Only the earlier D-type overdrive needs the vacuum switch and relay, which
is maybe where the comment 'most cars didn't have them' came from. It was
to prevent the overdrive disengaging under conditions of high manifold
vacuum - like the overrun - and was probably something to do with the high
torque reversals that can occur. The LH was either of a different design or
just stronger, and didn't need them. So it all depends if you have a D-type
or an LH-type. If you have the earlier one I would either fit the
additional parts or be careful when disengaging.
PaulH.
----- Original Message -----
From: <Mgbbob@aol.com>
To: <mgs@autox.team.net>
Sent: Thursday, November 09, 2000 11:12 PM
Subject: Early overdrive questions
> Hi there Listers,
> I've been away from the list for a while and it's a real pleasure to get
back
> in.
>
> I have a few questions that I'd like the list to comment on.
>
> I just acquired an overdrive for my 1966 B (GNH3L78708) with a GB series
> engine.
>
> 1. Bentley's wiring schematic (diagram 2) shows items 68, 71, 72, 73
and
> 74 as part of what seems like a separate harness. It's shown in
> phantom so I assume that this is not available unless the
> overdrive is ordered. Is this true?
> Will I have to make my own harness?
>
> 2. I've been told that the OD relay unit (68), the gear switch (73),
and
> the throttle switch (74) are all included in the main harness. Is
this
> true? Are they available?
>
> 3. Are there any other problems I'm likely to encounter in this
> conversion?
>
> Thanks in advance for your comments listers..........I really need to
resolve
> these issues.
>
> Bob Stahlbush
>
> 66 MGB RD GHN3L 78708
> 60 TR-3A TS 81398 L
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