speedo musings

[jlagnese at massed.net (John Lagnese)]

I had the same loud noises from the speedo when cold. I tried to lube 
the speedo and changed the cable to no avail. The only help was to move 
the cable when it was making noise. I changed the oxs counter in an 
unrelated fix and lo and behold, noises were gone! Coincidence, maybe, 
but I don't think so.
John
87 16V

Michael Abatzis wrote:

> note: original post broken up. see subject "my car is fast again" for 
> more exciting speedometer related insights!
>
> 1) anyone know how to calibrate a speedo? the mechanism's interesting, 
> for those who've never seen it. there is no direct connection, through 
> gears or otherwise, between the speedo cable and the needle. the cable 
> runs into a metal disk, which spins within, and doesn't actually 
> touch, a (magnetized, i assume) metal cup. the cup is connected to the 
> needle, and the whole thing is preloaded with a small coil leaf spring 
> (like the kind in a thermostat). calibration is (i think) achieved by 
> turning the needle itself, which should affect the amount of preload 
> on the metal cup. this seems like it would be extrordinarily difficult 
> to calibrate, but hopefully it's something easy like "adjust it so the 
> needle JUST returns to the stop when moved". otherwise you'd need to 
> do something like "at this rpm, speed should be x mph". install 
> speedo, compare, take speedo out, move needle, repeat until you get it 
> right. this would be a colossal PITA.
> 2) the motometer and vdo units are very different. the vdo is much 
> lighter, and harder to dissassemble. i couldn't figure out how to get 
> it completely apart. the motometer was easy. the gearing systems for 
> the odometer also looked different, more than just the difference 
> between plastic and metal gears (the motometer has some plastic gears 
> in the mechanism also, btw, although these apparently don't break much).
>
> my car is fast! woo woo! as a side note, that screeching when the 
> speedo is cold is now gone. i don't know what the hell that was.
>
> -Michael Abatzis
> New Orleans!
> 1988 Scirocco 2L 16v RIP
> 1987 Scirocco 2L 16v...
>
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