Thanks for that, but I’m now more confused! The diagram seems to show both bores that feed the brakes are actually the same size and the bigger bore just pushes fluid up into the reservoir once the piston has moved past the right side feed.
I guess the bigger bore could push fluid past the rubber cup if the yellow thing is some sort of one-way valve?
FYI, for my 144 rally car, I use a 240 master and booster. I’ve changed the pipe work to feed the front cylinders only from the rear outlet of the M/C , and use a single line from the front outlet to the rear brakes through an adjustable pressure valve. My reason for this was that the surface area of the front caliper pistons was close to twice the surface area of the rear ones and the cross section of the 7/8” bore in the M/C is close to twice the cross section of the 5/8” bore, giving similar fluid volumes front and rear.
From the diagram, that now seems rubbish! But the braking system is well balanced.
The background to all this is to see if I can delete the booster without needing huge leg muscles. One issue is that the standard brake crossbar setup on my 144 has the LHS actuation lever (that pushes the booster and M/C) on the bar is twice as long as the RHS lever that the pedal moves. This effectively halves the input into the booster (which the 1974 brochure says is 3:1).
So if I can move the M/C to the RHS (if it fits) maybe I can delete the booster and only have a 50% increase in legwork. Maybe...
I'm currently a long way from home so I can’t measure, just think - and ask questions!
