Barney: Wow! Thanks. That is a great deal of very useful info that I will surely
use. I guess the first thing is to determine which gearbox I have in my car.
Will
the year of VIN number help is identifying how "late" or "early" the MGA is and
thus help me to identify just which box I have? You indicate a body modification
to accomodate a later tranny with the "high" starter. Are the later MGA bodies
slightly different to accept this box or would I have to modify the body as well
as the gearbox?
Thanks for the great information. I am certain there are others on the list who
can use this data.
Frank "Swamp Yankee" Krajewski
Barney Gaylord wrote:
> Frank,
>
> At 03:54 PM 10/19/2000 -0400, you wrote:
> >.... I have been saving a pristine MGA tranny, still crated, as a spare
> for my 1958 1500 MGA and now think the tranny is for a 1600 MGA. Can anyone
> inform me as to the difference between the 2 trannies, ....
>
> There were actually four physically different gearboxes fitted to MGAs, not
> even counting close ratio variations. They can be converted from one
> flavor to another by changing (as required) rear housing and mainshaft (and
> matching propshaft), front housing (and matching engine rear plate), input
> shaft (and matching clutch disk adn spigot bushing).
>
> Early 1500 (one or two years): Low starter position (about equal to
> crankshaft height), 1-inch 10 spline input shaft, 1-inch 10-spline output
> shaft for sliding spline coupling, externally mounted rear seal.
>
> Mid 1500: Same as above except, 1-1/16-inch 10-spline output shaft for
> sliding spline coupling, and internally mounted rear seal. Everything
> ahead of the rear main bearing is identical. Stuff in the tail housing
> (including the main shaft) interchanges as a set. This one requires a
> different propshaft, slightly different length and different splined coupling.
>
> Very late 1500, all 1600, and part of 1600-MK-II production: High starter
> position (about 1-1/2" higher), which is interchangeable if you use the
> matching engine rear plate, but also requires a bump in the bulkhead and
> tunnel to clear the bendix end of the starter motor. These also have a
> ball bearing in the tail end, internal tail seal, and a 4-bolt flanged
> output coupling. This requires use of a 2-piece prop shaft with a sliding
> splined joint just behind the front universal joint. Front housings and
> all internals ahead of the rear main bearing are interchangeable, so you
> could change the front housing to the low starter position to get it into
> the 1500 without tunnel modification (but you still need the 2-piece
> propshaft).
>
> Very late MK-II only: Same as 1600 gearbox except, change to 23-spline
> input shaft with larger spigot diameter, and the addition of some ribbing
> in the case to accomodate a little more torque, and it has a rubber front
> seal that other models didn't. The front seal can be fitted to the earlier
> units by changing the front cover.
>
> So the mainshafts and rear housings are in three flavors, interchangeable
> as sets (along with matching propshafts. Input shafts are in two flavors,
> interchangeable and identical except for the splines and spigot on the last
> units. All internal parts inside the front case are always identical
> except for input and output shafts, except for close ratio gears which are
> interchangeable as sets.
>
> So now maybe you want to keep your spare gearbox and just figure out how to
> adapt it to your car when you need it. Worst case senario is that you
> disassemble and reassemble two gearboxes to swap mainshafts and the two
> aluminum housing pieces. In other words, reassemble the identical 1600
> innards into your 1500 housing. In the end you don't have a complete spare
> gearbox, but you have all of the pertinent spare parts to repair anything
> inside.
>
> BTW, I have there spare gearboxes here, all rebuilt and ready to run, and I
> would like to sell (or trade) two of them. One is early 1500 type fitted
> with the late style font cover and rubber seal. One is mid 1500 type also
> fitted with the late style font cover and rubber seal. And one is
> assembled as 1600 type in a later style MK-II ribbed housing, but still
> with the 10-spline input shaft.
>
> Just a thought,
>
> Barney Gaylord
> 1958 MGA with an attitude (an too many spare parts)
> http://www.ntsource.com/~barneymg
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