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Gents,
Does anyone know the thread pitch of a PBR clutch & brake master cylinder reservoir ?

I'm guessing this reservoir to master cylinder seal is NLA?

Reckon I got one in a kit recently. Also the rod grommet seal thing. Anyway it is just an o ring Phil. Don't know the thread size sorry. There was an earlier ABS one which was different but the PBR are later type. There appears to have been a change in size when they changed between the original tin types. One was a tall skinny tin and the other shorter and wider.

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Tall skinny tin was EH , short fatter tins for our girls.

Sorry I don't know the thread pitch, but I can confirm that there are 2 different threads for both types of master cylinders (factory, PBR & other aftermarket types).

The early tin type (FE to early HD) had a rounded thread form which was smaller in diameter to the later cylinders. ABS & other companies did produce a plastic version of this smaller thread type. You occasionally see these at swap meets.

The later (plastic) reservoirs had a larger diameter, squarer ACME type thread as in your 1st photo.

Holden introduced the plastic reservoirs in June 1965 when disc brakes first became available in mid-HD. They needed a larger volume to cater for the piston travel of the front calipers.

To replace the rubber seal (pictured) I use a standard BS O-ring, BS215 for the smaller reservoir & BS217 for the larger one.

Dr Terry

Double post !!

As always great info Dr Terry

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