Converting a smiths clock to positive ground

[drambuie]

Hello everyone,

I would like to ask if anyone has converted a smiths negative ground clock to positive ground? What proceadure or components may be needed for such a conversion? I know there are shops out there that specialize in conversations to smith gauges as well as doing a quartz conversation to clocks as well, which would make the most sense to me. However, if anyone can chime in with the proceadure to convert this smiths clock to positive ground myself to save a few bucks....that would be preferable to me.

I am also looking for a good used 2 inch smiths black faced volt,amp and vacume gauge as well.Thanks everyone. Michael.

 

[57_BN4]

Best I know is that it depends on the model. Early clocks were not polarity sensitive as they used a swamping resistor on the coil whereas later ones used a selenium rectifier (early/unreliable diode) which burns up if you put the power on backwards, if it hasn't already burned up due to age. You'd have to disconnect the rectifier and replace it with a diode or transient voltage suppressor (TVS) like on the fuel pumps.

I haven't changed polarity on a Smiths clock but I do know that they are extremely unreliable due to arcing and wear on the contacts inside and the burnt metal that is flung off from the arcing gets into the bearings and making the movement stiff. If your one still A) works continuously and B) keeps time then it is a small miracle. If it doesn't work when put on a battery on the bench then I'd spring for the quartz mod and you'll never have to think about it again. Andy.

 

[drambuie]

Hello Andy,
Thank you for all your in depth advice relating to my smiths clock...it is in great condition like new in fact! However, I want to mount it in my 67 BJ8 which remains positive ground as it came from the factory. After reading your response, I have decided to just get the quartz modification and be done with it. If I ever sell the BJ8.....I will remove it and install it in my next Healey. Thanks Again Andy, Best regards! Michael.

 

[57_BN4]

No problem Michael, it was a good test of the grey matter.

A few years back I attempted to get several Keinzel clocks to work reliably but with only minimal success. They are purely mechanical except for an electromagnet and contact that operates with a clack about every minute and a half to recharge the mainspring. They keep time as long as the temperature doesn't change and of course a hot day with the windows wound up can get very hot inside the car. I'd think the Smiths clock would respond similarly.

One advantage of the quartz mod is that you can choose the option of running the clock off an AA battery so it isn't bothered by turning off the battery iso switch.

Andy.

 

[Patrick67BJ8]

Hello Andy,
Thank you for all your in depth advice relating to my smiths clock...it is in great condition like new in fact! However, I want to mount it in my 67 BJ8 which remains positive ground as it came from the factory. After reading your response, I have decided to just get the quartz modification and be done with it. If I ever sell the BJ8.....I will remove it and install it in my next Healey. Thanks Again Andy, Best regards! Michael.

Are you installing the new gauges in your existing dash or under it?

 

[tahoe healey]

I have neg ground and have been looking for a Smith in neg ground for years. I only find pos ground. They come up a lot on E-bay. You can also look on the Smith web sight. I have a neg quartz now. They are cheap. I paid $12 for a period (70's) looking one and it matches pretty well to the other Smith gauges. The Smiths are very expensive.

 

[drambuie]

Here is a picture of the Smiths clock I plan on installing after a quartz conversion. It is in excellent condition and running fine when powered up.

 

[drambuie]

Are you installing the new gauges in your existing dash or under it?

Hello Patrick, I am considering 2 ways of mounting the smiths clock and volt gauge... I may order another speaker grill from moss and save my original speaker grill...then cut two holes in the new speaker grill and fit clock and volt gauge side by side in the speaker grill so the back of the gauges are hidden behind the console and the faces of the gauges are flush with the speaker mesh... They look like a factory installation that way same as the dash mounted gauges.

Or.... I may just buy a 2 hole gauge mounting plate and cover it in the same thin foam and black vinyl to match the factory console and then mount it under the dash in a vertical postion next to the shifting console. My goal is to make the installation look as factory as I can.

 

[Patrick67BJ8]

Hello Patrick, I am considering 2 ways of mounting the smiths clock and volt gauge... I may order another speaker grill from moss and save my original speaker grill...then cut two holes in the new speaker grill and fit clock and volt gauge side by side in the speaker grill so the back of the gauges are hidden behind the console and the faces of the gauges are flush with the speaker mesh... They look like a factory installation that way same as the dash mounted gauges.

Or.... I may just buy a 2 hole gauge mounting plate and cover it in the same thin foam and black vinyl to match the factory console and then mount it under the dash in a vertical postion next to the shifting console. My goal is to make the installation look as factory as I can.

I am planning on mounting two gauges in my dash. I used a spare dash I had laying around and drilled the two extra gauge holes and it looks like it's going to work.

 

[drambuie]

I am planning on mounting two gauges in my dash. I used a spare dash I had laying around and drilled the two extra gauge holes and it looks like it's going to work.

Patrick, i don't where you drilled your holes for the 2 gauges, however if I where taking your route modifying a spare dash, I would move the heater controls down to the speaker grill or below the speaker grill where the 3000 blanking plate is. Then mount 3 gauges across where the heater control panel used to be...volt, amp and clock.

 

[tahoe healey]

The two inch gauges will not fit the speaker grill with out modifying the surrounding chrome frame.

 

[Patrick67BJ8]

Patrick, i don't where you drilled your holes for the 2 gauges, however if I where taking your route modifying a spare dash, I would move the heater controls down to the speaker grill or below the speaker grill where the 3000 blanking plate is. Then mount 3 gauges across where the heater control panel used to be...volt, amp and clock.

Here's what the spare dash I used to do the layout looks like. I'm going to use a clock in the center and a voltmeter above the Safety/Fuel gauges.

 

[drambuie]

The two inch gauges will not fit the speaker grill with out modifying the surrounding chrome frame.

The back body of the gauges are smaller and fit through the speaker grill with no modification, A rubber O ring would be seated between the back of the chrome bezel and the speaker grill so no mod is needed to the outside speaker frame. I am still toying around with other locations. When I find the other gauges I need and make the installation I will post a pic on the forum.