how do I convert my mechanical speedo to an electrical?
 

:confused:
I once read a thread of someone who did the conversion, using a 964's speedometer. I also know that one way or another I can attach the electric sensor to my gear box. My question is, what do I exactly need besides the above? Is it a plug in? or how do I attach it? Do I have to make any modification to the gear box? It is a 915 from a 1974 Carrera.

I bet someone would trade you a trans with electric pulse out for your 7:31 trans....

The mechanical drive on the early 915 and the electric drive look very different. You might have to get into the case and change the shaft...seems like a lot of work..but someone like John Walker would know for sure.

You could just cut the cable and adapt a pulser on the stubby end of the speedo cable inside the tunnel that would send a pulse to an electronic speedo that is available from a number of venders. Might even be able to make t work with a stock VDO speedo, if you could range the pulse factor.

Why would you wnat to change it?

There is a hollow spot on the right side of the tranny case where the sensor goes, so it isn't an easy proposition.

What are you trying to do?

Tom

my speedo is not working so I want to upgrade whit a 964 RS Cup that I found in a local shop this one is 320 kms.

It would be cheaper and less of a PITA to send you broken one to North Hollywood Speedo or Palo Alto Speedometer to get repaired/refaced/recalibrated.

They can put any face on it you want, and your odometer will be correct.

Tom

pretty much takes a trans swap. there's a magnet ring on the side of the differential that works the sensor, that doesn't simply swap onto yours.