Changing the 55 chevy stock single pill box master cylinder to a duel one. Which one?

Hi,
Not much on the project to do list this fall and winter so I am planning on changing my single pill box master cylinder for a duel one. I am keeping it simple so I am not looking put in power brakes or changing out the front drum brakes. Keeping it simple. What has worked for you?
Thanks Jay

 

I just swapped from a dual to a single. For keeping the drums, a dual from a late 60s car with drum brakes would work, although you need to check the pushrod length. They switched to duals around 1967-68.

 

I would consider a '67-70 Chevy drum-drum master myself. I did that in my '65 Belair, it shouldn't be that hard in your '55.

Bob

 

My 57 and most kit installations I've seen use the "corvette" drum drum cylinder from the late 60s.

 

I though all vettes got 4 wheel disks starting in 65?

 

I believe mine is for a 68 impala non-power drum brakes on my 57.

 

check out 67-70 chevy truck.

 

I have always used a 68-72 chevelle, 68-74 nova, or 67-69 camaro master. Just specify 4 wheel drum brakes.

 

Any of those are close enough. I always try to match up the approximate weight and vehicle type, which excludes pick ups in this case.

It helps to have access to a full machine shop.. always something has to be modified or made up in a swap like this.

Bob

 

Lots of good ideas here. I have been googling images and specs of some of your ideas so far. 67 vette seems really close. Will I need to add a proportioning valve or can I get away without one?
J

 

As posted on several other forums over the years...

These are the parts needed for the conversion.

Master Cylinder = 1968 Chevelle (drum/drum)
(1) 9/16” to ¼” Brake Adapter
(1) ½” to 3/16” Brake Adapter
(2) 3/16”X3/16” Union
(1) 3/16” Plug
(2) 3/16”X 40” brake line
(1) ¼”X 30” brake line

Remove the original M/C and install new cylinder after bench bleeding.

Disconnect the line going to the rear brakes at Tee on p***enger side.

Install the 3/16” plug into the Tee.

Install the 3/16 brake lines with unions to the rear brake line along the frame and cross member to the M/C.

Replace the ¼” brake line from the old M/C with new ¼”X 30” line to the driver side Tee.

Install the brake pedal rod and adjust the rod for ½” to ¾” free travel and tighten nut.

 

I did my 55 thirty plus years ago. What I do remember is I had to cut some off the pedel rod. I had a friend that didn't and his brakes looked up on him.

 

Just a suggestion but I converted my 55 to power booster and dual master cylinder all at one time....all bolt on. I used a 62-64 full size Chevy power booster with a 70 Nova dual master cylinder for 4 wheel drum brakes. I retained the porportioning valve with the Nova....all done in a day. Being so used to the daily drivers that had power ***ist then driving the 55 without took some getting used to, so the power booster on the 55 was a welcome addition.

 

Use a drum/drum master but make sure it has a small bore like 15/16 or 1 inch.
Pipe in 10 lb residual check valves if your new master doesn't have them in the ports.

 

I used a 77 Monza booster.

 

65 corvette no power drum brake NAPA part#M390372

 

I'd suggest getting the junction block from the matching all drum car to plumb it the same as GM did on the dual cars. Not sure if it has a dump valve in it or just what, I have one here I intended for my '50 Chevy that I pulled off a '72 Cutl***.

 

Mustang dual from the early 70's are a Chevrolet about the same era. New should have a 7/8 bore are 1 inch