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The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components
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56D500boy
Posted 2020-12-30 5:09 PM (#607269)
Subject: The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components



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My main goal is to add a dual drum/drum master cylinder to my 1956 Dodge D500 equipped with 1956 Chrysler 12" x 2.5" Center Plane drum brakes from the factory. I know that going discs on the front might be smarter but that would take away from the D500 system components (315 cu in 4 bbl 260 hp double rocker engine, 12" Chrysler brakes and heavy duty suspension (the latter, not on my car)). Even if I went with discs on the front and used a disc/drum dual master, there would still be an issue with the clearance between the dual master and the double rocker valve covers, i.e. impossible to remove the cover or access the No. 7 (and maybe No. 5) spark plug(s)).

I was inspired by some others who have made a conversion that didn't interfere with the valve cover/spark plugs or the generator-drive Power Steering pump (like the owner of this 1955 Desoto):



I soon realized that the solution to this conversion needed to start with a power brake pedal assembly from a 1955 Mopar (Chrysler, Desoto, Dodge or Plymouth - all the same) because that system mounted the booster and the master cylinder up high, out of the way. With that decided, I was able to purchase one from John F. at Big M (thanks John) and have proceeded to investigate it and purchase the other components that I will need.

Pedal investigations: http://www.forwardlook.net/forums/forums/thread-view.asp?tid=75160&...

So this is what I am starting with:







This is the 55 Chrysler Power Brake Pedal system that I got from John F. at Big M (after a bit of clean-up (surface rust removal):



This is the basic arrangement of the 1955 Power brake system with its high-mounted master cylinder and booster:



This is where I hope to be going, using the booster from a 1975 Chrysler New Yorker and the drum/drum master cylinder from a 1968 Dodge Charger (below). I know that there will be issues that will be discovered along the way that will need solving but, hey, what else am I doing with my time? This will keep me out of trouble (or get me into more?)



Edited by 56D500boy 2020-12-31 2:42 AM




(55ChryslerPowerBrakePedalDiagram_withCardoneBoosterAndRaybestosDualMaster_Annotated_Rev1.jpg)



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Attachments 55ChryslerPowerBrakePedalDiagram_withCardoneBoosterAndRaybestosDualMaster_Annotated_Rev1.jpg (208KB - 15 downloads)
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56D500boy
Posted 2020-12-31 1:27 PM (#607289 - in reply to #607269)
Subject: RE: The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components



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Dels56 has pointed out that I made a mistake on the MC part number. It should be Raybestos MC 36221 (not 36223). In my defense, I probably got a bit confused with the Cardone equivalent, 13-1323.

Revised sketch/mock-up:





(55ChryslerPowerBrakePedalDiagram_withCardoneBoosterAndRaybestosDualMaster_Annotated_Rev2.jpg)



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Attachments 55ChryslerPowerBrakePedalDiagram_withCardoneBoosterAndRaybestosDualMaster_Annotated_Rev2.jpg (206KB - 17 downloads)
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56D500boy
Posted 2021-01-01 11:24 PM (#607326 - in reply to #607289)
Subject: RE: The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components



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The Cardone 54-73702 1975 Chrysler New Yorker power brake booster that I ordered for this project from PartsAvatar.ca (Canadian and free delivery) arrived, as scheduled, yesterday (Dec 31, New Year's Eve day). I didn't do much with it then but, today, I got right at it.

First thing was to measure the mounting bolt spacing and redrill the 1955 Chrysler Power Brake pedal assembly and reinforcement plate (actually I drilled the reinforcement plate first and checked it on the new booster before using it as template for marking the new holes on the pedal bracket). After a bit of fiddling (and clearancing of 2 of my eight not too precisely hand-drilled holes (I really need a drill press) holes in a couple of spots on the peddle bracket), I put things together in stages to check how things are going to work out (or not)

There might be a conflict between the external (engine bay side) reinforcement mounting plate and the booster and there seems to be tightness between the rubber boot on the booster push rod and the pedal bracket that might have to be resolved (with an angle grinder, etc.). Not 100% sure at this point.

The booster sits a bit higher at the top than I wanted but I don't think it will cause any conflicts. (fingers crossed). I know one big potential conflict with this booster is potentially hitting the voltage regulator. I will need to investigate that more in the coming days. (I think an off-set mounting plate will to the job - moving the voltage regulator over an inch or so)

One thing that I've noticed is, because of the length of hose from the bottom of the OE single channel MC to the OE distribution "Tee" on the frame is quite long, I think that I will be able to dismount the MC from the firewall, remove all the existing PB stuff, install the new stuff (pedal bracket and booster) (once the conflicts are resolved) and then re-install the single channel MC on the new PB booster - just as an interim measure - with the dual channel drum/drum MC to follow afterwards.

