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MG MGB Technical - OD Trans. Oil Change

I recently had the transmission in my 1970 BGT replaced with an overdrive transmission. I am not certain of the year of the OD. Where is the drain and filler located. When I reach through the opening on the top of the transmission case I cannot feel the filler stick.
What weight oil is recommended.
Lee

Lee. You probably have a later model "side filler" transmission. Look for a hex headed plug on the right side of the transmission. If you have one, that is the fill hole. Drain plug is the hex headed plug on the bottom of the tranny. In theory, all of the oil will drain out of both the transmission and the overdrive unit through the bottom hole.

The overdrive has a filter gasket at the right, rear, a rectangular plate. This, when I last changed the oil in my OD tranny, was removed for replacement. Very minimal amount of oil was released when the plate and gasket were removed.

Suspect normal draining and refilling will work fine for most tranny oil changes.

What to use in the tranny is subject to some debate amoung the experts. Chris Betson, who has spoken with the people currently producing this overdrive unit, has written that anything from ATF to 90 weight gear oil will physically function the overdrive unit. As I remember it (would have to check my e-mail) Chris recommended I use 30 weight motor oil as my regular tranny fluid. Just spoke to a fellow who had been on the phone with Quantum Mechanics, a noted use rebuilder of overdrive transmissions. Paul informed me that he had been told to avoid the ATF and 90 weight with the recommended fluid being 30 weight, non-detergent oil.

The factory says you can use any oil in the tranny you can use in the engine and give a complete list of what oils are acceptable. However, the two sources I trust the most, based on personal experience and recommendations by people I trust, seem to feel the SAE 30 motor oil is to be preferred.

Les
Les Bengtson

Les,

Once again I am impressed with your knowledge. Thanks for your help. Looks like I will have some oily fingers next weekend.

Lee
Lee

Here is a useful link:

http://www.quantumechanics.com/categories.php?op=newindex&catid=11

Specifically the 4/05 and 6/05 articles.
Steve Simmons

FWIW, make sure you can remove the filler plug (ie that it is not 'welded' in place) before you remove the bottom plug to drain the gear box.
Regards
Roger
Roger T

This thread was discussed between 06/03/2006 and 07/03/2006

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