Schwinn Serial Number Stamping

[momo608]

Luck of the draw, my two Sports Tourer's 72 and 73 frames and 76 Superior frame look as bad or worse than that black 80 cruiser. They will undoubtedly be almost invisible after a base coat clear coat paint job. The 73 already is. I picked out the serial numbers with a needle just to be sure that they were absolutely clean before the paint went on. Primer, sealer, several base coats and then the clear, they did not have a chance.

 

[Jeff54]

I don't think you can ascribe that to a given year or a specific change over time. I'd say the stamps were affected more by the operator and machine settings, combined with wear on the dies. Given they stamped more than a million bikes some years I'd imagine the dies would have to be changed from time to time. For example here is a '73 Continental with a very light stamp:

Yeah, it was that up-side-down blue 80's cruiser that kicked me off, as its stamp sucks in all directions! [grin] , and my 80 black seems not to swell, but, I looked at others too. This set on a late 80 frame 1981 build, and it's tight..

Come to tink on it, I'm tinkin now, that, errors in such things devalues a collectible as, peps like accuracy as much as best original paint too. I mean, like, if they'd put decals on a bike as crappy as some numbers were, who'd pick that 1st? ? Who's Choice bike was built on 'Hangover Monday', and loves it? [grin]

BTW CDS, your's is an MR, my black is an HR, and so, this below, truly really is 'close' in time.. just 1,705 lower, like, within a day or so. An me bets that your build date, on your badge, is 81 too.

Regardless we're getting side tracked, while that brown set Metacortex posted today raps the subject tight, like earlier, the green, there's no way they'd been stamped on flat pre-molded metal.

 

[Metacortex]

Somebody who is an SBF member should point them over here for more accurate information http://www.schwinnbikeforum.com/index.php?topic=33816.0

 

[GTs58]

All I'm seeing from the link is this.

 

[Intense One]

1975 Speedster with stamp off centered as well

 

[Metacortex]

View attachment 287882 1975 Speedster with stamp off centered as well

From the pic it looks like the serial number starts with "LJ", which dates the frame (or at least the head tube) to Nov. 1973. However the bike is painted Opaque Red (a 1974 only color), which means it wasn't painted and built into a bike until early in 1974. That of course makes it a '74 model, here is the catalog page for that year:

 

[jnewkirk77]

Here's the SN from my new '76 Continental ... I thought it was a little odd that the CM isn't lined up with the numbers. They sure nailed that "3" in there good, though. :eek:

 

[Intense One]

From the pic it looks like the serial number starts with "LJ", which dates the frame (or at least the head tube) to Nov. 1973. However the bike is painted Opaque Red (a 1974 only color), which means it wasn't painted and built into a bike until early in 1974. That of course makes it a '74 model, here is the catalog page for that year:

From the pic it looks like the serial number starts with "LJ", which dates the frame (or at least the head tube) to Nov. 1973. However the bike is painted Opaque Red (a 1974 only color), which means it wasn't painted and built into a bike until early in 1974. That of course makes it a '74 model, here is the catalog page for that year:

Agreed, Metacortex...the Speedster is a '74 model built late '73 in one year only Opaque red. I have a stingray with JK stamp also a '74 model built in Sept. '74 and in one year availability opaque red too

 

[prax garcia]

Referencing this topic showing an upside-down serial number stamp (and I've seen and heard of several others http://thecabe.com/forum/threads/someone-please-explain-this-photo-for-me.85709/

I just acquired the May 1978 Schwinn Reporter filling in a gap in my collection and finally have located definitive documentation about how and when the serial numbers were stamped in the frame manufacturing process:

View attachment 607409

View attachment 607410

As the article states the serial number was stamped as part of the very last operation in the headtube manufacturing process (along with drilling the badge holes). Considering the shape of the headtube and the stamping process you can see how easy it would have been to stamp some upside-down.

Thinking about this further, I've never seen or heard of a fillet-brazed bike with an upside-down serial number. The fillet-brazed bikes would have had this stamping and drilling done on a bare tube with no protrusions (meaning no up from down other than the serial number location). Since in that case the serial number would be the only indication of up or down and since they were subsequently hand-brazed it is no wonder you never see a fillet-brazed bike with an upside-down serial number. Comments anyone?

I have a 1970 Schwinn Varsity in campus green with an upside down serial number on the top left side of the head tube.

 

[Schwinn Sales West]

Wow, an eight year old thread and no one suggested the most plausible answer. Schwinn stamped Men's Frame Heads, and Ladies Frame Heads. The Ladies heads were only in one height. The Men's were stamped in several different heights (17&20", 22", 24", 26" frame sizes). The machining, drilling, and stamping were done on the loose parts "before the head was welded onto the rest of the frame. My thought is, this was "just easier", likely faster. If they broke off a drill bit while drilling the name plate holes, just toss the part, save the production time, they had another 1000 frames to build "that day".

Out of all the examples you have presented of "upside down stamped serial numbered frames", NOT ONE is on a ladies frame? The men's frame heads are symmetrical, and it would be very easy to stick the part into the frame welding fixture "upside down". The stamping is not upside down, it's the frame head welded into the frame "upside down". It would be impossible to weld a ladies head upside down, and that's why you have no examples.

The stamped frame serial number was not a 17 digit DOT Vehicle Identification Number. It was just a number that helped a dealer, and a customer have a way to help identify the bicycle from another one like it. The dealers and sometimes Police Departments used the numbers for registration purposes. Schwinn did not hold the stamped numbers in any great importance. When the potential for CPSC product recalls came up in the 1970's, Schwinn adopted the date of manufacturer system by stamping the date on the name plates. If Schwinn placed the importance of having the exact correct dated stamped serial number on the frame there would have been no reason for the financial expenditure of adopting a stamped name plate program. Any Schwinn Dealer of the 1970's will confirm that when they placed their orders, they received a confirmed shipping date. They routinely ran at three to four weeks out. That means they knew, and planned for how many bikes were going to be built on any particular day "ONE MONTH" from the date of the dealer order. The guy that stamped the serial number knew how many he had to make, call it a quota for the day. The next guy that placed the finished heads into the frame fixture had the same quota number for that day. As a Schwinn Dealer on the other end of that pipeline, I had already sold and taken deposits for the bicycles that had not yet even been built. There was pressure to hit the quota number in order to make everyone happy.

John