Joined: Wed Aug 11 2010, 10:15AM
Location: E WA
Posts: 1230
Mike66Chryslers wrote ...
For disc brake conversion on one of my Chryslers I plumbed it exactly as Kevin (Twostick) describes. For my other one, which I just converted to a dual-res master but kept the drum brakes, no proportional valve needed but the plumbing is otherwise identical.
IMO, the conversion to dual reservoir MC is easy enough that there's little reason not to do it. The only tricky part was finding the right part numbers to adapt the standard brake line fittings to the oddball sizes in the MC ports. Weatherhead makes the required fittings.
When I did the single reservoir to dual reservoir swap on my 64 Imperial the local NAPA had the adapter fittings to connect to the new master cylinder. I believe that one is 1/2" to 3/16" and the other is 9/16" to 3/16" but don't quote me on those.
They were maybe $8 each at the NAPA.
I agree that the single to dual reservoir swap is one that everyone with a 1966 or older car should do. Easy, cheap and certainly gives me better peace of mind. I always cringe when I see the single reservoir cars.
Joined: Sat Aug 19 2006, 05:03PM
Location: Ontario, Canada
Posts: 2919
You are correct Flj, the adapters have 1/2" and 9/16" male threads. Found from one of my old forum posts, with some added specs I just looked-up:
Weatherhead part numbers: 131X4 1/4" inverted flare plug (for top of distribution block) 302X3 3/16" inverted flare union (plumb existing rear brake line to front port on MC) Master cylinder adapters (Weatherhead numbers): 7909: 5/16" (1/2-20) male, 3/16" (3/8-24) female 7910: 3/16” (9/16-20) male, 3/16" (3/8-24) female
The MC port adapters are also available under the following part numbers: FMSI #3230, 3231 AGS #BLF-20, BLF-27
I'm sure I used the same two MC adapters for both drum-drum and disc-drum applications. NAPA should stock them under the Weatherhead part numbers.
OK. So if I update my 1966 300 with power drum brakes to a 1967 dual master cylinder, which reservoir is for the front and which is for the rear? They both look to hold the same amount of fluid. Or does it matter?
Joined: Sat Aug 19 2006, 05:03PM
Location: Ontario, Canada
Posts: 2919
Front reservoir for rear brakes, rear reservoir for front brakes, even for all-drum-brake cars.
EDIT: I just checked the 1967 Polara/Monaco FSM at the following link and confirmed. Page 5-11 shows the MC and specifies front outlet for rear brakes and rear outlet for front brakes. http://www.mymopar.com/index.php?pid=109
Inside, the rear reservoir (front brakes) is slightly larger than the front reservoir (rear brakes), so both fluid levels go down at about the same rate over time, accounting for the front brake shoes wearing down faster than the rear ones. The exploded diagram on a later page also shows a spring between the rear piston and the front piston. I believe that causes the rear port (front brakes) to apply slightly sooner than the rear brakes, to prevent rear wheel lockup on sudden heavy braking.