My Speedster Stumbled - Tachometer Died!

I was accelerating in 2nd gear when the engine coughed, stumbled and then the tachometer went crazy (gyrating wildly) and died. The engine stumble lasted only a half second and everything is running just fine, but now the tach is now pegged at zero.

What drives the tach and how do I trouble shoot it?

I have a 2010 Vintage Speedster.

Thanks!

Cole

u might have to have it rebuilt by N hollywood. Kirks tachs and speedos are chinese and have a short life span. I had my tach rebuilt and it was perfect after that.

But before you go to all that trouble, replace the ignition module inside of the distributor. It may or may not be electronic. If not, put in a Pertronics module and forget about points. If it already has an electronic module, try replacing it with a new one (they're reasonably cheap) and clean up all of the distributor wire connections and re-connect. If that doesn't cure your tach, try following the sender wire from the distributor to the tach to see if there is anything amiss. If not, THEN think about getting the tach fixed.

What should the Positive voltage be at the coil? I'm seeing 10.5V?
Is there a resistor in the + line? Does not appear to be 1 at the coil.
Thanks

Should be 12V or better. 10.something sounds a bit low...

These cars don't have a dropping resistor for the coil.

My mechanic says the tach is bad.

Is it worth it to have it rebuilt, or should I just buy another Chinese one from Vintage Speedsters?

Are there other options?

Cole

Palo Alto Speedometer or North Hollywood Spedometer will build you a better tach than a replacement Chinese one.

Thanks Gordon. I'll look into it.
Doug

I contacted Palo Alto Speedometers and they suggested it may not be worth it to have it fixed, $145. But said they'd be happy to help if I didn't have any other solutions.

I called Kirk at VS and he said they'd been having troubles with the tachs since they started making them in China. He offered to send a replacement if I'd return the broken one so they could have it repaired.

What great service from Vintage Speedsters! Kirks a good man.

Cole

Same story repeated over and over again. Kirk is a great guy but the Chinese tachs are not up to par. My car came new from the shop with a non working one. Kirk sent a replacement which worked for a while and then died. I got mine "VDO'd" (basically replacing the innards with VDO stuff) by North Hollywood Speedometer for around $160.00 a few years ago. Don't know if they're still doing it. Still working fine after all these years...

Like Yogi Berra said "It's deja vu all over again".

And that, folks, is one of the reasons I'm running 912 gauges in my new build!

What he said ! !

Although, if you don't shift on the tach you can swap in 914 guts and the Chinese faces across the board. It's really easy to do., honestly, removing the bezel is the most difficult part . . .

OK TC. We would all love to see the instructions for removing the bezel and getting it back on with out it being totally trashed.

Use the small bladed screw drivers that come in the little kit for glasses repair and just sit down, watch some TV and work around the rim. Eventually it'll open up enough for one area to come up a bit. You can grab the case and sort of twist/pull the bezel off with some effort. No distortion at all, just gotta be willing to sit through all of "Castle" to do it.

When putting it back on, use a silver spoon to roll the bezel back into place. The bezel is soft enough to re-seat on the gauge and the silver is forgiving enough not to do any harm. The biggest trick of the whole "procedure" is using the silver spoon, otherwise you get scratches and gouges and such from a screwdriver or whatever else you try.

Comes off fairly easily, even the older original brittle brass based 356 bezels. Goes on with difficulty, but can be done.

Any errors will be hidden by the rubber trim/gasket between the gauge and dash face. The edge of the bezel will "bed" into the gasket when you tighten the bracket in place and hide all of your mistakes.

Easy Peasy, done it to every single gauge that I've had. The needles ALWAYS need to be repainted and the bugs cleaned out of the bottom between the face and glass.

TC

Thanks TC. I'll give it a try. The glass on some of my gauges is hazed-up on the inside and I was going to send them to Palo Alto Speedometer for a $35 repair.
Troy

Success! Using TCs method, I was able to get the ring off of my gauge to clean the inside of the glass. I would suggest a slight variation however. Use a small jewelers screwdriver to get the edge up to start with and then switch to a regular screwdriver with a long blade. That will give you more leverage as you move around the case and made it much faster and easier than using the small jewelers screwdriver.

Caution... Do not be tempted to insert the screwdriver further under the lip and pry forward against the edge underneath. The glass is right there and you risk prying against the glass and breaking it. Use the leverage of the longer blade with the fulcrum point at the rear of the gauge housing.

It will not go back together perfectly smooth, but it's only the back edge that is a bit rippled and it will not show.

Now the question is. Can we save some money and buy the VDO inerds for a tach and fix our own tachs???

Yup.

It's actually a very easy replacement. So easy, I often wonder why the speedo places get such big bucks to replace them. Maybe because the VDO innards are $$$ to start with? Dunno.