alero complete manual

8/8/2019 Alero Complete Manual

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1999

Pontiac Grand Am

and Oldsmobile Alero

Panel Identification .....................................................2-1

Front End Assembly .....................................................2-3

Front Wheelhouse Assembly .......................................2-4

Front Lower Rail Assembly .........................................2-7

Door Frame Opening ..................................................2-17

Roof Panel ...................................................................2-22

Quarter Panel..............................................................2-24

Rear Wheelhouse ........................................................2-28

Rear Floor Assembly ..................................................2-31

Rear Rails .....................................................................2-35

Rear End Panel Assembly...........................................2-36

Body Dimensions ........................................................2-37


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1999 Pontiac Grand Am/Oldsmobile AleroCollision Repair 2-1

Panel Identification

Two-SidedGalvanizedS

teel

High-StrengthLow-Allo

ySteel

ThermoplasticOlefin

white

Coupe


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2-2 1999 Pontiac Grand Am/Oldsmobile Alero Collision Repair

Tw

o-SidedGalvanizedSteel

High-StrengthLow-AlloySteel

Th

ermoplasticOlefin

white

Panel Identification

Sedan


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Front End Assembly

The front-end structure consists of sixresistance-welded components. The upper tiebar and upper reinforcement panel are servicedas individual components. The brace, (front-endlower structure) includes rail reinforcement

gussets, which provide cross-car alignment ofthe service assembly. Left and right impact barbrackets are serviced separately and must beinstalled using three-dimensional coordinates(Fig.2.1).

REMOVE OR DISCONNECT

1 Remove all related panels and components.

2 Visually inspect and restore as much of thedamage as possible to factory specifications.

3 Remove sealers and anti-corrosion materialsas necessary.

4 Locate, mark and drill out all factory welds asnecessary. Note the number of welds for

installation of the service panels.5 Remove the damaged panels in the upper tie

bar assembly and the front end lower brace,as necessary.

INSTALL OR CONNECT

1 Prepare mating surfaces and check forproper fit of the service panels.

2 On the service panels, drill 8mm (5/16) plugweld holes as necessary in the locations

noted from the original assembly.Notice: If original components aredamaged beyond recognition, place plugweld holes every 40mm (1-1/2) inchesapart.

3 Position the service panels, check fit usingbody dimensions, and plug weld accordinglywith frequent measurements to ensureproper fit.

4 Clean and prepare welded surfaces.

Important: Prior to refinishing, refer toGM P/N 4901 M-D Refinish Manual forrecommended products.

5 Apply approved anti-corrosion primer

6 Apply sealers and refinish as necessary. Donot combine paint systems. Refer to paintmanufacturers recommendations.

Notice: Upper tie-bar service parts donot have mounting locations for (3) centerlatch-support holes. Use threaded insertssuch as Riv-nuts, available through Kent-Moore tools (Riv-nut Kit P/N J42151-8MS).

7 Reinstall all related panels and components.

Fig.2.1 Front end structure


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The left and right front wheelhousings areavailable as complete assemblies (Fig.2.2).Additionally, the front portion of the apronsand upper rail can be ordered and serviced as apartial assembly (Fig.2.3). Strut mounting holes

are pre-drilled in the service assemblies. Thefront wheelhouse assembly is serviced withoutthe form and pierced fender mounting locations.When replacing as an assembly, technicians mustthree-dimensionally locate fender-mountingholes and use threaded inserts for fender boltsand body shims to achieve correct height(Fig.2.4).(Riv-nuts with crimping tool areavailable from Kent-Moore tools: Riv-nut Kit,P/N J42151-8MS).

Sectioning procedures have been developed tosimplify wheelhouse repairs. Use the followingguidelines to determine whether wheelhouse canbe sectioned or should be replaced at factory

seams.

Front Wheelhouse Assembly

Fig.2.2 Wheelhouse service assembly

Riv-nuts

, , ,

Fig.2.4 Use threaded inserts at fender

mounting locations

Fig.2.3 Front assembly also available


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Wheelhouse Sectioning

Notice: Inspect the cowl panel for damagewhere the wheelhouse is attached. If thepanels have been separated, it will benecessary to repair the cowl panel and

replace the wheelhouse at factory seams. Ifpanels have not been separated and there isno damage in this location, the wheelhousecan be serviced as follows.




