goosabell

I am looking for swapping out my current 2015 Fit EX MC with something larger. Any suggestions for a Honda or Acura compatible part?

claymore

Why???

Ryanthegreat1

Less pedal travel? Firmer pedal? Bigger calipers? Many reasons to go to a bigger master.

I typically like a master that is larger than what Honda put in from the factory.

Sr. Kaku

Subscribing since the info and upgrade look pretty nice....

claymore

The only thing it would help is with larger calipers.

Sr. Kaku

Not 100% sure but if it works similarly, it WOULD work... for example... i had a 91 CRX and the first brake upgrade i made was installing a 89 prelude MC and steel braided lines... and it made a WHOLE LOT of a difference.... again... it was my experience.... so theoretically it should work, since a larger piston is pushing.... I mean... why not try....

MasterKwan

It'll change the pedal feel on standard brakes too. Larger piston in the MC should require more foot pressure for the same braking pressure. I imagine you'd get less pedal movement too. I'm going all wheel disks and larger calipers on my Fit. I imagine I might have to change the MC to accommodate it.

claymore

Well duh you can't compress any liquid no matter how much MORE force you try to apply. And all your "feeling evidence" is worthless.

"Larger piston in the MC should require more foot pressure for the same braking pressure."

A larger piston would require LESS foot pressure.

MasterKwan

Assuming that the brakes remain the same, the lines remain the same, the fluid remains the same, changing the MC will change the feel. The amount of foot pressure and distance needed for the same PSI in the brake lines will change. The reasons brakes pedals have travel isn't because the fluid compresses but because of pad knockback (pulling away from the caliper), the bending of the brake pedal, flex of the firewall and other slop built into the mechanical bits of the brakes.

You have this backwards. PSI is pounds per square inch, by increasing the diameter of the MC piston you increase the flow of fluid for distance traveled by increasing the SI. The additional surface area means more push back (pedal effort) at the same line PSI.

It's just not theoretical, I've changed to a larger diameter MC for a clutch in a manual swap and pedal effort was quite a bit higher.

MasterKwan

You made me do math....

Civic MC is 13/16 with a surface area of .051 sq/in
MDX MC is 7/8 with a surface area of .060 sq/in

F = P * A, I picked 2000 PSI just as a reference number.

F of a Civic is 1030 lbs.
F of a MDX = 1200 lbs.

Assuming the rest of the system remains the same.

Keep in mind that the brake pedal and booster gives a bunch of leverage so, 100 lbs on the pedal might be 1000lbs on the MC.

claymore

Change the feel means nothing it's all supposition. No such thing as "pushback" in a hydraulic system. A larger master cylinder piston DECREASES the the force need because it is moving more fluid in the same time frame.

MasterKwan

That's a very Trumpian statement.... Despite the math you continue to claim something that isn't true.

What do you think it is that keeps the brake pedal off the floor when you press on it? The 100 lbs of pressure your foot is pushing on the brake pedal is being resisted by the pressure of the brake fluid. The harder you press, the more pressure you generate, the more the piston in the MC is pushing back on your foot.

I guess we can agree that a larger piston moves move fluid for the same travel.. It's not timeframe but the travel of the piston that moves the fluid. So, for 1/4" of travel, the larger piston will move more fluid than the smaller.

claymore

I give up you have no clue what you are talking about.

Sr. Kaku

have you ever seen a brake booster.....? whats inside of them and the pedal assembly?....

Ryanthegreat1

For the same braking force, pedal pressure, line pressure, stopping power, however you want to define it.
Smaller master = longer softer pedal
Bigger master = shorter firmer pedal