Research Bulletin 1993-9

1990-93 Geo Storm Front Lower Rail Extension and Radiator Side Panel Installation

Introduction

This bulletin will describe the procedures and address specific issues concerning replacement of the front lower rail extension (without side panel), and also full replacement of the radiator support side panel assembly (including the rail extension) for the 1990/93 Geo Storm. The primary focus will be on proper weld attachment of a replacement rail extension. Improper weld strength as well as weld location can affect the structural performance of the vehicle front structure during a subsequent collision involving this area of the repaired vehicle.

The replacement part assembly for the left or right side includes the radiator support side panel and the front lower rail extension. This assembly is held together by three spot welds which are not in the same locations as the factory spot welds that join the assembly to the main lower rail. Refer to Photograph 1.

A complete radiator support assembly is also available for this vehicle which includes both side panel assemblies and upper tie bar. Although installation of the complete radiator support assembly will not be covered, the concerns and procedures for installing each side panel assembly will apply to the complete radiator support assembly installation. Procedures for individual left and right sides are the same.

Although the rail extension is not serviced separately, it can easily be separated from the replacement side panel after drilling out the three spot welds that secure it to the side panel. To simplify weld application and improve weld quality, all MIG plug welding is performed from the front side of the vehicle.

Replacement of Rail Extension Only

Remove any necessary components (front cover, reinforcement and absorbers) to gain access to the front lower rail extension (absorber mounting bracket).
CAUTION: A portion of the lower rail protrudes into the lower section of the rail extension. This area is visible when looking inside the attached rail extension after the absorber is removed. Exercise extreme care so as not to cut off this protruding portion of the lower rail. Refer to Photograph 2.
Using a cut-off wheel or reciprocating saw, remove all but 1/2" of the damaged rail extension leaving the flange attached to the side panel. Do not cut into the lower horizontal portion of the rail that protrudes approximately 1/2" forward into the lower section of the rail extension. Refer to Photograph 3.
On the replacement part assembly, locate the three spot welds that join the two panels together. With a miniature hole saw, drill out the welds by drilling from the back side of the panel only. Carefully remove the remaining spot weld nuggets on the replacement rail extension. Do not thin the base metal by excessive grinding.
On the damaged vehicle locate the two spot welds on the lower portion of the rail extension. Measure these two locations and transfer the measurements to the replacement part.
Using masking tape or a scribe tool, outline the rail extension flange location on the radiator side panel. This will enable exact positioning of the new replacement rail extension.
Using a miniature hole saw, cut out the two spot welds that are located on the lower horizontal portion of the rail extension. Refer to Photograph 2.

Cut the spot welds on the vertical flanges that attach the extension to the side panel. CAUTION: EXERCISE EXTREME CARE WHEN CUTTING OUT THE SPOT WELDS. ONLY DRILL THROUGH THE RAIL EXTENSION MOUNTING FLANGE AND NOT INTO THE SIDE PANEL SURFACE. The flange can now be removed and will serve as a template for marking the plug welding holes on the replacement part. Refer to Photograph 4.
Remove any remaining spot weld nuggets using an appropriate abrasive disc without cutting into the surface of the side panel.
Remove any material that will interfere with fitting the front surface of the rail extension template flush against the replacement rail extension. Position the front side of the template to the rear side of the replacement part flange and accurately mark the spot weld hole locations. Refer to Photograph 4 above.
Center drill each location including the two previously marked weld locations on the horizontal flange using a 1/8" drill bit. Using a 5/16" diameter drill bit, drill these locations from the backside of the extension flange to provide plug welding holes.
Remove any drilling burs as necessary, as well as the factory applied E-coat on the back side of the extension flange. Apply an appropriate weld-through coating to any bare metal area of mating surfaces on the vehicle and replacement part areas.
Accurately position the new rail extension referencing the previously taped or scribed outline on the side panel, and securely clamp in place. Refer to the welding information prior to performing welding operations.
After verifying the replacement part is in its proper location, it can be plug welded in place using appropriate welding procedures. Because the plug welds have been placed in exactly the same locations as the factory spot welds, the mig plug welds will become part of the factory spot weld and attach the rail extension directly to the main unirail behind the radiator side panel. After welding, grind any plug weld nuggets for cosmetic appearance. Wire brush or abrasive blast both the front and back sides of all plug weld locations.
Remove any loose paint or galvanize residue from inside the rail and at both sides of the weld sites using compressed air. Apply an appropriate corrosion resistant primer to the weld joint from both inside and outside the joint area and refinish the repair as necessary.
Apply a creeping/waxy type corrosion inhibitor to the inner and outer portion of the rail extension.

