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PROPELLER SHAFTS
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PROPELLER SHAFTS
CONTENTS
page
page
GENERAL INFORMATION . . . . . . . . . . . . . . . . . . 1
PROPELLER SHAFT REPLACEMENT . . . . . . . . . 7
SERVICE DIAGNOSIS/PROCEDURES . . . . . . . . . 3
TORQUE SPECIFICATIONS . . . . . . . . . . . . . . . . 14
UNIVERSAL JOINT REPLACEMENT . . . . . . . . . . 9
GENERAL INFORMATION
PROPELLER SHAFTS
The function of a propeller shaft is to transmit
power from one point to another. The shaft is de-
signed to send torque from the transmission (transfer
case on 4WD vehicles) to the axle (Fig. 1,2).
The propeller shaft must operate through con-
stantly changing relative angles between the trans-
mission and axle. It must also be capable of changing
length while transmitting torque. The axle rides sus-
pended by springs in a floating motion. The prop-
Fig. 1 Propeller Shafts (XJ Vehicles)
Fig. 2 Propeller Shafts (YJ Vehicles)
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PROPELLER SHAFTS
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shaft must be able to change operating angles when
going over various road surfaces. This is done
through universal joints, which permit the propeller
shaft to operate at different angles. The slip joints (or
yokes) permit contraction or expansion (Fig. 1,2).
Tubular propeller shafts are balanced by the man-
ufacturer with weights spot welded to the tube.
The propeller shaft is designed and built with the
yoke lugs in line with each other which is called
phasing. This design produces the smoothest running
condition, an out of phase shaft can cause a vibra-
tion.
Before undercoating a vehicle, the propeller
shaft and the U-joints should be covered. This
will prevent the undercoating from causing an
unbalanced condition and vibration.
CAUTION: Use exact replacement hardware for at-
taching the propeller shafts. The specified torque
must always be applied when tightening the fasten-
ers.
Fig. 3 Single Cardan Universal Joint
UNIVERSAL JOINTS
Two different types of U-joints are used with the
propeller shafts:
•
Single cardan U-joint (Fig. 3)
•
Double cardan U-joint (Fig. 4)
LUBRICATION
The slip yoke and certain universal joints are
equipped with zerk type lubrication fittings. They
should be lubricated with a multi-purpose NLGI
Grade 2 EP lubricant. All U-joints should be in-
spected for leakage and damage each time the vehi-
cle is serviced. If seal leakage or damage exists, the
U-joint should be replaced.
Fig. 4 Double Cardan (CV) Universal Joint
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PROPELLER SHAFTS
SERVICE DIAGNOSIS/PROCEDURES
INDEX
page
16 - 3
page
Universal Joint Angle Measurement . . . . . . . . . . . . 4
Vibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
•
Inspect the propeller shaft for missing balance
weights, broken welds, and bent areas.
If the pro-
peller shaft is bent, it must be replaced.
•
Ensure the universal joints are not worn, are prop-
erly installed, and are correctly aligned with the
shaft.
•
Check the universal joint clamp screws torque
(1) Raise the vehicle.
(2) Remove the wheel and tires assembly. Install
the wheel lug nuts to retain the brake drums.
(3) Mark and number the shaft six inches from the
yoke end at four positions 90° apart.
(4) Run and accelerate the vehicle until vibration
occurs. Note the intensity and speed the vibration oc-
curred. Stop the engine.
(5) Install a screw clamp at position 1 (Fig. 1).
(6) Start the engine and re-check for vibration. If
there is little or no change in vibration, move the
clamp to one of the other three positions. Repeat the
vibration test.
(7) If there is no difference in vibration at the
other positions, the vibration may not be propshaft
unbalance.
Runout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Unbalance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
VIBRATION
Tires that are out-of-round or wheels that are un-
balanced will cause a low frequency vibration. Refer
to Group 22, Wheels and Tires for additional infor-
mation.
Brake drums that are unbalanced will cause a
harsh, low frequency vibration. Refer to Group 5,
Brakes for additional information.
Driveline vibration can also result from loose or
damaged engine mounts. Refer to Group 21, Trans-
missions for additional information.
Propeller shaft vibration will increase as the vehi-
cle speed is increased. A vibration that occurs within
a specific speed range is not caused by propeller
shaft unbalance. Defective universal joints or an in-
correct propeller shaft angle are usually the cause.
UNBALANCE
If propeller shaft unbalance is suspected, it can be
verified with the following procedure.
Removing and re-indexing the propeller shaft
180° may eliminate some vibrations.
•
Clean all the foreign material from the propeller
shaft and the universal joints.
