Hi Chris, interested in my Midget overdrive conversion ?
I'm posting this to the list (I think) 'cos there has been quite a lot of=
intertest.
I had been planning to get round to this conversion for a long time as th=
e
1500 Midget (mine has the 3.7 diff) is undergeared and feels rough and
noisy above 65mph
I saw an advert in the MGOC magazine for a gearbox / overdrive unit which=
I
got at a real bargain price of =A360 (not sure how that compares to your
prices, but it was really good for UK prices)
Better still I found that the unit had been fully reconditioned.
That is all that I actually bought in for the job, other than oils and I
also took the opportunity whilst the thing was stripped down to get the
crank reground and fitted new bearings.
I had to remove the bellhousing from the new gearbox - I don't know what =
it
was made for, but it didn't match the Midget engine plate, so I just
swapped the bell housing off my old g/box. Same reason had to swap the
g/box input shafts over. Used the same clutch which was in good condition=
=2E
Cut out the chassis cross member welded a replacement 2" X 3"X 21" chassi=
s
cross member in line with the cut out section but beneath the floor pan
Spread the gearbox tunnel by about 1.5" using a sissor jack.
Fitted new engine/gearbox/overdrive unit in place (it is a good deal
bulkier and awkward than the standard, but it does fit. No modification t=
o
prop shaft needed.
Hardest part was to design and fabricate a rear gearbox mounting as the
space is very limited and it needs to consist of two rubber supports at 9=
0
degrees to resist torque twist on the engine unit. Eventually got it to f=
it
by trial and error. Took a fair bit of welding (MIG), trying, cutting dow=
n
with the grinder and re-welding until I got the dimensions right.
The gearbox mounting then fits to a sort of "H" shaped sub-frame that bol=
ts
up through the floor in line with the seat runner reinforcing channels
Only thing not yet sorted is the odometer drive. I need one with a femal=
e
screw fitting at the gearbox end, but don't know where to get one. Does
anyone know what the MGB cables are like at the O/D gearbox end? Would th=
ey
fit ?
Guy
78 Midget 1500 + Overdrive
70 Sprite 1275
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