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Clock

This component is part of Dashboard Instruments. Most of this material was originally written by Jim Mahaffey

Definition

VDO subcontracted the job of building mechanical clock movements to the German firm of Kienzle in about 1958 to about 1975. There were two major patterns of Kienzle movements made. Let's talk about the common, drum-shaped movement. It's a basic Borg-wind, anchor-escapement clock, shock-mounted, built on two nickel-plated brass plates. Winding period is about three to five minutes (sounds like a muffled jolt.) The balance is not temperature compensated, and usually runs in one jewel. (There are rare examples of two-jewel movements.)

The clock is electro-mechanical. The spring is wound by an electromagnet that is energized when a set of points close within the mechanism. When the points close, the electromagnet "rewinds" the mainspring. The clock will run for about 3 to 5 minutes or so before it is rewound again. You can hear "click" from the clock each time the spring is rewound. The electromagnet is protected by a permanently-mounted fuse inside the clock. Usually, when the clock fails the cause is that this fuse has opened (blown). The fuse can be replaced, but it has to be cut out with wire cutters and a replacement soldered in), but the clock must be dismantled to do so. If the fuse has blown, it was probably caused by the points sticking together (the winding electromagnet is designed for momentary-duty only). The points can be separated and burnish them with a small, VERY FINE file or a nail emory board. BUT (and, this is a big but), they will probably stick again since filing removes the coating from them.

Early movements have all brass gears; later movements have plastic escape-wheels with coaxial aluminum flywheels. There are some basic case patterns: 115 (short case), 114 (long case), 113, 107 (SLs have internal lighting and connector blocks on the back), etc... Adjustment is with a jeweler's screwdriver through a port on the back, covered with a paper tape, usually labeled "VDO."

Here is a sampling of the dash clocks that one may find in a Pagoda:

Left: Sharp Bezel, original from my 66 230SL, Part #113 542 00 11, date code 11/65.
Center: Smooth Bezel, Part #113 542 01 11, Date code, 4/69.
Right: Quartz Replacement Clock, Part #100 542 01 11, date code 12/79.
(From: http://www.sl113.org/forums/index.php?topic=9521)

Maintenance

Describe common maintenance procedures, and common faults that may occur. Describe how these may be diagnosed and resolved. Again, include diagrams, photographs and explanations. Where possible, include measures, tolerances, weights etc.

Removing the clock

To remove the clock do this:

  1. Remove the glove compartment
  2. Remove the two thumb screws that hold the metal bracket that secures the clock
  3. Unplug the cable from the clock
  4. Pull the clock out of the dash

Reverse the procedure to re-install it. CAUTION: if you remove the glove compartment you may have one heck of a time getting it properly aligned with the rest of the dash when you re-install it.

Adjusting the clock

To adjust the clock, set up the clock on a bench with a 12-volt power supply. Make EXTREMELY small movements of the adjustment pinion, and allow the clock to settle for at least 24 hours between adjustments. Turn clockwise to reduce speed and counter-clockwise to increase speed. To get a really fine adjustment can take a week, and it will be spoiled as soon as the car heats up inside. An inability to achieve adjustment indicates wear on the plates. Altitude compensation for the case is provided by a labyrinth vent, hidden under the plastic tape with fuse specs. One of three nuts on the back of the case is warranty-sealed with a two-part plastic lock.

Troubleshooting

Normal failures are as follows:

  1. The thermal fuse. This fuse is installed as a rivet, made of bismuth/tin alloy, and is intended to prevent fire in the rare event of a failure of a flat, phosphor bronze spring on the wind clapper. These fuses eventually fail out-of-specs. A bronze spring separates the electrodes, and the remains of the fuse are usually evident somewhere in the case. I suggest replacing the fuse with lead-tin solder, with the warning that this voids the purpose of the fuse.

In addition to fire prevention, this fuse serves to protect the magnetic coil winding from overheating. Substituting tin-lead solder circumvents that purpose as well. Replacing the low melting point solder can be expensive...$100.00 for as 3ft coil. Fortunately I was able to re-solder using the original material, but had considered substituting a thermal fuse, "Cantherm part # DF119S, which fails at 119C. That temperature is very close to the melting point of the original solder, and the "Cantherm" fuse appears compact enough to be installed adjacent to the winding. DigiKey price is $0.98

Picture of fuse in place (a working clock!):

Picture of fuse gone. Strap separates when the fuse has failed.

