VDO Tacho setting

[discodevil94]

Hi, Can anyone tell me what rpm my 300 tdi 1994 130 dual cab should be doing at what speed?
I have thought of getting it calibrated but why re-make the wheel,
someone has already be where I am at and figured it out right?:)

[slug_burner]

not the best method of calibration as the speedo itself can be out 10% or there abouts. when comparing to a gps my 300 tdi 110 reads higher than the speed the vehicle is doing.

[discodevil94]

Are you referring to ground speed or just the spedo gauge being out 10% ?
How else do you check the accuracy?

[d2dave]

Are you referring to ground speed or just the spedo gauge being out 10% ?
How else do you check the accuracy?

If you want to find out speedo accuracy find a speed camera. Make sure you are speeding and note the speed on your speedo. When the fine comes in the mail you can compare the readings.:twisted:

Dave.

[slug_burner]

I was referring to the speedo speed vs that on the GPS which I take to be ground speed.

The way to calibrate a tacho is to use an already calibrated tacho to compare against. Alternatively you can use a signal generator to produce a pulse train at a known rate and compare that against what the tacho reads. With diesels you will need to take into account the size ratio on the alternator pulley to the crank driving pulley.