Drivers handbook specifically says not to dip the clutch or feather the
throttle when switching in or out. Some recommend it, but the OD is
stronger than that. The only thing you should not do is manually disengage
OD at high rpms, where the resulting increase in engine speed would take it
into the red sector of the tach.
Early cars (before late 67) had a different model of OD which would *not*
disengage under conditions of high manifold vacuum, i.e. on the overrun.
This was because they were weaker than the later models.
North American cars from late 76 had OD on 4th only as the gearbox switch
was used for something else as well (vacuum advance) which was only powered
in 4th.
You will destroy the OD if you attempt to reverse with OD engaged, which can
only happen if the gearbox switch is bypassed (only an idiot would do this,
but I've heard of some who have) or is faulty (I've never heard of one
failing closed, only open i.e. engagement can be iffy but never engaged when
it shouldn't be). However to eliminate both possibilities drive along at a
constant speed in 4th manually switching OD in and out and see the revs
change as you do so, then do the same thing in 1st and 2nd gears, where
there should be no change in revs. DON'T try this in reverse until you are
*sure* OD isn't engaged in 1st or 2nd!
I got so fed up with OD automatically clonking in when changing up from 2nd
to 3rd because I had forgotten to switch it out when changing down that I
devised a lock-out circuit that prevents it engaging again until you have
turned the manual switch off and back on again.
PaulH.
----- Original Message -----
> When I switch into overdrive, it shifts nicely and I get a suitable drop
> in
> RPM. When I switch out of overdrive, it does not always downshift so
> smoothly (I seem to remember this on Mom's, as well). Is it better to - or
> is it at least okay to - depress the clutch pedal when switching out of
> overdrive?
>
> Also, does switching out of overdrive work no matter what the transmission
> is doing? In other words if I notice the overdrive switch is on when it
> shouldn't be (in neutral, in 1st, etc.), can I just switch it out with no
> concern?
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