Clock repair
 

I have a problem with the clock in my 1971 Trans Am. The clock works (I don’t know how accurate it is), but I can't set the time because the knob that adjusts the time is broken. In order to set the time you're supposed to pull on the knob and turn it one way or the other, which moves the clock hands. I assume there is some type of clip that holds the knob stem in place, but it must be missing or have fallen off, because when I pull on the knob, it just comes out of the clock. Any ideas on repairing this myself, or will I need to send it to a gauge repair shop?

There's tons of resources on the internet, a quick search found this:

http://www.oldcarsweekly.com/restora..._old_car_clock

There are YouTube vids too, search it.

You can have them repaired/restored:

http://www.instrumentsrus.com/gm.htm

Or you can have them upgraded to quartz:

https://www.instrumentclusters.com/clock-repair

They make kits with instructions to repair them yourself:

https://www.clocksandgauges.com/

They are Borg clocks, you can search it that way, or 'ticktock tach', something along those lines.

Quartz upgrades and kits are less expensive than original movement, but some like and want the original movement.

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Thanks HWYSTR455.

I found a picture which shows the back of a clock, and I think I found the answer to my question. There is a spring with a gear pressed onto the back of the clock adjustment stem. It looks like the spring keeps the gear away from the clock gears. In order to adjust the clock, it's necessary to pull the adjustment stem outward (against the spring tension), which will allow the adjustment gear to engage with the clock gear, so the time can be set. The gear probably fell off my adjustment stem. I'm hoping the gear and spring are still inside the clock and I can just reinstall them.

nice detective work!

I see what you mean now, yeah, that gear is probably pressed on there, but maybe JB weld or something. I don't see any room for an E clip or anything?

There's tons of parts out there for them, so if you do need something, it's probably available.

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Yeah, that looks like an E clip or cup at the base, that holds the spring and shaft with tension.

The gear does look pressed on too, so to install, you probably have to come from the back, with the spring on, and no knob on the shaft, and go through the face. Then put the E clip/cup in place.

(raggedy editing or photos, sorry!)

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There must be a back plate to hold the shaft in place. From coming back through the face.

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Its an easy fix. I don't think I'd use glue or jb weld though. If you do, be sure that the knob will come off easy enough, or else It may never coma apart again.

That tiny gear is made from brass, the inside diameter of that gear and the end of the thin black shaft are designed so that when the parts are new it is a press fit-interference so that the gear stays on the end of the shaft. In-between the teeth of the gear the brass is very thin. After 100s of "pulls" on the set stem it is common for the gear to come loose and fall off. I would check the gear using a magnifying glass for cracks. I have seen several cracked gears also gears with chipped teeth on older car clocks. I would not try & re-use a cracked gear.

Anyone know a source for a new tiny brass gear for the clock stem? Mine came off stem and after removing dash I can see a crack in the gear. Rally clock on 68 GTO. I replaced mechanism with quartz and works great otherwise.

Some times the easiest way to set the clock is to disconnect the battery, wait until the clock time and actual time agree and hook the battery back up. If desired you can drink your favorite beverage while waiting.

I wound up sending my gauges out to Redline Gauge and Clock Repair in Tennessee to have them repair the clock. They were very helpful when I spoke to them by phone, so you might want to contact them to see if they can sell you the gear.

https://www.redlineg.com

I'd be interested in your experience with them, I would make a mental note, and reference folks to this thread.

So you're going for a repair, and not a quartz upgrade?

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I used a gauges restorated, and got my clock quartz working. Took them a long time...

http://i284.photobucket.com/albums/l...psgkhaw4sh.jpg

The originals did not have a quartz movement but instead used a long but very fine spring and a set of contact points. As the spring it set it then starts ticking down - letting the spring contract until the contact points touch once again, forcing them open as far as possible and stretching the spring back out as far as possible. Then lather, rinse, repeat. If the car voltage runs down toward a dead battery it can get to where it doesn't have enough energy to force the points back open again and the points can burn some or fuse together. Clock won't work again until some corrective action is taken.

Here's a video I made with the clock hooked up and running outside of the car. You can see and hear the tic-toc sounds it makes. Quartz movements are essentially silent and the clock second hand will sweep smoothly around instead of the tic-toc movement of the second hand in an original. You can probably see the second hand stops for a split-second every second, unlike quartz clocks.

Also, when the contact points touch it makes a very distinct sound. You can hear it reset and see the contact points on top move back fully open again.

https://www.youtube.com/watch?v=wZQg3hc0nr0

Chad

One of the clocks I've taken apart had a bad spring in it. The loop on one end had broken letting it free. The clock, of course, won't rewind correctly if the spring is broken. Once the contact points touch and are then forced apart there is no spring to begin contracting so all movement stops.

http://i636.photobucket.com/albums/u...ps40rpf0bz.jpg

Even though there are roughly 100 winds to the spring it is VERY small. Compare to a dime, 1/16" thick drill bit and a toothpick.

http://i636.photobucket.com/albums/u...psevtaifxp.jpg

I like to wind springs. Usually a little bigger than this one. The 1/16" mandrel is slightly too big so I'll have to find something slightly smaller in diameter to wrap the spring, but not terrible for a first attempt. Springs can take a few tries to get right and a lot of patience. The wire is .006" or just about the size of thicker human hair. I have about 2 miles of the wire so plenty to practice with.

http://i636.photobucket.com/albums/u...pspnkuzowa.jpg

Chad

VERY cool!!!

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That's great stuff Chad!

Do like a working clock...

Converting to quartz will give a much more reliable clock but if you are going for 100% originality it can be a cool feature. Keeping a battery tender on a car will usually keep it running and the points won't burn. Either that or disconnect the battery when not being used. I like a tender so I don't lose a battery as often from sitting discharged. No surprises there.

The spring is so small I couldn't count the number of winds even with my glasses on and a magnifying lens so I took that close up of it and then zoomed in on it and made little yellow marks at every ten. Slightly less than 100, I get about 98, but count the end loops and it's back to 100. I'm sure I could take the spring and simply bend out the last coil to make the loop and hook it back up again, but I wanted to try making my own.

http://i636.photobucket.com/albums/u...psoxrnvahx.jpg

Chad

Incidentally, and not to waste all of your time, the owners manual describes this procedure for the clock.

ELECTRIC CLOCK - Automatic regulation is built into the setting device of the electric clock and operates only when the clock is manually adjusted to reset the time. If the clock gains time, pull the stem out and turn the hands counterclockwise to correct the time. If the clock loses time, turn the hands clockwise to the correct time.

Chad

That spring is crazy Chad ! Something like that would drive me crazy.
I had the clock for my t/a repaired and rebuilt by 'jerrys clock works' in Minnesota. Turn around time was about a week, price was around $100. That included a new stem (mine was broke). He has an add on charge to convert to quartz but I left mine as original. Very happy with the communication and service.