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Manual vs Power disc brakes what to do...

64SF

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Am in the process of converting my 64 Sport Fury from drum to disc. It came from the factory with power brakes. I've read different thoughts on keeping the power or converting to manual. I'm about to order a the master cylinder and proportioning valve (some call it the pressure valve) and am seeking advice from those who have been here before me. As always comments, recommendations and opinions are most appreciated.

Also, from all that I've researched the master cylinders from the mid 70's A bodies are the best choices. Thanks
 
There are better brake guys on here than me. Having driven manual brake cars I'd say keep the power assist. That Sport Fury isn't too light of a vehicle.
 
I have a used OE master and brake booster for sale if you maybe interested. Its of a 1968 B-Body 440cu in. Was working fine when removed.

IMG_20170328_095247735.jpg IMG_20170328_095252087.jpg
 
It really comes down to pedal leverage. If the leverage is enough, you can stop a train without power assist.
I didn't see if the system was disc & drum but I'm guessing it is. There were many 3400 lb A body cars with manual master cylinder front disc setups and they stopped great.
I have a power setup in my 70 Charger but plan to do a manual swap to make the engine bay less cluttered. I'm hoping for identical braking ability with less weight and complexity.
 
I went with manual also, didn't want to be on the edge with vacuum due to cam choice. But I'm not on the road yet either.
 
It really comes down to pedal leverage. If the leverage is enough, you can stop a train without power assist.
I didn't see if the system was disc & drum but I'm guessing it is. There were many 3400 lb A body cars with manual master cylinder front disc setups and they stopped great.
I have a power setup in my 70 Charger but plan to do a manual swap to make the engine bay less cluttered. I'm hoping for identical braking ability with less weight and complexity.


Not to thread jack but what pedal and master you gonna go with? I'm wanting to keep manual on my car as well but use wilwoods. The wilwoods I've put on other cars so far 3x have either been power or hydroboost
 
Not to thread jack but what pedal and master you gonna go with? I'm wanting to keep manual on my car as well but use wilwoods. The wilwoods I've put on other cars so far 3x have either been power or hydroboost

Not jacking at all...any and all comments are helpful. I'm leaning towards manual. Now the master cylinder selection, specifically piston bore size, is the issue.
 
My old 74 Dodge D100 had manual disc/drum setup on it from the factory and it stopped fine even when pulling a 5x9 trailer full of roofing shingles. I could feel the difference in having to apply more pedal pressure but it did the job ok. The truck was a /6 with no options but it was still around 3600 lbs and why my 95 Dakota needs a booster is beyond me. I have a pickup manual disc MC that I could open up and see what bore it is but it can probably be looked up too. Keep in mind that a smaller bore MC will produce higher PSI for the same pedal pressure than a larger bore will.....
 
My old 74 Dodge D100 had manual disc/drum setup on it from the factory and it stopped fine even when pulling a 5x9 trailer full of roofing shingles. I could feel the difference in having to apply more pedal pressure but it did the job ok. The truck was a /6 with no options but it was still around 3600 lbs and why my 95 Dakota needs a booster is beyond me. I have a pickup manual disc MC that I could open up and see what bore it is but it can probably be looked up too. Keep in mind that a smaller bore MC will produce higher PSI for the same pedal pressure than a larger bore will.....

Thanks I'm reading the smaller diameter is what most are using - 15/16- I believe. The 73-76 Volares (spelling?) manual disc/drum seems to be the one.
 
My Charger currently has a power booster and master cylinder from a 75 Dart. The M/C is a iron 15/16" unit spec'd for disc drum even though I am running a 4 wheel disc setup.
The A body cars had a reduction in the pedal leverage for the power assisted cars. The brake pedal pushrod connected to a bellcrank setup between the firewall and the booster. I have not measured it to see what the actual leverage is. The way I know to measure is to compare two measurements. 1) The distance between the center of the brake pedal foot pad and the point at the top where it is mounted under the dash. 2) The distance between the hole for the pushrod and the point at the top where it mounts.
If the 1st number is 14" and the 2nd number is 2", the leverage is 7 to 1. The higher the leverage, the less effort required by your foot to stop the car. I took a spare pedal assembly and drilled another hole above the stock one, then welded a washer around it to reinforce it all.
To recap, currently my pedal leverage ratio is less than what a stock manual setup would be due to the reduction in the linkage. The manual/non power master cylinder I have to use is an aluminum 15/16" from Dr Diff. My hope is that with the improvement in pedal leverage, (But without any power assist) the same bore size master cylinder should provide similar brake force with similar effort as now. The gain is a simpler setup not dependant on engine vacuum AND less weight and clutter.
 
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