Full Replacement of the Apron/Rail Assembly
1991 Ford Escort and Mercury Tracer

Introduction

In 1991 Ford Motor Company began using the structural platform from the Mazda 323/Protege for their Ford Escort and Mercury Tracer models. When these vehicles are involved in front end impacts, buckles may form in the lower front unirail which will require replacement of the apron/rail assembly. This bulletin will describe a method of replacing this structural assembly without removal of the driveline or suspension crossmember. Although actual installation may vary slightly between Ford and Mazda vehicles, the basic installation procedure and concerns will be common to all models that use this structure. READ THIS BULLETIN COMPLETELY PRIOR TO THE START OF ANY REPAIRS!

Safety/Cautions

1. Observe all safety precautions and use appropriate safety equipment while performing this repair.
2. DO NOT lower the suspension crossmember without first completely disconnecting the steering coupling (intermediate shaft) from the steering pinion shaft.
3. DO NOT attempt to disconnect any of the motor mounts without first supporting the engine/driveline assembly.
4. Remove the passenger seat, right side kick panel, glove box and supporting hardware and wire harness before jacking the vehicle or disconnecting the driveline. Pull back the carpeting and remove any sound deadening or insulation material to expose the floor pan reinforcement and all apron/rail weld locations.
5. Pull and align the front unibody structure including A-pillars, floor and firewall areas. The reinforcement located inside the vehicle at the floor/firewall area may need particular attention during stress relieving to ensure proper fit up with the new service part assembly.
6. Solidly support the vehicle on a level surface while performing this procedure. (i.e. jack stands, repair bench, hoist.)
7. Refer to the WELDING INFORMATION for general welding guidelines.

Full Apron/Rail Replacement Procedure

Since this procedure was performed with a right side damaged vehicle, this bulletin will reference right side components in pictures and content. The left side procedure is similar to the right side.

1. Support the lower right side of the engine with a bottle jack and wood block at the area of the oil pan and air conditioning compressor mounting bracket. Due to the forward pitch of the engine be sure to balance the load before removing the right upper engine mount. If the radiator support assembly is also being replaced, remove the lower front engine mount bolt and the two engine crossmember mounting bolts at the bottom of the radiator support.
2. Remove the front suspension strut assembly on the damaged side only.
3. Support the middle of the suspension crossmember with a suitable jack which will allow raising and lowering of the assembly.
4. From inside the vehicle at the driver side firewall area disconnect the steering coupler (intermediate shaft) from the steering gear pinion shaft.
5. Remove the four rear crossmember mounting bolts (two right and two left). Locate the forward mounting bolt on the undamaged side and loosen the nut to the end of the threads. On the damaged side remove the nut completely. With the steering shaft separated, lower the suspension crossmember evenly until contact is made with the remaining nut on the forward crossmember mounting bolt. The crossmember must remain supported by the jack throughout this procedure.
6. Since the suspension crossmember will not be removed, the forward crossmember mounting bolt on the damaged rail must be cut between the lower rail surface and the lowered suspension crossmember.
7. From inside the vehicle identify the weld locations at the floor and firewall areas that attach the apron/rail assembly to the vehicle structure. Locate the center of each spot weld and drill a 1/8" pilot hole. Using a 3/8" diameter standard drill bit, drill out the spot welds at the floor/firewall locations by drilling through all layers of steel from inside the vehicle.
8. From inside the vehicle locate the welds at the inner rocker area and use a spot weld removal/cutting tool to separate the panels (i.e. miniature hole saw). Do not drill through the inner rocker as it will be reused. Two welds also exist on the exterior wheelhouse side.
9. From outside the vehicle remove the attaching welds on the vertical and horizontal rocker flanges. Any open holes must remain accessible as they will later serve as plug welding holes for installation of the new assembly.
10. Using a spot weld removal tool separate the apron reinforcement from the cowl side panel. Do not drill through the cowl side panel. It is not necessary to remove the welds connecting this reinforcement to the apron assembly unless it will be reused.
11. Locate approximately fifteen spot welds remaining in the apron to cowl pinch weld flange. Clamp and/or support the damaged apron/rail assembly before removing the remaining welds. Center drill each with a 1/8" bit followed by a 5/16" standard drill bit which will again provide plug welding holes for the new apron/rail assembly.
12. Prepare any apron/rail mating surfaces on the vehicle. This should include deburring the plug weld holes, removal of caulk and other organic contaminants and careful grinding of any spot weld nuggets.

