Brake master cyl question

Stevehose

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I can’t get a grip on which master cylinder I have on my car. It appears to be original but who knows. The replacement I bought a long time ago appears to be the wrong one (smaller nose diameter-not sure on internal diameter) and is also missing the little lock bolt hole that my current one has (in the second pic next to the circlip).

So a ‘72 3.0 is supposed to have the larger or smaller diameter cylinder? Part numbers:

34311103271 is 23.81mm
34311120832 is 23.81mm
34311120479 is 22.20mm

I think I remember reading that the 2800cs had the larger diameter cyl because it used the thinner booster?

If I am reading this correctly mine measures 23.72 so clearly the larger one (I measured the diameter of one of the internal metal pieces).

I’d like to rebuild this but don’t want to buy the wrong kit or if that doesn’t work another wrong complete master.

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From our FAQ:

  • Brake booster changes from pancake style to thicker style at 2240222 and 2250146, Master Cylinder diameter changes from 23.8mm to 22.2mm
 
From our FAQ:

  • Brake booster changes from pancake style to thicker style at 2240222 and 2250146, Master Cylinder diameter changes from 23.8mm to 22.2mm
Right, so I have a 2800cs master on a 3.0cs booster? Any issue keeping this combo? Was working great before I sent the booster for rebuild. Plus I’d like to keep the 1.5mm for extra pushin!
 
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