ahardb0dy Posted December 31, 2013 Share Posted December 31, 2013 (edited) This is a guide on how to fine tune your cable driven speedometer if it turns out it is off. As always make sure you have the correct speedometer gear first and if the tires are a different size than stock you may not be able to use this method to bring the speedometer back to being accurate. First step is to determine if the speedometer is correct or the reading is off, you can do this a few ways: 1. By having a friend drive next to you, providing his vehicle has not been modified at all (tire size,etc) 2. drive by one of those police MPH trailers 3. use a app on your phone that determines MPH using GPS ( this is only as accurate as the App and how accurate may be unknown) 4. have a cop check your speed using their radar gun ( not recommended unless you have a friend who is a cop !) Once you determine your speedometer is reading incorrectly you can follow the steps below to get it closer to the actual speed, keep in mind this will take more than one try and you must be careful when removing the gauge cluster as the plastic end of the cable is fragile and if it is original it may be brittle and break ( I know from experience !!) steps to calibrate: 1. Remove gauge cluster from vehicle ( not going into specifics on how to do this as each vehicle will be different, check the FSM if you are unsure how to do this) your cable driven gauge cluster should look something like this: Front: Rear: 2. remove clear plastic that covers gauges, you need to press in on the clear tab there should be four of them, two top, two bottom tab: clear plastic removed: 3. remove the black bezel that the clear plastic cover sits on, by pressing in on the black tabs, top and bottom: tab: black bezel removed: 4. remove two screws on rear of gauge cluster that hold speedometer in: one screw: other screw: 5. grab the odometer reset shaft and pull outward carefully, speedometer removed from cluster: Edited December 31, 2013 by ahardb0dy 1 Link to comment Share on other sites More sharing options...
ahardb0dy Posted December 31, 2013 Author Share Posted December 31, 2013 (edited) There is an electrical plug on the rear of the speedometer, the speedometer will not work without being plugged into the cluster: connector pic: socket on cluster where plug goes into: 6. looking at the back of the speedometer notice a copper colored disc inside of a silver metal cup seen below, pic is blurry but still can be seen, it is behind the odometer wheels and the shaft goes into it that the speedometer needle pushes on too: to adjust the speedometer you need to turn the copper disc with your thumb, so that the needle raises to a speed and hold it there, for example to make it easy I would raise the needle so it is indicating say 35 MPH and hold it from moving, pic below: depending on how far off your speedometer is reading, in this example let's say your speedometer is off by 10 MPH too high, than you turn the copper disc which will cause the speedometer needle to raise, continue to rotate the copper disc until the speedometer needle is pointing to 35 MPH, see pic below: now while holding the copper disc with your thumb which will hold the speedometer needle at 35 MPH, turn the speedometer needle to read what ever amount it is reading high or low, in this example turn the needle down 10 MPH so it is now sitting at 25 MPH, now let go of the copper disc and the needle should return back to zero. You can rotate the copper disc to raise the speedometer needle to any MPH, I usually will bring the speedometer needle to a whole number jus to make it easier to know how far from that speed the speedometer needle needs to be moved either up or down. You now need to re-install the speedometer into the cluster, make sure the plug is in that I posted pics of earlier, re-install the 2 screws that hold the speedometer into the cluster from the rear. You do not need to re-install the black bezel or clear cover at this time, place the gauge cluster into the vehicle, re-connect the plugs on the rear of it that were removed when removing the cluster, and take the vehicle for a test drive, using what ever method you used originally to determine the speedometer was off and check it again, if the speedometer is still off, you must repeat the above until you have it perfect or as close as you wish to make it, this procedure can take several times. When you are satisfied with the results, remove the gauge cluster and re-install the black bezel and clear plastic, than re-install and do one final test drive, if all is OK you are done. When the clear plastic is removed it is a good time to use some plastic polish on each side to clean and polish any scratches out of it. Edited December 31, 2013 by ahardb0dy 4 Link to comment Share on other sites More sharing options...
SkiBumBrian Posted January 1, 2014 Share Posted January 1, 2014 Nice write up ahardbody, my Garmin says mine is pretty much on the money but it sure is nice to know how to do it. Maybe when I go to 33s it would be a good time to recalibrate. Thanks! Link to comment Share on other sites More sharing options...
ahardb0dy Posted January 1, 2014 Author Share Posted January 1, 2014 Welcome, I don't think you can recalibrate for a larger tire change, haven't tried it. This was how I did the speedometer in my 90 sentra when I swapped clusters going from the stock non-tach ( used for these pictures) to tach cluster. Last time I did it my speedometer was like 15 MPH over, it's perfect now. Link to comment Share on other sites More sharing options...
92Path_68CJ Posted March 11, 2014 Share Posted March 11, 2014 Just bumping this to the top. Has anyone actually tried to recalibrate for larger tires since this was posted? Link to comment Share on other sites More sharing options...
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