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'55 power brake M/C failure - while trick-or-treating  

Eminent Member

My Wife & I decided to take our boys out for Halloween in our '55 this year. On one of our last stops the brake pedal got very hard and you could hear a vacuum leak under the dash. (Car still stops with heavy effort on pedal) My guess is that the vacuum diaphram failed. I know that this master cylinder is not serviceable (by a kit anyway)

What have other owners done?

Is there a dual chamber M/C that can be grafted into place? I'm not worried about keeping everything original. My interior is not original materials, 12v starting system has been added etc...

Thanks in advance for any advice you all can offer!

Steve Hart

Posted : November 1, 2013 12:34 pm
Estimable Member

aajbrakes.com may be able to help. I haven't used them but have heard good things. I had a 55 that had M/C failure at 60 mph, thank god the park brake worked and I had room. I put a late 60's full size Dodge drum/drum M/C and booster in it but sorry, it's been so long ago I can't remember the details. I'm not a fan of the 55 set up and consider it a hazard. When I do my 55 NY it won't have the stock M/C and booster. As I tell my customers when it comes to brakes "It doesn't matter how well it runs if it won't stop."

Tim Mabry
The Lost Cause Garage
47 Suburban
57 Sportsman 4dr HT

Posted : November 4, 2013 2:40 pm
Jay Vargas
Eminent Member

Hey - You ever get these brakes figured out? I appear to be having the same issue. I just emailed the company in this link, hope they are still around. I am not interested in keeping original either, just want safe.



Posted : June 7, 2019 8:49 pm
Reputable Member

I rebuilt both the master cylinder and the power brake booster on my 55.

A company called Harmon Classic Brakes sells the rebuild kits. Or you can buy a fully rebuilt m/c and booster assembly. Here's the link (it says Chrysler, but it's the same parts exactly).

Harmon Classic Brakes


Posted : June 8, 2019 7:10 pm
Reputable Member

I don't see the listing for the master cylinder rebuild kit, but here is there listing on ebay:

55 Desoto master cylinder rebuild kit


Posted : June 8, 2019 7:11 pm