Full Replacement of the Radiator Side Panel Assembly

CAUTION: A portion of the lower rail protrudes into the lower portion of the rail extension. This area is visible when looking inside the attached rail extension after the absorber is removed. Exercise extreme care so as not to cut off the protruding flange of the lower rail. Refer to Photograph 2.

Remove any necessary components (front cover, reinforcement and absorbers) to gain access to the front lower rail extension (absorber mounting bracket).
Using a cut-off wheel or reciprocating saw, remove all but 1/2" of the damaged rail extension leaving the flange attached to the side panel. Do not cut into the lower horizontal portion of the rail that protrudes approximately 1/2" forward into the lower section of the rail extension. Refer to Photograph 2 above.
Locate and center punch all spot weld locations. Measure the location of the two spot welds on the lower portion of the rail extension and transfer these measurements to the replacement part.
Using a miniature hole saw, cut out the two spot welds that are located on the lower horizontal portion of the rail extension and on the vertical flanges that attach the rail extension to the side panel. It is only necessary to drill through the rail extension mounting flange. The flange can now be removed and will serve as a template for marking the plug welding holes on the replacement part. Refer to Photograph 4.
Remove the mounting flange to expose the side panel surface. Using the miniature hole saw, drill through the side panel surface only at each spot weld location. Do not drill into the lower unirail front flange surface areas. Refer to Photograph 5.
Locate all other spot weld attachment locations and center drill with a 1/8" drill bit without drilling into the underlying structure. Drill out all weld locations using a miniature hole saw or equivalent spot weld removal tool. CAUTION: EXERCISE EXTREME CARE WHEN CUTTING OUT THE SPOT WELDS. DO NOT DRILL INTO THE UNDERLYING STRUCTURE.
The side panel can now be removed exposing any spot weld nuggets. Refer to Photograph 6. Remove any of the remaining spot weld nuggets using an appropriate abrasive disc without cutting into any adjacent surfaces.
IMPORTANT: THE AMOUNT OF PLUG WELD HOLES AND THEIR RESPECTIVE LOCATIONS ARE TO BE IDENTICAL IN NUMBER AND PLACEMENT AS THAT OF THE ORIGINAL FACTORY SPOT WELDS. On the replacement part assembly, locate all plug weld locations using templates or measurements. Where two layers of steel exist at the rail extension mounting flanges and side panel, drill 3/8" diameter plug weld holes from the back side. Refer to Photograph 7. All other plug weld holes are to be 5/16" diameter and should also be drilled from the back side.
On the replacement part, remove any factory applied coatings at all plug weld hole locations and apply an appropriate weld-through coating. Prepare the corresponding plug weld locations on the vehicle and apply a weld-through coating to the weld areas as necessary. Refer to the welding information prior to performing welding operations.
Install the replacement part in its proper location on the vehicle and clamp as necessary. After checking and verifying all body dimension measurements are correct, plug weld the assembly in random order using appropriate welding procedures while monitoring all measurements until finished.
After welding, grind any plug weld nuggets for cosmetic appearance. Wire brush or abrasive blast both the front and back sides of all plug weld locations.
Apply an appropriate corrosion resistant primer to the weld joints from both inside and outside the joint areas. Apply any necessary caulking and refinish the repair as necessary.
Apply a creeping/waxy type corrosion inhibitor to the inner portion of the rail and rail extension.

Welding Information

Prior to any welding operations, the weld site must be cleaned to remove grease and dirt as well as primers and paint, 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 overlap area of 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 which can cause metal strength loss and/or panel distortion. The welding equipment must also be properly adjusted by making and testing practice welds on similar materials.

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.