Speedometer help please !!!

[ischmitz]

Please can someone take a look at a 74 mechanic speedometer and tell me the calibration number embossed or printed on the back. I should say something like

k=## or m=##/m where ## are numbers of some sort.

or something similar. It might be a sticker on the back or printed on the back. I need to know how many times the mechanic speedo cable rotates per wheel rotation or per kilometer or per mile. I am currently in Germany sourcing parts for a conversion from mechanic to electronic speedo and NEED this number.

Ingo

[k9handler]

Ingo,
I would if my car was here...so maybe if you contact Harald he will pull it out and look for you? Just a thought, if not I will have the car tomorrow afternoon and I will look then.

[1974carrera]

Ingo,

I just pulled the speedo in my '74 U.S. Carrera and looked at the back of it. There is no sticker on it and the only thing embossed in the metal case is VDO Made In Germany . I was using an inspection mirror so maybe I'm not looking in the right place?

[ischmitz]

Bob, thanks for your help. It might have been a sticker that since fell off. Who knows.

k9handler, I asked Harald to take a look but he was too busy. I might come up to Wegberg tomorrow to take a look myself.

Hopefully, one of the speedometer place is able to answer my question. I just need to know how many times the speedo cable rotates for one full rear wheel rotation of both wheels.

[Joeaksa]

Ingo,

I have two older cable model speedos here. Both are in kilometers and were from my cars when living in Berlin/Osnabruck.

One says nothing on the back but the born date of 3.73.

Then second one says in a stamped triangle:

52 in the top part, then on the bottom A.70.

No other markings on the back. On the side of the units is stamped:

#1. T w+0,5
3 73 26/30/1

#2. w=0.5 4.70
35/51/1 t

Both units are the same part number: 911 641 501 00

If you need more info, pls email.

JoeA

[ischmitz]

So far I found the folllowing:

The speedo gear ratio for the 915 should be 1:1. One rotation of the rear wheels equals one rotation of the speedo cable. The mechanic speedometer expects about 810 rotations per mile or 506 rotations per km.

I got myself an adapter that produces 8 pulses per rotation. This gets me to 4052 pulses per km which is the calibrated value on the new electronic speedo. I´ll see if I can get this to work.

Ingo

[k9handler]

Hay Ingo....I just missed you at Haralds! Maybe next time we will meet. SO what did you think of the ride? All I can say is WOW...that is HOLY CRAP FAST!!!!