On Sun, 16 Feb 1997 18:26:47 -0800 "Vince J. Pujalte" <pujalte@stic.net>
writes:
>Paul,
> I may be mistaken, but I believe that it IS necessary to disconnect
>and
>"tie up" the driveshaft in most manual transmissions when towing. This
>is
>because the tranny innards don't receive any splash lubrication
>when receiving input from the rear in Neutral.
> I would be happily disabused of this notion, should it prove
>incorrect.
When a car is towed in neutral with the driveshaft still connected, the
mainshaft will turn inside the gearbox. At least in MG gearboxes, first
gear will always turn at the same speed as the mainshaft and, if the oil
level is correct, its bottom teeth should always be in the oil, giving
some splash effect.
However, the mainshaft is also turning inside the second and third gears.
They are in constant mesh with the laygear which, in turn, is in constant
mesh with the input shaft. The input shaft cannot turn as it is held fast
by the clutch, attached to the back of a "dead" engine. So, the mainshaft
is spinning inside second and third gears, which are not getiing any
fresh lubricant fed to them.
Conclusion? Short trips with the driveshaft connected should not cause a
problem. If you're going any distance, you could damage the bearings
inside second and third gear if you don't disconnect the driveshaft.
Lawrie
British Sports Car Center
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