3 Remove all sealers and anti-corrosionmaterials as necessary.

Fig.2.5 Create weld flange from original panel

4 At wheelhouse to cowl panel joint, measureforward 75mm (3 inches). Mark a vertical linefrom strut cap to frame rail (do not cut intostrut cap). Cut the wheelhouse along thisline, from rail up to strut cap (Fig.2.5). This

will provide an overlap flange for welding theservice part to the original wheelhouse,without welding directly to the cowl panel.

Notice: Drill through strut cap welds tolocate areas to be re-welded at cowlpanel.

5 Locate, mark and drill out the factory welds,which attach the wheelhouse assembly to thecowl panel, radiator support and lower frontrails.

6 Remove the damaged wheelhouse assembly.



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INSTALL OR CONNECT

1 Clean and prepare surfaces to be welded.

2 Trim and discard tab off service part which isnormally welded to the cowl panel (Fig.2.6)

3 Drill 8mm (5/16-inch) holes for plug welding

in the locations noted from the originalassembly.

4 Drill six holes for plug welding every 40mm(1-1/2 inches) along the overlap whichattaches service part to flange remainingfrom original assembly. (Fig.2.7)

5 Check the position of the wheelhouseassembly using three-dimensional measuringequipment and plug weld accordingly. Installone weld in the tab from cowl to strut cap.(Fig.2.8)

Notice: The welds which attach the strutcap to the cowl can be installed from the

cowl plenum side of the joint (Fig.2.8).6 Clean and prepare all welded surfaces.


7 Locate and drill 2 fender-mounting holes innew wheelhouse using three-dimensionalmeasuring equipment.

8 Apply approved anti-corrosion primer.

9 Apply sealers and sound deadeners andrefinish as necessary. Do not combine paintsystems. Refer to paint manufacturersrecommendations.

10 Install threaded inserts at fender mountinglocations. (Kent-Moore tools: Riv-nut KitP/N J42151-MS). Reuse original fastenersor equivalent.

11 Install all related panels and components.


Cowlplenum Wheelhouse

Fig.2.6 Trim weld flange

from service assembly

Fig.2.7 Drill 8mm (5/15 inch) holes

along overlap

Fig.2.8 Weld plenum to strut cap from plenum side


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Replacement of the engine compartment lower railassemblies has been improved on the GrandAm/Alero through the use of a sub-assembly servicepart. The lower rail service part comes completewith all brackets and reinforcements (Fig.2.9). When

sectioning, order the entire assembly and extractthe necessary parts (Fig.2.10).

Front Lower Rail Assembly

Fig.2.9 Left side service assembly

Fig.2.10 Extract parts for sectioning


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Lower Rail SectioningSectioning procedures have been developed tohelp simplify repair of the lower rails, provided themajority of damage can be returned to factoryspecifications. This allows technicians to repair the

damaged front section without having to make acomplete rail replacement. Sectioning of the lowerrail does not require removal of the powertrain.

Fig.2.11 Unique rails, unique repair procedures left to right


Left rail, inner

Right rail, inner

Right rail, outer

Important: Damage to the front lower railsmust be limited to the portion of the railforward of the sectioning joint, if damageexceeds the forward portion, completereplacement of the rail is recommended.

(See complete rail replacement procedures.)Notice: The lower rail sectioning cut linesvary from left to right. Be sure to use thecorrect procedure. (Fig.2.11)


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Fig.2.12 Cut the outer panel

along forward edge of tape

Fig.2.13 Mark a line on the damaged rail


LEFT - FRONT LOWER RAIL SECTIONING


1 Remove all related panels and componentsincluding left front cradle bolt.



4 Apply 25mm (1 inch) wide tape on the lowerrail outer panel following the contour of thecowl (Fig.2.12). Cut the outer panel alongthe forward edge of the tape. This willprovide an overlap tab for welding theservice part to the original rail withoutwelding directly to the cowl panel.

