Thoughts on Removing Flywheels and Keys

By Staff
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Route 1, Glouster, Ohio 45732

Having been a reader of GEM for along time, it has become
apparent that many engine men have problems with removing keys and
pulling off flywheels without damage. Here are a few ideas that
have worked for me, and may well work for others.

Gib keys, the ones with the little ‘toe’ can often be
pulled with the aid of a shop made puller like the drawing. Measure
the gap between the flywheel hub and the toe of the key, and use a
piece of steel as big as you can fit into the gap. Make the puller
as wide as practical. Cut a square notch in the center of this bar
which will allow the bar to straddle the key. Carefully measure the
spacing of the two draw bolts, and locate these as close to the key
as practical, as a close spacing will lessen the tendency to bend
the puller.

Drill, tap and fit up two fine threaded grade 5 bolts, using
care to allow the bolt heads to pass a wrench. Locate the draw
bolts in line with the bottom of the notch in the puller bar. This
will locate the line of pull with the top edge of the key, and
lessen the tendency of twisting out of the key on a hard pull.

When you have the puller made to your satisfaction, set the
puller on the key, and hand tighten the draw bolts. Be sure the
bolts bear on a flat part of the hub, as far as possible. On small
or chipped hubs, it may be necessary to use a thin piece of steel
as a bearing point for the draw bolts. If you anticipate a hard
pull will be necessary, chamfer off the first thread to eliminate
damage.

When you are ready for a trial pull, lubricate the bolt threads
with grease or anti-seize, put a few drops on the end of the bolts
and wind a strain on the key, taking care to keep the puller square
with the key. Tightening the draw bolts will put a very strong,
straight line pull on the key. If the key is too tight and will not
loosen, generally no damage will be done, as the puller will bend
before any damage is done to the engine. I have driven the key with
a copper or brass hammer in an attempt to break loose any rust
bond, and of course, soak the key with your favorite
‘soak-them-loose’ solution.

In extreme cases it may be necessary to heat the hub with an
acetylene torch, expanding the hub a bit and possibly loosening
it.

For keys without the jib, the problem is a little more spicy.
First look on the inside of the flywheel and determine if a driver
can be inserted into the keyway, allowing the key to be driven out
from the inside.

If this idea is not practical, it may be possible to drill the
key, tap threads in it and use a slide hammer to remove it. If this
is necessary, use care in selecting as large a size of draw bolt as
the key will permit. Since most drilling will be done with a hand
drill, be careful to align the drill straight down the center of
the key. Make the hole plenty deep and use a coarse thread, as
these threads are much deeper than fine ones.

A slide hammer can be made of a bolt, about 16 inches long, or a
piece of cold rolled the same sizes with a nut threaded or welded
on one end. If your key is large enough to permit a ‘ hole to
be made in it, weld a ‘ grade 5 bolt to the end of your slide
hammer, screw this bolt into the key, and using care not to pinch
your fingers, try a few raps, increasing the strength of the impact
as your judgment dictates. On mean keys it will help to fit an eye
on the end of the slide hammer bolts, and pull a strain on it with
a small chain hoist or a come-a-long. This method will put a
terrific strain on the key, and will remove all but the most
stubborn of them. Obviously, if your flywheel is of the split and
bolted type be sure to loosen the bolts and wedge the gap to
eliminate the clamping force.

To remove flywheels, belt pulleys, gears, etc. from shafts, it
is often possible to use a hydraulic jack. Using the proper size
jack for your shaft, locate the head of the ram against the end of
the shaft. Loop a chain through the spokes, as close as possible to
the hub, and around the base of the jack. Keep the pump of the jack
on the bottom side so it will work in a horizontal position. Try to
loop the chain around two spokes, if possible, on each side of the
jack. Snug up on the jack and render the chain as necessary to
achieve a straight pull. Since a jack will have no mercy, use
common sense when applying the pressure and do not use enough force
to risk breaking the spokes. If possible, two healthy steel bars
can sometimes be located behind the wheel and against the shaft and
the chains looped around these bars.

I have pulled off some tight fits in this manner, but as with
anything involving high pressures, use your best judgment. Keep
your nose well away from the work. If the chain should break, it
could fly off with considerable force. Practice safety at all
times.

A thin coat of anti-seize compound on shafts, keys, bolts and
gaskets will allow them to be removed much easier in the
future.

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