Disk Brake Conversion Discussion

[Guest]

Howard; I got the booster M/C and bracket from MBM thru Carolina Trucks. The bracket was suppose to fit a Ford. It didn't have enough rise to clear the back-up light switch and the steering column since my car has a straight stick and the shift linkage hit. I ended up using my old booster bracket and modifying it to fit the MBM booster. The original pedal link was retained since it was my original bracket. I had to cut a hole and bend the sides to clear the snout on the MBM booster. I also had to enlarge the bracket holes to fit the MBM studs. They were about the same size but not quite. The original bracket piviot linkage was retained to hook up to the booster rod.
I had the slug you're talking about in the master cyl. so that was not a problem. The master cyl. supplied only had ports on one side so I had to plumb the stop light switch in a tee. The combination valve I used was designed to mount on the side of the Master cyl. but it stuck out too far and hit the fender well so I mounted it under the master cyl. instead. That worked better anyway. I got a ford combination valve from Ray but could not get it to mount the way I wanted.
I am going to have to remove the booster and put a jam nut on the push rod that goes into the booster. I thought it would be OK but it has to have a jam nut on the rod to keep the booster rod from turning by itself which causes the brake pedal to lose all the free play and makes the brakes drag and the brake light stay on also. When the engine is running the vacuum lets the rod spin real easy if no jam nut is there to stop it. I had to cut the booster rod to fit and put the clevis on without the jam nut. My mistake.
The reason I asked you about your piviot linkage a few days ago was to get an idea of the mechanical advantage gained or lost by the lever setup thus making the stroke of the booster too long. My original stock piviot had the brake pedal rod which curves inside the piviot so it attaches in the center of the piviot so the stroke of the pedal is the same as the stroke of the booster rod. If the pedal rod is closer to the bottom of the piviot the stroke of the booster rod stroke will be longer than the pedal stroke. I don't know how much of a problem that might create if any.

If you have any questions just ask. I will help if I can.
I hope this helps some,
Gary

Here are some pictures of the booster mounted to the original bracket and of the original ford bracket. These were a rough-in of the setup. I also spaced the booster from the bracket a little more as can be seen in the pictures.

[Howard Prout]

Gary: I'm surpriised you didn't have to raise the booster more than you did. I raised mine 5 inches above the center of the brake pushrod in order to get enough height to clear the valve cover.

Things have changed at lot since I answered your prevous post. The leverage ratio on the pivot arms was far too high. I ended up using a 'hockey stick" pushrod to get a pushrod leverage ratio of 1.875. Yours looks close to that. I also found that I had to stiffen the pivot arms to reduce the amount of sideways bending in them. The attached drawings show where I am at the moment.

[Guest]

Howard; Looking good. The original pedal rod on mine looked like the hockey stick shape you describe. The original ford booster bracket had a 4" rise to it and is 4" deep to the firewall. It would be interesting to see if a stock ford underhood bracket would clear on an A/C equipped car.
My car had a power booster under the hood and not under the dash. I figured all straight stick birds had an under the hood booster but there is a pedal setup on eBay with a stick setup with the Kelsey Hayes booster still there on the side of the brake pedal. My bird was produced in Dec 59 so I am not sure when Ford started using the underhood booster and with what transmission setup. I know they used the under dash setup for the automatic transmissions much later in the production because back in the late 70's I had a 60 automatic coupe with a K/H booster. I don't know if all A/C equipped cars had the K/H booster or not or when they changed over to the underhood setup.

I got my brake booster rod fixed today so now my brake pedal has the free play it needs. It is weird that the lack of a jamnut would let the rod rotate in the clevis and cause the free play to disappear but it did. I also cut another quarter inch off of the rod where the clevis screws on. It was almost hitting the firewall. Now it's about 1/2" away and looks very close to what the old booster clevis did. Oh well it's fixed now.

I would think that Old Irish Dave should have the master cyl. slugs to make your master cyl. fit the booster he sent you. If that is where you got them from.

It sounds like you are making progress and will have a setup that will work on A/C equipped birds soon.

