On-Vehicle Service: Two Wheel Drive Independent Front Suspension; Shock Absorber; Stabilizer Bar - GMC 1986 P-Truck Service Manual

3C-8 FRONT SUSPENSION
TWO WHEEL DRIVE INDEPENDENT FRONT SUSPENSION

SHOCK ABSORBER

«--► Remove or Disconnect (Figures 5, 6, 7, 8, and
9)
• Raise the vehicle on a hoist.
1. Shock absorber (20) from the lower control arm.
• Nuts (23), washers (22) and bolts (21)
(Figure 9).
2. Shock absorber (20) from the frame.
• Nuts (16), washers (17), and bolts (21)
(Figure 9).
BENCH TEST: SPIRAL GROOVE SHOCK
ABSORBERS
1. Purge the air from the pressure chamber.
• Extend the shock vertically—top end up.
• Turn the shock over and c o lla p se it
vertically—top end down.
• Repeat the above step five times.
2. Place the shock absorber in a vise with the jaws
clamped onto the shock's bottom mount.
— Shock absorber should be positioned
vertically in the vise—top end up.
— Do not clamp the vise jaws on the shock's
reservoir tube.
3. Pump the shock absorber at various rates of
speed and observe the rebound force.
— Rebound force is normally stronger than the
compression force (approximately two to
one).
— Rebound force should be smooth and
constant for each stroke rate.
4. Compare with a good shock absorber.
5. If one of the following are observed, replace the
shock absorber.
— A skip or lag at reversal near mid-stroke.
— A seize (except at the extreme ends of
travel).
— A noise (grunt or squeal) after completing
one full stroke in both directions.
— A clicking noise at fast reversal.
BENCH TEST: NON-SPIRAL GROOVE
RESERVOIR SHOCK ABSORBERS
• P urging air from non-spiral groove shock
absorbers is not necessary. The shock absorbers
have a gas filled cell in their reservoirs (as
opposed to the air filled cell in the spiral groove
shock absorber reservoirs).
1. Place the shock absorber in a vise with the jaws
clamped on the shock absorber's top mount.
— Shock absorber should be held vertically in
the vise with its bottom end up.
ON-VEHICLE SERVICE:
— Do not clamp the vise jaws on the shock's
reservoir tube.
2. Pump the shock absorber at various rates of
speed and observe the rebound force.
— Rebound force is normally stronger than the
compression force (approximately two to
one).
— Rebound force should be smooth and
constant for each stroke rate.
3. Compare with a good shock absorber.
4. If one of the following are observed, replace the
shock absorber.
— A skip or lag at reversal near mid-stroke.
— A seize (except at the extreme ends of
travel).
— A noise (grunt or squeal) after completing
one full stroke in both directions.
— A clicking noise at fast reversal.
Install or Connect (Figures 5 through 9)
NOTICE: Refer to "Notice" on page 3C#1 of
this section.
1. Shock absorber (20) onto the vehicle.
• Bolts (21), washers (17, 22), and nuts (16, 23)
(figure 9).
Tighten
• C and P series upper mount nuts (16) to 190
N m (140 ft. lbs.).
• C and P series lower mount bolts (21) to 80
N m (59 ft. lbs.).
• G series upper and lower mount bolts (21) to
103 N m (80 ft. lbs.).
2. Lower the vehicle.

STABILIZER BAR

Remove or Disconnect (Figures 5-8 and 10)
• Raise the vehicle and support with suitable safety
stands. Remove the wheel and tire assembly.
1. Stabilizer bar (59) from the frame.
• Bolts (54), nuts (58), washers (55, 57) and
clamps (52).
2. Stabilizer bar (59) from the lower control arm (36).
• Bolts (43), nuts (38), washers (39, 41) and
clamps (42).
• Stabilizer bar (59) drops down—remove the
bushings (40, 53).