Last night I got bored and decided to finally use my tach overlay. I purchased 3 monster tachs about a month ago at a flea market for 50 bucks. One was an 8K and the other 2 are 10K. I used the one in worst condition just in case since there are no instructions as to how to do it. I only included 2 pictures before and after but I have a tach in pieces that I will use to explain the details with. It was straight forward removing the silver bezel using the widest flat blade screwdriver that I could find using the shortest upward prying motion that I could. I didn't want to give the trim ring the pryed can opener effect look. This tach has the 3 nuts on the back that were removed and the brass looking studs and wires were pushed up thru the grommet. I removed the 2 tiny screws that holds the original tach face on. Now here's where the big issue comes into play. I have purchased tachs before that had the fluorescent needle sitting at the bottom of the tach and I've tried to reattach them and it never read correctly. Maybe there is a calibration process involved that I don't know of or the pin that the needle rides on is supposed to be much longer inside the motor assembly that controls it. I do have 2 more play with. With this very first one that I did I cut a slit in the overlay and slid it under the needle. It was tough but it worked and looked great. You couldn't see but about 1/2" of the slit cut because of the tach controls on the right. If I hadn't told you, you would have never noticed. With this one I marked where the needle was and pried it up, and installed the overlay. I cleaned it up along the way but I still don't like the tach controls on the right, red push button is missing and the lettering is almost gone. My soldering equipment is at my shop and I will take it off of my junk tach and respray the needle before I officially put it back together again. I have an original keyed BMS 3 5/8 tach and I remember how hard it was to come by so this was a great alternative and much cheaper.
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