Packard Forum Index » Post-War (1946-54)

Interesting about the springs. I'm not sure the sound emanates from the drum. It sounds more like chattering shoes and the noise comes more from the backing plate, not the drums, but I could be wrong. It's not really a high pitched squeal like is sometimes heard from a brake, but a lower pitched howl. I probably didn't describe it very well.

The contact points on the backing plate are not excessively worn -- no groove -- but it looks like they would soon end up that way if I continued to drive the car with that howl. The metal was already worn rather shiny behind the shoes but had a rusty color when assembled. I reapplied a thin film of brake grease on those points while I had the shoes off for cleaning.

I took the car for a drive today. The howl is mostly gone. It was silent at first but with continued use it has resumed a faint howl within a certain range of moderate pedal pressure.

One thing I did not do as part of the brake job was to resurface the drums. They are very polished and wear appears even -- probably glazed. Deglazing likely would help. All I had done was to clean them out with steel wool. It's odd just the left front wheel made such a loud noise. That wheel does not have a history of leakage, but the right front wheel has had some minor leakage in the past. I did also install new wheel bearing seals when I replaced the brakes.

So if the problem persists I guess I'll have to pay more attention to the drums and scuff the surface.

Scott

You might pull the drums and put them on a drum lathe and check to see if the surface has warped (i.e., out of round), it wouldn't be at all uncommon and will cause rapid shoe chatter - think about it - the shoes would have to move in and out a small amount with each revolution of the drum. If so you'll want to turn them true (assuming you can stay within safe limits) and then have the linings arc-ground to the new diameter, again standard drum brake service work. If the drums have been cut significantly you may either have to use thicker linings before arc-grinding, or if riveted, another technique shown in Chrysler service manuals of the era is to use a metal shim between the lining and the shoe to give the effect of a larger diameter, and then of course arc-grind the shoes. There was a time when this was everyday common brake shop work but finding a shop to arc-grind the shoes to match the drum diameter is getting a bit more difficult - you might try shops that work on large trucks as many of them still use drum brakes.

My brake lathe has large rubber straps with lead weights to go around drums and rotors, the strap eliminates the harmonics as the bits move across the surface while cutting which can cause the carbide bits to dance and cut the metal leaving a rough cut rather than a non directional smooth cut. The spring around the drum eliminates sound harmonics caused by the brake shoe sliding over the braking surface of the drum. Like wetting your finger and going around the lip of a glass until it starts to sing.