At 06:58 PM 4/14/02 -0700, Dave Hammond wrote:
> 1. I'm starting the complete restoration of my 62 MGA MKII and would
> like to find an overdrive unit to mate to the transmission. ....
Quite a laundry list of troubles here, and I don't personally recommend any
of this, but I do have some information. To begin with, the MGA was never
built with an overdrive option, so it is not designed to accept one as a
bolt-in conversion. Almost anything you do to try to fit an overdrive into
an MGA will require some cutting and welding, and usually some modification
of the center tunnel and frame, floorboards, maybe even the seats and the
handbrake location.
An overdrive gearbox uses a shorter mainshaft, after which the overdrive
unit generally bolts up to the back of the main housing in place of the
original tail housing. Overdrive mainshafts for the MGA gearbox may well
be non-existent, as the car was never built that way. This problem even
applies to the MGB which did have a couple of different overdrives
available, but the mainshafts for those overdrive gearboxes are currently
not available as spare parts, so you generally have to buy a complete
overdrive gearbox just to get the mainshaft.
So this problem gets down to how much cutting and welding and other
modification you are willing to do to fit a non-standard overdrive gearbox
into the MGA. The biggest problem with the overdrive units is that they
are rather wide aft of the main housing, which generally requires widening
the tunnel to make them fit. The early MGB 3-syncro unit is a bit smaller
(narrower) than the later 4-syncro unit, and would be easier to squeeze in
with less radical modification of the tunnel. But the earlier MGB unit is
also more rare, and either one requires some cutting and welding to
fabricate a new rear mount for the gearbox.
The MGB overdrive gearboxes are currently in high demand and (relatively)
short supply, so you might expect to pay something like $400 to $700 USD
for one used, and it may require some more money to repair or prep it for
use, or a reconditioned one may cost as much as a 5-speed conversion set
(including the gearbox).
Now if you don't mind some non-MG parts in your car, and you have about
$1400 burning a hole in your pocket, you can buy a 5-speed gearbox setup
that is (for the most part) a bolt in conversion for the MGA. You can
start here:
http://www.classicconversions.co.uk
and there are other suppliers and other 5-speed units that can be made to
fit, generally easier than the any overdrive unit.
Or if you want to get a little more whacky you can do a different 5-speed
gearbox and slip in a 160hp fuel injected V6 engine along with it. I still
don't personally recommend this, but for kicks you can check here:
http://www.classicconversionseng.com
These kits are designed to fit the MGB, but a little more money can go a
long way towards a little more adaptation to fit the MGA.
Barney Gaylord
1958 MGA with an attitude
http://www.ntsource.com/~barneymg
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