I installed a '77 or '79 model overdrive (type LH) on my
'80 MGB about six months ago and have a couple of
questions about it:
1. What type of oil are you supposed to put into the MGB
gearbox/overdrive? The original owner's manual for my car says to
put in the same type of oil as you put into the engine. Before installing
the overdrive I was using Castrol GTX 10w40 in the gearbox and
I used the same initially when I put in the overdrive. I have since
heard that you should use only nondetergent straight 30 weight
oil in an overdrive.
2. When I changed the oil in the gearbox/overdrive, I tried to
follow the instructions in the manual for cleaning the filter
on the relief valve. On removing this collection of springs
and other bits, I found that it looks quite different from
the illustrations in the manuals and the Moss catalog (p. 43 -
MGB-13).
What I have is roughly as follows:
The whole setup is surrounded by a cylindrical mesh
screen which seems to be intended to keep out the large
bolders.
Going from top to bottom:
A plunger with a hole down the middle and a flange at one end.
Inside of this there is a small ball bearing held in place by a small
spring.
A larger spring.
Some shims or thin washers.
A tube with another piece which fits inside of it. The inside piece
sticks up a bit and has a slot in the top. There is a fine mesh screen
which surrounds the bottom of this part and is, I assume, the part
that I was supposed to clean. ( I did.)
The plug which holds all of this in place and has a small o-ring
set into groove cut into its top surface.
The overdrive worked fine after I reassembled all of the above bits
and filled it with my usual 10w40, so I assume that I have all of the
pieces I am supposed to have. Can anyone tell me what this
device is supposed to do and how I will know if it is not working
properly?
Thanks,
Peter Schauss
Long Island, NY
1963 BJ7
1980 MGB
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