DRIVELINE VIBRATION
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PROPELLER SHAFTS
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(10) Increase distance between the clamp screws
and repeat the test until the amount of vibration is
at the lowest level. Bend the slack end of the clamps
so the screws will not loosen.
(11) Install the wheel and tires. Lower the vehicle.
(12) If the amount of vibration remains unaccept-
able, apply procedures at the front end of the propel-
ler shaft.
RUNOUT
(1) Remove dirt, rust, paint, and undercoating
from the propeller shaft surface. Areas where the
dial indicator will contact the shaft must be clean.
(2) The dial indicator must be installed perpendic-
ular to the shaft surface.
(3) Measure runout at the center and ends away
from welds.
(4) Refer to Runout Specifications chart.
(5) Replace the propeller shaft if the runout ex-
ceeds the limit.
Fig. 1 Clamp Screw At Position 1
(8) If the vibration decreased, install a second
clamp (Fig. 2) and repeat the test.
RUNOUT SPECIFICATIONS
Fig. 2 Two Clamp Screws At The Same Position
(9) If the clamps cause an additional unbalance,
separate the clamps (1/4 inch above and below the
mark). Repeat the vibration test (Fig. 3).
UNIVERSAL JOINT ANGLE MEASUREMENT
INFORMATION
When two shafts come together at any common
joint, the bend that is formed is called the operating
angle. The larger the angle, the larger the amount of
acceleration and deceleration of the joint. This speed-
ing up and slowing down of the joint must be can-
celled to produce a smooth power flow. This is done
through phasing and proper universal joint working
angles.
A propeller shaft is properly phased when the yoke
ends are on the same plane or in line. A twisted
shaft will throw the yokes out of phase and cause a
noticeable vibration.
When taking universal joint angle measurements
or checking phasing with two piece shafts, consider
each shaft separately. On 4WD vehicles, the front
shaft input (pinion shaft) angle has priority over the
caster angle.
Ideally the driveline system should have;
•
Angles that are in equal or opposite within 1 de-
gree of each other
Fig. 3 Clamp Screws Separated
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•
Have a 3 degree maximum operating angle
•
Have at least a 1/2 degree continuous operating
(propeller shaft) angle
Engine speed (R.P.M.) is the main factor though in
determining maximum allowable operating angles.
As a guide to maximum normal operating angles re-
fer to the chart listed (Fig. 4).
PROPELLER SHAFTS
16 - 5
Fig. 4 Maximum Angles and R.P.M.
INSPECTION
Before measuring universal joint angles, the
following must be done.
•
Inflate all tires to correct pressure
•
Check angles in the same loaded or unloaded con-
dition as when the vibration occurred. Propshaft an-
gles will change according to the amount of load in
the vehicle. Always check angles in loaded and un-
loaded conditions.
•
Check the condition of all suspension components
and verify all fasteners are torqued to specifications.
•
Check the condition of the engine and transmis-
sion mounts and verify all fasteners are torqued to
specifications.
MEASUREMENT
To accurately check driveline alignment, raise and
support the vehicle at the axles as level as possible.
Allow the wheels and propeller shaft to turn. Remove
any external bearing snap rings (if equipped) from
universal joint so protractor base sits flat.
(1) Rotate the shaft until transmission/transfer
case output yoke bearing is facing downward.
Always make measurements from front to
rear.
(2) Place Inclinometer on yoke bearing (A) parallel
to the shaft (Fig. 5). Center bubble in sight glass and
record measurement.
This measurement will give you the transmis-
sion or OUTPUT YOKE ANGLE (A).
(3) Rotate propeller shaft 90 degrees and place In-
clinometer on yoke bearing parallel to the shaft (Fig.
6). Center bubble in sight glass and record measure-
ment. This measurement can also be taken at the
rear end of the shaft.
This measurement will give you the PROPEL-
LER SHAFT ANGLE (C).
Fig. 5 Front (Output) Angle Measurement (A)
Fig. 6 Propeller Shaft Angle Measurement (C)
(4) Subtract smaller figure from larger (C minus A)
to obtain transmission OUTPUT OPERATING AN-
GLE.
(5) Rotate propeller shaft 90 degrees and place In-
clinometer on pinion yoke bearing parallel to the
shaft (Fig. 7). Center bubble in sight glass and record
measurement.
This measurement will give you the pinion
shaft or INPUT YOKE ANGLE (B).
(6) Subtract smaller figure from larger (C minus
B) to obtain axle INPUT OPERATING ANGLE.
Refer to rules given below and the example in (Fig.
8) for additional information.
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