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70 Road Runner going from drum to manual disc brakes #2084846
06/02/16 09:35 PM
06/02/16 09:35 PM
Joined: Jan 2004
Posts: 204
Panama City, FL
R
rickinpc Offline OP
enthusiast
rickinpc  Offline OP
enthusiast
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Joined: Jan 2004
Posts: 204
Panama City, FL
Can anyone provide a workable combination of master cylinder and proportioning valves to make this work? Send a link to rtoalson@me.com or call 850-866-0909. Any help would be appreciated.


Rick
Re: 70 Road Runner going from drum to manual disc brakes [Re: rickinpc] #2084881
06/02/16 10:32 PM
06/02/16 10:32 PM
Joined: Dec 2014
Posts: 4,223
ohio
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ruderunner Offline
master
ruderunner  Offline
master
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Joined: Dec 2014
Posts: 4,223
ohio
I did my 69 decades ago. I used the large bore Mopar performance master and a Willwood adjustable valve


Angry white guy
Re: 70 Road Runner going from drum to manual disc brakes [Re: rickinpc] #2084896
06/02/16 10:59 PM
06/02/16 10:59 PM
Joined: Jun 2005
Posts: 6,257
gulfport, ms, west mi
rowin4 Offline
master
rowin4  Offline
master

Joined: Jun 2005
Posts: 6,257
gulfport, ms, west mi
I did the conversion on my barracuda years ago and used a 1978 dodge pickup manual disc brake master cylinder. I also used a Willwood proportioning valve


it's ok to butt heads, just don't do it with a butthead
Re: 70 Road Runner going from drum to manual disc brakes [Re: rowin4] #2084908
06/02/16 11:19 PM
06/02/16 11:19 PM
Joined: Jan 2007
Posts: 7,664
IN
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ahy Offline
master
ahy  Offline
master
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Joined: Jan 2007
Posts: 7,664
IN
Disks need more line pressure vs drums. A smaller diameter master helps. I understand a 15/16" master is about as small as you can go and still maintain adequate fluid volume. Dr Diff offers a 15/16" AL master with adapter. I run one on a PB setup.

As far as the prop valve, an adjustable valve on the rear line is best with a disc/drum setup. Wilwood or similar.

Will you like front discs on a "B" without power assist? Not so sure! It depends in part on the calipers and friction material. Stock calipers can have generous piston area and are probably best for this swap. Some aftermarket calipers have smaller piston area and really need the booster. Low cost organic pads also have more cold bite. Hi- po/high temp pads not so much and you may like the booster.

Re: 70 Road Runner going from drum to manual disc brakes [Re: rickinpc] #2085051
06/03/16 06:54 AM
06/03/16 06:54 AM
Joined: Jun 2008
Posts: 9,982
Oakdale CT
gdonovan Offline
master
gdonovan  Offline
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Joined: Jun 2008
Posts: 9,982
Oakdale CT
I converted my GTX over to the big 11.75" rotors, big piston slider calipers last year. It also has 11" drums out back.

Left the prop valve alone, even under hard breaking it stops even with no lockup of any particular end. The car can stop fast enough now that it will uncover the oil pickup and flash the Autometer warning light with 20 psi sender which never happened with the drums.

I need to fool about with the master, I think I had a 7/8 unit which was too soft and now I have a 1 1/8 unit which is a touch on the hard side. Have not had a chance to tinker with it further and it does work pretty good. Pads are a Wagner semi-metallic police application.




"I think its got a hemi"






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