Preparation of the New Apron/Rail Assembly

1. Using a standard type cutoff wheel remove the welds that secure the head of the crossmember forward mounting bolt to the top of the rail. This bolt is threaded into the lower portion of the rail and must be removed with a wrench or socket. Removal of this bolt is necessary to achieve fit-up with the vehicle while the suspension crossmember is still basically in place.
2. Properly position the new apron/rail to the vehicle and temporarily clamp it to the cowl flange. From inside and outside the vehicle scribe the factory weld locations (now plug welding holes). Remove the replacement part from the vehicle and observe the scribed weld locations on the apron/rail assembly. Where two layers of metal exist on the eplacement part drill 5/16" plug welding holes in one layer of metal only. Weld these rail locations before installing the assembly. This eliminates the need for welding through multiple panels and assures proper weld penetration through all panels. Be sure to dress these welds appropriately before continuing with this procedure.
3. The apron/rail assembly must be refinished prior to installation with the exception of the welding flange surfaces. Remove the factory coating on all welding flanges and mask off the areas with tape. Duplicate any factory caulked seams prior to refinishing the assembly.
4. After proper priming and color coating, remove the masking tape and clean any residue off the welding flanges before applying a weld through coating to the bare metal.
5. Apply a weld through coating as necessary to the corresponding surfaces of the vehicle structure.
6. Install the apron/rail replacement part on the vehicle and clamp it to the cowl flange.
7. Install the crossmember mounting bolt into the rail and tighten, being careful not to crush the top of the rail. Weld the bolt head to the top of the rail similar to the factory weld which was previously removed. Raise the suspension crossmember evenly into place. Install the four rear mounting bolts and two front mounting bolt nuts but do not fully tighten. This will allow some movement of parts during fit up. The jack under the crossmember must also remain in place.
8. After verifying all upper and lower body measurements, secure the apron/rail assembly to the vehicle.
9. Locate approximately four weld locations. These weld locations MUST BE plug welded prior to the installation of the apron reinforcement/closure panel.
10. Clean these weld locations before installing the reinforcement/closure panel. Refinishing and corrosion protection can be accomplished after the panel is installed.
11. Complete the plug weld installation on all attaching areas while continuing to check vehicle measurements. Remember to alternate weld locations and follow appropriate welding procedures and safety precautions.
12. Locate the area with three layers of steel at the upper tower flange. All three layers of steel must be joined by common welds. If a new reinforcement/closure panel is installed, drill 5/16" plug welding holes into the two outer layers of steel. If the reinforcement/closure is undamaged and reused, fit and mark plug weld locations,then drill 5/16" plug welding holes into the second layer. This will provide adequate weld penetration into the heavier portion of the strut tower flange.
13. Clean all weld areas both inside and outside the vehicle.
14. Using a small brush carefully apply an epoxy or self etching primer to all unprotected metal in and around the weld locations.
15. Apply caulking to the top and bottom of weld flanges to seal out moisture and contaminates.
16. Again using a small brush, carefully apply body color over all primed and/or caulked areas.
17. Torque all engine motor mount and crossmember bolts to proper values.
18. Reassemble the vehicle suspension and body parts. Verify that all fasteners are in place and torqued to the proper values.
19. Wheel alignment should be checked and corrected as necessary after assembly of the vehicle is complete.

Welding Information

Prior to any welding operations, the weld site must be cleaned without removing factory corrosion protective coatings or thinning the base metal. Do not remove any preexisting galvanized coatings. Do not use an oxyfuel (oxyacetylene) gas torch. After cleaning, a weld-through coating must be applied to all bare metal in the weld sites. All welding should be performed with a M.I.G. welder (Metal Inert Gas, now called G.M.A.W. or Gas Metal Arc Welding). Welding wire should be either 0.023" (0.584 mm) or 0.025" (0.635 mm) diameter which meets or exceeds the American Welding Society Standard (AWS-E-70S-6) with a mixture of 75% argon and 25% carbon dioxide shielding gas. Do not concentrate all welding efforts on one area, but alternate sites so that each welded area has time to cool down before the welding is continued. All continuous welds must be made in 1/2" - 3/4" (13-19 mm) increments which helps to minimize heat build up and panel distortion. The welding equipment must also be properly adjusted by making and testing practice welds on similar materials.

Remember, Corrosion Protection, including the refinishing of replacement components should be performed as outlined in Tech-Cor 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.