Master cylinders and power brake boosters: P/D/C 1969-1971

ayilar

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I recently acquired another 1970 Dodge convertible. The car came equipped with all the round drum brakes. The brakes work well at high speed but not at low speeds, so my plan was to have the power booster rebuilt by Booster Dewey. It now appears that there is a slight brake fluid leak too, between the master cylinder and the booster, so I might as well rebuild or replace the master too.

@DocMcNeedy has had good experiences with Midwest Power Products in Morris, IL. So, one possibility would be for me to send what is on Regina (PB and MC) to MPP, have them both rebuilt, and hope that the result works.

However, and this is the reason for this thread, the MC shown in the parts manual and the one in my car look different. Regina's master looks like a 1969 unit or (maybe) a 1971.

Regina (DL27L0D148841):
Untitled.png


1970, as per the parts manual (scans of the latter were made available by MyMopar.com):
Image 11-9-20 at 10.34 AM.jpg


1971, as per the parts manual:
Image 11-9-20 at 10.40 AM.jpg


My worry is two-fold:

1. that the booster and the master might not work well together even after being fixed, if they were not correct for the car to start with;

2. even if everything works, it would still not be the correct equipment -- but I'd be out 3-400 bucks for the rebuild. In that case, rather than pay for a MC rebuild, I might as well buy the Raybestos MC36221, which is not correct for my car but which I have seen on numerous 1970 Dodges (and is the kind of MC that was installed during restoration on Poppy, another 1970 Polara 'vert of mine, on which it works very well).

Here is a view of Poppy’s braking (DL27G0D170979) when she was for sale; the master has since been replaced, but I still have her original MC on a shelf at home:
B51 master cylinder on Poppy.png


Regina was built on Oct. 31, 1969; Poppy was built on Dec. 4, 1969. So, it is not a question of Regina's being a "late build" and therefore looking like a 1971. It might be a question of her being a fairly early-build and having something that still looks like the 1969 MC.

With this in mind, I searched yesterday for pictures of fusies with seemingly original masters and boosters. Well, I have found several on FCBO that look like what the parts manual shows -- but also several that look like Regina!

--> I'd love to have folks whose cars still have their original 1970 power drum brakes post pictures of their cars;

--> it would also be great if folks who have a setup looking like Regina's could share pics of their rigs, and the story of what changes have been made over their cars' lives (assuming they know);

--> finally, if I were to rebuild the booster, is there any risk that the Raybestos MC36221 might not work?

For comparison, here are a few master cylinders on other 1969 and 1970 model-year P/D/C cars:


CE23G9C160090 -- 1969 but MC looks like Regina's rather than 1970 in the Parts Manual unit:
g-m9ln_twhv_x2f-z4rdexxybhhjde_ffcgnroba-_nc_ohc-aw-7p4uz2dgax-ybomj-_nc_ht-scontent-fadl3-1-jpg.jpg



CE23L0C268284 -- 1970 whose MC looks like Regina's rather than 1970 in the Parts Manual unit:
B51 master cylinder on CE23L0C268284.png



CM27T0C169137 -- 1970 whose booster and master both look just like Poppy's and those in the Parts Manual -- but not like Regina's:
B51 master cylinder on CM27T0C169137.png



CM27T0C222965 -- 1970 whose MC looks like the 1971 in the Parts Manual (not Regina's, not Poppy's):
B51 master cylinder on CM27T0C222965.png
 
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Davea Lux

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The master currently on the car is probably an after market replacement. As long as the MC bore is the same the unit should still work. There are always some production variants, most notably if the car was Canadian production, so I would not worry too much about which master cylinder is correct as long as the bore size is right and you are not going for a high point restoration. The center bolt cover appeared on most '67 and later split brake systems with drums. These days you can probably buy a new after market MC cheaper than you can rebuild your old one if you are sending it out for a rebuild.

Dave
 

ayilar

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Thank you as always for your rapid and helpful replies!

The master currently on the car is probably an after market replacement. (...) There are always some production variants, most notably if the car was Canadian production

I wonder, though, if the differences are not something related to manufacturing date. Here's why.

