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MG MGB Technical - Overedrive MGB GT 1980

Hi All
Just got a 1980 MGB GT I have noticed the overdrive jumps out occassionally (seems to be more frequent when hot ? or is this my imagination ?)Any suggestions as to the most likely Problem.
Thanks
Bill
Bill Jones

Hi Bill.

There is a common fault that can result in a wiring meltdown on cars with a gearlever mounted O/D switch.
The fault is the result of the wires in the gearlever chafing and shorting to ground.
I don't know if this is happening in your case, but I would certainly fit a fuse in the white/brown wire that goes from the bulkhead to the gearlever. (unless this has already been done).

Don
Don

After checking the wiring (all of the circuit, especially at chafe points and any connectors) ensure the oil in the gearbox is at the correct level. It takes a while for it to work back to the OD so if you have to fill, fill "just" slightly too much.
If it still gives you trouble, Try pulling the OD sump (use an oil-pan!) and clean the screen and magnet. Top-up as above.
If it STILL gives you trouble, it may be the solenoid. Invest in a Bentley service manual!

Mike!
mike!

My 77 BGT has a Mountney leather rim steering wheel and if my fingers happen to be touching any of the metal parts when overdrive is switched in or out, I get a tiny shock! Wiring to gearknob switch is good as it has only recently been repaired after breaking out of a connector. O/D functions perfectly, so are my fingers just providing a secondary route to earth for the switching current?

Laurie
L Webb

This thread was discussed on 21/06/2004

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