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'56 Disk brake impression

CT Car Guy

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Hi all:

I am new to Thunderbirds (Not AACA). Came across a 1956 Sunset Coral car in beautiful condition. Now my wife wants it for herself. The previous owner put in power front disc brakes. I found that the car seems to take longer to stop then my other all drum brake cars. I also noted it took a fair amount of pressure. The master cylinder is a 2 circuit design with the rear brakes without power assist. The booster unit is the old style located remote (after) from the master cylinder. If I am going to get her to drive the car, I need to make it easier to stop. I am waiting on some service manuals. Ideas?


Larry (AKA CT Car Guy)

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It sounds like your booster is not working. I'm assuming by a circuit design you mean a dual chamber master cylinder. If that's the case you can not have power front disk and manual power brakes. Power brake boosters are always used with disk brakes because of the high pressure required by disk brakes. How about a photo of your setup (especially the dual circuit master cylinder set up) and we may be able to give you more help.

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In 1999, I put what sounds like the same setup on my 55. It used a spacer on the spindle, new wheel bearings, modified Granada rotors, Fairlaine calipers, and custom brackets. Dual master,boost on the front only using the OEM power booster and mount. It also included new rear wheel cylinders, of a different bore, to balance the system. I don't remember the pedal effort as being high. I do remember keeping the rear shoes properly adjusted was more important than usual.

While I suspect Dave is correct about the booster, it could also be a mis match of parts.

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Relying on my somewhat rusty memory, that looks like the setup I had.

You might try disconnecting the booster vacumn and plugging it. You should feel a difference, if you don't, I'd start with the booster.

it sounds like you also might have a lot of free pedal travel. I don't remember the particulars, but there's some difference in pushrods length between power and manual master cylinders on some cars. A rebuild master might come with a bore size spacer. Using it when you shouldn't preloads the brakes. Leaving it out means you run out of pedal travel before you apply full pressure. You need some pedal free play in a bird, the heat from the exhaust manifold will "apply" the brakes if there too little. Ask how I know.

If those don't pan out, next step is probably to bleed everything, and check the adjustment on the rear shoes.

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