Quote:
Originally Posted by Dannydangles
During testing the tach seems correct at idle 650rpm ish but reads low at higher rpm.
Dan
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This is not a result of putting in the wrong number of teeth. If you put in a lower tooth count then the rpm would register higher across the board. The opposite if you input a higher one.
Sorry I know that doesn’t really help you out. But, if the tach is just a frequency counter, getting it right at idle should make it right everywhere.
ETA - if I had to guess it’s 144 teeth. VDO put the full scale pulse output on the Back of the W123 tachs. 6000 for the old crank pickup systems and 14000 and for the ring gear systems. On your W124 tach I can decipher a sticker that says 12/14 400 Hz. My guess is that is German for 14,400 Hz full scale which would suggest a 144 tooth ring gear. Just a guess tho.