Servicing car door locks

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Lock service can be divided two ways : the easiest and most frequently performed is that of cleaning and lubricating lock mechanism. Oil should never be used in locks. Oil is likely to gum or collect dust and cause sticking of the delicate lock mechanism. Nevertheless many car owners oil their own locks which make it necessary for the service man to clean them out.
Servicing car door locks

A pump type oil can filled with carbon tetrachloride or high-test gas can be used to flush out a lock. This breaks down, dislodges, and flushes out accumulated grease, oil, and dirt. Then, after waiting a minute or two for this cleaning liquid to evaporate or, better yet, after blowing the lock out with compressed air, a lubricating gun of fine graphite is used and a charge of this is forced into the lock mechanism.

After having done the foregoing, the key should be inserted and moved slowly in and out to distribute the graphite over all moving surfaces.

The foregoing will put most locks into such condition that they will operate smoothly; but where it does not it is usually best to replace the entire lock cylinder with a new one, since repairs to the many parts that would be worn would cost more than the new cylinder.

Replacing lock cylinders is generally accomplished in one of two ways. Either the cylinder is held by a retaining screw as shown in figure left and may be removed by loosening the screw, or in the constructed illustration below.


Door cylinders

Here the key is inserted and turned to the left while a sharp instrument (a paper clip will do) is inserted in a small hole in the cylinder to depress a retaining spring.

The key is then further turned to the left and the cylinder removed with the key. The following information on key service covers specifically Briggs and Stratton locks used on 1938 Chevrolets (but applies to many other cars, too).

The side bar type lock is used on all 1938 passenger cars for the ignition, door, and deck. This lock has six tumblers cut to four different depths. Service locks have the tumbler depths indicated by colors, "B" for black, "N" for nickel, "Y" for yellow, and "C" for copper. Key codes, furnishedwith all key-cutting machines, consist of numerals for the tumbler positions and letters for the tumbler depths.

To assemble tumblers in an uncoded lock cylinder :

First, hold cylinder in the left hand with head of the cylinder away from you (left) and insert tumblers, ribbed side toward you and long point down.

Car door tumblers

Second, start from the head and drop the indicated tumblers in their proper slots in the order called for by the code. After all are in place, check for correctness with the code (centre). Press tumblers down with finger (right).

Tumbler spring

Third, insert one tumbler spring above each tumbler in round cavity (left).

Caution: If springs are tangled do not pull tumbler springs apart—unscrew them.

Fourth, reverse cylinder in left hand so that head of cylinder is now toward you. Insert spring retainer (right), so that its six sprongs each slip into one of the springs, and the two large end prongs slide into the slots at either end of the cylinder.

Holding retainer

Press retainer down with forefinger of left hand and in that position insert cylinder into checking and staking tool (left). Still holding retainer in place with finger, pull lever on the tool over top of retainer to hold it in position (right).

Fifth, to check : Insert the proper key and rotate cylinder clockwise about 1/8 turn. If lock is properly set up, cylinder will turn, otherwise the bar will not be released and cylinder cannot be rotated ; in which case remove and reset tumblers properly.

Sixth, if cylinder rotates, return it to the original position and remove key. Tighten set screw in left end of tool to prevent turning of cylinder.

Seventh, stake down the retainer. The retainer is held in place by forming the cast metal over both edges of the retainer ends from the outside, using staking tool provided. Hold staking tool at a right angle. Form the cast metal of the cylinder over the retainer with a single stroke of a light hammer for each of the four staking positions.

Eighth, release set screw and remove cylinder.

Note.—If tumblers have been improperly assembled and not according to code, the tumblers can be removed from cylinder by holding cylinder with the tumbler slots down and pulling the bar out with fingers and jarring cylinder to shake the tumbler out. This procedure is necessary because after the tumblers have been pressed down into the cylinder as illustrated, the tumblers are held in their slots by the bar.

Side bar key cutting machine

When cutting keys in the key cutter, the cutting positions are located by the spacer lever and the depths by the depth bar. To cut a key proceed as follows :

First, insert blank from right, with edge to be notched toward punch. Push blank all the way into stop. Tighten thumb screw to hold key blank in place.

Pull spacer lever down to position 1 for first cut. Then adjust depth bar by compressing carriage with the thumb of right hand; in the direction indicated by arrows, move depth bar with left hand until depth letter required appears in indicator window. Release carriage.

Caution: Be certain that the spacer lever is in correct indent and depth letter appears fully in the indicator window.

Second, to cut key, hit punch a quick, sharp blow with a light hammer.

Third, move spacer lever to position 2, compress carriage, and shift depth bar to letter required. Punch depth.

Fourth, continue as above, cutting required depths for positions 3-4-5-6.

Check cut key with codes by inserting it into key decoder.

Note.—When there are two or more depths the same, after once setting the depth bar you can shift the spacer lever to any position calling for this depth, and make all these cuts without changing depth bar.

Using key decoder

  1. Hold key decoder in left hand, and insert key from the right.
  2. Read code from head of key to tip, from positions 1 to 6. The depths cut are shown by the indicators under each position number.
  3. An indicator reaching into the copper strip indicates depth "C." Indicator reaching into nickel strip indicates depth "N" in black strip "B" and in yellow strip “Y”
  4. The code of the key illustrated in the key decoder reads :

Caution: The tip of the indicator must split the colored strip. Save the gauge key, furnished with each key decoder, to frequently check key decoder. Gauge key is cut Y-B-N-C-C-C.

Car key decoder