GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2002 🢒 Venture Ext. 🢒 Body and Accessories 🢒 Collision Repair 🢒 Front Lower Rail Sectioning - Left Side

Important: If the damage exceeds the recommended area for sectioning and the rail cannot be straightened, the complete rail must be replaced.

Sectioning procedures have been developed to simplify repair of the lower rails, providing the majority of the damage can be returned to factory specifications. This will allow the damaged front section to be replaced without performing a full rail replacement. The rails come as a complete assembly or may be purchased as the front portion of the rail for sectioning. Bumper mounting bracket can be serviced separately.

Failure to follow the instructions may lead to improper rail sectioning, which may compromise the structural integrity of the vehicle. Be certain to use correct procedure for proper rail sectioning. Left and right side rails have different cut measurements.

Removal Procedure

Important: The additional 10 mm (13/32 in) metal measurements will be used to create a flange for welding the new service part to vehicle.


    Object Number: 478860 Size: SH
  1. On the top of the rail, locate the last cut-out square (1). From the front edge of square, measure forward 47 mm (1 7/8 in) and scribe a line.
  2. Add 10 mm (13/32 in) and scribe a second line. The second line 57 mm (2 1/4 in) is cut location.

    3. Object Number: 478858 Size: SH
  3. On the inboard side of the rail, locate hole (1). Measure forward 54 mm (2 5/32 in) and mark location. Scribe a straight line on rail.
  4. Measure forward 10 mm (13/32 in) and scribe a second line. The second line 64 mm (2 19/32 in) is the cut location.

    5. Object Number: 478860 Size: SH
  5. On the outboard side of the rail, locate where brake line bolts to rail.
  6. Remove bolt and bracket.
  7. At larger hole, pull tape measure tight from forward edge of hole (2) and mark a line at 416 mm (16 in).
  8. Scribe a line with a straight edge. Make it as square as possible to inboard and top rail markings.
  9. Add 10 mm (13/32 in) and scribe a second line. The second line is the cut location, 426 mm (16 ¾ in).

    10. Object Number: 478863 Size: SH
  10. Make certain all 3 sides are aligned.
  11. Cut through all 3 sides of rail.
  12. On the bottom of the damaged rail (1), scribe a line from the outboard to the inboard cut locations and cut remainder of the rail from the vehicle.
  13. Remove the damaged section of the rail.

Service Part Preparation

    Object Number: 478873 Size: SH
  1. On the original rail, cut and remove 10 mm (13/32 in) of the outboard (1) and downward (2) turned flanges of the rail.
  2. Cut 10 mm (13/32 in) gaps along the corners of the original rail.
  3. Step the top, bottom and side tabs inward (3) to allow the service part to fit over the original rail.
  4. Clean and prepare mating surfaces as necessary.

Installation Procedure
  1. Position the service part over the original rail.
  2. Align and check fit with 3-dimensional measuring.

    3. Object Number: 478874 Size: SH
  3. Stitch weld along the entire sectioning joint.
  4. Make 25 mm (1 in) welds along the seam with 25 mm (1 in) gaps between.
  5. Go back and complete the stitch weld to create a solid weld joint with minimal heat distortion.
  6. Clean and prepare all welded surfaces.

    7. Important: Prior to refinishing, refer to GM 4901MD-99 Refinish Manual for recommended products. Do not combine paint systems. Refer to paint manufacturers recommendations.

  7. Prime with 2-part catalyzed primer.
  8. Apply sealers and anti-corrosion materials as necessary.
  9. Install all related panels and components.