GMC 1986 P-Truck Service Manual page 378

DIAGNOSIS OF THE PROPELLER SHAFT AND
UNIVERSAL JOINT (CONTINUED)
PROBLEM I
K nocking Or 1. Worn or damaged universal joint.
Clunking Noise In
2. Side gear hub counterbore in the dif­
The D riveline When
Operating The
Vehicle In A Floating
C ondition In High Or
Neutral Gear At 10
MPH (16 km/h)
Roughness Or 1. Bent or dented propeller shaft.
V ibration 2. Undercoating on propeller shaft.
3. Tire unbalance, 30-80 mph (48-
4. Tight universal joints.
5. Worn universal joints.
6
7. Propeller shaft, parking brake drum or
8
9. Excessive looseness at the slip spline.
10. D istorted or dam aged yokes or
1 1
12. Propeller shaft runout at 50 mph (80
Scraping Noise
Roughness Above
35 MPH (56 km/h)
Felt And/O r Heard
1. Lack of lubricant.
Squeak
2. Center bearing.
POSSIBLE CAUSE
ferential is worn oversize.
129 km/h). Not throttle conscious.
. Burrs or gouges on companion flange.
Check snap ring locating surfaces on
flange yoke.
companion flange is unbalanced.
. Incorrect rear joint angle. The angle is
usually too large when it is a factor.
flanges.
. Yokes out of phase.
km/h). Throttle conscious.
Slinger, companion flange, or end yoke
rubbing on rear axle or center bearing.
Tires unbalanced or worn.
PROPELLER SHAFT 4A-5
CORRECTION
1. Replace the worn or damaged uni­
versal joint.
2. Replace the differential case and/or
the sidegears.
1. Replace propeller shaft.
2. Clean propeller shaft.
3. Balance or replace as required.
4. Impact yokes with a shaft hammer to
free up. If unable to free up or if joint
feels rough when rotated, replace.
5. Replace.
. Rework or replace the companion
6
flange.
7. Check for a missing balance weight
on the propeller shaft. Rotate the
companion flange 180 degrees.
. Check and correct trim height at curb
8
weight. Check and correct joint an­
gle.
9. Replace necessary parts.
10. Install new yokes or flanges.
. Remove companion flange, turn 180
1 1
degrees from the original position, lu­
bricate the splines and install.
Tighten bolts to specified torque.
. Check propeller shaft runout at front
1 2
and rear. Should be less than speci­
fied. If above, rotate propeller shaft
180 degrees and recheck. Replace
the propeller shaft if runout is still
over specification.
Correct the interference.
Balance or replace as required.
1. Lubricate joints and splines. Also
check for worn or brinelled parts.
. Replace or lubricate.
2