Back at the begining of December I fitted an overdive gearbox in my Midget
and was so chuffed with the result I posted the following on the MG list.
Thought I would copy it here in case anyone is interested,
AND
because I still have not sorted the speedo cable problem - can anyone help
?
I had been planning to get round to this conversion for a long time as the
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 £60 (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.
Cut out the chassis cross member welded a replacement 2" X 3"X 21" chassis
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 to
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 90
degrees to resist torque twist on the engine unit. Eventually got it to fit
by trial and error. Took a fair bit of welding (MIG), trying, cutting down
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 bolts
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 female
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 they
fit ?
Guy
78 Midget 1500 + Overdrive
70 Sprite 1275
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