Continued success, Gary

[Howard Prout]

Attached are pix of the current version of my booster bracket. The center of the booster is 5 inches about the brake pushrod and the face of the booster is 5 inches from the firewall. The sides haven't changed except they are narrower at the bottom so as not to contact the steering column. In the second pix you can see the hockey stick brake arm pushrod now connects to the pivot arms just above the midpoint. This gives a leverage ratio on the pivot arms close to 1.875, the same as the arms received from OID. The third pix shows the pivot arms with the hockey stick brake pushrod attached as well as a stub where the booster pushrod attaches. The unused hole in the pivot arms is where the brake pushrod would have connected without a hockey stick. The new connecting point is 1 1/2" higher on the pivot arms. There are a couple of things that still have to done to this assemble. First, I will weld a brace along the back (booster side) of the pivot arms to make them more rigid as well as weld a cross tee near the top of the pivot arms to keep the pivot arms centered in the bracket. The other thing I will do is weld a brace between the brackets sides below the firewall faceplate to keep the bracket from twisting.

[Howard Prout]

My project is finally done. I tried two used Ford style proportioning valves and neither of them worked properly so I ended up buying a new GM style proportioning valve. It works fine. The brakes aren't as crisp as I would like them but they are feel much better than the old drum brakes. You may notice that the booster is upside down. I did this on purpose as I still have the K-H unit in place and functioining. I put a tee in the vacuum line from the manifold to connect to the new booster with the continuation going to the check valve for the K-H booster and vacuum reservoir.

[ncbird]

congrats

Nice job Howard!!!!! It looks like it belongs there and the plumbing on the lines looks like a production job. You should be very proud of your self and your perseverance. Grant

[Guest]

Looks good Howard. Glad you got it done. Have you tried to run the new booster with the vacuum hooked up directly with out going to the K/H or resevoir tank? I wonder if that might make a difference in the feel of the new setup. I did not hook up my resevoir to the new booster and the brakes feel fine. Just a thought.
Gary

[simplyconnected]

Howard's power disk brakes w/dual M/C.

I am particularly proud of Howard. He jumped through difficult hoops, persevered, and came up with a beautiful working system using quality components.

Howard MADE parts he couldn’t buy, and he drove round trip from St. Catherines, Ontario, to Detroit, just to prove fitment and find facts. He spared no expense and took his time. He is a pioneer, offering valuable info and advice to Squarebirders who plan on converting their 430 cu. In. Thunderbird with A/C, to power disk brakes.

As shown in Howard’s setup pictures, he has a chromed 8” two-stage booster with a chromed dual master cylinder and a GM-type brass combination valve. Howard couldn’t find one for sale, so he designed and made his firewall bracket and had it chromed. At the front wheels, Howard uses Scarebird brackets with S-10 calipers and Mustang rotors. His lines are all-new rustproof 3/16” tubing with inverted flare brass nuts.

All Howard’s efforts are a great time and money-saving asset to anyone attempting this work. Thanks from all of us, Howard. - Dave

[YellowRose]

Disk Brake Conversion Discussion

I echo the words of Dave regarding Howard! He is a terrific mechanic and designer! He kept working on that dual mc and dual booster system until he figured out how to get that bracket he designed from scratch to work right, and the rest of the mounting hardware. While he was perfecting it for himself, he was also doing it for me. He made me a set as he went a long. Unfortunately, the idiot who ran my beloved Rose up the tailpipe of a F250 has caused a delay in me getting my disc brake and dual mc/booster project done. I wanted to get that completed before Rose was painted. But that will have to wait as the paint job is about to commence shortly. Great work, Howard!

[tbird430]

All I'm saying is this thread has to be setting a thread length RECORD here on Squarebird's.org

[Guest]

PAGE 24! I Agree............

[simplyconnected]

Look at the number of hits! That's what happens when:
* Squarebird owners from all over the world plan on retrofitting Power Disk Brakes
* Members and visitors are searching the WWW on this topic,
* People want to hear first-hand accounts of the trials and tribulations, so they can avoid costly mistakes.
* They also want to know what is the best system to use.

