[Mgs] Determine build date for an O/D transmission?

Charley Robinson Charley38 at twc.com
Mon Nov 11 11:56:01 MST 2019

That might be handier than the stalk switch in my '69.  I'm not a fan of 
running wires down a gear lever & through the tunnel. Just don't like 
the potential for fraying the wires.


On 11/11/2019 11:32 AM, Max Heim wrote:
> Exactly. I have a 1977 vintage blue label OD transmission in my 66. I 
> have a dash-mounted switch to the left of the steering column. The 
> wiring couldn’t be simpler. No weird expensive parts. The straight (as 
> opposed to crookneck) dash OD switch is cheap.
> You might not think the dash switch is as convenient as the gear lever 
> switch, but it is really pretty ergonomic. You can flick it with the 
> side of your hand while it is still in contact with the wheel — you 
> don't have to go groping for it.
> --
> Max Heim
> '66 MGB
>> On Nov 11, 2019, at 8:08 AM, Charley Robinson via Mgs 
>> <mgs at autox.team.net <mailto:mgs at autox.team.net>> wrote:
>> I've swapped OD gearboxes into two CBBs.  In both cases I used the 
>> gear levers from the original non-OD transmissions.  I don't see any 
>> reason that you can't use the gear lever you already have for the OD 
>> box.
>> As to the OD switch, I'd put it on the dash if I had an open spot for 
>> it that was handy to my right hand.  In the CB cars the wiring and 
>> switch are already installed but there's no reason you can't find the 
>> white circuit that Paul mentioned and run a wire from it to your 
>> switch and from the switch to the lockout switch on the OD box.  
>> Looks like there are a couple of switches in the Moss catalog that 
>> would look OK on the dash.  The switch is just a SPST that can handle 
>> the solenoid current.
>> My $ .02,
>> CR
>> On 11/11/2019 7:35 AM, Andrew Lundgren via Mgs wrote:
>>> I have a '78. The transmission is a blue label, but the seller 
>>> doesn't have the shift lever.
>>> A lever for a '78 is not a cheap thing, and my son who is driving it 
>>> a lot right now likes the Walnut MG logo shifter it has.  So I'm 
>>> looking at options for how to install the O/D switch.
>>> From the moss catalog, it looks like the '76 switch won't work with 
>>> the '78. So I might have to buy the parts to put together the 
>>> shifter switch or put it in the blank accessory switch above the fan 
>>> on the dash.
>>> On Mon, Nov 11, 2019, 1:45 AM PaulHunt73 <paulhunt73 at virginmedia.com 
>>> <mailto:paulhunt73 at virginmedia.com>> wrote:
>>>     None of that is to do with the OD itself.
>>>     Which gears it operated on is a function of the linkages on top
>>>     of the gearbox, and you can have it on 3 and 4 or 4 only as you
>>>     wish. When the TCSA was introduced in late 76 to control
>>>     'surging' a third switch was added to the top of the gearbox
>>>     that operated in 2nd and 4th, and this was wired in series with
>>>     the OD switch operating in 3rd and 4th to produce a 4th gear
>>>     only output controlling the TCSA and vacuum advance.  I suspect
>>>     that was not very reliable as it was an external micro-switch so
>>>     it was deleted and the gearbox components changed so the switch
>>>     operated in 4th only, as done to the V8 several years
>>>     previously.  The gearbox switch now controlled both OD and TCSA.
>>>     The gear lever itself changed for the 77 model year to
>>>     incorporate the OD manual switch, but that can also be fitted to
>>>     any year, or the 77 converted back to some other switch, as you
>>>     wish.
>>>     The wiring prior to 77 was from the manual switch on the dash or
>>>     the column, to the gearbox switch on a yellow and a yellow red,
>>>     then from there to the solenoid.  For 77 on it was from the
>>>     ignition supply on a white to the gearbox switch, then from
>>>     there to the manual switch on the gear lever, and from there to
>>>     the solenoid.
>>>     Black label or blue label determines which speedo is compatible
>>>     - black label was used on CB cars and used a 1280tpm speedo. 
>>>     Blue label was used on RB cars and used a 1000tpm speedo.  But
>>>     speedos can be recalibrated if you end up with the wrong
>>>     combination.
>>>     So as a 78 it should have a blue label OD and the manual switch
>>>     on the gear lever, as the column switch - which together with
>>>     the plastic dash was new for the 77 model year - won't have that
>>>     function.  But if the car has the earlier RB dash and column
>>>     switches you don't need the gear lever switch, which is prone to
>>>     shorting out and causing harness damage.
>>>     PaulH.
>>>         ----- Original Message -----
>>>         Not so much. It will be a a bit still until the transmission
>>>         arrives. (Freight from NY to UT) I'm just trying to figure
>>>         out which shifter it should have had as well as which gears
>>>         it should work on.
>>>         I'm going to be putting it into a 78, but the current owner
>>>         is still trying to track down the shifter from his friend,
>>>         the previous owner. He doesn't know if it was a late shifter
>>>         or an early one.
>>>         I'm trying to determine how to wire it in.
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