Gas Tacho / Revcounter Conversion to Diesel W terminal

[Rabbit on Roids]

:O what cars came with that fancy MPG gauge? i got one in my MFA, but that would be cooler, or is it just a vacuum gauge?

[Andy@React]

the clocks are from a mk1 GTi, it has a vac connection on the back (well, a pipe connection anyway!) its just redundant on my clocks (obviously)

[avocado_tom]

Ok, I know this is going to sound a bit daft, but please bear with me.

I would like to build a circuit to convert a VDO tach to use the W terminal (as opposed to using an induction system).  I'm planning on buying a tach off of e-bay or some such.  I know I can use Smokey Eddy's method (and still might) but was wondering how I would use one of the other circuits posted if I wanted to...

I guess my question is: The other circuits appear to be specific to modifying your stock gauge cluster for a tach.  I don't have a stock gauge cluster (this is a conversion project) and therefore don't have the eight connections to the instrument cluster board (labeled 1-8).  I assume, therefore, that those are not something I can use and therefore I should just investigate using the Eddy method?  Or...

Any help in clarifying would be appreciated...

[crewcabcaddy]

And for those of us in not familiar with all the different types/styles of capacitors:

I am in the USA so I first went to Radio Shack and they did not have the appropriate size resistors or capacitors...(small town  ).

So did a bunch of web surfing and found Mouser Electronics (http://www.mouser.com/Passive-Components/_/N-5g73/) to have the best web site and best available stock for small purchasers like me.

Resistors are pretty easy to sort out...I selected 1/2 watt, 1% tolerance, metal film, axial, like you would get at Radio Shack.  I purchased 4 of the lower ohm needed and 4 of the higher ohm needed (I swapped from the tach board where possible so only needed two new resistors per tach conversion).  I purchased 4 of each to work on additional tachometers when/if needed and in case I messed up the first one!

Capacitors seem a bit more difficult to choose, and those more knowledgeable than me should chime in here:
It appeared to me that polypropylene film was the best type for smoothing signal and oscillations.  I chose radial, metalized polypropylene film with the appropriate ratings (0.010 uF aka 10 nF and 0.047 uF aka 47 nF) and appriate space (pitch) between the wires (10 mm for the 0.01 uF and 15 mm for the 0.045 uF).  FYI, the F stands for Farads...the unit of measure for capacitance.  I used 250 volt for the 0.047 uF cap and the only voltage available for the 0.01 uF cap that I chose was 400v.  I kept tolerance below 10%.  the 1431 series (on Mouser's website) worked best for what I thought I needed

I bought 4 each of the two resistors and of the two capacitors and the total with UPS ground shipping was just over $10 U.S.

Hope this helps some of you find the right stuff.

[crewcabcaddy]

1996 1Z TDI in MK1 Rabbit:

Made the tach mods and had trouble with the needle not dropping back down to idle RPM...on a whim attached ECU tach signal wire directly to signal terminal on an unmodified tach (with cluster hooked up so it had power and ground already)....and it worked perfectly.

So, if you have this VDO MK1 tach:




And you are working with a TDI motor...try hooking the TDI ECU tach output wire directly to the signal terminal...or to slot 5 on your cluster electrical connector.

There are other circuit boards out there for these tachometers, so not sure if it would work for others...but worth a shot before you modify it.

[Apsik]

OK....at the behest of others interested....here is the part number of the Ford inductive pickup I used for my tacho conversion........................... XR3Z-7H103AB ....retails for $23.90 stateside....as far as I know this pickup can be found on all 99' and newer T5's, T45's, and 3650 manual transmissions used in Ford Mustangs....have fun!!

I have tried your idea but it does not work for me. I have tryed it twice already.
I have imported the sensor from USA.
I have equiped the crank pulley with 2 nuts (180* apart)
I have made the bracket for the sensor.
One wire to the Ground, another to the tacho (red/black wire - terminal 1) and it does not work.
Multimeter detects 0,8Volts when on the "AC Volts" setting. CE1 tachometer rev counter - frozen
I have tested it the 1st time on my 1.9D. It didn't work and I simply bought the diesel tachometer (it is the easiest way in Euope I gues).

Lately I have SWAPed the 3.6 FSI into my friends MK2 Golf and the last thing of the puzzle is to make the CE1 rev counter work. So I have tryed the Ford Sendor Idea again and no luck so far. What am I doing wrong? Any ideas? Or maybe the techometer is differend
The alternator on the 3.6FSI has the W terminal so probably I will buy the Universal Diesel Alternator Tachometer Interface From Dakota Digital to make the rev counter work.

