I've owned two 64's. Both appeared to have original equipment brake drums on the front. The external springs (which I believe are there to dampen noise) were different side to side. One side has a finer round wire banding spring and the other a beafier flatish wire spring. Any comment? Was it random or different on purpose?
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Re: Brake Drum Springs
Yes, the springs are there to attenuate brake squeak. I have also observed the two different spring material geometries, so I assume both were approved by Chevrolet Engineering. I have also observed drums without the springs. I can't recall now if some of my original J-65 drums didn't have springs or if some of the GM replacements were missing same. In any event, I had enough to place the anti-squeak springs on all four drums.
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Re: Brake Drum Springs
I believe that the finer round wired spring is a replacement part, whereas the flat stock spring is the original equipment. The finer wire round stock springs are/were available from GM as PN 3694290 for about $9.00 each.Comment
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Re: Brake Drum Springs
My 62 also has the flat type springs. No telling if the drums are original, but they appear as though they certainly could be. They have the right "patina'.Comment
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Re: Brake Drum Springs
If your drums are stamped or debossed in the casting with a maximum diameter they are post '68 replacements.
Original or pre '68 replacement drums would not have a maximum diameter indicated as this was not a requirement until the first of the new FMVSS that went into effect on January 1,1968.
As far as the anti squeak springs are concerned my guess is that they were were used interchangeably. It's not that uncommon for vendor sourced parts or parts from different GM manufacturing plants from to have different physical characteristics, but this has caused lots of problems in judging trying to figure out what is "original" and what is replacement. In some cases the answer is both.
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