As you may know, I am rather keen on 1970 Polara convertibles and, as such, I have a library of photos and details about a non-trivial proportion of all cars produced. I went through that information this evening, and I can find no master cylinder like the one in the 1970-1971 Parts Manual on any of the Polara 'verts produced before until Nov. 5, 1969. To wit, here are pics from cars for which I have no reasons to believe that the MC was changed:

DL27G0D101373 (SBD in Aug. 1969)
00q0q_gsbo5r8midf_0ci0ip_1200x900-jpg.jpg


DL27G0D132053 (SBD in Sept. 1969)
00a0a_lkwzrbautm4_1200x900-jpg.jpg


DL27L0D148841 (SBD of Oct. 31, 1969): That's Regina -- and she is the last Polara 'vert in my database with the "looks like 1969" MC -- see pic in the OP.

DL27L0D151852 (SBD of Nov. 5, 1969): first Polara 'vert in my database with the "looks correct for 1970" MC:
upload_2020-11-9_17-1-18.png


After that, I only have photos with the "matches the parts manual" booster (unless it's been replaced by a generic one like the Raybestos I posted earlier).

I hope that @polara71 and @Fratzog, who have been keeping track of minute differences on 1970 Polara 'verts, could also chime in.
 

CBODY67

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Parts books and related service manuals were finalized and printed in about the middle of July, back then, so they could be at the dealerships when the new cars were delivered in (about) September. That lead time can sometimes, by observation, tend to compromise these books' use as "absolute reference authority" in documenting what allegedly a vehicle should be equipped with as factory-correct equipment. Which will explain the issue you mention about what the parts book illustrates not matching the vehicles you have documented. Even IF the parts book pictures were accurate for when they were shot, vendor issues could have arisen after that, which meant a different item than pictured was what actually went onto the production vehicles.

In general, all of the factory publications can be trusted, but sometimes, due to issues beyound the control of the photograpic operatives, accuracy might suffer a bit. Which would be where your own archives might come into play.

Enjoy!
CBODY67
 

Davea Lux

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Thank you as always for your rapid and helpful replies!



I wonder, though, if the differences are not something related to manufacturing date. Here's why.

As you may know, I am rather keen on 1970 Polara convertibles and, as such, I have a library of photos and details about a non-trivial proportion of all cars produced. I went through that information this evening, and I can find no master cylinder like the one in the 1970-1971 Parts Manual on any of the Polara 'verts produced before until Nov. 5, 1969. To wit, here are pics from cars for which I have no reasons to believe that the MC was changed:

DL27G0D101373 (SBD in Aug. 1969)
View attachment 414202

DL27G0D132053 (SBD in Sept. 1969)
View attachment 414203

DL27L0D148841 (SBD of Oct. 31, 1969): That's Regina -- and she is the last Polara 'vert in my database with the "looks like 1969" MC -- see pic in the OP.

DL27L0D151852 (SBD of Nov. 5, 1969): first Polara 'vert in my database with the "looks correct for 1970" MC:
View attachment 414201

After that, I only have photos with the "matches the parts manual" booster (unless it's been replaced by a generic one like the Raybestos I posted earlier).

I hope that @polara71 and @Fratzog, who have been keeping track of minute differences on 1970 Polara 'verts, could also chime in.


The parts book photos from the '68 and '69 would appear to be the same. Does not necessarily mean that the bale type was not used but I suspect the single bolt type was a lot more common. The production lines did sometimes run out of a specific part and could substitute parts from a different supplier. Sometimes the parts book will show a date range for substitute parts and sometimes it does not. Photos attached below, click on mail not the icon.

Dave
 

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kosovocop05

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thanks for the part number too, I am thinking of moving from a single well M/C to a double for safety reasons. I have four big drums and they seem to give me plenty of slow down when asked.
IMG_0390.JPG
 

ayilar

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Thanks to @Megawattkid, we can add another datapoint. Build date for his 1970 Polara ‘vert, DL27G0D118871 , was 9/8/1969. Her master cylinder, which I assume is original, looks like the equipment on all cars built till at least Oct. 31 / before the change to the center-screw unit, which took place no later than Nov. 5, 1969.

upload_2020-11-11_23-25-47.jpeg
 

kosovocop05

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Thank you Ayilar. Good photo too. Looks like I can slap one of those in and do some plumbing. Cheers
 

ayilar

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Thank you Ayilar. Good photo too. Looks like I can slap one of those in and do some plumbing. Cheers
Glad if this info is helpful!

