3000M master cylinder mystery

[plasticpig72]

I just removed the Brake Master Cylinder and found for me something strange.
Both Brake Pipes from Master Cylinder the same Dia BUT the Thread Dias of Fittings different. front one is 3/8" unf and back one 7/16" unf.
I can't understand why the Threads should be different Dias.
Maybe in the past someone stripped the rear Thread and Tapped it out to the next size up.
Alan

[TwinKam]

It's common practice on master cylinders... prevents incorrect connection.

[ATE399J]

Yup, Twinkam is quite correct, fittings are different sizes to ensure that front and rear circuits are correctly connected to the M.C.

[plasticpig72]

Many thanks,
i'm still a bit of a Virgin with TVRs
Alan