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Re: Filling Gearbox

Subject: Re: Filling Gearbox
From: Bob Howard <>
Date: Thu, 26 May 2005 10:41:46 -0400
   The MGB gearbox can have either a top-fill with dipstick  or a side
fill.  The 1979 car would have been built with the sidefill, but as
gearboxes are interchangeable, you could have the earlier type. 
   If it's a side-fill, the fill plug is accessible when the car is up on
a lift or blocks. Fill 'till oil dribbles out, then put car on the flat
pavement, let any excess dribble out, replace the plug and you're done.  
   If it's a top fill, peel back a little flap of carpet behind the
radio, remove the rubber plug, fumble a socket wrench into the dark hole,
remove the plug.  There are various ways to fill. Some are:  1) long,
clear plastic tube reaching from filler hole to bottle of oil held at
window-sill level; 2) drill-driven pump to pump from bottle of oil into
the gearbox, 3) syringes of oil squirted in.    1 works best for me, 
using about four feet of tubing and a screw-on adapter I found at
hardware store.  Top filling is a messy job for one person; I recommend
having a helper.  If you have a helper, you can have him pour into a
funnel into the tubing, and won't have to go searching for the adapter.  
  Check the specified quantity for oil in the handbook.  Fill using
slightly less than specified quantity, then check the level with the
dipstick.   You don't want to over-fill the top fill gearbox, as draining
off a little from the bottom is messy.  
  There has been considerable discussion of the correct oil for
gearboxes.  MG said to use engine oil, whatever is in the engine. We
infer from that that it doesn't matter much. Some experienced owners
prefer straight 30w, and some suggest that non-detergent oils are better
for gearboxes than detergents.  An increasing number of owners consider
synthetic oils to be the best thing these days, though it seems to be
almost universally agreed that synthetics should not be used in an
overdrive gearbox.  

On Thu, 26 May 2005 10:00:42 -0400 "Randy Widman"
<> writes:
> Hi Listers,
> I need to drain/re-fill the gearbox on my 79 MGB. I have no idea 
> if/when it  was ever done before. From what I can see in the book the
> hole is behind the radio console (What a great place to put it). Since
> looks like it is going to be a real headache just getting to it to
unscrew the 
> cap and look into it, can anyone give me ideas on HOW to get the
> fluid INTO the hole in that location?
> Thanks for any ideas.
> Randy Widman
> Red '79 B

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