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MG Midget and Sprite Technical - Changing gearbox oil on 1979 Midget

I have a 1979 UK midget and want to change the gear box oil. Where/how do you put the new oil in?
I have a Bentley's Manual which shows a sketch of the filler plug on the driver's side of the car but I can't see where that is in relation to the engine/vehicle. Someone mentioned that there is a plug inside the car, under the carpet near the gear shifter/selector but I couldn't find anything!
Do you have to raise the car to access the filler plug or am I looking in the wrong spot?
Pictures would help.
S Travis

Also, I am trying to change the diff oil but can't get the filler plug out. I have a 1/2 inch socket driver but it doesn't go in to the plug far enough to get any purchase to undo. Also tried multigrips but they don't grip tight enough. I checked with the 3 local auto parts outlets and none have such a tool/adapter.
Where can I get a tool or adapter to remove this plug? Does it have a name?

I think I found the filler plug for the gearbox oil but can't see how to access it without lifting the car. Might be able to just reach it from the engine bay, although the carbs restrict access, but would be very difficult to fill from there.
S Travis

Hi Travis,
These tools come up on Ebay..
should work..
T Dafforn

I raise mine up off the ground, put it on jack stands, then pump the lube into the gearbox.

Very simple & cheap pump from the auto parts store:

Dave Rhine ('78 1500)

G'day, Steve.

Right, the filler port for the 1500 tranny is located about halfway up the RH side of the box. I've filled mine from underneath and through the engine bay, and I'm not sure if either method is better than the other. Either way, you can't remove the filler plug from above. As I recall, it's just too far to reach. So it's probably better to elevate the car on ramps and jackstands and go at it from beneath.

The oil pump bottle that Dave mentioned is spot-on, as well as the type printed on the bottle - 85/90 gear lube. It would probably be best to drain the box first via the plug on the bottom, and do a full replacement.

As for the diff, yeah, that one can be a challenge. I can fit a square socket drive in there and break it loose that way, but if yours hasn't been out for a couple of decades it may put up more of a fight. I think somebody on here said that they fabricated a tool by bending a stout rod and grinding the end to a tapered square.

Best of luck, and keep us posted.

Gryf Ketcherside

I usually just use a 3/8" breaker bar or ratchet. It doesn't fit well. but the corners will grab well enough to work. The tool acutally does exist to remove these plugs, but I'm not sure of the exact size. One came with a David Brown tractor when I used to work on a farm. Probably some weird Whitworth thing or something like that. Found the Case IH part number online- it's K39426. If you have a Case dealer down under, he may be able to track it down for you. HTH
Tim Michnay

Hey Steve,
I just did a 79 I purchased as a parts car but it was to solid not to restore. I put it on jack stands and removed the bottom plug. Then I removed the shifter collar and boot from above and with my buddy underneath I handed him a two foot long tube attached to a fill/siphon gun I purchased at carquest. Same on the rear-end, I stood by the rear wheel and handed my buddy the tube and then pumped away...
GF Greg Smith

This thread was discussed between 19/06/2010 and 22/06/2010

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