Remember, WE scoured the web for these answers, too. We found expensive kits, kits that didn't work, and a lot of hot air from vendors that said one thing, and changed their story later on. Folks are very interested in this topic. Inexpensive power disk brakes are a challenge. Many of the current kit sellers are checking our site, because there is very little competition. Our success may cause them to reduce their selling prices by a hundred bucks or more.

So what you see in the numbers, represents many reasons for inquiry. - Dave

[YellowRose]

Disk Brake Conversion Discussion

Here is some information that I came by from corresponding with Gary ~ 1946hamm about the KH under dash booster system. I thought it would be good to add this for other members, and Gary agreed to let me post it.

"Hi Ray; I meant that I did not hook up the reserve tank in the fender well. Since the dual booster has a kind of built in reserve with dual chambers I didn't think I needed the tank in the fender well. I do not have the Kelsey Hayes setup under the dash like you and Howard. I thought maybe the odd feeling he was getting might be from the old K/H unit or the reserve tank in the fender well. My brakes feel fine. Like a new cars feels. Much better than the old setup. I thought maybe Howard might try just hooking up the new booster and bypassing the old booster and tank and see if that feels different. I also did not use the inline check valve from the old setup since the new dual booster has a check valve where the vacuum line plugs into it. The reserve tank in the fender well was to provide a reserve vacuum to operate the booster after the engine was shut off. The stored vacuum was only good for about one application of the brakes if the engine is not running. If I were doing the conversion with the K/H setup, I would mechanically unhook any linkage to the K/H unit so there would be no restrictions or binding that could occur with the new setup. I don't think there would be any problem leaving it hooked up but if it were mine I would remove any of the old stuff that might create a problem. I would also not hook any vacuum to the old stuff."

(These are my comments. - Ray) I happen to have what I call the "Tomato Juice" can on the passenger fender well. I do not know if this vacuum can is an aftermarket thing or came on the car from the factory. I assume it is after market because I have not seen this on other Squarebirds. I assume that I also have this reservoir behind that fender well, that Gary speaks of, but I have never seen it. Here is what else Gary had to say.

"I might make a further note on vacuum controls. The tomato juice can looking vacuum reservoirs on modern cars does not have anything to do with brakes. It stores vacuum for other controls like the heater/defrost and air conditioning control levers and switches so you can direct air flow in the heater or A/c circuit to defrost or the floor when the engine is not running. The vacuum switches use vacuum from the can only when the engine is not running and providing a vacuum source. I'm sure you have noticed that you do not have power brakes on modern cars when the engine is not running. The only reason you had a vacuum storage tank on the squarebirds was to give you one or two power assisted stops if the engine quit suddenly while going down the road and you needed to stop.

The squarebirds had vacuum wipers as well so ford decided to add a vacuum pump on top of the fuel pump to run the wipers so they wouldn't rob any vacuum from the power brakes and for cars not equipped with power brakes. You might have noticed that the wipers will slow down or quit entirely when you stomp on the gas on your bird. Let off the gas and they start again. That is the reason for the vacuum pump on top of the fuel pump. If you install electric wipers you do not need the vacuum pump on the fuel pump and can get by with just a regular fuel pump. It was just a junkyard way Ford had to make your wipers work when accelerating. Kind of like their attempt at early powered windshield washers instead of the squeeze bulb on the floor. I don't know if Ford used the squeeze bulb on the thunderbirds or not. I have not seen one with that setup. Ford used the squeeze bulb washers up into the seventies and eighties on some of their bigger trucks. When Ford went to electric wipers and electric washers they simplified a lot of other things."

I hope this additional information will be helpful to our members. Thanks, Gary!

[Guest]

Hey Guys,
Here on the right of the picture is the tomato juice can Ray was referring to. This is under the hood of my 1978 Thunderbird!
Richard D. Hord

[KULTULZ]

Let Me Attempt To Confuse You Further

Here is some information that I came by from corresponding with Gary ~ 1946hamm about the KH under dash booster system. I thought it would be good to add this for other members, and Gary agreed to let me post it.

