Auto Gearbox -Lost Drive

[spursman66]

Hi All, not new to minis but new to automatics. I have a 92 1275 Mayfair auto in blue. She only has 24k miles and after the fitting of a new rear subframe last week or so, she is pretty much fault free......so I thought.
Driving along today about 30mph when I suddenly lost any drive. Pulled over and tried every option, 1,2,3 and D as well as reverse. It seems to engage for half a second then disengage. Any suggestions, is it terminal. It has been suggested that I change the oil and filter. What oil and what filter. Other user on mini forum suggests motorcycle oil. Anyone with a suggestion. I am no expert but I like a tinker..

[Stu]

I wouldn't have thought an oil & filter change will sort it if you've suddenly lost drive all of a sudden. It's more likely to be one of the following -

Selector linkage disconnected in neutral or selector cable disconnected / ill adjusted (correctable with engine in).
Planetary gears sheared (terminal requiring new geartrain).
Oil pump drive sheared (requires replacement).
Valve block sticking (requires cleaning).

Regarding a possible damaged geartrain, on cars with transmission numbers prior to E14429, if the loss of drive is associated with a slight reaction when the selector lever is moved into the 3rd and 4th gear position the loss of drive can be due the shearing of the brazing on the planetary pinion, although I guess your car is later than this.

Have you checked the oil level is correct? If it's too low, or you have a leak this could easilly prevent drive as there won't be enough pressure to work the gearbox properly.

The sudden loss to me sound like mechanical failure, so would probaby require engine out / splitting from the gearbox to examine and re-building.

Having said that I'd try to do everything you can, including the following in order, and trying the car after every check / adjustment -

1. Change the oil and filter (Oil recommended on here is Japanese specification oil MA2, which is a motorcycle oil, however it must NOT be confused with MA or MA1 which are not the same and are useless for wet clutches which the MA2 excels. make sure to get 10W40 grade so the pistons and valves work as they should).

2. Check oil level in accordance with correct method.

2. Check / adjust the selector cable.

3. Do an oil pressure test to see whether you have adequate pressure.

4. Remove / clean and re-fit the valve block.

Hope you get sorted. Keep us posted