>I am putting a Datsun 5-speed in my street car. What are my options as far
>as
> the speedometer is concerned? TIA.
Bud,
Rivergate has a $125 conversion kit, consisting of a special cable and a
90-degree angle-drive to correct the rpm of the cable to retain the stock
speedo. They have a form to fill out so that they can gear the adapter
correctly for your diff and tires. One of these days I might actually get
it...
They also tell you in their installation instructions that you can take a
Datsun cable and use it with a Spridget threaded connector at the
speedometer end, but that it will tell you the wrong speed and distance.
I have found that with a 3.90 diff and Yoko Avid TS 175/70R13 tires, the
speed in fifth gear (about the only time you are really concerned with your
speed you WILL be in fifth) will be RPM/100*2. In other words, if the tach
says 2000rpm, you are doing 40mph (2000/100=20, 20*2=40); very easy
conversion.
Another alternative is to buy a Sigma Sport Bicycle speedometer (I use the
discontinued BC1200 model), readily available on eBay. You will need to
extend the wires, but there are only two conductors involved. Don't be
tempted to use the wireless sender; I understand that they do not work well
in an automotive environment since there will always be a sheet of grounded
metal between sender and head. Do NOT set it up to read driveshaft rpm. Yes,
it will seem to work fine, but at speeds over 60mph, the pulses per second
are too high for the odometer function to calculate and your speed will be
correct while all of your distance functions will be wrong. Ask me how I
know ;-) My third attempt was to JB-Weld a magnet to the outside of the RR
brake drum and mount the reed switch to a bracket attached to one of the
backplate mounting bolts. Works great. With this you have functions like
average speed, max speed, odometer, trip odometers, clock, stopwatch, etc.,
depending on the model purchased. Mine has no backlight, however, so I
generally just run from the tach readout when driving at night. The
speedometer reads up to 199.5mph and is configurable for wheel sizes from
around 1/8" to about 8'... Why? Only the Germans know!
David Lieb
1972 5-speed
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