Not sure how it does it (PFM), but they used these to keep static out of the radio is what I've always heard.
i'll add another "what i think". i think it's to dampen harmonics, to keep the drum srom ringing when the brakes are applied.
you are correct the spring absorbs ant harmonic and prevents the dreaded drum ring. Have you ever watch the brake shop turn drums/ they apply a strap for the same reason, if they didnot apply the strap the drum would resonate and the cutter would chatter. Same princpals.
AR AR AR AR AR AR radio static? Oh man...I'm older than Moses and I've never heard that one - harmonics is the correct answer, but I think I like the radio static one best...did the guy that told you that have a tin-foil hat on so the Martians can't send messages to his "brain"? "do not attempt to adjust your set...." dj
Again, Harmonics is correct. That's the same reason you wrap a drum with a rubber strap when turning them. Keeps them from vibrating and "singing" at you.
Yep, the spring around the drum is to reduce harmonics, but there WAS also a tire static collector spring that came stock on my '55 Buick and prolly a lot of other cars back in the 40's & 50's. It was mounted between the front wheel grease retaining cap and rode on the end of the wheel spindle.
The springs around drums are not just a GM thing. They came on all the "finned" brake drums of the early 30-40s era as this set of 39-41 Lincoln Drums, that I am runing on my coupe. They also can be found on the Stude drums that are finned. (havent seen stude drums upclose but told they had springs...) Here are the lincoln drums (with a Wheel adapter mounted on it..) Pretty cool eh?? Got these from Rory Forbes (R&C NOV '06 Cover) dad Ray, as he just wanted the backing plates! You may beable to find the springs on Ebay or some NOS Ford/GM supplier. They are used for harmoics as mentioned eariler.
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