Tim
generally the recalibration is a change of gear in the gearbox that fits on
the end of the speedo cable. The speedo indicates speed based on the revs
the speedo cable is doing.
I would think you only need to change the cable if it doesn't reach or wont
fit the OD gearbox.
Speedo shuld not be affected by positive or negative earth.
If your cable fits a quick check is to drive over a measured distance say
5milesor Km. and note the Odometer reading. the ratio of actual distance
travelled and the indicated distance gives the error. A speedo specialist
can tell you how many teeth are required on the gearbox drive gear to get it
right. If you fiddle with the speedo to make it read the correct speed the
odometer will still be off.
The workshop manual may even specify the gears to use.
Speedos indicate speed at a standard number of rpm on the speedo cable and
the gear selection in the gearbox matches this. Manufacturers do not
individually calibrate every speedo in the car but alter the gears in the
gearbox to accomodate rear end ratio changes.
Also the speedo drive is after the overdrive so if the rear end ratio has
not been changed the driveshaft will still be rotating at the same speed,
just the engine will be at lower rpm.
Try my easy check and see what you get. It may be that you need to change
nothing.
Keith
55 Californian
----- Original Message -----
From: "Tim Stiffy" <tstiffy@pulsenet.com>
To: <alpines@autox.team.net>
Sent: Sunday, February 09, 2003 8:37 AM
Subject: Overdrive Speedometers
> Hi List,
> Last fall I finally installed of my overdrive in my S1 (B9009694). To
complete
> the project, I need to replace the speedometer with one calibrated for an
> overdrive. My SI has the standard 3.88:1 rear end. The transmission I
> installed is a SV. My question to all is, what S/N speedo do I need. Do I
need
> a speedo for a SI or SV?
>
> Here is what the parts book lists for overdrive speedometers in MPH:
> S/N 6117/02 - Up to B9105974
> S/N 6117/11 - From B9105975 up to Series 3
> S/N 5324/18 - Series 3
> S/N 5324/23 - Series 4
> No listing for Series 5
>
> Will it make a difference with my S1 being positive ground?
> Sunbeam Specialties list different speedometer cables for SI thru SIV, SV
> (non-overdrive), and SV (with overdrive). Do I need to change the cable
also?
>
> Can anyone help? As always, I'm appreciative to all replies.
>
> Tim
> Bentleyville, PA
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