FWIW, armed with my conviction that the bail-type master is correct for my car, I will have both MC and PB rebuilt by the same company. To that effect, I have contacted Midwest Power Exchange (which moved last year from Illinois to Florida) and will be shipping them both the booster and the master. Cost is $225 for the booster rebuild ($25 more than Booster Dewey charges) and $165 for the master cylinder (which Dewey does not rebuild), plus shipping. Turnaround time is predicted to be 4 weeks.
 

ayilar

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The parts book photos from the '68 and '69 would appear to be the same. (...) Dave
Thanks! Here is a picture of the engine bay of DL23F9D144724 -- a 1969 Polara that must have been build in Fall 1968. Same master cylinder as shown in the parts manual. The mystery of why the first-3-months-of-production 1970 Polaras have a bale-type MC remains.
 

1970cat

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the bail wires are different on most of the pictures you posted. don't know if it makes a difference or not.
 

live4theking

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Glad if this info is helpful!

FWIW, armed with my conviction that the bail-type master is correct for my car, I will have both MC and PB rebuilt by the same company. To that effect, I have contacted Midwest Power Exchange (which moved last year from Illinois to Florida) and will be shipping them both the booster and the master. Cost is $225 for the booster rebuild ($25 more than Booster Dewey charges) and $165 for the master cylinder (which Dewey does not rebuild), plus shipping. Turnaround time is predicted to be 4 weeks.
Just wondering if you have sent these out yet. Also, what was the experience like?
 

ayilar

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Just wondering if you have sent these out yet. Also, what was the experience like?
Just saw your message. Not yet. Ming and Buttercup have been receiving attention, and @71Polara383 suggested that it'd be a good idea not to have another car that can't be readily moved.
 

PH27L7

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My 2 cents...
Ayilar, I believe all of the bail-type units you show like below are actually aftermarket. That's a very common replacement that was used for decades. To my knowledge there were no bail types used through 1970 on any mopar with 4 wheel drums. One dead giveaway on non-OEM units of that vintage is that they have a machined divot on the nose; OEM units are smooth. They make repros of the original types but there are differences between them & OEM if you know what you're looking for. The most critical dimension is the bore size which should be 1" in your case if you want it to function as originally intended. I have some detailed pictures of a 100% original drum MC if you need.

I saved an old magazine article that discussed all of the old MC types, I believe the Ram Man put it on his site. I've found it to be pretty darn accurate although there are some cases where there is overlap between years that doesn't necessarily follow the parts books. I attached a few excerpts.

upload_2020-11-11_23-25-47-jpeg.jpg

Master cyl article page 2.jpg
Master cyl article page 4.jpg
 

Furyman

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PH27L7 is correct ...bail was introduced in 1971 on drum brake applications. Disc brake applications used bail wires from 1967 on. As far as parts books go there are usually 3 or 4 print dates in a model year. Each one is revised...the last one published is called Final Edition and is usually printed up to a year after the model years ends. This edition is the most common as most dealerships threw out the earlier editions.
 

ayilar

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To my knowledge there were no bail types used through 1970 on any mopar with 4 wheel drums. One dead giveaway on non-OEM units of that vintage is that they have a machined divot on the nose; OEM units are smooth. They make repros of the original types but there are differences between them & OEM if you know what you're looking for. (...) I saved an old magazine article that discussed all of the old MC types, I believe the Ram Man put it on his site. I've found it to be pretty darn accurate although there are some cases where there is overlap between years that doesn't necessarily follow the parts books. I attached a few excerpts.
Thanks a lot. I found the article here. Below is another relevant excerpt from the article, getting straight at my question (the MC with bail wire is parts nbr 3461184 and for 1971-72):
upload_2020-12-18_14-7-16.png

I also found a 2009 Moparts thread on the topic, with similar conclusions as yours.
 
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