My 1954 coupe was off the road for 40 years before I got it running again earlier this year. The tach originally did not work and was stuck, but seemed to come back to life for a while. I pulled, cleaned and greased (with Bosch distributor grease) the cable and it quietened it down and the tach came back to life. This weekend though it started to stick until it got fully stuck at zero RPM. I feared that I had filled the tach with grease/oil through the cable as often happens, but no oil or grease at the tach end of the cable. This afternoon I pulled the tach and carefully opened it up to find the issue, and it appears it was just the result of dried dirt grime from 70 years. A good clean and flush with electrical switch cleaner in the needle bowl, cleaned it all up and very light oiling and it’s working perfectly again!
Simple job, took about an hour to do, just fiddly work and need to be careful with gauge faces etc. My car is a patina car, so did not clean up faces or bezel too much.
July 54 tach for my Oct 54 car.
I laid the tach face down on a cloth on workbench and then very carefully and slowly worked with a small screwdriver to praise the lip of the bezel up a little at a time, working around the tach. You don’t need to prize it all the way off, just enough so that you can try and pop the edge of the bezel over the tach body, and then work around the tach to pop it off. Be patient and it will come off fairly easily.
Once the bezel and glass it off, undo the two screws on the back of the tach top and carefully remove the mechanism. Try not to touch the gauge face or needle.
There is two smaller screws that then hold the tach cable drive assembly to the face mechanism. Remove these and you can separate the two main pieces of the magnetic disk and bowl.
there was no oil or grease in my tach, just lots of very old dirt. I flushed behind and around the needle cup with electrical switch cleaner and this dislodged a load of dirt. I also gently cleaned inside the cup, and lubricated the needle bearing with a small drop of light oil on a long pin.
I removed the screw that holds on the end of the tach drive input shaft, and then cleaned the shaft and the drive body, I greased the shaft with some bosh distributor grease, reassembled carefully. There is adjustment on the end of the shaft clamp, but be careful with this as it will adjust the calibration.
To test my tach I filed the end of a plastic rod to the appropriate sized square, and used an electric drill to spin the input. Spin in the direction of the needle travel.
Reassemble in reverse and very carefully. Good opportunity to clean the inside of the glass. I then placed the bezel and glass face down on cloth on bench and put the tach down into it and then carefully ‘popped’ the bezel back on. I then used a small hammer to carefully tap the edge down again and all looking good and working again!
