After thinking about this some more today, I had to post to acknowledge what Jerry said as being correct. I was too caught up in thinking about what is happening inside the lines, and I should have been only thinking about what is happening at the caliper.

I am correct in that any given volume of fluid will have to travel a further distance in a smaller diameter line than a larger one. The flaw in my thinking, however, was then just assuming that would also translate into the piston having to move a further distance. It does not.

The piston doesn't care what happens inside the line. It only cares how much extra volume is delivered to it. It's movement is only dependent on how much extra volume is delivered to it, and in both 3/16 and 1/4 lines, the volume stays the same and is determined by the master cylinder. The velocity in the smaller line will be higher, but that doesn't matter either.

This does make me wonder why it seems to be a common recommendation to run 3/16" line to the front brakes, and 1/4" to the rear T, then 3/16" from the T to the drums. I've seen this recommended over and over again on different forums. What would be the purpose behind the 1/4" line to the rear T?

Last edited by RBs36; 06/19/2025 7:37 PM.
1936 Chevy Low Cab
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