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TD42 conversion done with blood, sweat and beers
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Discussion Starter #41 (Edited)
Correct me if im wrong im defiantly no expert i thought you put it on 6cyl in and 4cyl out and do the test signal and make adjustments until it hits the 2000rpm test signal. So maybe mine is wrong.
Yeah it had be buggered for a while too, but there seem to be a few different ways of making it work. On Bexi's thread I think it was, I saw he had to do something similar. Maybe if you bypass the ECU altogether then you can run it 6 in/4 out? @JFF45 ran his this way I think, but you use different wires to the one I did. But on another thread again, I read that the cam pos sensor by itself does not generate enough current to move the gauge- I don't know for sure. I'm just glad it's working now, and it should be reasonably accurate if the fella who wrote the formulas for that calculator knew what he was doing.

Edit: I did get the 2000rpm test signal when I set it at 6 in/4 out. That was when it was giving me about 1000rpm at 100km/h... dunno what it thought it was doing!
 

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Gu TD42 series 3 wgn
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OK got the Dakota SGI-8E and the tacho working perfectly... Did a bit of research and found a thread that suggested this calculator to work out what the tacho should be doing at a given speed, with the correct tyre sizes, differential, gearbox ratios etc. Gear Ratio Calculator (need to enter transfer case as Nissan Patrol TX12A).

This thread had the correct ratios for gearboxes, diffs etc. (see post# 2) Reference: Y61 Specifications

The calculator told me that with the FS5R50B gearbox that came in my ZD30 wagon (I had to enter the gear ratios manually as that option wasn't in the drop-down list), the 4.375 diff, the TX12A transfer case, and 265/75/R16 tyres, in 5th gear the engine should be doing 2453rpm.

With the Dakota wired in between the ECU and the tacho (pin 5, yellow with black trace) and set at 6 cyl in and 4 cyl out, I was getting about 1000rpm at 100km/h (speed verified by GPS).

Fiddled with the settings and eventually changed it to 8 cyl in and 10 out, and now at 100km/h the tacho reads 2450 or thereabouts- happy days. (y)
So i checked my rpm today at 100kph i sit on 1820rpm in 5th running 35s Td42 formaly 2003 zd30. I tried that calculator but cant get my head around it to check if i have set my Dakota properly.
 

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Discussion Starter #43
So i checked my rpm today at 100kph i sit on 1820rpm in 5th running 35s Td42 formaly 2003 zd30. I tried that calculator but cant get my head around it to check if i have set my Dakota properly.
@pootroll_4x4 OK so here's how I did it... First select the unit of measure (SAE or Metric):
520710


Then, assuming gearbox ratios given on the thread I mentioned above are correct for your gearbox, enter them as follows. There is an option to select the gearbox from the drop-down but the FS5R50B (the one that came with my ZD30) isn't in there:
520705


Then select transfer case:
520706


Then underdrive- I don't actually know what this is, I assume it's reduction gears or something so I selected "None":
520707


Then axle gear ratio- your diff ratio, which if it was a ZD30 should be 4.375:1 unless it's been changed at some point:
520708


Then your tyre size. You can be very accurate, and measure the actual diameter of the tyre, or get the numbers off the side like I did, or just do this (I reckon possibly the least accurate method):
520709


Down the bottom there are 4 charts with various numbers determined by the data you have entered. The one we are most interested in is the third one:
520711


You can play with the RPM numbers and it will give you different speeds. In the above example, with the combination of gears and tyres given, at 3000RPM in 5th gear you should be travelling at 135km/h.

In the example below, I have entered your stated RPM @ 100km/h (1820) and it has calculated you should in fact be travelling at only 82km/h.
520712


Therefore mate either the calculator is wrong, the variables entered are wrong, your speedo is wrong, or your Dakota needs fiddling with ;)

Without changing any of the other variables, I entered 2220 RPM and in 5th that will give you 100km/h.
 

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@pootroll_4x4 OK so here's how I did it... First select the unit of measure (SAE or Metric):
View attachment 520710

Then, assuming gearbox ratios given on the thread I mentioned above are correct for your gearbox, enter them as follows. There is an option to select the gearbox from the drop-down but the FS5R50B (the one that came with my ZD30) isn't in there:
View attachment 520705

Then select transfer case:
View attachment 520706

Then underdrive- I don't actually know what this is, I assume it's reduction gears or something so I selected "None":
View attachment 520707

Then axle gear ratio- your diff ratio, which if it was a ZD30 should be 4.375:1 unless it's been changed at some point:
View attachment 520708

Then your tyre size. You can be very accurate, and measure the actual diameter of the tyre, or get the numbers off the side like I did, or just do this (I reckon possibly the least accurate method):
View attachment 520709

Down the bottom there are 4 charts with various numbers determined by the data you have entered. The one we are most interested in is the third one:
View attachment 520711

You can play with the RPM numbers and it will give you different speeds. In the above example, with the combination of gears and tyres given, at 3000RPM in 5th gear you should be travelling at 135km/h.

In the example below, I have entered your stated RPM @ 100km/h (1820) and it has calculated you should in fact be travelling at only 82km/h.
View attachment 520712

Therefore mate either the calculator is wrong, the variables entered are wrong, your speedo is wrong, or your Dakota needs fiddling with ;)

Without changing any of the other variables, I entered 2220 RPM and in 5th that will give you 100km/h.
Mate you truly are a legend you have been so helpful
 
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