[ There is a smattering of applause as Bob climbs atop the soapbox.]
The CGT is back on it's feet. It'll be a little while before it can go
out and howl. The car loosened it's crank pulley at the Missouri
Endurance Rally and I have made repairs.
The crankshaft pulley also contains a vibration dampner. The purpose of
the dampner is to absorb the shock on the each cylinder power stroke.
That is, each time the spark fires off a mixture over the piston, the
piston is slammed down with great speed. The purpose of the vibration
dampner is to absorb some of that energy.
The crankshaft pulley is actually a two peice affair. There is an inner
hub that attaches to the crank and there is an outer shell separated by
a rubber ring. In the 'C', the inner hub is about 4 1/8" in diameter.
The rubber ring is 1/4" thick, and the outer shell is fairly larger and
narrow measuring about 8 1/4" inches overall. The pulley for the
ancillaries is with the outer shell thus the water pump and generator
see's a dampened pulse from the motor and the drag of the ancillaries
contributes to the dampening action.
The crankshaft is held in place by a nut and lock washer on the
crankshaft snout. Also, the pulley is keyed to the crankshaft with a
woodruf key. Normally the crankshaft pulley should be a press fit to the
front of the crankshaft. On my 28 year old, there seems to be some wear
in that the pulley is merely a slip fit. Also, the groove in the crank
and the pulley that holds the woodruf key seems to have opened up a
little bit.
I have heard that the greatest stress on the crank pulley and key is
when the car stumbles when starting or shutting down. A few misfires and
some carb spitting can really shake the crank. The C/GT with the three
Webers is certainly guilty of that.
When I began the repair, the crank pulley would rotate about 2 degrees
without the crank. I purchased a new woodruf key (88 cents!) and then
the play dropped to about 1 degree of rotation. The woodruf key is a
half-moon shape about the size of a nickel and about two nickels thick.
Amazingly, Vicki Brisith has them in stock as well as a new lock washer.
The parts cost $4 and the Loc-Tite $6.
What I choose to do was use Loc-Tite 'red' to 'glue' everything back
together. I cleaned up the crank snout, pulley, and the woodruf key
grooves with lighter fluid, dried everything well, and then appplied the
Loc-Tite. After about 15 minutes I slid the puley onto the crank.
I placed a new lock washer ($2.75) on the crank and then screwed down
the nut coated with Loc-Tite 'blue'. It is difficult to get the motor to
stand still to tighten the nut. The nut size is 1 11/16". I used an
8-sided 1 3/4" socket and a long breaker bar and a big hammer. After
tightening up as much as possible with strength, I then gave the breaker
bar a dozen hard taps with the hammer.
The crank pulley is now tight. This can be attributed to some
combination of a new woodruf key, the 'red' Loc-Tite, the new lock
washer, and firmly attaching the crank nut. We shall see.
The 'red' Loc-Tite is used for parts that you really want to stay
together. It should now be very difficult to remove the crank pulley. (I
may regret this later on an engine rebuild.) I used 'blue' Loc-Tite on
the crank nut threads so that the nut can be removed with reasonable
force.
The Loc-Tite should be allowed to set-up and cure for 24 hours so now
the C/GT is sitting in the garage waiting for the next sunny day before
fire up.
I'll let you know if this solution holds up. There wasn't very many
other options. The crank and pulley is out of prodcution, of course.
Having a machinist build up the crank or crank pulley would like be very
expensive *after* you have pulled and torn down the engine.
So we shall see.
Bob Allen, Kansas City, '69CGT Under Observatiuon
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