5 Drill out all factory welds attaching the outerpanel to the rail inner panel, be sure not to

drill through the inner panel.Notice: Welds on engine cradle mountingbracket must also be drilled out to removeouter panel.

6 Remove the rail outer panel.

7 Locate the 16 x 35 slot on the in-board sideof the rail (Fig.2.13). Using the hole as aguide, mark a line on all three sides of therail.

8 Cut the rail along the marked line andremove the damaged portion of the rail.


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PREPARING SERVICE PARTFOR INSTALLATION

INSTALL OR CONNECT

1 Locate and drill out factory welds attachingthe outer panel to the inner panel on the

service part. Drill through one layer ONLY atthe front half of the rail.

Notice: Welds on engine cradle mountingbracket must also be drilled out to removeouter panel.

2 Separate inner from outer rail using an airchisel. Remove the outer panel and set aside.

Fig.2.14 Left rail service part, add 30mm for weld tabs

Fig.2.15 Cut corners and step tabs inward on service part


30mm

1. Cut Corners

2. Step tabsinward

3 On the left inner rail service part, mark a linearound the panel 30mm (1-1/4 inch) rearwardof the 16 x 35 hole on the inner rail. Using thehole as a guide, mark a line around the rail(Fig.2.14).

4 Cut the service part along the marked lineand discard the unused section.

5 On the sectioned service part, cut a 2mm (1/8inch) gap approximately 30mm (1-1/4 inch)deep along the corners of the inner rail tocreate tabs (Fig.2.15).

6 Step the tabs inward to allow the service partsection to fit inside the original rail (Fig.2.15).


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7 Drill 5 holes for plug welding along theoverlap, approximately 13mm (1/2 inch) fromthe sectioning cut (Fig.2.16).

8 Position the modified service part inside theoriginal rail align using three-dimensional

measuring equipment.9 On rail outer panel, trim off tab that attaches

to cowl panel. Drill three 8mm (5/16 inch)plug weld holes along overlap.

Notice: Be certain the engine cradlemounting location is in the properposition. Align and hand tighten bolt.

Important: When stitch welding, make25mm (1 inch) welds along the seam with25mm (1 inch) gaps between. Then goback and complete the stitch weld alongthe seam.


Fig.2.16 Drill 8mm (5/16 inch) holes for plug welding

Fig.2.17 Plug welds and stitch welds completed

10 Position the outer panel, check for proper fitand alignment.

11 Stitch weld along the entire joint. Plug weldall holes drilled during the removal processincluding holes drilled along overlapped

areas (Fig.2.17).12 Clean and prepare welded surfaces.






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RIGHT - FRONT LOWER RAIL SECTIONING





4 Apply 25mm (1 inch) wide tape on the lowerrail outer panel following the contour of thecowl. Cut the outer panel along the forwardedge of the tape (refer to Fig.2.12). This willprovide an overlap for welding the servicepart to the original rail, without weldingdirectly to the cowl panel.

75mm

Right rail, inner

Right rail, outer

5 Drill out all the factory welds attaching theouter panel to the rail inner panel, be surenot to drill through the inner panel. Removethe rail outer panel.

6 Measure 75mm (3 inches) forward of the

engine mount brace located inside the railand mark a line (Fig.2.18). Drill a 1/8 inchhole on the line. Using the hole as a guide,mark a line around the outside of the rail.

7 Cut the rail along the marked line andremove the damaged portion of the rail.

Fig.2.18 Remove outer panel and measure damaged inner rail



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PREPARING SERVICE PARTFOR INSTALLATION

INSTALL OR CONNECT

1 Locate and drill out factory welds attachingthe outer panel to the inner panel on the

service part. Drill through one layer ONLY atthe front half of the rail.

Notice: Welds on engine cradle mountingbracket must also be drilled out to removeouter panel.

2 Separate inner from outer rail using an airchisel. Remove the outer panel and trim offthe rear edge that welds to the cowl panel.

