Research Bulletin 2000-2

Dodge Ram 1500 4x4 Front Frame Horn Replacement

Introduction

This bulletin details a sectioning procedure for replacing the left front frame horn on 1994 - 2000 Dodge Ram 1500 4x4 pickup trucks. Sectioning of a damaged frame horn can be performed to avoid replacing the entire vehicle frame.

This bulletin references only the left side frame rail of the Ram 1500 4X4. Repair procedures for the right frame rail or 4x2 models are not covered by this bulletin.

Procedural Notes

Prior to beginning this procedure, the vehicle frame should be checked for proper structural alignment. Any variances that exceed OEM tolerances must be corrected before removing the damaged rail section. This procedure can only be used if there is no damage or distortion in the steering gear box mounting area.

Certain mechanical components must be removed to gain access for cutting and welding operations. The radiator will need to be removed, although the core support can be left in place. The air conditioning condenser (on models so equipped) will also need to be relocated. If undamaged by collision forces, the refrigerant system can remain closed and intact throughout the repair procedure. Finally, the steering gear box and stabilizer bar will need to be temporarily removed or moved aside for the sectioning procedure.

Due to the thickness of the mild steel frame rail, proper welding equipment and procedures must be utilized to ensure sufficient weld penetration and strength.

A continuous welding technique should be used for all four sides of the rail. Full fill of the 4 mm (5/32 inch) root gap between the base metals is expected in one continuous welding pass. Slight weaving from one side of the joint to the other may be necessary for complete penetration of the filler metal into the base metal sections and the insert material, as well as completely filling the root gap. Cosmetic completion may also be necessary.

Practice welds should be made on a discarded portion of the frame horn and tested for adequate weld penetration prior to welding the replacement frame horn section into position.

Repair Sequence

Using a wax and grease solvent, remove the rustproof coating from the outside surfaces of the damaged frame and the replacement frame at the cut-line area.
The damaged portion of the frame rail will be removed along a line located between the rear steering box mounting holes and the front suspension crossmember. On the outer surface of the damaged rail, mark a point at the upper corner of the rail 155 mm (6 1/32 inches) from the control hole as indicated in the photograph below. Mark a similar point 140 mm (5 ½ inches) forward of the control hole at the lower corner of the rail. Using a straight edge, connect these two points to form the outer cut-line.
Repeat the procedure described above on the inner surface of the damaged rail, marking points 195 mm (7 21/32 inches) and 75 mm (2 31/32 inches) from the rearward mounting holes for the steering gear box.
Next, connect the ends of each vertical cut-line across the top and bottom of the rail. A continuous cut-line should now be scribed on all four sides of the damaged rail. Use a reciprocating saw or cut-off wheel to remove the damaged frame horn. NOTE: The section joint is not a true, straight cut. The outer cut-line is rearward of the inner cut-line.
On the replacement rail, duplicate the marking procedures as described in Step #2 and Step #3. Then, measure 4 mm forward (toward the front end of the rail) from the scribed line and mark a cut-line. This new cut-line allows for a 4 mm (5/32 inch) root gap when welding the replacement section in place. Do not cut directly along the new cut-line. Fit-up the replacement part and grind back as necessary to ensure a consistent 4 mm (5/32 inch) root gap. Do not grind back on the original frame rail. Use a reciprocating saw or cut-off wheel to remove the replacement frame horn.
Fabricate a 13mm (1/2 inch) wide weld backer insert from a similarly shaped portion of the undamaged frame. The insert must fit inside the frame at the repair joint.
Remove any rustproof coatings from the inside surfaces of the vehicle frame and the replacement frame horn at the section joint location and all surfaces of the weld backer inserts. These procedures will help ensure a strong weld by minimizing contamination.
Carefully grind a 30 degree bevel along the scribe line at the cut edge, on all four sides of the original and replacement frame. This procedure will form a "V" with a 4 mm (5/32 inch) root gap at the inside surface of the frame material which contacts the weld backer insert. This weld joint preparation will allow for sufficient weld penetration into the backer plate while fusing the replacement and original frame materials together.
Remove any foreign material or debris, such as weld splatter and cutting burrs, from the existing frame and the replacement part within 13 mm (1/2 inch) of the repair joint to allow easy and proper fit-up during assembly.
On the vehicle frame at the cut-line, cut or grind a 6 x 6 mm (1/4 x 1/4 inch) notch at each corner. Install the weld backer inserts halfway into the existing frame and tack weld them into place at the notched areas and inner rail surfaces as necessary.
Install the replacement frame horn over the backer inserts. Clamp the replacement frame horn section securely in place, leaving a consistent 4 mm (5/32 inch) root gap between the replacement frame horn and the original vehicle frame. Tack weld the replacement section in place.
Re-check all measurements to verify that the replacement frame horn is properly positioned. Following the procedures described earlier in this bulletin, weld the upper and lower horizontal joints from corner to corner. Then, weld the vertical joints from corner to corner.
Finally, weld the front part of the rail to the crossmember.
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.
Restore the original corrosion protection by re-coating the repaired area and the replacement frame horn, both inside and outside, with a wax-like, creeping rustproofing material. The enclosed portion of the section joint can be easily reached with a typical rustproofing applicator spray wand.

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.