1928 Cadillac - GM Heritage Center

34 CADILLAC OPERATOR'S MANUAL
Inflation Pressure
For normal driving, the 32 by 6.75 low pressure tires, which are
standard equipment on Cadillac cars, thould be inflated to a pressure of
40 lbs. per square inch. The inflation pressure should be checked at
least weekly and should not be permitted to drop more than 5 lbs.
On cars driven at high speeds, the front tires should be inflated to 50 lbs.
or higher if necessary. This is important.
Tire Air Compressor
To use the tire air compressor with which the car is equipped, proceed as
follows:
Turn back the left-hand side of the front carpet and lift the small ovalshaped
cover which is in the floor just to the left of the transmission control
lever. Reach through the hole in the floor and remove the knurled cap from
the connection on top of the compressor. Connect one end of the air hose
(in the tool equipment) to this connection and the other end of the hose to
the valve of the tire to be inflated. Do not connect the bose to the tire first if
there is pressure in the tire.
The control shaft by which the compressor driving gear is placed in mesh
with the transmission gears projects through a small hole in the floor just in
front of the large hole over the compressor. To start the compressor, if
the engine is running, disengage the clutch and hold the pedal down until
the transmission gears have ceased to revolve. Then, with a screw-driver,
turn the slotted head of the compressor control shaft clockwise. If the engine
is not running, simply turn the control shaft clockwise without disengaging
the clutch and then start the engine.
The compressor gives best results when the engine runs at a speed of
approximately 1000 r. p. m., which is about three times the normal speed of
the engine when idling. Do not race the engine in operating the compressor,
or, for that matter, at any other time when it is not driving the car.
Racing the engine beyond the recommended speed not only decreases the
efficiency of the compressor, but is one of the worst forms of abuse. To stop
the compressor, turn the control shaft counter-clockwise.
Do not turn the compressor control shaft to start the compressor when the
engine is running and the clutch is engaged.
Tire Holder
The tire holder is designed to carry either one or two standard-size tires
mounted on rims and inflated. Each rim has on it three lugs which are
Figure IS. The spare rim and tire can be
removed after unlocking the clamp and unscrewing
it.
OPERATION 35
located so as to engage with notches on the support arms and on the adjustable
clamps. There are two sets of these notches in the support arms.
When two rims are carried, the rim nearest the car should be placed so
that the side with the lugs is away
from the car and the lugs should be
inserted in the inner set of notches.
The outer rim should then be placed
so that the side with the lugs faces
toward the car and the lugs of this
rim should be inserted in the outer
set of notches.
When only one rim is carried, the
side of the rim with the lugs should
face away from the car and the lugs
should be inserted in the outer set
of notches. This permits the rim to
be clamped by the outer clamp.
The tire holder lock is in the
upper end of the outer clamp screw
and is protected by a dust cap which
must be unscrewed to insert the key.
Turning the key clockwise disengages the lock, permitting the clamp
screw to be turned.
To lock the outer clamp, screw the clamp down firmly against the rim
or rims. Adjust the clamp screw handle so that it points squarely across the
car. Then turn the key counter-clockwise. Care should be exercised in
removing or replacing a spare tire not to strike the body of the car.
Note: If a tire cover is used, it should have slots cut in it opposite the
two upper lugs on the rim so as to permit these lugs to seat in the notches in
the support arms.
Wire Wheel Carrier
To remove the spare wire wheel from the carrier, first unscrew the dust
cap which protects the lock. Insert the key in the lock and turn it to the
nght. Then unscrew the large nut, using the hub cap wrench. The wheel
can then be taken off the carrier.
When installing the wheel on the carrier, tighten the nut as far as it will
£0. Then insert the kev and turn it to the left.