Here are the photos from today:





Edited by 56D500boy 2021-01-02 2:30 AM




(CardoneBoosterMountingBoltSpacing3point5inchesCtoC.jpg)



(MarkingThe55ChryslerPBExternalReinforcementPlateForReDrillingForCardoneBoosterMountingBolts.jpg)



(CardoneBoosterFitmentAgainstExternalPedalBracketReinforcementPlate_BackSide.jpg)



(CardoneBoosterFitmentAgainstExternalPedalBracketReinforcementPlate.jpg)



(CardoneBoosterBootConflictWith55ChryslerPedalSupportBracket.jpg)



(RaybestosMC36221MountedToCardoneBoosterMountedTo55ChryslerPBPedalAssembly.jpg)



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Attachments CardoneBoosterMountingBoltSpacing3point5inchesCtoC.jpg (96KB - 16 downloads)
Attachments MarkingThe55ChryslerPBExternalReinforcementPlateForReDrillingForCardoneBoosterMountingBolts.jpg (101KB - 16 downloads)
Attachments CardoneBoosterFitmentAgainstExternalPedalBracketReinforcementPlate_BackSide.jpg (103KB - 16 downloads)
Attachments CardoneBoosterFitmentAgainstExternalPedalBracketReinforcementPlate.jpg (118KB - 15 downloads)
Attachments CardoneBoosterBootConflictWith55ChryslerPedalSupportBracket.jpg (119KB - 16 downloads)
Attachments RaybestosMC36221MountedToCardoneBoosterMountedTo55ChryslerPBPedalAssembly.jpg (104KB - 16 downloads)
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56D500boy
Posted 2021-01-02 3:30 PM (#607336 - in reply to #607326)
Subject: RE: The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components



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I've been contacted by a couple of forum members who are machinists and who blanched at my use of a framing square to measure the C to C distance of the booster mounting studs.

Maybe I just like to make machinists crazy.

The holes didn't have to be all that precise, in fact a little looseness might be a good thing. I have a good eye, good to within 1/32" or less so I wasn't that worried.

It was suggested that I should buy and use a vernier caliper. I already own three vernier calipers. One full old school manual, one electronic metal (with decimal inches, fractional inches and millimeters) and one electronic plastic for rough measurements (typically when I am laying under the car). For this booster mount mock-up, I was just too lazy to find/use one of the vernier calipers and the framing square was right there and handy.

My holes are fine enough. I just had to open two up on the pedal bracket a bit (Dremel with a die grinding tip).

*BUT* what I do really need is a small center punch. I used to own one but it went walk-about years ago.

In the future, I will try not to make the machinists in the crowd crazy and use a vernier caliper.

Maybe.



Edited by 56D500boy 2021-01-02 4:37 PM
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56D500boy
Posted 2021-01-06 9:49 PM (#607466 - in reply to #607326)
Subject: RE: The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components



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Got some proper sized nuts the other day at Lowes and attached the 67 Charger Drum/Drum dual channel MC to the 1975 Chrysler PB booster and the Booster to the 1955 Chrysler PB pedal assembly. It's going to work.

Now I just need to figure out/design a clevis/push rod system between the 55 Pedal Link and the 75 PB booster. Naturally they are both different sizes (both in hole/pin diameters and widths). Looks like I will need to get out the vernier calipers and precisely measure things and then sketch up what I need. I think I will use a 3/8" threaded rod (or bigger? 7/16"??) and then see what I can scrounge for clevises. I would really like to see what was used between the 1975 Chrysler brake pedal and the PB booster.

This is what I am now challenged by:





(1975ChryslerPBboosterOn1955ChryslerPBPedalAssembly_ShowingRelativeLengthtForTheClevisPushrodSystem.jpg)



(1975ChryslerPBboosterOn1955ChryslerPBPedalAssembly_relativeSizeOfHolesForAClevisSystem.jpg)



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Attachments 1975ChryslerPBboosterOn1955ChryslerPBPedalAssembly_ShowingRelativeLengthtForTheClevisPushrodSystem.jpg (146KB - 12 downloads)
Attachments 1975ChryslerPBboosterOn1955ChryslerPBPedalAssembly_relativeSizeOfHolesForAClevisSystem.jpg (154KB - 12 downloads)
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56D500boy
Posted 2021-01-07 6:46 PM (#607485 - in reply to #607466)
Subject: RE: The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components



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56D500boy - 2021-01-06 6:49 PM I would really like to see what was used between the 1975 Chrysler brake pedal and the PB booster.


