Date:          Sat, 22 Mar 1997 19:09:50 -0800
Subject:       Re: <280> Speedo Error

The following is from my historical file on speedometers.  You can 
change the relationship between the rear wheel circumference and the
speedometer by changing the pinion in the transmission.  If you need
any help in the mathematics of this change, let me know. Regards, Dick

         Speedometer Pinions 
        Tue, 21 Jan 1997 12:42:06 -0500 (EST) 

Just replaced my speedometer pinion gear and replacement unit has one
more tooth than the old one.  Did a little homework and discovered
that Nissan actually makes ten different pinions, each with a
different number of teeth.

Obviously the increase in the number of teeth will result in the
slowing down of the speedometer reading.  My question is how much?
Other question is at what point would you WANT to change this gear.
Naturally tire size (increasing or decreasing) would be one reason.
Anyone have any other specific examples?  Here are the different
colors and number of teeth.  How much (in MPH) difference are we
looking at per tooth added to the gear does the MPH decrease?

16 tooth Speedo Pinion (yellow) (*My original)
17 tooth speedo pinion (black)  (**My replacement)
18 tooth speedo pinion (blue)
19 tooth speedo pinion (white)
20 tooth speedo pinion (red)
21 tooth speedo pinion (purple)
22 tooth speedo pinion (orange)
23 tooth speedo pinion (green)

16-19t require standard sleeve assembly
20-23t require special sleeve assembly

Thanks Doug Manney
IZCC #337