Convert from single to dual master cylinder

[rannugno]

Hi,

I plan to do some rebuild of the brakes in my 58 T-Bird. I plan to convert from single to dual master cylinder for safety reasons. I plan to keep all four drum brakes and also keep the original vacuum booster under the dash.
It's not easy to find a dual replacement cylinder for this car...
But after some searching I found this Doorman cylinder, originally meant for Fords newer than 67: http://www.dormanproducts.com/itemde...&SEName=m39495

Have anyone used this? Will it fit the car without too much modification?

Thanks in advance,
Gunnar

[DKheld]

Haven't used that particular one but you may be able to make it work. In theory - you should be able to pick a vehicle of that era with 4 wheel drum brakes and the master cyl would be compatible with the 4 wheel Tbird drum brakes. For instance - my friend has a 1970 Ford F-100 with 4 wheel drum brakes so that might be another cross reference option.

Mounting the master cyl and the master cyl rod lengths will be the biggest obstacle.

I tried to do the same thing with mine years ago. Mine has the external booster in the engine compartment but the 4 bolt pattern on the end of the booster in the engine compartment is the same bolt pattern on the firewall with your booster under the dash.

The problem I ran into is that every master cyl I looked at (like the one you show) had 2 bolt mounting tabs and the Tbird has a 4 bolt mount. Might be able to remove 2 of the old studs and install new larger ones to mount the new style master cyl. Not sure that will work when leaving the old booster under the dash but all I can think of at the moment. Also your old master cyl to booster rod may or may not be the correct style and length for the new master cyl.

When doing this you would most likely split the current common one line system into a separate front and rear system. That dual circuit system might now require a proportioning valve to balance correctly. I would say that if the master cyl you choose comes from a system that has a proportioning valve you will need to add one to the Tbird.

I believe the easiest route would be to install one of the newer dual action boosters and brackets under the hood with the dual drum master cyl already attached and matched to the booster. You would still have to split the brake system but not sure if you would need the proportioning valve.

Hopefully Dave will see this post and chime in with better info.

I finally had my booster modified to accept a 2 bolt style master cyl. Unfortunately this modification cannot be done with the under dash booster.






Eric

[simplyconnected]

Gunnar, Eric is right. Your original booster and firewall holes use four mounting bolts. Most modern master cylinders use two mounting bolts. The M/C you show is very typical of a modern M/C.

The bellows-type booster hardly helps at all. Ford quickly dropped it in 1959 and they never went back. Instead, Ford used a diaphragm type booster under the hood exactly like Eric's. By the way, Eric had his booster professionally modified to accept the two-hole M/C. That booster is the OEM original for drum brakes, not disk.

Squarebird original brakes were marginal at best. Drum brakes in front are a thing of the past because disk are so much better. I have converted both my Ford cars to disk brakes. It was the best move in the right direction. Now my car will put you through the windshield. Like a modern car, disk brakes won't pull to the side or fade.

Rather than doing this job many times, I suggest you convert to disk brakes and re-pipe your car. The work is very easy and the payoff is tremendous. At the same time, replace three rubber hoses (not five).

Because disk brakes do not retract, any car with disk (front) AND drum (rear) brakes needs a combination proportioning valve. Drum/drum or disk/disk do not need the valve. - Dave

[Tbird1044]

Gunnar:
I did the conversion a little over a year ago. I used a master cylinder from a 1969 mustang, V8, with power drum brakes. Master cylinder had a 1" bore. I redid the tubing to isolate the front and rear brakes. Some of the tubing fittings were a bit of a challenge to find, but they are all available. The brake light switch will need to be installed in the tubing lines with a tubing X 1/8" NPT tee. I also did install a proportioning valve. Not 100% if it is needed, as the wheel cylinders are different sizes to compensate for braking pressures. Either a proportioning valve or pressure differential valve should be installed so a warning light can be hooked up if one side of the hydraulic system fails. The M/cyl did bolt right up to the firewall with the 2 bolt pattern. Just make sure that you also install nuts and washers on the remaining 2 bolts to retain the bracket to the firewall.
I also installed self adjusters on all 4 wheels to help keep the brakes adjusted.
Nyles

[DKheld]

Great info and pics Nyles. It's been a while and I thought those bolts on the firewall were shorter and barely came through the flange on the master cyl. They are smaller than the 2 larger bolts on the later systems so probably why 4 were used previously but looks like yours is working fine - nice job.

Eric

[rannugno]

Thanks all for all tips My plan was to keep the engine bay as original as possible and my under dash vacuum bellow is still working. I've tried the brakes with and without the engine running and there is still good helping from the vacuum booster (and it's a bit fun to show people this a bit unusual vacuum booster).
The one in Nyles car looks very similar to the one I found from Doorman. And it looks nice.

Hmmm, have to think a bit more. This is going to be a part of this winter car project…
Thanks again for all answers!

[rannugno]

Hi folks,

I freshet up my engine bay last winter and planned to also to change to two circuit brake system. But the winter went to fast....
I finished the engine bay. but not the brake upgrade.
After one more summer with rather heavy brakes, I've also decided to do something to the vacuum system. The old vacuum system directly on the brake pedal under the dash may not work that good.....

I've found this Ford Fairlane & Torrino Power Brake Booster Conversion Kit on e-bay: http://www.ebay.com/itm/1966-71-Ford...item2eedf7b454

Do you guys think this will work in a Squarebird?
The cylinder has 1" bore instead of the original 1 1/8" bore is a thing that bother me a bit

[simplyconnected]

Gunnar, the short answer is 'NO'. If you plug-in your car and model the web site confirms that this is NOT for your Squarebird.

