electronic speedo and early 901 trans?

[degreeoff1]

hello all,

Can a electronic speedo from a 75 or newer car be made to work with my early 901 mechanical speedo trans??....

PS its in my 914...

Thanks

Josh

[Early_S_Man]

1976 models were first to get an electronic speedo ...

Two methods can be used:

1. VDO has a converter to change from cable drive to an electronic signal for the '76 and later speedos.

2. An opto-interrupter can be mounted to the side of the differential cover, and a slotted wheel can be bolted to the CV-joint to generate eight pulses per revolution of the CV and axle.

Here are some typical opto-interrupter sensors:

http://www.allelectronics.com/cgi-bin/category.cgi?category=435&item=OSU-54&type=store

http://www.goldmine-elec-products.com/prodinfo.asp?number=G14268&variation=&aitem=12&mitem=39

Here is the Omron data sheet:

http://oeiwcsnts1.omron.com/pdfcatal.nsf/PDFLookupByUniqueID/8B0566C69A59D72A86256FC80071B5E7/$File/D21EESX460P10305.pdf?OpenElement

Here is the Omron Tech Notes document explaining the operation and design guidelines:

http://oeiwcsnts1.omron.com/pdfcatal.nsf/PDFLookupByUniqueID/EFFD47E704CCD33586256FC8006311C6/$File/C21photomic0305.pdf?OpenElement

[degreeoff1]

Hmmmmm.....build my own eh? My creedo is just that when cost effective. How hard would the wiring for that be? I think I could manage the slotted wheel end of it.

or what would it take to convert the 911 tranny sender?

Thanks

Josh

[randywebb]

Hey - think of the wt. savings! You are replacing a mechanical cable with a wire.