Speedo Drive Conversion Auto Manual
When doing the auto to manual conversion, you're stuck with the automatic diff ratio, and the speedo drive gear from the manual gearbox. This can invoke speeding fines as your speedometer will show roughly 10% out (travelling 110km/h instead of 100km/h, whilst showing a speed of 100).
There is a simple fix for this problem, and can be done in roughly 10-15 mins.
Tools Needed:[edit]
- A small nail
- A small Hammer
- A good working bench with a small slot
- Long nose pliers
- Angle grinder
- A file
- 10mm spanner/socket
Mechanical[edit]
Firstly, you want the gearbox on its side or at a dry weight(empty), so you dont make a mess with all the oil.
Start by removing the speedo drive off both gearboxes by unbolting the 10mm bolt and putting the bolt and tag in a safe spot. Usually, the speedo housing will be stuck in there, so armed with a medium sized flat blade screw driver, gently pry on the groove to lift the housing out. Don't get them mixed up, a simple marking would do the trick.
On the drive's shaft, you will see a very small rail pin, this needs removing to be able to remove the centre from the housing. Insert the nail, about the size of the rail pin, and tap it in. Place the other end of the rail pin into a small gap as you dont want to bend it. Tap away until you get to half way and use the pliers to remove the nail, and then remove the rail pin.
Next step is to remove the drive and shaft. Repeat same steps on the other one.
As you can see, there is a difference in size between the two, but there is only a one tooth difference. The lower of the two is from the manual gearbox.
Above is a picture of why we need to use the manual gearboxes speedo drive housing. Although the auto housing can be machined down to fit inside the manual box, the shaft's hole on the manual housing (to the left) is offset in centering. It is like this so that the speedo gear from the automatic gearbox, can touch the drive inside the gearbox by spinning the housing 180 degrees around. If you were not to spin it around, the gears simply wouldnt touch, as the auto is visually smaller than that of the manual.
Above, is a picture of the housing's tag slot. The tag holds the drive in the gearbox. We need to make a new one directly oposite the old one. This can be done with an angle grinder and a file. Mark the new side with a centrepunch so you dont get confused.
Now, reinsert the shaft into the housing, tap the rail pin back in, and insert it into the gearbox using the tag on the new groove.
Congratulations, you now have a speedo. Test by spinning the input shaft whilst the gearbox is in gear, and looking for the drive to turn. Add the big round black speedo sensor from the auto or using the original manual if need be.
-Shawn
Wiring S1/S2[edit]
This applies to the series 1 and 2 automatic transmissions ONLY.
On the drivers side of the jatco automatic, there is a 8 pin plug on the shift selector. Tracing it back towards the battery you will find its other end.
A few of these wires will enable you to start your car.
The following is the wiring: Red + Black and white stripe - Reverse; on the manual gearbox there is a 2 wire plug at the drivers side on the base of the bellhousing. These must be connected, they are universal, as it is a switch, hooking them up allows you to have reverse lights.
Red with black stripe + Black with Blue stripe- Neutral; join these two into the neutral switch on the gearbox.
Red with black stripe + Black with yellow stripe- Park; join these two together to disable the inhibitor switch, this one will allow you to start your car.
Congrats, you now may start your car. To test with gearbox out, make sure the starter motor is grounded to the engine block.
Wiring S3[edit]
S3 wiring is different. The speed sender connection is a seperate loom from memory - just use the auto loom for that - easy.
There is a grey 2 pin connector with really thick wires near the battery - bridge these 2 wires to disable the start inhibit - easy.
For the rest, I used the connectors from both looms to make a custom loom, that is really the only way to go with an S3.
In the same area as the grey 2 pin connector there is a grey 8 pin, you want to use this plug from your auto box to make the custom loom.
Looking at the front of the connector from the auto loom, it goes like this:
On mine the colours were:
- 1 – Black
- 2 – Orange
- 3 – Red
- 4 – Yellow
- 5 – Blue
- 6 – Brown
- 7 – White
- 8 – N/C
Connect Pin 1 and Pin 5 to the neutral switch, and Pin 1 and Pin 6 to the reverse switch, and you're done.
Now, my car is actually one of the very last s3s to be built, and actually had a 300ZX auto box, but I am now 99% certain that the early s3s use identical wiring
You don't really need to connect the neutral switch, all it does is improve fuel economy when the car is in neutral (i.e. never). But since I was making a new loom anyway, I figured I might as well do it.
HR31[edit]
Hey, just like to clear up the pinout on the inhibitor switch plug on HR31's to make them start and reversing lights work - I just worked this one out today. This is the grey 8 pin plug near the battery on an auto HR31:
Splice 1 to 7 to bypass the inhibitor switch, which you can now snip off! Connect 1 and 6 to the reverse switch on your newly installed manual gearbox and voila! My car had the inhibitor switch jammed under the brake booster all taped up, the other unused wires (2, 3, 4, 5, & 8.) aren't needed and can be chopped. Colours are all different to S3 Ausdel as well.
-crayman
Contributors: projekt31, Smity42, crayman