Suspension - Torsion Bar Adjustment
88chevy03Number: 88-131-3A
Section: 3A
Date: Jan., 1988
Subject: TORSION BAR ADJUSTMENT
Model and Year: 1988 K-1500, 2500, 3500 MODELS
TO: ALL CHEVROLET DEALERS
1988 K models which are intended for snow plow applications may require front suspension option F60. When F60 is ordered, the vehicle's base torsion bars are upgraded to the next higher rate bars to compensate for vehicle trim changes due to the extra weight of the snow plow assembly. Vehicles that were built with Z71 off road chassis package were equipped with F60 as part of the Z71 package.
Some vehicles equipped with base level torsion bars may only require minor trim height changes to be adaptable for snow plow applications. Variations in the assembly plant build and torsion bar settings may allow for additional trim height changes which can be made by adjusting the torsion bars. On vehicles built before the VIN breakpoints provided on page 2, it is not recommended that the torsion bars be adjusted more than four or five times. Vehicles built after the breakpoints can be adjusted multiple times without detrimental effects on the adjustment mechanism. Those vehicles equipped with base level torsion bars requiring additional trim height beyond that which is attainable through a trim height adjustment must have the F60 torsion bars installed in place of the base bars.
To determine which torsion bar is installed in the vehicle, the three digit code stamped on the end of the bar must be noted. These three digits are the last digits of the part number, which can be found in the base production torsion bar chart listed on page 2. To determine the correct F60 bar to be used, the part number from the base production torsion bar side of the chart must be cross referenced to the corresponding F60 torsion bar on the right half of the chart.
When replacing or adjusting torsion bars, follow the procedure in Front Suspension and Axle, Section 3C of the 1988 C/K Service Manual. The front suspension alignment specifications, for vehicles which have had F60 installed at the dealer level are provided on the chart. Most vehicles which have F60 installed will not require caster and camber adjustments, however, toe-in must be set at "0" degrees at vehicle curb trim.
VIN Breakpoints:
Fort Wayne Chevrolet JZ186298
Pontiac Chevrolet JE153765
Oshawa Chevrolet J1199957
Adjustment or replacement of torsion bars to compensate for vehicles not equipped with F60 (snow plow package) is not covered under the terms of the New Vehicle Warranty.
K TRUCK TORSION BAR USAGE
Base Production Torsion Bar K-1500
Left P/N Right P/N
15528951 15528952
15528955 15528956
15528959 15528960
15528963 15528964
K-2500-3500
Left PIN Right P/N
15528953 15528954
15528957 15528958
15528963 15528964
15528965 15528966
F60 Torsion Bar K-1500
Left P/N Right P/N
15528955 15528956
15528959 15528960
15528963 15528964
Not Available
K-2500-3500
Left P/N Right PIN
15528957 15528958
15528963 15528964
15528965 15528966
Not Available
SPECIFICATIONS
Camber Caster Toe
Caster angle must be corrected to level frame angle.
Note: Vehicle must be jounced three times to eliminate false geometry readings.
A - Left and right side to be equal within .5 degrees. B - Toe-in left and right side to be set equally per wheel and steering wheel must be held in straight ahead position within +/- 5.0 degrees.
NOTE - Service checking and setting at settled (Z) heights for vehicles equipped with F60 torsion bars are:
TRIM HEIGHTS
"Z" HEIGHTS WITH F60 TORSION BARS
K-1500-2500 K-3500
161 mm +/- 6 mm 151 mm +/- 6 mm