"Hi Ray; I meant that I did not hook up the reserve tank in the fender well. Since the dual booster has a kind of built in reserve with dual chambers I didn't think I needed the tank in the fender well. I do not have the Kelsey Hayes setup under the dash like you and Howard. I thought maybe the odd feeling he was getting might be from the old K/H unit or the reserve tank in the fender well. My brakes feel fine. Like a new cars feels. Much better than the old setup. I thought maybe Howard might try just hooking up the new booster and bypassing the old booster and tank and see if that feels different. I also did not use the inline check valve from the old setup since the new dual booster has a check valve where the vacuum line plugs into it. The reserve tank in the fender well was to provide a reserve vacuum to operate the booster after the engine was shut off. The stored vacuum was only good for about one application of the brakes if the engine is not running. If I were doing the conversion with the K/H setup, I would mechanically unhook any linkage to the K/H unit so there would be no restrictions or binding that could occur with the new setup. I don't think there would be any problem leaving it hooked up but if it were mine I would remove any of the old stuff that might create a problem. I would also not hook any vacuum to the old stuff."

Correct. If one is doing a later style conversion (Single or Dual Diaphragm booster), the original KH system should be negated (hopefully removed and saved). The Dual Diaphragm booster is designed for small spaces. The reservoir(s) will give you 1 to 2 stops after loss of engine vacuum. It is the purpose of the reservoir(s).

The old reservoir is not needed (or vacuum check valve).

(These are my comments. - Ray)

I happen to have what I call the "Tomato Juice" can on the passenger fender well. I do not know if this vacuum can is an aftermarket thing or came on the car from the factory. I assume it is after market because I have not seen this on other Squarebirds. I assume that I also have this reservoir behind that fender well, that Gary speaks of, but I have never seen it. Here is what else Gary had to say.

"I might make a further note on vacuum controls. The tomato juice can looking vacuum reservoirs on modern cars does not have anything to do with brakes. It stores vacuum for other controls like the heater/defrost and air conditioning control levers and switches so you can direct air flow in the heater or A/c circuit to defrost or the floor when the engine is not running. The vacuum switches use vacuum from the can only when the engine is not running and providing a vacuum source. I'm sure you have noticed that you do not have power brakes on modern cars when the engine is not running. The only reason you had a vacuum storage tank on the squarebirds was to give you one or two power assisted stops if the engine quit suddenly while going down the road and you needed to stop.

The can is a vacuum reservoir (not sure of need on an early BIRD as most heater controls are cable, correct?). You start seeing them come into use with the introduction of vacuum servo motors. It is not large enough to give an additional vacuum signal for power brakes. It provides a constant vacuum signal for vacuum accessories as manifold vacuum drops/rises in normal engine operation.

The squarebirds had vacuum wipers as well so ford decided to add a vacuum pump on top of the fuel pump to run the wipers so they wouldn't rob any vacuum from the power brakes and for cars not equipped with power brakes. You might have noticed that the wipers will slow down or quit entirely when you stomp on the gas on your bird. Let off the gas and they start again. That is the reason for the vacuum pump on top of the fuel pump. If you install electric wipers you do not need the vacuum pump on the fuel pump and can get by with just a regular fuel pump. It was just a junkyard way Ford had to make your wipers work when accelerating. Kind of like their attempt at early powered windshield washers instead of the squeeze bulb on the floor. I don't know if Ford used the squeeze bulb on the thunderbirds or not. I have not seen one with that setup. Ford used the squeeze bulb washers up into the seventies and eighties on some of their bigger trucks. When Ford went to electric wipers and electric washers they simplified a lot of other things."

I hope this additional information will be helpful to our members.

Thanks, Gary!

The purpose of the two-stage fuel pump (vacuum over pressure) was to supply a continuous vacuum signal to the wipers as manifold vacuum dropped. The power brake reservoir maintained sufficient vacuum to operate the brakes.