shaft are not turning
(relative to the case, and the all inportant oil). Since the engine
is not running, the counter shaft gears are not splashing around the
oil and all is not well (lubricated). In fact the only lubrication is
what gear oil just happens to be on the bushings between the
stationary gears and the rotating output shaft. NO new oil is
splashed into the mechanisms.
What does all this mean? In reality, not much. You could probably
get away with towing you car without disconnecting the
drive(prop)shaft - plenty of people do, but why not spend a little
time to do it right and not worry about it?... As for me, when I move
across country (several times now), I put the Lotus on a 6.5 foot by
12 foot single axle flatbed utility trailer (very small car, weighs
about 1550 lbs).
Tim Mullen mullent@ymv5.ymp.gov Chantilly, VA
72 Elan Sprint "For the few who know the difference" - Lotus slogan
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