  1. Points. Causes stalls at the end of the wind cycle without solenoid meltdown. The precious-metal points can become burned or distorted. Lubricant evaporates and is burned to soot in the points, and this can cause overheating. Metal can also sputter and migrate from point to point. Dress the points with fine abrasive.
  2. Flywheel bearing failure. Causes uneven force on the first wheel and stalls between winds. The heavy steel flywheel on the solenoid plate should not wobble on its bearing. For some reason these things wear out prematurely on some cars, particularly on SLs, and it may be high-frequency vibration related. It is held on its shaft by an E-clip. On later models the clip is built with a bronze tail, so you can't lose it. Replace the flywheel. Lubricate this bearing.
  3. First and second wheel bearing failure, back plate. Causes the clock to stall between winds. The first wheel takes a severe side load from the winder, and this will eventually doodle out the back bearing. The second wheel can also lose its back bearing. Replace the back plate (with attached balance), or repair the bearings. The bearings respond to shrinkage under a staking punch (with subsequent reaming), or to bushing. As good back plates are becoming rare, I find myself resorting to staking punch more and more.
  4. Setting knob (rare). The rubber suspension goes soft, and you can't reach the hands with the setting knob clutch. Use the clock for parts.
  5. Front plate bearings (very rare). The wheels wobble on the front bearings. Use the clock for parts.
  6. Weathering. Red rouge on a cloth wheel can do wonders for the plating on the brass bezel, and even for scratches on the plastic crystal.
  7. Cracked or smashed crystal (very rare). Use the clock for parts. Assure the owner that they're all just alike, and he won't notice the difference if he buys a new one.
  8. Previous repair work (more common). Note extra stickers or the absence of the nut seal. Note a promiscuous use of lubricant. Stalls in mid-wind. Clean it thoroughly. If the pivots and plates are not too worn, a tiny drip of watch oil on each of the pivots and the pins of the anchor escapement will make the clock's regulation less affected by changes in temperature. Do not, repeat DO NOT spray the movement with WD 40 or any type of spray lubricant, a drip of 3 in 1 oil from the tip of a toothpick makes a good substitute for a watch oiler.
  9. Salt water immersion. (More common than you'd like to think.) Excellent source of parts - the brass bearing plates are unaffected. Springs will be ruined.
  10. Only seen once: Winding pawl worn out. Clapper spring breakage. Clock possessed by demons.
  11. Clock Wiring

Suggestions:

Be careful of the cleaning fluid you use to remove old, oxidized lubricant. Most organic solvents will play havoc with the various plastic components. The best is freon, which to my utter dismay is no longer available. Professionals advise the use of detergent in water. Lubricate conservatively, using only fine watch oil. Silicon-based oil is certain not to harm plastic components.

Light bulb

The correct light bulb for these clocks is a 12V/2W incandescent bulb with a Ba7s base:

Quartz replacement clocks

As parts get more difficult to find for these clocks, and replacement clocks are getting harder (and more expensive) to buy, you may be able to replace it with a more accurate quartz clock.

A source for clock repair and replacements is Palo Alto Speedometer ( http://www.paspeedo.com/) in Palo Alto, California. They calibrated it too and it has been keeping virtually perfect time for four years (it gains about 1 minute a month).Great points, however you should ALSO note that Palo Alto Speedometer can "rebuild" the clock with a quartz movement. Not original, but it is better, will probably last forever, and is way more accurate. The movement isn't visible; the clock looks the same, it just works better.

An alternative supplier for VDO clock from my 1970 280 SL repair is David Lindquist, 12427 E. Penn St., Whittier, CA 90602. His phone # is (562) 698-4445. He is listed in Hemmings magazine, a highly recommended source for vintage/classic cars. David is pleasant, reliable and reasonable. He specializes in auto clock repair. He rejuvenated mine for $45 (2002 prices) and I had it back in 2 weeks. He also offers a quartz conversion if originality is not an issue. My clock has been accurate ever since.

Clock Repair

The following are companies able to undertake repairs of the clock (and frequently other instruments):


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