How to swap in tachometer (56K warned)

[g6civcx]

The information presented herein is for reference only. The author and Zilvia.net are not responsible for content or misuse. Please consult qualified technician for all automotive services.

This writeup is part of the series of the Zilvia.net comprehensive SR wiring guide. You can expect more to follow in the series containing the same degree of precision and illustration. Please add your constructive comments as appropriate.
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The purpose of this exercise is to swap in a tachometer. This is necessary for those with single overhead camshaft (SOHC) KA24E engine that came on the 1989 and 1990 model year Nissan 240SX, and would like to swap in a newer double overhead camshaft (DOHC) KA24DE or SR engine. The SOHC tachometer is not compatible with the DOHC engines, and vice versa.

There may be other useful purposes for this writeup as well, such as how to remove and replace (R/R) a defective instrument cluster, how to R/R broken switches, so on and so forth.
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Before we begin, let's identify the different types of tach.

• KA24E - 6,500 RPM redline. 8,000 RPM max indicated.
  
• KA24DE - 7,000 RPM redline. 8,000 RPM max indicated.
  
• SR - 7,500 RPM redline. 9,000 RPM max indicated.
  

You can generally find the KA24DE tach on Ebay on in junkyards. The SR tach is generally available on Ebay as well, or in the car if you have a front clip. You can use the same procedures to extract the tach from the front clip.
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I highly recommend that you perform this swap prior to doing your engine swap, and while your current engine is operational. It will allow you to diagnose and troubleshoot any problems. If you can get your entire cluster minus the tach to work, you can be sure that your swap was done correctly.

I also highly recommend that you address any thing that is broken in your current cluster. The speedometer and odometer are notoriously prone to failure. So fix these as appropriate. Please note that swapping in odometers may introduce odometer discrepancy, and, when not disclosed to the buyer, constitutes odometer fraud (which may be a felony).

I will keep the scope of this writeup to swapping a DOHC tach into a known good cluster with no mechanical malady.
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Tools required:

• Ratchet
• 10mm socket
• 12mm deep-well socket
• 6" extension
• Phillips screwdriver
• Small, dull screwdriver for prying
• Torque wrench

Note: I don't have the driver side kick panel installed on my car. If you feel that your kick panel gets in your way, remove it first before you proceed.

1. Start by unbolting your knee bolster. The left side is shown here. You can use a 10mm socket or a Phillips screwdriver to remove the screws. There are 2 screws holding the hood release. You can't see it in this angle, but if you get down there you will see them. Remove all the screws shown here.



2. This is the right side. Same procedure.



3. Carefully lower the knee bolster.



4. Carefully remove the hood release. Notice how it goes together for when you put it back later. Store the knee bolster in a safe place.



5. It is absolutely imperative to lower the steering column when you remove the cluster lid. Otherwise you will break it. You can remove it without dropping the steering column if you scratch it, but this is the proper way. Get your 12mm deep-well socket, a 6" extension, and crawl under the steering column. Start first by removing the 12mm nuts shown here.



6. Next get a helper to help support the weight of the steering column. Remove the two (2) 12mm bolts shown here. Please note that these bolts are load-bearing. So as soon as you unbolt them the steering column will drop. Be careful that you do not get caught.



7. Carefully lower the steering column.



8. Next we will remove the cluster lid. Start by removing these two (2) Phillips screws.



9. Now look under the lid and you will see this tab. This is the left side. Carefully pull back the tab and free the lid from the dash.



10. Slide the tab back and out like so.



11. Do the same for the right side and slide it out.




12. Very very carefully maneouvre the lid out of the dash. Take your time and carefully work it out. Don't pull too hard or it will break.



13. On the other side of the lid will be wire harnesses for the various switches on the lid. Depending upon the equipment you have, you may have more switches. Be very patient with these as they are rather difficult to remove. You remove them by pressing in the retaining clip and the harness will come out. You can use a small, flat screwdriver to depress the retaining clip. Just take your time with these so you don't damage anything.



14. Remove all the harnesses and the lid will be free. Set it aside in safe place.



15. Now we will work on the instrument cluster. Start by removing the three (3) Phillips screws shown here.



16. Carefully pull out the cluster. Tip: it helps if you tilt the cluster back slightly to free it from the heater vents. Just take your time and be careful.

