nuts and bolts

[KarstenH]

Hello,

i have a question to the dimensions from nuts and bolts in the parts book.
What ist the difference between the Dimension MA and MB?
Ducati 4 speed monza/diana
8MA x 10,5 part nr. 0400.92.330 engine mount plate
8MB x 12 part nr. 0440.83.010 screw in the extra thread in frame

What material are the screws: steel is clear, what quality, what surface refinement?

Regards Karsten.

[Rick]

External threads are MA, internal threads are MB, if I remember right.
Rick

[Jon Pegler]

MA is standard metric coarse thread, 8mm is x 1.25 pitch
MB is metric fine thread, 8mm is x 1mm pitch

[Rick]

I wasn't really sure- found this in a book, but it may be a later standard than used in the 1960s.
Rick

MA MB 1.jpg

[KarstenH]

Hello Rick, hello Jon,

after extensiv surching in my parts list i found some external threads with MA or MB dimension.
Thats why i agree with Jon - standard thread MA and fine thread MB.
Has anybody some ideas about the surface refinement.
I think zink plated, passivated or galvanised colorless

Karsten

[Ventodue]

MA is standard metric coarse thread, 8mm is x 1.25 pitch. MB is metric fine thread, 8mm is x 1mm pitch

+1.

Metric screw thread pitches.jpg

Has anybody some ideas about the surface refinement. I think zink plated, passivated or galvanised colorless

The original finish was Cadmium plating. Depending on where you live, Cadmium can be difficult/expensive to get done these days. But Zinc is just as good (maybe try to avoid 'Bright Zinc', aka 'BZP').

[DucMonzter]

Hi Karsten,

If you're referring to the original surface finish on the hardware, I believe they were cadmium plated.

- Jeff