brakes

Posted by Bob Carabbio on Oct. 23, 1998 at 00:22:28

In Reply to: Adjusting hydraulic brakes with "stick method"?
posted by Paul Reasenberg on Oct. 20, 1998 at 14:07:29

The adjustment of the brakes is pretty much as stated. If you are using '39-41 backing plates you must "centralize the shoes" by turning the anchor pinswith the brake pedal released AND showing some free play (as Glen says) before the push rod contacts the master cylinder plunger.
Basically the nut on the anchor pin is loosened and the pin itself can be turned which moves the shoe up and down relative to center. keep adjusting the shoe OUT till there's heavy drag, and then turn the anchor to see if you can loosen the drag a bit. when the drag is tightened when moving the anchor pin either way - it's about right - tighten the jam nut and move on. If you have 42-48 units the shoes will self-centralize and you don't have to worry - just hit the pedal solidly a couple of times before adjusting.
Then set the shoes with the adjuster till thay just scrape a bit on the high spots with the wheel installed. If you can feel a perceptable drag on the tire when turning it's a bit too tight.
The '39-41 front cylinders were smaller than the rears, but they're no longer available, and 42-48 cylinders are all alike except for the hose fitting. The "Leading shoe" (the one that tends to get pulled into contact with the drum in the forward direction) has the larger half of the cylinder driving it.
There is a relief valve built into the master cylinder that maintains about 10 P.S.I. in the plumbing when the brakes are released. If this valve is bad, or if there's a system leak at one of the wheels, the pedal gets spongy.
With the 39-48 brakes it's IMPERATIVE to re-build the cylinders when the linings are renewed since the wheel cylinders move outwards when wear occurs, and garbage builds up in the cylinder behind the expanding cups. If the cylinders are simply compressed back over the contamination with new shoes, leakage will almost certainly result - ruining the new shoes. Ford and Chrysler shared this problem till the late 40's (Chrysler till the mid '50s).

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