To all fellow Jag owners suffering from Tachometer (Tach) issues with their antique Smith gauges.
Intermittent, non-working Tach can stem from several issues like the old parts get gummed up, corroded, the coil in the gauge burns out or the thing simply wears out. I took my gauge to a couple of Jag shops and speedometer repair facilities with varied results and most wanting north of $250 to fix it with no real guarantee.
Well behold, I fixed it myself for about $50.00 in less than one hour.
When I say fixed it, I mean I resolved multiple issues in one move. While working on my car (a 1968 E-Type OTS) I also wanted to install an electronic ignition for greater reliability. The old Smith gauge was never designed to accommodate and electronic ignition since they were not available back then and it will simply not work (bummer).
I was amazed at just how simple the fix was. I was searching the internet for another working Smith Gauge (all of the usual Jag parts suppliers, google, then EBay and EBay UK when I discovered a company called Spiyda who sells a kit for about $50.
The kit takes the old Smith RVI (Tach current voltage sensing system) and converts it to a RVC (allows calibration to any number of cylinders in addition to letting you keep your old points distributor or upgrading to an electronic ignition system – win win). The kit comes with a great set of instructions and their website has links to a couple of YouTube videos that you can watch if you need help, the tech support online is awesome.
The kit even comes with a micro screwdriver so that you can adjust your tach to read spot on. In my case, I soldered their new electronics in (bypassing the old electronic parts and I had to make the hole in the rear housing a little larger so I could calibrate the instrument once installed with the micro screwdriver). By the way, I also bought an electronic tachometer on EBay so I could put a strip of reflective tape, that came with the unit, on my crankshaft pulley to be spot on accurate (it cost me about $20 and is small enough to fit in the palm of your hand – in case you are not certain where your car truly idles once warmed up).
While you are in the instrument, you may want to contact your parts supplier and get a new set of "O" ring gaskets for the glass especially since they are not expensive. The gaskets don't seal the gauge or make it air tight that could cause a condensation issue (there is a hole in the back that would prevent an air tight situation) they prevent the glass from vibrating.
Please be aware that I am not a mechanic or an electronics professional therefore I accept absolutely no responsibility for any of the information above and strongly encourage you to complete your own due diligence and be absolutely certain that you have the talent, skills and tools needed before proceeding. I am an E-Type owner who wants to help other E-type owners keep them on the road and only wish we lived in a world where this paragraph is never needed. This is also in no way intended to endorse, support or promote the use of EBay or EBay UK.
I searched EBay.co.uk for Smiths and also RVI - RVC and found it. You can also go to www. spiyda.com