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Michael the springs are often used when turning the drums to stop the chatter they look to me like a common screen door spring cut to fit the drum.
There are springs, rubber straps, and other anti-squeel devices used on a brake-lathe to prevent a drum from ‘singing’ while it is being cut. A brake lathe turns a drum a very slow speeds.
But the springs used on the drums, on the car are much heavier tension. This is necessary to prevent the spring from ‘growing’ from centrifugal force as the car travels at high speeds.
I’ve used a spring door return spring to stop a squealing drum, but they expand and fly off at about 40mph. I’d love to find a source for actual drum springs.
If you have them, I’d keep them and use them. Big drums are prone to ‘singing’ for various reasons.
A Pierce Brake drum, stood on “pointy” end and struck with wrench, makes a lovely sound.
McMaster Carr can fabricate custom extension springs any length, different materials and wire thickness. It would be interesting to see what one would cost, if you have a sample spring would be simple enough to measure length and size of wire…..and get a quote..
I was told, years ago, that these springs were there to relieve the static in the car radio. If so, then Greg has the closest definition. In the late ’50’s, my 1955 Olds convertible had them on all four wheels(?).
Another theory is that they helped cool the brake drum…which almost makes sense..it would be interesting to find a definitive answer, but all I’ve found so far is conjecture….there are all sorts of springs and straps sold to silence and prevent vibration when turning a drum, as mentioned….
I’m sure Greg is correct, the springs are harmonic dampers. Get a crystal glass and wet your finger, run your finger around the rim and it will sing. Place your other hand around the glass just below the rim as you continue to rub the rim and the noise will stop. Jim
The purpose of the drum spring was to dampen oscillation of the drums from squealing when braking. From what I have found in my research, they were mainly applied to the front drums but it is possible that the rear drums were also fitted to kill, or suppress, the squeal. In the 1961 Motors Manual this spring is called a “dampener”. Front drum dampening springs would help lessen the amount of vibration through the steering wheel when the brakes are applied.
To answer your question Michael, you could use the drum with a spring (or without a spring) as long as the drum fit’s correctly. There will be no difference in balance or drivability to the car. If you are going to make either of the 38’s or the 36′ a primary daily driver it might be nice to have drums with springs but it’s not needed.
I have turned thousands of drums and rotors in the decade I worked in the auto parts business. Like Greg mentioned, we used a heavy rubber belt to cut down the vibration, or chatter, when truing the drum. From what I remember, some drums had springs and a lot did not. Many of the new drums we sold did not come with a spring.