NOTE: Electronic components are very sensitive. Exercise extreme care so that you don't damage them. Follow the precautions you would for handling computer equipment.



17. When the cluster is free, look behind and you will see three (3) wire harnesses. Unclip these by pressing the retaining clips together as shown. Again, be very careful so that you don't damage the printed circuit board.



18. Remove the cluster after you unplug the harnesses.



19. Now find a safe, clean, static-free surface to work on your cluster. If you choose to swap in a complete DOHC cluster you can just plug it in at this point. I'll cover the tach swap for those who wish to do so.



20. Start by removing the clear plastic lid. Press the tabs shown here and the lid will slide out.



21. Remove the lid and set it aside.



22. Next we will remove the black trim piece. Again, depress the tabs shown and slide out the piece.



23. Slide out the trim piece and set it aside.



24. Flip to the back of the cluster. We will be removing these three (3) Phillips screws for the tach. Be careful because as soon as you remove the screws, the tach will fall out rather freely. Make sure you don't drop the tach.



25. Here are the screws removed.



26. And the tach drops out.



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Now is a good time to check all your bulbs. Make sure they're in good shape and repair as necessary. Also swap out your speedometer and/or odometer as appropriate.

Installation is the reverse of remove. Some installation notes for you:

* Make sure you don't overtighten the screws holding the tach. You can damage the component.

* Reinstall the black trim piece and clear lid. Be sure to align the pinholes with the adjusting knobs for time and trip odometer.

* Plug the harnesses back into the back of the cluster and reinstall the cluster with the screws you removed from before.

* Reinstall the harnesses on the switches on the cluster lid. Some switches may pop out. Just hold them in while you insert the harness.

* Reinstall the cluster lid. Slide the tabs on the bottom onto the dash. Reinstall screws from before.

* Reinstall the steering column retaining nuts and bolts. I recommend you install the bolts first since they are load-bearing. The bolts will hold the steering column up and allow you to install the nuts in the back. Torque these to 9-13 ft-lbs as per the FSM using your torque wrench. If you don't have a torque wrench, hand tighten then snug but not too tight. I highly recommend you use a torque wrench.

* Reinstall the hood release on the knee bolster. Reinstall the knee bolster onto the dash with the screws from before. If you look on the knee bolster, you will notice that there are 2 tabs that meet with the dash to give it a good tight fit. Make sure you install these correctly and don't bend them.

If you did it right, everything on the cluster should work except for the tach. This is okay. Make sure everything else works. Your tach will work when the new engine is in.

Also another note. If you would like to install a JDM 180 km/h speedometer, you can simply plug it in, whether by swapping the speedo over or simply bolting in the entire gauge cluster. Notice that the speedometer and odometer will now display kilometres instead of miles. What you could do is get a SpeedoHealer and wire it inline with the Vehicle Speed Sensor (VSS) output line. It will modulate the pulse signal. Set the calibration factor to 1.6. This will allow your odometer to read in miles, and your speedometer to show MPH. If you do it right, you will have a 180MPH speedometer. Just blur out the k on km/h so it becomes m/h and you'll be set

http://www.speedohealer.com/
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That's it. Please add any edits that I may have missed

Originally Posted by g6civcx

Updating with some comments:

* Cal Sportbikes, the US distributor of SpeedoHealer, has deferred me to their international distributor because the Nissan product has to be special order. So as of right now you cannot get it from Cal Sportbikes as I said above. Do a Google search for SpeedoHealer and you'll find their international site.

* You may not have to disclose mileage above 100K depending upon your state, but your title will be marked with actual mileage unknown or exceeds mechanical limit. This will show up on your CarFax when you try to sell the vehicle and it will hurt resale. It's best to keep mileage as accurate as possible.

I highly recommend that you document the mileage of the old odometer at the time of removal and the mileage of the new odometer at the time of installation. Attach this information to the driver's door jamb. When a mileage needs to be taken, you can take the old mileage and add in the difference in the new odometer's mileage. This will give you the true mileage of the car.

When you sell the car, you know the actual mileage so the title will not have an odometer discrepancy flag. Should help you get more money for the car.

* You can use the resistor, but it's harder to make on-the-fly adjustments. The SpeedoHealer is ideal for making these adjustments, as well as providing some data-logging functionality as well.