3 On the right side rail, measure 45mm(1-3/4inches) forward of the engine mountbrace (Fig.2.19), notice this is 30mm (1-1/4inches) less than the original sectioning cut.Drill a 1/8- inch hole on the line. Using the

hole as a guide, mark a line around the rail.4 Cut the service part along the marked line

and discard the unused section.

5 On the sectioned service part, cut a 2mm (1/8inch) gap approximately 30mm (1-1/4 inch)deep along the corners of the inner rail tocreate tabs (Fig.2.20).

6 Step the tabs inward to allow the service partsection to fit inside the original rail (Fig.2.20).

Fig.2.20 Cut corners and step tabs inward on service part


Fig.2.19 Remove outer panel to measure inner rail on service part

45mm

Right rail, inner

Right rail, outer

FRT

1. Cut Corner

2. Step tabsinward

FRT


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7 Drill 5 holes for plug welding along theoverlap, approximately 13mm (1/2 inch)from the sectioning cut (Fig. 2.21)

8 Position the modified service part inside theoriginal rail using three-dimensional

measuring equipment.Notice: Be certain the engine cradlemounting location is in the properposition. Align and hand tighten bolt.

Important: When stitch welding, make25mm (1 inch) welds along the seam with25mm (1 inch) gaps between. Then goback and complete the stitch weld.

9 Drill 3 holes in the rail outer panel in front ofthe cowl.

Fig.2.22 Plug welds and stitch weld completed



10 Position the outer panel, check for proper fitand alignment.

11 Stitch weld along the entire joint. Plug weldall holes drilled during the removal process(Fig.2.22).

12 Clean and prepare welded surfaces.Important: Prior to refinishing, refer toGM P/N 4901 M-D Refinish Manual forrecommended products.





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FRONT LOWER RAIL REPLACEMENT




3 Remove sealers, sound deadeners andanti-corrosion materials as necessary.

4 Using an air chisel, remove the rear enginemount.

5 Locate and drill out resistance welds intorque box panel (Fig.2.23). Drill throughone layer of metal ONLY.

6 From underside of vehicle, locate welds thatsecure the rail to the floorpan. Using a

1/8-inch drill bit, drill through floor to markwelds for removal.

7 Separate the floor pan reinforcement verticalflange from inside the lower rail. Care mustbe taken to not damage the flange.

8 Drill out factory welds along the lower flangeon the floor pan reinforcement and at thewheelhouse. Note that the flanges overlapthe rails.

9 From inside the vehicle, use an 8mm (5/16inch) drill bit to drill through the floor panand the reinforcement inside the vehicle(Fig2.24).

10 Remove the damaged rail.

Fig.2.23 Drill through rail in torque box to locate welds inside vehicle



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INSTALL OR CONNECT

1 Prepare mating surfaces and check forproper fit of the new rail. Apply suitableweld-through primer.

2 Position the new rail in place and check for

proper alignment using three-dimensionalmeasuring equipment.

3 With the new rail in place, plug weld all theholes created from the removal process. Inthe areas the floor inner panel does notcontact the floor pan, use a ball- peen

hammer to flatten inner panel against floorpan. Plug weld floor to new rail in remainingareas.


Important: Prior to refinishing, refer to

GM P/N 4901 M-D Refinish Manual forrecommended products.




Fig.2.24 Drill from inside vehicle at pilot hole locations using an 8mm (5/16 inch) drill bit



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The side door frame openings feature a uniquemodular build sub-assembly design to improvemanufacturing quality. They are composed ofnumerous individual components that arepre-assembled and then attached to the vehicle

as a single unit.The door frame can be replaced as a completeassembly or various segments of it can besectioned, which is usually much faster and morecost effective. However, there are some keystructural areas where sectioning should not takeplace (Fig.2.25). Since left and right door frameopenings are available as complete assemblies,service parts for sectioning must be cut from thecomplete assembly and modified as necessary.

Door Frame Opening

SECTIONING SHOULD NOTTAKE PLACE IN SHADED AREAS

Fig.2.25 Coupe and Sedan side door frames


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Door Frame OpeningFull Replacement


1 Remove all related panels and componentsincluding the roof panel, upper outer rail

reinforcement and, on coupe models only,the quarter panel.


