The earliest Kirby, Scott-Fetzer & Vacuette machines had those typical hard-rubber wheels of the era.
Originally all four wheels [or three, as in the case of the first Sanitation System machine] were of the same size and diameter.
Then when the first "Kirby Kirby" machine came out, the two rear wheels were the same thickness as the earlier wheels whereas the front wheels were quite fatter, rather fatter than the wheels which became the standard size on the 505 and up through the D80. The rear wheels were the same diameter, but not as thick.
Then with the 4C or 505 all four wheels were of the same diameter, and were the same size and diameter as all the wheels used until the Classic.
For some reason, with the 505-515 machines the two rear wheels were mounted inside-out, e.g., the flat 'outer' face of the wheel was turned inward and the side of the wheel with the inner 'lip' faced outward.
When I used to find old Kirbys with the rear wheels turned inside out, I assumed some lunkhead had done it and I'd always "correct" it.
But after finding so many of them like that over the years, I finally came to realize that that's how they were installed when the machine was new, and that those machines with the rear wheels in the "correct" manner had been changed later.
I'm wondering why they did this. The rear wheels fit equally well either way, and to me they look better when all four "match." I imagine the change from narrower rear wheels to all wheels the same size was a manufacturing cost-cutting measure and that makes sense. But I have never been able to figure out why the rear wheels were installed inside-out.
I have never seen any of the later 500 machines with the gray alathon (plastic) wheels turned that way, just the earlier vulcanized rubber wheels.
Anyone have any thoughts on this? Anyone else besides me lie awake at night sleepless, endlessly obsessing over this?! ;)
I have wondered the same thing. At first I also thought that some people may have put them on backwards, but most of the machines I have seen have the wheels on the back with the flat side facing in. I even noticed it in a picture in one of the Kirby owner's manual, so my guess is that is how it's supposed to be. I was thinking maybe it had something to do with making the machine more stable in the back, but then I would think having the flat side facing out would make it more stable. Just my thought.
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