Alternator pulley nut M14, what??

[motomiata]

Had to change my alternator pulley nut and bought the original Porsche item. Which is M16x1 mm and fits all 911’s from ‘65 to ‘89.

However my alternator has a M14 mm thread This does not make sense unless the alternator is non standard 911? Looks fully original apart from the nut and runs fine.

Any clues to which alternator has settled in my engine….?

[Flat6pac]

If the center shaft is fine thread, the nut is 22 mm across the flats. If fine threads are damaged they recut the shaft to SAE size
If the center shaft has 8 mm hexcnter and coarse threads it’s the larger 24mm nut. Includes
Internal voltage regulator.
Bruce

[Dpmulvan]

Originally Posted by motomiata

Had to change my alternator pulley nut and bought the original Porsche item. Which is M16x1 mm and fits all 911’s from ‘65 to ‘89.

However my alternator has a M14 mm thread This does not make sense unless the alternator is non standard 911? Looks fully original apart from the nut and runs fine.

Any clues to which alternator has settled in my engine….?

14/ 1.5 Could be a Bosch, there’s several different thread sizes 16:1 17:1.5 et.

[theiceman]

yeah the one on my 78 Marchal was near impossible to find ... but now i have a spare, i remember it was a very odd thread..