3 Remove sealers, sound deadeners and anti-corrosion materials as necessary.

4 Locate, mark and drill out all factory welds.Note the number of welds for installation ofthe service assembly.

5 Remove the damaged doorframe opening.

INSTALL OR CONNECT

1 Prepare mating surfaces and check forproper fit of the door frame opening serviceassembly.

2 On the service assembly, drill 8mm(5/16-inch) plug weld holes as necessary inthe locations noted from the originalassembly.

Notice: In any area damaged beyondrecognition, space plug weld holes every40mm (1-1/2 inches) apart.

3 Position the service assembly, check fit usingbody dimension and plug weld accordinglywith frequent measurements to ensureproper fit.

4 Inject expandable foam into the A Pillar

through the bottom interior trim-mountinghole. This helps reduce noise in the pas-senger compartment.




7 Apply a full-bodied caulk along the surface ofthe baffle to ensure a proper seal with theinner cowl plenum (Fig.2.27).

8 Apply sealers and refinish as necessary. Donot combine paint systems. Refer to paint

manufacturers recommendations9 Reinstall all related panels and components.

Fig.2.26 Remove upper outer rail reinforcement

Fig.2.27 Apply sealer along inner cowl plenum

Door Frame Opening

Do not plug drain slot


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General Sectioning ProceduresWhen sectioning areas other than the hingepillar, a 100mm (4 inch) backing plate must beused behind the joint to ensure a solid andsecure weld in areas where there is no inner

reinforcement. Backing plates can usually be cutfrom the unused portion of the service part or anundamaged section of the doorframe opening.

Notice: There are some key reinforcementsthat are to be replaced at factory seams only(Fig. 2.28). Sectioning these panels maycompromise the structural integrity of thevehicle.

The rocker panel can also be replaced in itsentirety when the quarter panel has beenremoved.

Door Frame Opening

Fig.2.28 Door frame reinforcements are part of the service assemblies



2 Visually inspect and restore as much of thedamage as possible to factory specification.

3 Remove sealers, sound deadeners and anti-

corrosion materials as necessary.

4 Cut the doorframe opening where it is to besectioned. Do not damage any inner panelsor reinforcements.

5 Locate, mark and drill out all necessaryfactory welds. Note the number of welds forinstallation of the service part.

6 Remove the damaged section of thedoorframe opening.

Reinforcements are replaced at factory seams only


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Door Frame Opening

INSTALL OR CONNECT

1 Cut the service part to match the undamagedsection of the door frame opening andremove unused portion of the service part.

2 Cut an appropriate-sized backing plate from

the unused portion of the service part orundamaged section of the doorframeopening. Modify the backing plate asnecessary so that it will fit behind thesectioning joint (Fig.2.29).

Fig.2.29 Door frame sectioning specifications

100mm

100mm

50mm

50mm

100mm

100mm

100mm(4 in)BackingPlate

Gap = one andone-half timesthe thicknessof the metal


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3 Windshield pillar sectioning requires a 50mm(2 inch) backing plate. Section within therecommended areas (Fig. 2.29).

Notice: The striker plate is mounted in acage that allows some degree of

adjustment independent of the outerpanels. Use body dimensions to ensurethe striker mounting location falls withinthe plates range of adjustment

4 Sectioning the rocker panel requires a100mm (4 inch) backing plate forreinforcement (Fig. 2.29). Section within therecommended area.

5 On the service part, drill 8mm (5/16-inch)plug weld holes as necessary in the locationsnoted from the original section. Also, drillplug weld holes along the sectioning cut onboth the service part and the remaining

original part. These will be used to weld thepanel to the backing plate.

6 Prepare mating surfaces and slide thebacking plates halfway under the sectioningcuts on the vehicle and plug weld in place.

7 Position the service part, allowing it tooverlap the exposed portion of the backingplates. Check fit using body dimensions andplug weld accordingly with frequentmeasurements to ensure proper fit.

8 Stitch weld along the sectioning joints. Make25mm (1 inch) welds along the seam with25mm (1 inch) gaps between. Then go backand complete the stitch weld. This will createa solid joint with minimal heat distortion.

