Ford Taurus Front Unirail Sectioning

Introduction

This bulletin will provide a step-by-step procedure for sectioning the lower left front unirail on 1996-2000 Ford Taurus/Mercury Sable vehicles. Sectioning procedures can provide significant savings over replacing the entire rail assembly when structural damage is confined to the front portion of the rail.

Procedural Notes

Prior to beginning this procedure, the unibody structure should be checked for proper structural alignment. Any variances that exceed OEM tolerances must be corrected before cutting or removing any primary structural member.

Proper welding equipment and procedures must be utilized to ensure sufficient weld penetration and strength. Practice welds should be made on the discarded portion of the damaged rail and tested for adequate weld penetration prior to welding the replacement section into position.

This rail sectioning procedure can be performed without removing the engine cradle and powertrain. However, the left front cradle mount will need to be removed to provide easier access for welding and refinishing operations.

Repair Sequence

1. This sectioning repair will feature an overlap procedure to attach the replacement rail to the existing vehicle structure, except at the two rail flanges. These areas will require butt welds.

2. On the damaged portion of the frame rail, measure and scribe vertical cut-lines on the inner and outer surfaces of the rail as shown. The inner cut-line is marked 10 mm (13/32 inch) forward from the leading edge of the rectangular opening in the frame rail.
   

   The outer cut-line is located 25 mm (1 inch) forward from the front edge of the outer control hole.

   

   Next, connect the ends of each vertical scribe line across the top and bottom of the rail. A continuous cut-line should now be scribed on all four sides of the rail.

3. Use a reciprocating saw or cut-off wheel to remove the damaged portion of the rail end.
   
   

4. On the flange areas of the damaged rail, measure back 5 mm (3/16 inch) and cut out the required material as shown. Also, cut a 5 mm x 5 mm (3/16 x 3/16 inch) notch at each corner of the rail, enabling the rail surfaces to be turned in.
   

5. Following procedures similar to those described in Step #2, measure and scribe vertical cut-lines on the inner and outer surfaces of the replacement rail.

   The inner cut-line is marked 5 mm (3/16 inch) forward from the leading edge of the rectangular opening in the rail.

   

   The outer cut-line is located 20 mm (25/32 inch) forward from the front edge of the outer control hole.

   

   Scribe cut-lines across the top and bottom of the rail by connecting the ends of the vertical cut-lines. Then, with a reciprocating saw or cut-off wheel, remove the replacement rail section. The difference in dimensions between Steps #2 and #5 will provide for a 5 mm (3/16) overlap at the section joint.

6. Remove grease, dirt and any rustproof coatings from all surfaces of the vehicle unirail at the section joint location. Also, carefully remove any e-coat, primer, paint or cutting burrs from the existing rail and the replacement part at the weld joint area as well. Do not removing any pre-existing galvanized coatings or thin the base metal. Apply weld-through primer as necessary.

7. Install the replacement frame horn over the turned-in end of the existing frame. Clamp the replacement section securely in place.
   
   

8. Re-check all measurements to verify that the replacement rail section is properly positioned. Weld the horizontal and vertical joints in 19 mm to 25 mm (3/4 to 1 inch) increments while alternating weld locations to minimize heat build-up.

9. After all welding is complete, grind the weld material so that it is flush with the original rail surface. Be careful not to grind into the base materials.
   

10. Restore the original corrosion protection by re-coating the repaired area and the replacement rail section, both inside and outside, with the proper primer, base and top-coats. Complete corrosion protection recommendations can be found in Tech-Cor Automobile Research Bulletin 1986-7, Restoring Corrosion Protection During Vehicle Repair.

The information provided in this bulletin is for educational purposes only. Although every effort has been made to ensure the accuracy of the information contained in this bulletin, Tech-Cor assumes no responsibility or liability for any repairs performed using information from any publication issued by Tech-Cor.

Any person performing repairs must determine whether any suggested or recommended procedures or repairs are suitable or appropriate for the particular vehicle being repaired. The repairer remains solely responsible for such determination, as well as for the proper completion of the repairs.

Reproduction of this bulletin is not permitted without the written approval of Tech-Cor.