I couldn't find a 1975 Chrysler FSM for photos of the brake pedal and power brake booster but I did find one in a 1970 Chrysler FSM. There was no link between the pedal and the PB booster, at least in 1970. The booster push rod was attached directly to the brake pedal, as hinted below:



Edited by 56D500boy 2021-01-07 6:48 PM




(1970ChryslerPowerBrakeBoosterAndPedalArrangement.jpg)



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Attachments 1970ChryslerPowerBrakeBoosterAndPedalArrangement.jpg (129KB - 12 downloads)
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56D500boy
Posted 2021-01-08 6:32 PM (#607514 - in reply to #607466)
Subject: RE: The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components



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56D500boy - 2021-01-06 6:49 PM
Now I just need to figure out/design a clevis/push rod system between the 55 Pedal Link and the 75 PB booster. Naturally they are both different sizes (both in hole/pin diameters and widths). Looks like I will need to get out the vernier calipers and precisely measure things and then sketch up what I need. I think I will use a 3/8" threaded rod (or bigger? 7/16"??) and then see what I can scrounge for clevises.


Scrounged. Got a couple of small ones that use 3/16"-24 rods but they are kind of wimpy and the clevis is quite long. I have to bridge in the order of 5.75" and if the clevis is say, 2.5" (each), that doesn't leave much room for adjustments.

So I got on the internet and found some larger ones that use 1/2"-20 rods and are used in the trucking industry (If it's good enough for a MACK, it will be good enough for a 56 Dodge (?)). Located a supplier this AM and went out and bought two. They are about 1.75" from the start of the threaded boss to the center of the pin hole. That leaves me with about 2" of exposed threaded rod, less the two locking nuts that I will add. Only issue was I thought Lowes would have some suitable 1/2"-20 UNF Redi-rod (or a long bolt) but nope. So I will have to go to a specialty bolt and nut place to find what I need.

Lowes does a selection of both nylon and bronze bushings from "Hillman" (probably Chinese) that merits further investigation. I bought a nominal nylon bushing (2 in a package) but further work will be needed.

Today:





(ClevisYokeOptions.jpg)



(55ChyrslerPBPeddleAnd75ChrylserPBBoosterWithTwoHalfInchClevisYokes.jpg)



(55ChyrslerPBPeddleAnd75ChrylserPBBoosterWithTwoHalfInchClevisYokes_CloseUp.jpg)



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Attachments ClevisYokeOptions.jpg (165KB - 11 downloads)
Attachments 55ChyrslerPBPeddleAnd75ChrylserPBBoosterWithTwoHalfInchClevisYokes.jpg (157KB - 10 downloads)
Attachments 55ChyrslerPBPeddleAnd75ChrylserPBBoosterWithTwoHalfInchClevisYokes_CloseUp.jpg (179KB - 11 downloads)
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56D500boy
Posted 2021-01-11 8:27 PM (#607636 - in reply to #607514)
Subject: RE: The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components



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After "Trialing" the connection between the two larger clevises using a piece of 1/2" dowel on Saturday (the fastener shops were closed), I bought a 3 ft piece of 1/2"-20 threaded rod today and cut a piece that was long enough to make the full connection between the two clevises (about 3.5"). At the suggestion of one machinist (Dels56), I turned the clevis at the booster by 90 degrees to the one at the pedal (by simply turning the booster push rod 90 deg.) and then connected the two with the 1/2"-20 threaded rod.

I haven't checked the thrust angle between pedal clevis and the booster push rod clevis yet. I know there will be some upward thrust at the booster push rod end early in the stroke but I don't think that it will be too much. More testing to follow. If there is an issue, I can always drop the booster a bit (by drilling new holes in the pedal bracket and opening up the 2" hole for the booster boot).

UPDATE: I gearhead friend (not on this forum) from whom I have asked for comments, asked "Does it concern you that the clevis pin or clevis itself could hook or jam anywhere on the frame keeping in mind the clevis may turn?". I hadn't thought of that so I went downstairs and checked things out. I don't think that it will be an issue. However, if there was a jamming possibility, there is material on the frame that I could remove to create more clearance. That said, I might have to go back to Clevis Plan A: Design and make (or have made) the required clevis. I think that the store-bought clevis at the booster push rod will be fine but the one at the pedal (the one that might need the frame to be clearanced) might warrant a narrower design with a smaller clevis hole (to match the hole in the pedal "lever"). I've added two more photos in this regard.

