<VV> Conversion of speedometer to read kilometers per hour

[jryall at juno.com]

To convert a speedometer to read kilometers per hour, wouldn't one just
renumber the dial?  I mean mark 62 mph as 100 (KPH), and space the other
readings to match.

John Ryall


On Wed, 20 Sep 2006 19:04:48 EDT BobHelt at aol.com writes:
>  
> In a message dated 9/20/2006 11:49:46 AM US Mountain Standard Time,  
> 
> dmonasterio at megared.net.mx writes:
> 
> I am  playing with my Rampside's speedometer to make it reading Km 
> instead of 
> miles  (have several disassemblied GM speedos) but, as a starting 
> point, I 
> don't  remember two things:
> 1.- How many turns on the speedometer  shaft for each mile ?
> 2.- I remember that the drive gear  pressed on the diff's pinion 
> shaft has 
> multiple threading but, don't remember  if 3, 4 or 5 threads. 
> This is for doing the necesary math in  choosing gears.
> 
> As always... thanks in advance for any  input.
> 
> Daniel Monasterio
> 
> 
> 
> 
> Hi Daniel,
> I don't know just how much help I can be, but here's what I  know.
>  
> Early model Corvairs (and i believe FCs too) odometers were 
> calibrated for  
> 1001 cable revs per mile. This resulted, as I remember, in a speedo 
> and odo 
> that  was about 5% fast. However, again as I remember, the spyder 
> odo was geared  
> differently. I'm not sure how,  just that when I was "repairing" my 
> spyder  
> odo (years ago) , the standard gear spun the odo way too fast.
>  
> The FC's used two different pinion gears with eight threads. A large 
> one  
> (1.884 in. diam) was used with 20, 21, and 22 tooth driven gears. 
> The smaller  
> pinion gear (1.766 in diam) was used with the 23, 24, 25, and 26 
> tooth driven  
> gears. For application of these different driven gears, see my 
> article printed  
> in the Commumique a year ago or so. I don't know exact date. It's 
> also in my  
> Corvair Secrets book.
>  
> Frankly, I'd suggest that you follow Seth's recommendation and look 
> for a  
> metric speedo.
>  
> Good Luck,
> Regards,
> Bob Helt