suspension sag

Discussion in 'General Chevy & GM Tech Questions' started by bigdawg, Mar 18, 2012.

  1. bigdawg

    bigdawg New Member

    I got a 2004 Silverado short bed standard cab. For some reason the truck sits about 2 inches lower on the left front than the rest. When your standing at the rear of the truck you can tell theres a big difference in the stance. When i bought the truck the dealer put a new set of shocks on the front but it didnt help any. I think it may just be a weak coil spring but im not sure. If anyone can help or give any ideas of what to check id appreciate the help. Thanks Brian
  2. Z71_guy

    Z71_guy Epic Member 5+ Years 1000 Posts

    This truck has torsion bar suspension so no coil springs. Commonly called the chevy lean the left hand torsion bar gets week and starts to sag you fix this buy buying new torsion bars or cranking the adjusting bolt to level it out
  3. bigdawg

    bigdawg New Member

    I didnt see any torsion bars under there all it is is a coil spring with a regular ole shock thru the middle.

    99'HEARTBEAT MODERATOR Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    Brian, from what you have mentioned, and if your 04" is a 2WD....1500(1/2 Ton)Series, then the below G.M. Service Bulletin may be able to help you with your concerns, regarding the left front of your Truck sitting lower than the rest of the truck,

    G.M. Service Bulletin Regarding the......Vehicle: Chevy Lean,

    Subject Vehicle Lean.......Left Front Sits Low or Right Rear Sits High (Add Spacer Between Left Rear Spring Pack and Axle) #06-03-06-005A - (01/12/2007)

    Models: 1999 to 2007 Chevrolet Silverado (Classic) 1500 (½ Ton) series

    Models: 1999 to 2007 GMC Sierra (Classic) 1500 (½ Ton) Series

    With Two-Wheel Drive
    This bulletin is being revised to update the models to reflect that the bulletin only applies to 1500 (½ Ton) Series. Please discard Corporate Bulletin Number 06-03-06-005 (Section 03 -- Suspension).

    .....Some Customers,
    Have commented that their vehicle appears to lean. In most cases, the vehicle will sit Low Left Front or High Right Rear.
    Measure fender wheel-opening heights, front and rear, to quantify vehicle lean. Fender wheel-opening heights are related to, but distinct from, trim height (a.k.a. Z and D height). The front wheel-opening height is known as P height, and the rear wheel-opening height is know as R height. The P and R heights are not set at the factory, nor is a specification given for them. However, they are the most direct and repeatable measurement of what a customer would see as the vehicle leaning. Perform the following before measuring the fender wheel-opening heights:

    • Make sure the vehicle is on a level surface, such as an alignment rack.

    • Set the tire pressures to the pressure shown on the certification label. Refer to Label - Vehicle Certification in General Information.

    • Check the fuel level. Add additional weight if necessary to simulate a full tank.

    • To ensure proper weight distribution, make sure the rear storage compartment is empty

    • Close the doors and hood.

    P Height and R Height Measurements
    P height and R height are measured the same way. They are the distance from the ground to the highest point on their respective wheel-opening, going through the center of their respective wheel. Record the measurement on the repair order.

    If the difference from left to right for P and R height is 15 mm (0.59 in) or less, no repairs are suggested as the vehicle is within specification. If the difference exceeds 15 mm (0.59 in) for either measurement, install the spring spacer to the left rear side of the vehicle following the procedure below.

    Raise and support the vehicle.
    Support the rear axle.
    Remove the U-bolt nuts, remove the U-bolts and anchor plate. Discard the U-bolts. DO NOT discard the nuts or anchor plate.
    Remove the lower shock nut and bolt.
    Raise the vehicle or lower the axle enough to allow for installation of the spacer. Install the spacer, P/N 15872657.
    Lower the vehicle or raise the axle.
    Install the lower shock nut and bolt.
    Tighten to 95 N·m (70 lb ft).

    Install the anchor plate, new longer U-bolts, P/N 15872655, and nuts.
    Tighten the nuts to 72 N·m (53 lb ft).

    Remove the axle support and lower the vehicle.
    Re-check the P and R heights in the previous location. Record these readings on the repair order.
    After all measurements are done, perform a road test and check headlight aim.
    If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

    Part Information,
    Part Number
    Description .....Rear Spring Spacer

    Part Number....15872657
    Description......Rear Spring U-Bolt

    Part for a rubber insulator the dealers use to space the driver side coil spring.

    ....Side Note....If your left front is 1" lower, you can add one digit to your Part # that come on your truck and it will raise your left front approx 1"


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