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MG MGA - MGA overdrive

I have pretty much figured out my trans mount,getting ready to install the trans. My question,I have an early LH B O/D.Good when pulled,but been stored for a decade.I want to drain the oil and fill with #2 diesel oil and manually hand cycle to flush and clean then drain.Will this be a good idea,or not.What have others done to clean the insides of thier O/Ds.Also the MG manual says 30wt oil,my TR manual for O/D says 90wt oil. What gives?
wc wolcott

WC, I really don't think the diesel oil will hurt anything but, a better way might be to drain then refill with 20w50 motor oil and drive a while (100 miles or so)then drain while warm and refill. Use ONLY 20w50 motor oil. NOT 90w gear oil!
John
john

WC, I would never install a od unit that has been sitting around for a decade without having it bench tested first. Its way to much work to install just to find out that it doesn't work.. Ship it to John @ Quantum Mechanics and aviod tears at bed time...
mackay

Good points fells,yes I am going to build a test bed first.
wc wolcott

I have not worked on the LH type overdrive as fitted to the MGB, but I have done a lot of work on the A type and J type as fitted on Triumphs. The Triumph gearbox and both types of overdrive do use 90 weight EP gear oil, but if the MGB manual says use 30 weight engine oil then you should use that (or the commonly used modern equivalent 20/50 engine oil).
I would not try and clean it with diesel oil, but as stated earlier, just use the correct oil and change it after 100 miles or so.
Setting up a test rig could be quite complicated as you cannot do a proper test unless you can build up the correct internal oil pressure and measure it. The A type runs at 350 lbs/sq in and the J type at up to 590 lbs/sq in.
I would check the filters. The A type has a round filter plug and the J type has a rectangular filter cover plate. I am not sure about the MGB LH type, but it would be at the bottom of the unit as with the other types.

Mick
Mick Anderson

I have found two photos of an MGB LH overdrive and put them on a website:

http://www.angelfire.com/amiga/mga/index.html

In photo 2 you can see the filter screen in the bottom left corner, with the rectangular filter cover plate. This must be clean.
Do not damage the cover plate gasket, or have a spare gasket ready.

Mick
Mick Anderson

This thread was discussed between 31/03/2006 and 02/04/2006

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