Flywheel Removal on Antique Gas Engines

Tips for easy and successful flywheel removal

| November/December 1984

  • Here the angle iron adapter is secured to the crankshaft by means of a
    #1: Here the angle iron adapter is secured to the crankshaft by means of a "C" clamp.
  • Gib head key puller
    #2: Gib head key puller, used with a slide hammer puller.
  • Railroad spikes wired to the spokes
    #3: Railroad spikes wired to the spokes, to be used in conjunction with a 3 Jaw puller to remove the flywheel.
  • Gib head key
    #4: Gib head key

  • Here the angle iron adapter is secured to the crankshaft by means of a
  • Gib head key puller
  • Railroad spikes wired to the spokes
  • Gib head key

Engine flywheel removal may sometimes be a problem. Especially after forty or fifty years abandonment to the elements of weather. The procedures discussed here for flywheel removal have resulted in success for me. The first thing I would do is to clean off the outer ends of the crankshaft. A file may be necessary to remove some nicks and burrs. After the burrs are removed I use a strip of medium grit emery cloth to clean and polish the crankshaft. Be sure to clean the key way too.

You will notice that most engines have a slight end-thrust on the crankshaft. Take advantage of this end-thrust! Tip the engine over on its side, with a block of wood supporting the end of the crankshaft. A 2" x 6" wood block may be used for this purpose. The reason for this step is to loosen the flywheel preparatory to flywheel removal.

A heavy pipe sleeve may be used over the end of the crankshaft to drive on the hub of the flywheel. However, I use an alternative adapter made from a heavy piece of angle iron about eight inches long. There is a 3/4" steel plate welded to the top of the angle iron, to drive on. This adapter is held in place with a "C" clamp, as shown in photo #1. Using an eight or ten pound sledge, tap lightly on the adapter. Now check the flywheel closely to see if it has moved.

Tap harder with the sledge, as necessary to move the flywheel. You should also check the end thrust. If there is no end-thrust do not pound on the flywheel any more. Remember, the movement may only amount to fifty thousandth (.050) of an inch. Now notice the shape of the key in the keyway. If the key has a head on it, and looks like photo #4 it is a gib head key, and must be removed before attempting to remove the flywheel. Standard square type keys do not have to be removed. Gib head keys are tapered to tighten up when driven into the groove.

Two chisels faced together between the flywheel hub and the gib key head may be used to loosen the key. However, I have found it very effective to make a gib head key puller, to use with a slide hammer.

There are three pieces welded together. The first piece was a rectangular stock the same width as the key-way. This is welded to an adapter nut that fits the slide hammer puller. The next piece is one puller jaw welded to the improvised piece that fits in the key way. The puller adapter is then clamped to the crankshaft by means of a hose clamp. (See accompanying photo #2.) Use a penetrating oil such as WD-40 freely. I do not recommend heating the flywheel hub with a torch for removal. The danger of warping is too great.


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