Can anyone tell me the application for Chevy number 3869532 (cast number on a pair of brake drums)? I was told the drums are part number 3872326 for 63-64 Corvette, but I would have thought the casting number would match the final part number on brake drums.
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Re: What does drum 3869532 fit???
Wayne------
The CASTING number found on most GM-sourced brake drums is usually NOT the same as the finished PART number. That's because several different drums may be manufactured from the same casting.
At the moment, I cannot tell you what PART number (or, consequently, what application) that this drum services. GM PART #3869537 is certainly one possibility, but there are others. GM #3869537 was a part number for brake drums used, front and rear, for C1 Corvettes with metallic brakes and, rear only, for C2 Corvettes with metallic brakes.In Appreciation of John Hinckley -
Drum 3869532 for '63???
Thanks, Joe, let's see if anyone out there can verify that 3869532 (NOT .. 537) drum casting number (on the raised bead of the drum very near the outer circumference) is the right casting number for a 1963 or 1964 Corvette front brake drum. I don't want to pay a lot of cash for a discontinued brake drum if I'm not getting the real McCoy.Comment
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Re: Drum 3869532 for '63???
Wayne-----
GM PART #3872326 was the part number first used for 1965 Corvettes (without disc brakes), although I'm fairly certain that it will also fit 63-64 Corvette front brakes.
I don't have my references available at the moment, but, as I think about it, the CASTING number 3869532 or PART NUMBERS 3872326 or 3869537 almost could not have been ORIGINALLY USED for a 1963 model, although they could be REPLACEMENT numbers. I don't think that any of these numbers would have been issued as early as 1963.In Appreciation of John HinckleyComment
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Hey, I can add to the confusion
Wayne - I still have the two original rear drums from my J-65 SWC. One has 3752623 debossed and was clearly part of the casting. The other has 3828688 in a similar location, but it almost looks like it could be die stamped. I'm certain these are the original drums. I had an e-brake cable drag problem in '68 and had the cable replaced along with the rear shoes, but the drums were not changed. (I just checked the receipt).
The replacement J-65 drums I bought in the mid-seventies were sold under p/n 3869537, but the drums have different casting numbers 3869538 and 3985845. Isn't it interesting that one of the casting numbers is "later" than the end item part number. To the best of my knowledge the only difference between base and J-65 drums was a finer finish on the J-65 friction surface, and I assume either a base or J-65 drum could be machined from the same casting.
Someday, I hope we can figure out all these different casting numbers.
DukeComment
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3869532 is the casting number of the replacement front J-65 drums I purchased in 1977. These are 2.5 inches wide. The originals are casting number 3728671.
DukeComment
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One more thing
The wear limit on these drums is (I think) .090" so the guy might be selling a boat anchor. One set of J-65 shoes could just about wear the drum to the limit, so the guy might be selling a boat anchor!
DukeComment
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Re: More
Duke-----
The situation that you describe regarding the casting numbers apparently "post dating" the part numbers is not so unusual. There may be numerous castings which GM could machine into a finished part number. And, the casting numbers could change over the years, but the part number for the finished part could easily remain the same. Also, and conversely, very often an "early" casting number could be machined into later part numbers or, even, a succession of later part numbers.
So, the information provided by casting numbers can be very ambiguous. However, what they can tell you about the originality of a particular part to a particular year model car is this: if the casting number significantly "post dates" the number series issued about the time the car was produced, then there is a high liklihood that the part is not original to the car. Now, bear in mind, that this is a "rule of thumb" and not absolutely definitive since part number issue dates is far from an "exact science". However, I've found this system to be pretty reliable.
And, this is not to say that a particular finished part produced from a later casting number is not correct for the car with respect to configuration. It just says that this particular part was probably not ORIGINALLY INSTALLED on the car.In Appreciation of John HinckleyComment
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Thanks, Duke, this is excellent information.... it would appear then that the 3869532 castings are in fact front brake drums that are mid-70's service castings, not original castings, to fit the '63 Vette. I probably ought to buy them. Any idea what a reasonable market value is today on these drums?Comment
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Re: More
Haven't got the foggiest what they might be worth, Wayne, but before you buy, get the guy to give you the ID of the friction surface, measured with a suitable disk brake drum gage."Max. Dia. 11.090" is debossed in the casting.
DukeComment
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