Power to manual conversion

[tasker]

Hi guys!  I am new to this forum and I have an experience that I'd like to share with you because I think some of you may be in the same boat (I know we're in the same car!)  I recently purchased a '69 RT that originally came from the factory with power drums and one of the previous owners converted the front to discs using the conversion kit from SSBC.  I didn't find them particularly more effective than the manual drums that I had on a previous '69 that I had owned, but I wasn't sure if it was the kit itself or that I was just so used to the modern sliding calipers on my much lighter Honda's.  Also, to make matters more complicated the engine has an overlapping cam that maxs out at 9 inches of vacuum.  So to solve the boost problem the previous owner installed an SSBC electric vacuum pump.  One day while pulling out of the garage I went to stop only to find that I had no boost and I think we all know what the pedal feels like on power brakes with no vacuum!  So I decided at that moment that I was not going to compromise my safety by relying on an electric pump.  I called Master Power Brakes and ordered a power to manual brake conversion kit which included a manual master cylinder with a 1" bore, combo valve, pushrod, and an assorted fittings/adapters package.  My plan was to first mount the manual mc on the booster so that: 1) I would not lose the appearance of a power brake car; 2) maybe get SOME boost from that 9" of vacuum; 3) save me from having to buy the manual mounting plate; and last, but not least, make the install quicker for my lazy butt.  I figured that this way even if I don't have vacuum or lose it that I will still have an easy pedal.  For those not familiar with MP Brakes set up, the combo valve is mounted underneath the mc on a slotted L bracket held by one of the mounting bolts.  The OEM proportioning valve is just replaced with a "T" fitting for the front and just a union for the back.  What I didn't realize was that on the power brakes that there is the so-called bell crank between the pedal and the booster!  Well at this point in the install I had to at least SEE what it felt like.  I had checked the vacuum on the line from the intake manifold to the booster prior to the conversion and it was at 9 inches, but I had failed to measure it on the line coming out of the booster which, as it turns out, was "0"!  You see as fate would have it the grommet for the check valve was torn inside and was causing the leak which probably would have saved me the entire conversion!  Oh well, full speed ahead!  With all the new gear mounted, lines cut and reflared, and the entire system flushed and bled, it was time for the moment of truth.  On the test drive around the neighborhood they worked okay, but almost like I had to "anticipate" my stops.  Not exactly confidence inspiring!  So I did what I'm sure a lot of you would do....I took it on a 240 mile trip!  At speed I decided that maybe the brakes would "feel" better if I burnished the pads to the rotors a little.  So 3 to 4 stops from 50 mph, then I laid off and just cruised to let them cool off a little.  Can you guess what happened at the next stop?  They grabbed (not locked up) like modern single piston sliding calipers and are now DEFINITELY confidence inspiring!!!  So to sum it up: if you have an engine with a radical cam that gives you less than adequate vacuum for power brakes, DO NOT go the route of the electric pump!  Your life is depending on that thing running.  The manual master cylinder is THE WAY TO GO because it will work even if your pump doesn't AND if you have a vacuum leak in the system.  PLUS, mounting through the booster gives you power assist brakes like a modern day car.  I hope somebody can use my experience to their benefit also, especially after reading ALL of this!  

[Just 6T9 CHGR]

Welcome to the site & it was good to hear that all worked out for you!

[charge69]

 That was a hard read with no paragraph markers but, you got your point across and  welcome to the board.  My car came originally with manual drum brakes and I will leave it that way even if it is not very good braking by today's standards.

Good info for the power brakes and also useful with an aftermarket cam.  Welcome again!

[tan top]

hello & welcome  thanks for the info !! intresting read thanks for sharing ,  would like to se some pictures of your charger sometime 

[tasker]

Thanks for the welcome guys!  Sorry for the long read, but when I tried to edit myself the story ended up losing a point.    The second reason I did the conversion (other than safety) was that I had friends telling me to "change to a milder cam", "get another $3-400 electric pump", "bring it to a professional" and I love a challenge!   As for the pics, here's a few taken by the previous owner when I bought the car.

[tasker]

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[tasker]

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[tasker]

Interior.  Is this even the correct thread to be posting these?