Just got my engine running again in my new chassis and over the past few weeks have been reassembling the rest of the car. Today I spent a few hours fooling with the gauge clusters.
As stated above, the JDM speedo modified with the resistor read accurately in MPH. However, the JDM odometer continued to read in kilometers even though the Zeroyon writeup said it would change over. I verified this not only by timing how long it took to turn over at 60 mph (should have been one minute) but by watching the odo and comparing it to the mile markers on the highway. We have markers every 1/10 mile (my tax dollars at work
) and by 3/10 it was clear that the odo was moving too fast. When the ones column rolled over at 6/10 I knew it was still reading kilometers.
My findings are as follows:
1. The JDM and USDM analog odometers are interchangeable. Either one will screw into either gauge cluster and will plug into either speedometer. The wires going to the odometer motor match colors and pin locations on both.
2. The USDM (don't know about JDM) digital cluster odometer will NOT go into the analog clusters. It screws in but the motor plug is different. After this whole experiment was over I figured you could probably switch the motors (see below for reasoning) but I didn't try it.
3. The gearing on the JDM and USDM analog odometers is different. The number of teeth on the drive gears is visibly not the same, even without counting. The colors of the gears are different too - one is blue, the other black, though I don't remember which is which.
4. The gearing on the USDM digital cluster odo and USDM analog cluster odo appear to be the same. They're also the same color.
5. The gear coming out of all three motors is the same. This is why I think you could probably swap the motors.
End result - I stuck both the modified JDM speedo and the JDM 7500 redline tach into a USDM analog cluster and voila, I had a working 180 mph speedo and an accurate odometer reading in miles. Then I just pulled the odo back out, took it apart and rolled it to the correct mileage for the chassis (matching the disfunctional digital cluster I took out of the car) and took it for a test drive.
Note - if you're going to take your odo apart to match it like I did, be careful as hell. Very easy to have little gears going everywhere.
