964 Speedo Sensor

[1972_911T]

Anybody know how the speedo sensor works on the 91 on 964's. I know upto 91 it works of a sensor on the diff housing same as the 87-89 911's, but from 91 they no longer have this and on the trans I have it has no visable sensor for speed.

Steve

[ischmitz]

It's off the front ABS wheel sensor. There is a special box in the relays sections that downconverts the ABS sensor signal to the 8 pulse per wheel rotation speedo signal.

[1972_911T]

Thanks for the responce, thats what I was hoping I wouldnt hear. Anyone know of any alternatives to get a speedo to work if you dont have a trans sensor? The only other option I can see if to have the diff casing changed for one with the sensor hole and have the magnetic wheel fitted to the diff. Not an ideal solution as the ring and pinion would need to be re-adjusted.

Steve

[MBEngineering]

HI give me a ring as i may have a solution to the speedo pickup,

regards mike

[ischmitz]

I sourced a little gearbox the size of a matchbox vom VDO/Kienzle in Germany that mounts directly to the mechanic speedo output of the transmission. It's part of the fleet management line of products. It delivers the 8 pulses per revolution. It is a tight fit but works fine. Unfortunately, I have not been able to find a source here in the U.S. so far.

The widely available sending units that you splice into the speedo cables to retrofit GPS systems into older cars typically deliver only 6 six pulses per revolution. I don't know if one could modify either the sender directly or come up with a frequency doubler and an 12/8 divider. Someone with solid signal processing background could most likely rig up something with a couple of OpAmps and logic gates....

Or you can have North Hollywood Speedo recalibrate the Speedo to 6 pulses per Rev.

[1972_911T]

The problem with that little device is I dont even have mechanical drive on this trans. Think I may have to look at an ABS style sensor on one of the wheels then try and get someone whos into electronics to help me convert what ever signal it gives off into 8 pulses per rev. Would be even better if I can get a 964 drive shaft in as that would have the ABS notches already on.

Steve

[mmasse]

ischmitz,

any contact info for the source of this piece. Maybe a website, or phone number?

Thanks

[ischmitz]

Steve, the 964 C4 91- has an electronic module that does exactly what you need. It converts the ABS signal into the speedo pulse. It is a simple frequency divider that downsamles the ABS sensor signal. It sits on the relay pannel. Part number 964.618.221.00

Mario, the device is made by VDO/Kienzle. Unfortunately, I never found a web site or type information online. I bought it at a shop in Germany that deals with professional speedo setups and loggong for trucks and busses.

Cheers,
Ingo

[hifeverz]

Ingo:
I read your OLD post of 2003 where u converted your '74 Targa with mechanical drive speedo output and need to use the 964 Speedo. You mentioned a VDO device to get electronic signal to the 964 speedo. Have u since found other better solutions? What is the best way to do the same as I too have a '74 911 and have, in 2005, installed the 964 Speedo. I tried using commercial adapters for mechanical to electronic output and they are way off. I think that the pulse output is incorrect(as I've also read your other posts). Please advise if you can. My email address is sotemp@yahoo.com

Thanks for your time.
Hz

[ischmitz]

Hey HZ, same thing as my answer over in the other thread. Your alternatives are to upgrade to a later tranny with electric output or find a similar device here in the U.S. (you need 8 pulses per ref.) or come up with a home-made solution. There was one post here a while back from a guy who used little metal angles vlamped to the CV joint with a hose clamp and a hall sensor. Pretty cool solution. The hall sensor can be bought from digikey.com and the rest is basic home depot stuff. Worked great and pretty ingenious. Do a search. It was on the 914 board here.

BTW, depending on your schedule I could take a look back in Germany at that shop during my next trip over there during the holidays. No garanties but if you are interested drop me an email or PM me. I think the thing was somewhere around a hundred Euros - not sure. I don't know if that shop even exists today. But you never know.

Ingo

[RR711]

Does anyone have info on what is needed to convert the electronic signal from an "84 SC 915 tranny to the signal required to make a 964 speedometer work? I know it has beemn done and the info is out there. Anyone?

[ischmitz]

Nothing but a simple wire. Signals are the same.

Ingo