conversion-single master cylinder to dual

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honcho

honcho

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My buddy says I need a porportioning valve for the conversion so the rears don't lock up. I was just gonna run everything thru the distribution block. What's the preferred method??? Thanks in advance Todd:finga:
 
If you are installing disc brakes up front, then yes, you need a proportioning valve. If you have drums at all four corners, you do not need a proportioning valve.
 
+1 for dan . . . I just did this over the weekend. Got a '66 cuda with 4 wheel manual drums, went with the 1.03 bore alum duel res MC from mancini's. I took out the old distribution block and then used a coupler to run the rear line right to the MC. For the front brakes I had an extra T coupler (the one used for the rear axle to split the brake lines to both rear tires). So rear brakes right to the MC and T for front brakes. Also note, with using the Mancini's master cylinder, its designed for Disk brakes and you have to use a 10psi residual pressure valve for each line out of the MC. I'll post some photos tomorrow to show how I did this, but its simply brake line from the MC, do the 90* bend down and install the pressure valves inline while the brake lines are on their way down infront of the firewall.
The 10psi valves are an extra 20 bucks each but for drums you need 'em. They keep 10psi of pressure in the lines so that the drum brake springs don't return the shoes too far. I've been told you can run without these but then there's much more peddle travel and it's actually possible for the wheel cylinders to leak fluid because they retract too far. (or something like that haha)

But no prop valve needed if its 4 wheel drums, only if disk/drums.
 
Residual pressure valves aren't needed -- they were dropped from factory drum brake master cylinders (and the drum brake half of disc/drum master cylinders) after the 1972 model year; in 1973 wheel cylinders all got redesigned seals that do the same job as the RP valve (keep air out of the system -- that's all the RP valve was ever for, not to keep the drums from retracting too far).
 
HMMM, I redid a f body disc conversion on my car, that was done by Prev Owner, as I could get no pedal. New metal and rubber lines, master, calipers, wheel clys, adj prop valve, drums, pads, shoes, everything....Bled:banghead: for weeks ( w/ 2 other Mopar Bros) Used the bottle method, so no air can come back up. I know it takes a bit when you change all the lines , but I have went through 6 quarts of fluid. The brakes are good.. But, the first pump is to the floor.....Not to hijack, but am I missing the residual valves? Car was 4 wheel drum, Now I am using early 70's type E body MC, for power brakes. Do I need a different Master? For non power discs? I have read e boogers stuff, but...
Any help is appreciated!
Thanks in advance,
Chuck (Iron-head)
 
Make sure the calipers are positioned correctly and not upside down. Is the bleeder screw on the top or bottom of the caliper? The bleeder should be at the top.
Make sure the M/C and proportioning valve has been bled. Normally you will have to wait a day and let everything settle and bleed again. Another way that I have done before is fill the M/C, crack the 4 bleeder valve,s and let gravity do the job. You do have to keep an eye on the fluid level periodically.
 
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