9 Complete all other welds as necessary.




12 Apply sealers and refinish as necessary. Donot combine paint systems. Refer to paint

manufacturers recommendations.13 Reinstall all related panels and components.

Door Frame Opening


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The roof panel is made of mild steel and weldedto the steel roof structure, including the outerpanel and the inner reinforcements. The roofpanel is serviced as a skin with noreinforcements, only sound-soak patches

pre-installed for efficient installation.(Fig.2.30)The roof panel must be drilled to remove theouter panel and inner reinforcements forservicing.

Roof Panel

FRT

Pre-installedsound-soak panel

Fig.2.30 Coupe roof panel with sunroof opening

Notice: The headliner, windshield andbackglass must be removed prior to theremoval of the roof assembly. Protect theinterior of the vehicle. Use care when workingnear adjacent panels, glass, weatherstrips and

moldings.Important: On vehicles equipped with asunroof, take care not to damage the draintubes. The drain tubes are located betweenthe inner and outer windshield pillar.


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Silicon BronzeJoint

Fig.2.31 Locate roof seam at quarter panel


1 Remove all related panels and componentsnecessary to access the welds attaching theroof assembly to the vehicle.

2 Visually inspect and restore as much of the

damage as possible.3 Remove sealers and anti-corrosion materials

as necessary.

4 Locate silicon-bronze joints which attach roofpanel to quarter panels (Fig.2.31).

5 Cut through the roof panel just above the leftand right silicon-bronze joints using adie-grinder or equivalent tool (Fig.2.32).

6 Locate, mark and drill out all factory welds.Note the number and location of welds forinstallation of the service assembly.

7 Remove the damaged roof panel assembly.

8 Grind off silicon-bronze weld and removeremaining roof panel tabs.

INSTALL OR CONNECT

1 Clean and prepare the mating surfaces asnecessary.

2 Position the roof panel on the vehicle. Checkfit and alignment.

3 When the service assembly is correctlypositioned, plug weld accordingly.

4 MIG stitch weld the quarter panel to roofjoints at factory seams.

Important: Make 25mm (1 inch) welds

along the seam with 25mm (1 inch) gapsbetween. Then go back and complete thestitch weld. This will create a solid jointwith minimal heat distortion.

5 Clean and prepare all welded surfaces.



Notice: The windshield and bonding areashould be a primer surface ONLY and notan aftermarket, top-coated (paint orcolor-coated) surface. Refer to Bulletin

#43-10-48 for more detailed information.7 Apply sealers and refinish as necessary. Do

not combine paint systems. Refer to paintmanufacturers recommendations.


DO NOT CUT SAIL PANEL REINFORCEMENT.

CUT ROOF PANEL ONLY

Fig.2.32 Rough cut roof panel above factory seam

Roof Panel


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The quarter panel is a service assembly thatincludes the gutter, lock-striker cagenut and anextension panel for the taillamp pocket (tail lamppocket is serviced separately). Replacement ofthe quarter panel requires removal of the back

light and quarter glass on coupe models. Onboth the coupe and sedan models, the quarter

Quarter Panel

SEDAN

COUPE

Taillamp pocketsserviced separately

Fig.2.33 Quarter panel service assemblies

panel is attached to the roof panel by asilicon-bronze welded joint. To maintain theintegrity of this joint, sectioning of the quarterpanel at sail panel will be performed 100mm(4inches) below this joint where roof overlaps

quarter panel (Fig. 2.33).


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100mmMeasure equal distance

between trim holes

100mm

Fig.2.34 Locating coupe quarter panel

sectioning locations

Fig.2.35 Measure and mark 100mm down

from silicon bronze joint

Coupe Quarter PanelService Procedure



2 Remove all related panels and components,including the side and back glass.


4 Locate silicone-bronze seam at roof/quarter-panel overlap. Measure down 100mm frompinch weld flange at side and rear window(door frame) locations (Fig.2.34). Mark cutline.

