'66 PB Master Cylinder Rebuilt questions

[Guest]

All - helping a friend with his "new" 1966 coupe fresh out of 20 years storage. Rebuilt all brake calipers, cleaned and replaced lines and rubber hoses. Everything had been rebuilt with Stainless steel sleeves including master cylinder (original part # 5467084). System was pressure bled. rear brakes work fine, but once you apply pedal pressure front brakes stay locked up. Left brake lines connected to master cylinder and removed from vacuum canister. Made no difference as front brakes stayed locked up. If you open bleeder and release some pressure the wheels spin. Based on this we're thinking it is an issue with the master cylinder. The rebuild kit came only with rubber gaskets and we have taken apart two or three times to triple check all components are in the correct order and seal face the right direction.

1) My '66 PB cylinder does not have a stop screw in the front brake hole nor is there any machining there. This master cylinder does have the hole, special bolt, and what looks to factory stlye machining around the bolt hole. Why would one cylinder have this and the other not?

2) In my friend's Master cylinder he has something that I'll call a brass spacer shaped a little like a top hat. Goes in between two piston assemblys If this is not included in the assembly the piston is short of reaching the snap ring. Why would this be in his master cylinder and not mine? It does not appear in rebuilt kit diagram, but without it we don't believe the rear brakes would work.

3) Any recommendations for rebuild services in NJ area if possible? Was sleeved and everything looks great, but we can't figure out problem.

4) Any recommendations regarding possible solutions would be appreciated.

Thanks - sorry for the lenghtly message.

[Jeff S.]

Re: '66 PB Master Cylinder Rebuilt questions

Eric

I am having some trouble following your post. Perhaps you took apart your own '66 p/b m/cyl to reverse engineer & compare what you found on your friend's unit ...? Anyway -- regarding your points;

(1) There should indeed be a piston-stop machine screw in the forward chamber. It must be removed in order to remove the front piston during disassembly.

(2) Perhaps the "top hat spacer" you are describing is the valve. If so, it should fit with the concave shape tucked into the forward piston's spring. Thus taking up very little real estate; only the flange thickness would be in the stack length. It is not a spacer; perhaps you've installed it backwards? The short (front) piston train (valve/spring side first) is installed in the bore, then pushed forward with a wooden dowel of sorts & held against the spring pressure while you install the piston stop machine screw which limits aft travel. Next, the long rear piston train in installed, once again pushing forward against spring pressure until past the c-clip groove. Install the c-clip and release the pressure and the rear train should spring back to the clip.

(3) I don't know about NJ, but White Post (VA?) is where I'd go for a rebuild.

(4) Maybe you have the wrong kit. Wagoner #59078 should have rubber, valve and c-clip. LICS at one time had full kits with pistons, springs, rubber, etc.

Good luck,

Jeff

[Guest]

Re: '66 PB Master Cylinder Rebuilt questions

Thanks for the info. The non original to my car PB master cylinder does not have machined hole or stop screw. Is there a first design versus second design? Also this unit works fine. Should I be concerned that my unit doesn't have this feature and if so why?

On bullet two (top hat spacer/Valve - sound like we are talking about the same part. Why would it be part of my friend's PB cylinder and not mine? Also why no picture of it in exploded diagram of rebuilt (kit was from LICS - rubbr parts only)?

Bullet three - I'll give them a call for advice.

We're taking apart for the fourth time with another friend. We'll see what happens later this week. Any other advice is appreciated. Spend over 10 hours rebuilding brake system and this is really frustrating.

[Guest]

Re: '66 PB Master Cylinder Rebuilt questions

Problem looks to be dirt that was not removed during cleaning. Will reinstall and test maybe tonight.