Without trying to research the details I am not familiar with, I can
say...
There are at least 2 versions of the 4-synchro OD tranny, with a
changeover in 1977, I believe. They use different speedo calibrations.
The later one has OD in 4th gear only. It used the same driveshaft as the
3-syncro tranny in my 66, but that may mean it's a different one for you.
The rear axle type (tube or banjo) also comes into play here, I think.
>From what I looked up previously, you do have a choice of drive gears,
but neither one may be correct, depending on the total combo of
gearbox/speedo. My rig is over 6% off, but the best I could do with a
gear swap is 4% the other way. They're pretty expensive, too.
Still, it's worthwhile, IMHO.
Let's see, Moss shows the following driveshafts:
Banjo axle (not relevant to you) - 30" standard, 31.125" OD
Tube rear axle - 31.125" standard, 32" OD, to #138400
31.125" all, from #138401 on
So, the driveshaft should be OK.
The shifter switch means it is from a 1977 or later.
There are a 20-tooth and a 21-tooth pinion available (for different
prices!). The gear is an internal part which you might not want to mess
with.
You could try Skye's speedo chart page to see where that falls in:
The MGB Experience <http://www.mgb.bc.ca/>
You could get the OD wiring sub-harness or you could just run your own
wires and be a DPO in the making, like I did. With the shifter switch I
think you might want the real thing, to avoid fitment issues.
Good luck.
Andrew Lundgren had this to say:
>I'm working out the details of getting an O/D tranny for my car and
>have a few more questions.
>
>I have a '70 B, non-OD
>
>This tranny is off of the later (non-crash box) car, it has the OD
>switch on the knob.
>
>Do I need a new speedometer or just the gear on the side of the
>tranny?
>Do I need a shorter drive shaft?
>
>Anything else I am missing here?
>
>Thanks!
>
>
--
Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the red one with the silver bootlid.
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