Front Disc Brakes, Brake Pedal Stop, etc.

[mynameismud]

My '56 is on a later pan / later pedal assembly and I have disc brakes in front / drums rear with a dual circuit master cylinder. I got brakes to bleed, brake pedal pressure and after multiple attempts all electrical to function properly so, I took it out for a short drive around the area. 1st run was good, brakes worked without issues. Several days later another short run with no issues. Last weekend again, a shortish run where maybe 1/2mile in (on neighborhood blocks) seemed I was losing power and then I realized my front discs were locking up. I limped it back home, let it cool and wondered WTF? I had zero brake pedal travel now? So, I started to dig into what the reasons "may be". I measured the brake pedal from firewall and it was sitting at 6". Even when losening the pedal stop to try and adjust I am unable to get anywhere close to the 7 7/8" I have read about. My questions are: 1) Since i have a later pan, would this measurement be different from a '56 firewall? 2) Can / should I replace the existing stop - or would it matter? 3) Is the MC pushrod a different length for a dual compared to single MC?.

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Even YOU can prevent FIRES!
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[Dan22]

I would check these things.
1. Is your master cylinder is made for disk brakes? No residual pressure valve for the pipes going to the disks. If you don't know, you may have to dismantle the M/C to see if there is one buried inside.

2. Your master cylinder piston is returning all the way back to the unloaded position.

3. Your pedal stop position should not change like that. Is there some debris down at the stop tab interfering? There should be no binding in the pedal when there is no push rod installed, and it should go full travel with the only the pressure of the axial return spring (seen in your pic).

4. Set the pushrod gap to the M/C piston at 1mm or 1/4" at the top of the pedal. This is a must so the bypass port is not covered when not applying brakes.
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1-0900722 die langsame grüne Schildkröte
https://www.thesamba.com/vw/forum/viewtopic.php?t=765074

[wimkever]

[mynameismud]

Thanks!
I'll check into the MC. I'm pretty sure it's for front disc's. I purchased complete beam mod, discs from Old Speed. As for the pedal stop, I completely removed, cleaned out any debris, reinstalled and still brake pedal won't fall more than what is shown. But, I will re-look at this as well.
_________________
Even YOU can prevent FIRES!
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[mynameismud]

[Rustforlife]

Hello, one other thing to consider is the condition of the rubber brake lines. I once had an experience where my pedal sort of locked up and the problem was traced to rubber lines that started to deteriorate internally. They looked perfect. If you don’t know how old they are, just replace them.
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1956 Ragtop

[mynameismud]

[KTPhil]

[mynameismud]