On-Vehicle Service: Two Wheel Drive Rpo Fs3 (I-Beam) Front S U S P E N S Io - GMC 1986 P-Truck Service Manual

ON-VEHICLE SERVICE: TWO WHEEL
DRIVE RPO FS3 (I-BEAM) FRONT SUSPENSION
SHOCK ABSORBER
Remove or Disconnect (Figures 32 through 34)
• Raise the vehicle and support it with suitable
safety stands. Remove the wheel and tire
assembly.
1. Shock absorber (113) from the leaf spring spacer
(158).
• Nut (109) and washer (111).
2. Shock absorber (113) from the frame.
• Nut (109) and washer (111).
• Pull the shock free from the vehicle.
BENCH TEST: SPIRAL GROOVE SHOCK
ABSORBERS
1. Purge the air from the pressure chamber.
• Extend the shock vertically—top end up.
• Turn the sh ock over and co lla p se it
vertically—top end down.
• Repeat the above step five times.
2. Place the shock absorbers 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 ABSORBER
• P urging air from n on-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.
FRONT SUSPENSION 3C-31
— Shock absorber should be held vertically in
the vise with its bottom end up.
— 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.
♦ i l Install or Connect (Figures 32 through 34)
1. Shock absorber (113) to the frame (figure 34).
• Insert the shock's upper stud into the hole in
the frame.
• Washer (111) and nut (109). Do not tighten.
NOTICE: Refer to the "Notice" on page 3C#1
of this section.
2. Shock absorber (113) to the leaf spring spacer
(158) (figure 34).
• Position the shock's lower mount onto the
stud.
• Washer (111) and nut (109).
Tighten
• Shock absorber upper nut to 185 N m (136
ft. lbs.).
• Shock absorber lower nut to 50 N m (37 ft.
lbs.).
3. Wheel and tire on the vehicle. Lower the vehicle
to the ground.