Today:

(and yes, I do have jam nuts for the threaded rod - just not on yet):



Edited by 56D500boy 2021-01-12 3:00 AM




(Jan11_2021ClevisConnectorRodTrial_1.jpg)



(Jan11_2021ClevisConnectorRodTrial_2.jpg)



(Jan11_2021ClevisConnectorRodTrial_3.jpg)



(Jan11_2021ClevisConnectorRodTrial_4.jpg)



(Jan11_2021ClevisConnectorRodTrial_5.jpg)



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Attachments Jan11_2021ClevisConnectorRodTrial_1.jpg (151KB - 10 downloads)
Attachments Jan11_2021ClevisConnectorRodTrial_2.jpg (167KB - 10 downloads)
Attachments Jan11_2021ClevisConnectorRodTrial_3.jpg (152KB - 9 downloads)
Attachments Jan11_2021ClevisConnectorRodTrial_4.jpg (161KB - 9 downloads)
Attachments Jan11_2021ClevisConnectorRodTrial_5.jpg (138KB - 9 downloads)
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dels56
Posted 2021-01-12 12:40 AM (#607640 - in reply to #607269)
Subject: Re: The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components


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Hi 56 D500, looking at your mock-up, the line between the lever of the apply portion of the pedal assembly and the connection at the booster, it appears to be a straight line. In order to avoid any thrust upward or down you could try locking the clevis tight against the eye of the booster rod. If there is a difference in the width of the eye of the pushrod and the inside of the clevis shim washers could take up this Space. A good bolt and bit of mussel would lock all together and in effect create a solid rod. Just a thought.

Del S
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56D500boy
Posted 2021-01-12 5:22 PM (#607664 - in reply to #607640)
Subject: Re: The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components



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Thanks for the ideas Del. I am going to "simulate" movement of the pedal arm, clevis(es) and the booster push rod - on paper (or maybe with cardboard mock-ups) to determine the amount of up/down movement that will occur at the booster rod. I think that a certain amount of such movement is allowed by the design of the booster push rod (the one connected to the brake pedal in some way).

I did physically move the brake pedal yesterday and got a 1:1 movement of the external pushrod (that goes into the master cylinder) and the passenger compartment side booster push rod. So nothing strange/magical going on inside the booster. That makes sense, based on this diagram (below) of a very similar 1970 Chrysler booster.

(Note the ball end on the passenger compartment side booster push rod - likely to allow some up/down deflection at the big "O" end of the rod.)



Edited by 56D500boy 2021-01-12 5:26 PM




(1970ChryslerPBboosterCrossSection.jpg)



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Attachments 1970ChryslerPBboosterCrossSection.jpg (212KB - 8 downloads)
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22mafeja
Posted 2021-01-13 1:52 AM (#607676 - in reply to #607664)
Subject: Re: The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components


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Sorry if I might ask a stupid question now...why didn`t you just prolong (or make a completely new) the pushrod. I would be unwilling to use the additional clevis yoke.
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56D500boy
Posted 2021-01-13 1:27 PM (#607686 - in reply to #607676)
Subject: Re: The Potential Conversion of a 1956 Dodge Power Brake System to Modern Components



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22mafeja - 2021-01-12 10:52 PM
Sorry if I might ask a stupid question now...why didn`t you just prolong (or make a completely new) the pushrod. I would be unwilling to use the additional clevis yoke.


Not a stupid question Ralf. Just one that I can't agree with: a) I am not going to take a brand new (rebuilt) booster apart and b) I have no skills (lathe, etc) to make a single piece rod from the booster to the pedal. And besides at this point, I don't know the exact length that the new single piece rod would have to be. Hence the threaded 1/2"-20 UNF rod right now. All that said, I single piece rod might be possible once I have it all figure out.

The current issues are:

1. A bushing in the new booster push rod that matches the diameter of its hole and the diameter of that thicker clevis pin.

2. A narrower clevis at the pedal end to alleviate potential concerns with binding at the pedal frame.

3. A bushing at the pedal end that matches the diameter of its existing hole (which I do NOT want to drill out, if possible) and the diameter of the pin for the narrower clevis.

I'm currently looking at Bronze Flange Bushings:

https://www.hillmangroup.com/us/en/Fastening-Solutions/Specialty/Spa...



And Nylon Spacers (used as bushings in my case):

https://www.hillmangroup.com/us/en/Fastening-Solutions/Specialty/Spa...



Edited by 56D500boy 2021-01-14 2:09 AM
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