Randy,
Unfortunately, you don't have quite the right explanation for the function of
that
vacuum switch. (This thread has either been bashed to death here or on the MG
Enthusiats BB, BTW.) The switch is only operative when changing in or out of
overdrive, and I'll be darned if I can remember which without my workshop
manual!
This is from memory, so I'll be happy to stand corrected, but I think it serves
to
inhibit engagement of the overdrive when there is a high manifold vacuum
present. For
example, when you are decelerating from fairly high rpms with your foot off the
throttle. (I'll go get the book and double check, later.) In any event, it
will not
serve to "automatically" drop you out of o'drive upon heavy acceleration.
In answer to one of Tom's original questions, I have been told that the switch
is
really not necessary. It's certainly not necessary for the unit to function
and I
don't know just how much protection it would provide anyway. If interested, I
can
copy the circuit diagram so you can see how it functions.
Bill Schooler
Randy Rees wrote:
>
> The vacuum switch is just so if your in OD and really put your foot into
> it (like to pass) it will automatically drop out of OD. Not really
> needed but nice. BTW it was also an option and not all OD equipped cars
> have it.
>
> >-----Original Message-----
> >From: Thomas_Mitchell@notes.amdahl.com
> >[SMTP:Thomas_Mitchell@notes.amdahl.com]
> >Sent: Wednesday, April 23, 1997 12:42 PM
> >To: mgs@autox.team.net
> >Subject: overdrive
> >
> >
> >
> >
> >
> >HI, I have a 1966 MGB-GT and I have overdrive type D and transmission
> >coming to my house and I am
> >researching what it will take to install them.
> >I cannot find the vacuum switch and have been told that they only used in
> >on the early overdrives and then got rid of it.
> >I have been told that I really don't need it, can I get another source on
> >if this is indead true? I hate to go through all
> >this expense and mess up my new overdrive. Can anyone help?
> >
> >Tom MItchell
> >1966 MGB-GT
> >
> >
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