[jimbote]

OK....at the behest of others interested....here is the part number of the Ford inductive pickup I used for my tacho conversion........................... XR3Z-7H103AB ....retails for $23.90 stateside....as far as I know this pickup can be found on all 99' and newer T5's, T45's, and 3650 manual transmissions used in Ford Mustangs....have fun!!

I have tried your idea but it does not work for me. I have tryed it twice already.
I have imported the sensor from USA.
I have equiped the crank pulley with 2 nuts (180* apart)
I have made the bracket for the sensor.
One wire to the Ground, another to the tacho (red/black wire - terminal 1) and it does not work.
Multimeter detects 0,8Volts when on the "AC Volts" setting. CE1 tachometer rev counter - frozen
I have tested it the 1st time on my 1.9D. It didn't work and I simply bought the diesel tachometer (it is the easiest way in Euope I gues).

Lately I have SWAPed the 3.6 FSI into my friends MK2 Golf and the last thing of the puzzle is to make the CE1 rev counter work. So I have tryed the Ford Sendor Idea again and no luck so far. What am I doing wrong? Any ideas? Or maybe the techometer is differend
The alternator on the 3.6FSI has the W terminal so probably I will buy the Universal Diesel Alternator Tachometer Interface From Dakota Digital to make the rev counter work.

power and ground to the tach? ....one lead of inductive pickup to the input "signal" terminal on the tach the other lead of the pickup to good ground....I don't think it has anything to do with the tach...I tested using a ford ranger pickup tachometer....do you have any pictures of your setup? ...how much clearance do you have between the sensor and the nuts?

[jimbote]

as far as the wiring very simple....one leg of the sensor goes to the tacho input....one goes to ground....of course you need battery positive and ground to the tach

So the wiring is *four* wires.  Ground for the pickup, the + from the pickup to the tach, ground for the tach AND +12V to the tach.   Do you have the +12V, ground and the signal from the pickup all connected to the tach?

yes four wires that's it....one leg of sensor to ground, one to tacho input.... the tach needs power and ground...simple.....make sure the gap is around .020 between the sensor and "reluctor" nuts

[RabbitJockey]

just converted over a motor meter cabriolet tachometer for diesel, haven't tested it yet but once i do and know it works i'll post it here

[RabbitJockey]

this is to convert a cabriolet motometer tachometer into a vw diesel tachometer

board with tracks drawn on to it (i'll add proper parts lables soon):



Original diagram i drew to make it easier for me to understand to convert it:



and i took my diagram and used to figure out how to make the cabby board match this:



directions

1. replace d1 with a jumper wire
2. remove r2 and r3
3. replace r1 with a 15k ohm resistor (you can use the original r7 for this)
4. replace r4 with 191 ohm resistor (i used 2 100 ohm in series)
5. replace r7 with 10k ohm resistor
6. replace c1 with a 10nF capacitor
7. replace c2 with a 47nF(.047uF) capacitor
8. replace c3 with a 47uF capacitor (i used electrolytic how ever i just realized that i only removed c3 and the tach still worked when i tested it, so i am going to guess it is only there for filtering because it goes from the signal input to ground, replace it anyway just to be sure)
9. replace c4 with a 3.3uF capacitor (i used 3 10uF capacitors in series)
10.  calibrate!!!! i usually put the pot on the end of a long wire that way i can fully install the cluster and then adjust the tachometer as i drive, and then when i am finished tuck the wire away neatly behind one of the dash blanks
11.  enjoy your accurate fully functioning factory appearing diesel tachometer

[GEE-BEE]

How about a pic of the complete cluster when done on here...

GB

[RabbitJockey]

almost done, i am quite proud of this one, i'll switch pictures once its totally complete

Guys instrument cluster, meister gauge faces, and also will have all blue led light, gonna be something for everyone to droll on, i know i have already.




with blue leds on:

[RabbitJockey]

here is the one i have in my jetta coupe, in person it is hard to tell that there is a sticker where it says sucks

[GEE-BEE]

Thanx it's perfect

The jetta dash is going in while I go to Japan and Boracay island

Jan 19/ 30

GB

[regcheeseman]

Guys instrument cluster, meister gauge faces, and also will have all blue led light, gonna be something for everyone to droll on,

If you've done a board mode then the revcounter spacings will be all wrong - it'll never calibrate properly. The diesel tacho should indicate 5500 rpm at full scale deflection.

If anyone wants fully vectorised clock layout files - just ask.