5 At B-Pillar location on outer panel only,measure distance between lower 2 trimholes. Scribe a line at half the distancebetween the 2 holes. This is therecommended sectioning point (Fig.2.34).

Notice: Do not cut into innerreinforcement.

6 At scribed line, cut quarter panel ONLY.Locate, mark and drill out the factory welds.Note the location and number of welds.

7 Remove damaged quarter panel.

8 Remove majority of baffle material in sailpanel and along rocker panel.

Quarter Panel


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PREPARING SERVICE PANELFOR INSTALLATION

INSTALL OR CONNECT

1 At the sail panel, measure and mark a line100mm from step at top edge of service part

(Fig.2.35).2 At B-Pillar location on outer panel only, measure

distance between lower 2 trim holes. Scribe aline at half the distance between the 2 holes.This is the recommended sectioning point (seeFig. 2.34).

3 Cut along line to trim service part and create a100mm backing plate. Remove the flange oneach side of backing plate so that it will fitbehind the sectioning joint.

4 Drill 8mm (5/16) plug weld holes as necessary inthe locations noted from the original panel. Drillplug weld holes along the sectioning areas of

the service part and original panel. These holesshould be located approximately 13mm(1/2inch) from the edge of the cuts (Fig.2.36).

5 Prepare the mating surfaces. Position andsecure both backing plates with half of thebacking plate exposed at each joint. Position theservice part to overlap the backing plates andbutt up to the original panel (Fig. 2.37). Checkfor proper fit and alignment.

Notice: Leave a gap of one and one halftimes the thickness of the metal at thesectioning joint.

6 Plug weld accordingly. Stitch weld along the

entire sectioning joint. Make 25mm (1 inch)welds along the seam with 25mm gaps betweenthem. Go back and complete the stitch weld.This will create a solid joint with minimal heatdistortion.

7 Plug weld all other areas as noted from theoriginal panel.


Important: Prior to refinishing, refer to GMP/N 4901 Refinish Manual for recommendedproducts.


10 Apply body sealers and refinish as necessary. Do

not combine paint systems. Refer to paintmanufacturers recommendations.


100mm

50mm

Important: Care must be taken to ensure that thefuel filler neck is properly sealed when replacing

the right side quarter panel. Use SPO Sealingstrip (P/N 12399117) between the quarter panel

and the fuel filler neck. Install according toprovided instruction sheet.

Fig.2.36 Drill 8mm 5/16 plug weld holes

along overlap

Fig.2.37 Use the correct size backing plateswhen installing new panel

Quarter Panel


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Sedan Quarter Panel ServiceProcedure


1 Remove all related panels and components,including the back glass.


3 Remove sealers and corrosion protectionmaterials as necessary.

4 Note the size of the service part and locatethe sectioning joint at the sail panel. Marka line 100mm below the silicon bronze jointand cut (Fig.2.39).

5 Locate, mark and drill out all factory welds.Note the number and location of welds forinstallation of the service assembly.

6 Remove the damaged quarter panel.

INSTALL OR CONNECT

1 Prepare the mating surfaces as necessary.

2 Temporarily position the service panel onvehicle. Trim the original panel to leave a gapof one and one half times the thickness of the

metal at the sectioning joint3 Cut 100mm (4-inch) piece from the original

quarter panel for backing plates. Remove theflange on each side of the backing plates sothat they will fit behind the sectioning joints.

4 Drill 8mm (5/16-inch) plug weld holes asnecessary in the locations noted from theoriginal panel. Also drill plug weld holesalong the sectioned area of the service part.These should be located approximately25mm (1 inch) from the edge of the cuts(Fig.2.39).

5 Prepare the mating surfaces. Position the

service part to overlap the backing plate andbutt up to the original panel (Fig. 2.40).

Notice: Leave a gap of one and one halftimes the thickness of the metal at thesectioning joint.

