School me on MC bore size (and in the process help me solve my brake problem.)

Seb, the area math is good, but the dual master cylinder stuff is wrong the dual cylinders are in tandem, the pressure is equal in both circuits to the single.

Mart.

 

Well finally had a chance to tinker and the new master from NAPA appears bad. Pumped it on my bench at least 100 times and no fluid coming out.

Just my luck.....

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rebuilt no doubt? have had same problems before . lots of good chinese rebuilds

 

Nope. Brand new. The new one was only $4 more than the rebuilt so I thought I would be safe.

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Are you bleeding it correctly? Just wanted to rule that out first. Most masters I've bled took less than 10 pumps to bleed them.

Either that or I'm astounded at the amount of bad rebuilt masters that are on the market.

Bob

 

Well, first I hooked up my bleed lines and bent them to return back into the reservoir. Pumped about 25 times and didn't get any fluid. Pulled the lines off and pumped another 25 or so times and not even a drip out of the ports. During the entire process only saw 2-3 air bubbles come up. Bugger!

 

You need a 10lb psi RPV if its a dual in front line and back line. Didnt reas whole thread, scratch this if you already do.

 

I have my own method of bleeding masters. I place the master in my bemch vise, fill it up with brake fluid. I hold a thumb and forefinger over the ports, push the piston in with a screw driver, let it spring back and repeat until no bubbles come up in the reservoir.

Top it off, put the top back on and install it and go on from there. Been unfailable in 40 years of doing it. I've probably seen 2-3 bad rebuilt masters out of the box, but maybe the quality ain't what it used to be.

Bob