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  View original topic: Dual master cylinder problems
Canlib Fri Nov 08, 2024 12:43 pm

I've changed the brakes on my 56 to Porsche discs using Lahner Kahn's excellent kit. He advises using a 19mm dual circuit master cylinder. I installed this one that I bought a couple of years ago and don't have the specs for.

It has 3 ports and I used the two closest to the firewall for the front and the other one which has an R in the casting beside it for the rear.
I started bleeding the brakes and the two front ones bled fine. I can't get any fluid to the rear. Several posts suggested the pushrod might need to be changed so I ordered a new style but it won't fit the pedal.

I'm bamboozled and in need of help.

vwhelmot Sat Nov 09, 2024 2:04 am

Have you had the Master apart? I would strip the cylinder and make sure its been assembled correctly if you don`t know where it came from. I had a similar issue once and it turned out that someone had put mine together incorrectly.

Canlib Sun Nov 10, 2024 10:58 am

I was hoping to avoid the brake fluid mess, but I think that's my next step.

OvalinAz Sun Nov 10, 2024 1:06 pm

the one on the right is correct for oval pedals, (more square shaped one) your pushrod looks short. that might be your issue. kinda looks like all thread rod. I have a dual setup in my oval, and just got my dads 55 dual set up working with no issues.

Canlib Mon Nov 11, 2024 2:21 pm

Problem solved. A trifecta of troubles. The master had water in it at some time and rusted the inner push rod so the secondary cylinder couldn't activate, one rear caliper was stuck so that line didn't bleed and the rubber hose on the other side appeared fine but had internal blockage. Day three of a two hour task.

rdwood Tue Nov 12, 2024 5:00 am

Thanks for posting what you found. That benefits as all to know the causes.



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