Though I haven't done a conversion (yet), and assuming that I'm following
this thread correctly, basic principles of hydraulics say you should be OK
going from the 7/8 bore master cylinder to the 3/4.
I'll try to explain. Let's say you have a small diameter cylinder hooked
up to a large diameter cylinder, and let's say for convenience that the
small cylinder is 1" and the large cylinder is 2". You stroke the small
cylinder 1" by pressing on the brake pedal, exerting a force of 10 pounds.
The big cylinder will move 1/2", but will exert a force of 20 pounds.
Half the stroke, twice the force. Larger differences in diameter change
the ratio upwards.
The MGB calipers have bigger cylinders (also bigger pads) than the Midget
calipers, hence with the same (7/8") master cylinder, more clamping force
(and friction surface) on the brake disc, more stopping power for the same
pedal pressure, at the price of a longer stroke (which might be okay if it
gives you better "feel"). Going to the smaller (3/4") master cylinder,
should make this effect more pronounced.
Does any of this make sense, or did I jump a tooth on my mental timing
chain?
Chris Kotting
ckotting@iwaynet.net
|