Sean Bartnik wrote:
>
> Hey all,
> A question on the MG overdrive unit. It appears that it is electrical,
> so I'm wondering how they do it.
>
> Is the OD unit separate from the actual transmission? How is it
> actuated? Do you flip a switch or is a switch activated when the
> shifter lever is moved to a certain position?
The OD unit is in line with the gearbox and prop-shaft, it replaces the long
gearbox extension on non-OD cars.
There is a driver-operated switch on dash, column or gear-lever depending
or year, plus a gear-box 'lock out' switch to prevent the operation of
overdrive in any gear except third or fourth. Use in first or second would
apply too much torque, and use in reverse wrecks the internals. Some cars
also had a vacuum swich and relay that over-rides the drivers switch (but
not the gearbox switch) on the over-run i.e. high manifold depression.
The switches control an electric solenoid which controls an oil valve, other
than that it works much like a two-speed automatic.
PaulH.
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