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As the saying seems to go. 1 thing leads to another.
Discussion about Master Cylinder change brings differences in what people say the gap between the Booster pin and the Master Cylinder piston should be.
I've seen .010, .060, 1/16"?
This should be interesting?
Let's hear it. What should it be?
Please include any links or evidence to support your answer.
You will get different opinions so let's look at some numbers and outcomes.
The human hair is around 4 thousandths thick. So, if you set the gap at 0.010 which is nothing. Guess what's going to happen?
I would bet that the booster rod expands three times that distance JUST from the heat of the engine bay.
You do not want a constant drag of pads on rotors. You do want a booster rod gap to allow the DOT3 to return back into the calipers, back into the brake-lines and back into the master.
What happens if the gap is set at a wide eighth of an inch? Plenty of room for expanding fluid and parts.
However, that much gap will result in a delay of brake pedal activation. Not much delay, but noticeable.
So, the happy medium is less than a 1/16 of an inch. You can always tweak your car to your liking if you feel there is too much pedal play.
But never allow a tight gap unless you enjoy replacing brake pads constantly.
Using the calculator linked above, I see less than 0.001" difference with a 30°F change (the rod isn't really subject to direct heat and it's insulated inside the master and booster).
CSSB has a video on setting the proper rod length. He says gap should be just a sheet of paper thickness (~0.005").
^^^^^ Nit-pick, Nit-pick, Nit-pick ^^^^^.
It was a figure of speech, to get a point across. Geez . .
And,
You didn't calculate the confines of a C3 engine bay that is near baking oven temps.
Just saying . . .
Last edited by HeadsU.P.; Mar 13, 2025 at 08:46 AM.
The master cylinder won't start to build pressure until the compensating port is blocked after the master cylinder piston travels approximately 1/16 of a inch. I set mile at zero and no problems.
^^^^^ Nit-pick, Nit-pick, Nit-pick ^^^^^.
It was a figure of speech, to get a point across. Geez . .
And,
You didn't calculate the confines of a C3 engine bay that is near baking oven temps.
Just saying . . .
What is is about not following the advice of the engineering department that built the damn things????
You mean like easy Heater Core removal?
Rear shock mount design?
Fuse Panel location?
Fan Shroud removal.
Or my personal favorite, heater hose vacuum operated shut-off valve?
Isn't that a piece of engineering!
What American car manufacturer in the 1960-1980's gave any quarter to repair and/or disassembly? And what has that got to do with design for proper function?
The master cylinder won't start to build pressure until the compensating port is blocked after the master cylinder piston travels approximately 1/16 of a inch. I set mile at zero and no problems.
Booster/Master Cylinder Pin Gap?
Nitpick is my middle name!
