robert williford wrote:
>
> my recently purchased '73B has a transplanted overdrive unit from an '80
> model, if what the PO told me is correct. the car was not originally
> equipped with overdrive, but i welcome the addition (that piece of mind
> thing...). i have yet to get the d*%n thing to work. as the car had been
> sitting for a few years prior to my purchase, i have been more concerned
> with just getting it running (i drove it to work for the first time today
> and was quite thrilled). but now my concerns have shifted to the od.
>
> 1) i know that i have to replace the wiper/od switch, as the wipers run
> constantly despite switch position (i currently just pull the fuse).
> but the car has a shifter knob from a 77-80 car with the od switch
> on the knob. the PO told me that he always had to use the column switch
> in conjunction with the knob switch in order to get the unit to
> engage. is it feasible to connect the wires from the shifter knob,
> thereby providing this with constant power, and just rely on the
> column switch, or will this cause problems? any ideas...?
>
> 2) what steps would be best to take (other than the obvious change of
> fluid--20w50, i think) in addition to the electrical work to get
> the unit running? as i am rather unfamiliar with these od's, i'm
> not sure if they suffer any grievous harm from storage, or require
> maintenance above and beyond simple fluid changes.
>
> thanks to all who responded to my earlier posting concerning suspension/
> steering parts and hydraulic hoses. once again, any help or advice
> would be greatly appreciated.
>
> robert williford
> 73 mgb--various shades of green...at the moment, function is more impt.
> than form :-) but aesthetic concerns loom (hopefully) in the
> near future...
Robert-
I am not quite sure why the previous owner has two switches in the
system - this seems idiotic to me. The overdrive is designed to operate
in third and fourth gears. A lockout/enable switch fitted to the tranny
(same part number as the reverse light switch BTW) is closed when 3rd or
4th gear are selected. A second switch should be located in the cockpit
for activating the unit. In your car, this switch was built into the
wiper switch. The knob mounted switch on your tranny is orginal for
cars 1977 through 1980. It is more conveinent in location. Basically
the wiring should go from +12VDC, to the cocpit switch, to the 3/4
enable switch, to the solenoid. Since the solenoid is grounded in the
tranny, it is essentially a one wire circuit, with two switches in
series. Your car has three switches in series - it will work, but why?
If you want to use the original switch, the knob mounted switch can be
removed from the circuit. If you want to use the knob mounted switch,
you can eliminate the wiper switch, and wire the knob switch directly.
As for O.D. problems, if your unit does not work, chances are good that
it may be either a clogged filter screen, or a defective solenoid. THe
solenoid is not cheap. With the car in 3/4 gears, with the ignition
"on" but engine not running, if you energize the solenoid, you should be
able to hear a faint click. Return of the solenid is assisted by oil
pressure in the O.D., and with the car not moving, it may take a couple
of minutes for the solenoid to return after removing power, so don't
expect to hear multiple clicks if you turn the unit on and off
repeatedly. On the plus side, both the solenoid and the screen are
easily accessed from under the car. As a matter of course I would
recommend changing the filter screen if the car has sat for a long
period.
Feel free to e-mail me direct if you need more info. I have just been
through this conversion, and most of it is still fresh in my ming.
Regards,
Chris
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