If you are looking for a power disk brake conversion these are the parts you need:
2-stage 8" Booster
A ONE-inch bore master cylinder (not 1-1/8").
***MOST IMOORTANT*** A firewall bracket that lifts the booster up five inches (away from the shift lever) and out five inches from the firewall (to give the center link room to swing).

The only kit I know of is from http://www.abspowerbrake.com KIT #9787
Make sure you also buy a disk/drum combination proportioning valve. I like the GM type because it comes with mounting holes. The finished job should look like this, with the valve bolted to your fender apron, to allow your hand under the M/C for spark plug removal:

Here's another:


At the wheels, I suggest you use Scarebird caliper brackets. They hold common S-10 calipers and the rotors for a Mustang. These rotors use your original bearings, seals and dust cap.

Many of our members have done this conversion and it works beautifully. If you need more detail or if you have more questions, please ask. Oh, and say 'Hi' to Irene for me. - Dave

[byersmtrco]

I would agree !!!

I don't see the advantage of a dual cyl (unless) you're converting to disc.
My 65 Tbird had the frt disc & the stock single M/Cyl. It had better brakes than my 60 with the conv kit.

58-60's REALLY need disc up frt in this day & age.
I need to get rid of my adjustable prop valve, repl rear shoes & whl/cyls. Hopefully that will improve my brakes overall. If I had the $$$$$$$$$ she'd have 4 wheel disc.

Gunnar, Eric is right. Your original booster and firewall holes use four mounting bolts. Most modern master cylinders use two mounting bolts. The M/C you show is very typical of a modern M/C.

The bellows-type booster hardly helps at all. Ford quickly dropped it in 1959 and they never went back. Instead, Ford used a diaphragm type booster under the hood exactly like Eric's. By the way, Eric had his booster professionally modified to accept the two-hole M/C. That booster is the OEM original for drum brakes, not disk.

Squarebird original brakes were marginal at best. Drum brakes in front are a thing of the past because disk are so much better. I have converted both my Ford cars to disk brakes. It was the best move in the right direction. Now my car will put you through the windshield. Like a modern car, disk brakes won't pull to the side or fade.

Rather than doing this job many times, I suggest you convert to disk brakes and re-pipe your car. The work is very easy and the payoff is tremendous. At the same time, replace three rubber hoses (not five).

Because disk brakes do not retract, any car with disk (front) AND drum (rear) brakes needs a combination proportioning valve. Drum/drum or disk/disk do not need the valve. - Dave

[jopizz]

I don't see the advantage of a dual cyl (unless) you're converting to disc.

The advantage is that if you break a line with a single master cylinder you have no brakes. With a dual master cylinder you will have either front or rear brakes.

John

[simplyconnected]

The advantage is that if you break a line with a single master cylinder you have no brakes. With a dual master cylinder you will have either front or rear brakes.

John

I'm with John...
I had a wheel cylinder cut loose. Good thing I had a dual system. - Dave

[simplyconnected]

...If I had the $$$$$$$$$ she'd have 4 wheel disc.

Why? Rear drums stop just as well as rear disks because rear brakes don't do much stopping, only about 25% before rear tires start dragging.

My wife's 2010 Escape has drum rears which shows how important rear disks are. - Dave

[scumdog]

The advantage is that if you break a line with a single master cylinder you have no brakes. With a dual master cylinder you will have either front or rear brakes.

John

Yep, that is THE main reason for a dual circuit brake system. Oddly, some earlier systems had a diagonal dual system, i.e each circuit did one rear brake and the diagonally opposite front brake.

[simplyconnected]

...Oddly, some earlier systems had a diagonal dual system, i.e each circuit did one rear brake and the diagonally opposite front brake.

That was the dumbest thing Ford came up with. A stop in snow or wet leaves would send the car in circles.

I was sitting and waiting for my sliders at White Castle's drive-thru window when all of a sudden my brake pedal eased down to the floor. Of course it was rain mixed with snow, dark and miserable outside, two miles from home.

After the tow truck left my 1998 Ford Escort up the driveway, I got out the cardboard and jack. Lo and behold, two brake lines graced the rear wheels as Scumdog described and BOTH had rusted through. Maybe that was a blessing since the car was stopped when it happened but that's my luck. (I once had a Pinto that burned out both headlights at once too, and I didn't believe it.)

Thankfully, both lines only took an hour to repair and bleed because all my tools and parts were in the garage. I hate working in the cold. I have a hard time doing this type of work wearing gloves. Sometimes it gets so cold my hands don't work and steel tools make it worse. No, I'm so cheap I refuse to pay someone else to do an inferior job when I'm perfectly capable, thank you very much.

(Electrical tape doesn't work in cold, either. At Ford, I used to keep a roll of black tape in my pocket just to keep it pliable and dry when a job came up in the tank farms outside.)

Now you know why us Snow Birds change our oil and maintain our cars in Spring and Fall, religiously. One Winter, my OEM thermostat BROKE half-in-two (as they say at Ford). The engine never warmed up and the idiot light was always on. <--my luck again only this time the wind screen was icy and me **** was frozen each 1/2 hr to work and back. I waited two weeks for a decent day to fix it. - Dave

[DKheld]

The later MG's ('72ish and on) had the cross circuit brakes. They used an external "shuttle valve" to make the dual circuit system.

First thing I do when I buy a new (but used) vehicle is go through the brakes.

My '96 Dodge snow beast. Knew I was going to have to do rotors pads, wheel cyls, etc but after finding about 8 splices in the hard lines I replaced everything.

Look at that first splice right at a bend.



Master cyl, booster, rear abs module etc.
Someone had airplaned one of the lines right next to the exhaust manifold. When I put the new lines in I ran it differently.



Brakes are tops on my list.
Eric