72442

The tick tock tach in my 72 442 does not work. However, I can get the second hand to run for a few seconds if I adjust the clock. After adjusting the clock, the second hand will move for maybe 8-10 seconds and then stop again. The tach does not move. Does anyone have recommendations on rebuilding these so both the clock and tach are functional again?

svnt442

I found this. Hope it helps.
Scroll down.

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

Allan R

Ok, for the clock it sounds like it really needs a good cleaning. The gears are probably gummed up. You can clean it yourself (take lots of pics when you break it down so it goes back the same way).

For the tach, check to see if your inline fuse has blown. If that's not the problem, it likely needs to have the circuit board checked. Have you checked the lead coming in off the distributor to make sure the contact is good (not corroded or loose)?

If you are looking for an inexpensive clock replacement, you can also check out this guy. I bought a clock movement for my rallye pac from him for a really decent price including shipping.
http://myworld.ebay.ca/gaugetweeker&...MEFSX:SELLERID

If he doesn't have it, he can rebuild yours. Never hurts to send an email and ask. BTW, he gave me a years warranty on the clock that I bought. Something that I haven't seen offered on other sites.

svnt442

That's Ebay Canada, isn't it?

72442

Allan, thanks for the recommendations. I will check these out. Based on everything I have read about these tachs, they were not of high quality and failed early and often. I did get an estimate to rebuild the internals and leave the original face on from a company that advertises in Hemmings. For both the clock and tach, it was almost $300

Allan R

Incredible power of observation. Yup it is, but that shouldn't make any difference. The guy is out of the USA and does quality work.

Allan R

You're welcome.
The faceplates run about 100 bucks - pretty pricey. Compared to today's products the quality was not too high. But also keep in mind that GM was building cars with the life span expectancy of about 4-5 years. The tach in my car ran for about 10 years before it needed any attention. It went out of calibration but was still operational. Anyway, the product, on average didn't have to last so long. Heck, I remember when I was much younger, I used to flip cars every 2 years or less just because I wanted something newer or a different body style. Wish I was as smart then as I am now. Would have built up a dream inventory.

You do know that you can get aftermarket rallye pacs from Parts Place and Fusicks right? Brand new (supposed to be reliable) they cost 429 a set, but the clock is quartz movement and doesn't have the "sweep" on the second hand so it's pretty easy to spot.

4fortwo

I opened mine up and did a good cleaning and everything works now.

For the tach, there is a insulating cover over the board which is likely dried up and you may be getting a arc to the ground. I also repaired a few questionable solder joints and cleaned up with emery cloth.

As for the clock, your auto wind is probably dirty. It looks like a set of points which spring open each time they close to wind the clock for another, 2 minute or so, cycle. Again, emery cloth on the contact faces and then I used Mass Air Flow sensor cleaner on everything to remove all lubricants and grime. Once that was done an ultra light weight oil on all the gear hubs. DON"T OVER LUBRICATE.

Assembled the unit and wired it to the coil. MAKE SURE TO GROUND IT or your in for a shock. Start the car and check the tach with a Tach/Dwell meter. There is a hole on the rear of the housing to adjust the tach.

Next, use the jumpers to the clock and see if it runs. You may have to give it a light shake every few minutes until the lubricant works its way into the gear shafts.

I did this last fall and everything still works. The only problem I have is the clock is running about 2-3 minutes fast per week.

72442

Based on what you said, a really good cleaning is worth trying first. I know it has to be connected to the coil and grounded. My other instruments all are working so I would like to just get this one working again without replacing them all. How hard was it to get the tach/clock out?

4fortwo

I have a '69 and it's pretty tight quarters to get to the underdash bolts. I'm pretty sure the '70-'72 comes out much easier from the front of the dash.
Can anyone here answer that?

Allan R

Yes, you're right.
Undo the 2 (philips) screws that hold the woodgrain trim plate in. Then undo the 3 bolts that hold the tach/clock in place. The assembly comes straight out. It should come out far enough that you can undo any connections. But if the harness is tight or binds on anything you might need to go under the dash to ease it out. My car is not AC and is also really easy to access from below. AC cars would probably need the lower valence removed if you wanted access to the rest of the wiring harness.