6 Plug weld all other areas as noted from theoriginal panel.




9 Apply sealers, sound deadeners andcorrosion protection materials.

10 Refinish as necessary. Do not combine paintsystems. Refer to paint manufacturersrecommendation.



Quarter Panel

Fig.2.40 Use 100mm (4 inch) backing plate

100mm

Fig.2.38 Measure 100mm below silicon

bronze joint


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The sedan outer rear wheelhouse (Figs. 2.41) canbe replaced at factory seams. Both models havea beltline reinforcement that overlaps a portionof the wheelhouses. Remove the reinforcementon sedan models according to recommended

procedures. On coupe models, templates havebeen developed to ensure proper wheelhouseinstallation on coupe models.

Sedan REMOVE OR DISCONNECT

1 Remove all related panels and componentsincluding the back glass.

2 From inside of vehicle, pull back and protectwiring along inner wheelhouse.

3 Locate and drill out six welds securingbeltline reinforcement to quarter innerassembly (Fig.2.42)

Notice: Drill through one layer only.4 Locate and drill out welds at factory seams

along perimeter of wheelhouse flange.

5 Remove damaged wheelhouse panel.

INSTALL OR CONNECT

1 On service part, drill 8mm (5/16-inch) holesevery 40mm (1-1/2 inches).

2 Prepare mating surfaces.

3 Apply suitable weld-through primer.

4 Position service part. Check for proper fit.

Notice: Outer wheelhouse positioning may

require dry-fitting of quarter outer panel.5 Clean and prepare welded surfaces.



7 Apply sealers and sound deadener materialsand refinish as necessary. Do not combinepaint systems. Refer to paint manufacturersrecommendations.

8 Install related panels and components.

Rear Wheelhouse

Fig.2.41 Replacement wheelhouse (coupe/sedan)

Fig.2.42 Remove beltline reinforcement

(SEDAN ONLY)


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Outer Rear Wheelhouse

Notice: It is recommended that the servicepart be prepared before removing thedamaged panel from the vehicle.

CoupePREPARING THE SERVICE PARTFOR INSTALLATION

1 Align the appropriate template along theservice part contour lines, per templateinstructions.

2 Cut service part as indicated on template toensure proper fit of service part.

3 Trim leading edge of service part to allowflush fit with rocker panel (Fig.2.44).

4 Remove the excess portion of thewheelhouse.

Beltline Reinforcement

Fig.2.43 Modify wheelhouse service

part (COUPE ONLY)

Fig.2.44 Apply tape as indicated to leave a

portion of the original wheelhouse

for efficient installation of the service panel

Rear Wheelhouse


1 Remove all related panels and components


3 Remove sealers and sound deadeners as

necessary.

4 Apply 25mm (1 inch) tape along perimeter ofbeltline reinforcement where it contactsouter wheelhouse.

5 Cut along outer (Fig. 2.44) edge of tape toform mating flange.

6 Apply tape to lower front portion ofwheelhouse, parallel to rocker panel edge,cut along top edge of tape from outer lip ofwheelhouse to valley (see Fig.2.44), creatinga flange for reattachment of wheelhouse partat rocker panel.

7 Cut along radius of wheelhouse (Fig. 2.45).

8 Remove the damaged wheelhouse.


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INSTALL OR CONNECT

1 Remove weld flange on remaining portion oforiginal wheelhouse (at rocker panel) toensure proper fit of service part.

2 Temporarily install service part over beltline

reinforcement flange and inside of originalwheelhouse (Fig. 2.46).

3 On the service part, drill 8mm (5/16 inch)plug weld holes every 40mm (1-1/2 inchesalong perimeter of entire service part.(Fig.2.47) Drill 4 holes on edge whereservice part mates to rocker panel.

4 Prepare the mating surfaces and position theservice part. Apply suitable weld-throughprimer.

5 Check for proper fit and plug weldaccordingly. Use care to not warp or distortthe metal.

Notice: Outer wheelhouse positioning mayrequire dry-fitting of quarter outer panel.




8 Apply sealers and sound deadeners asnecessary. Do not combine paint systems.Refer to paint manufacturersrecommendations.


Rear Wheelhouse

Fig.2.45 Separate wheelhouse from quarter

inner assembly (leave weld flange in place)

Inside

Over

Fig.2.46 Install modified wheelhouse

Fig.2.47 Service part modified (COUPE ONLY)


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The rear floor is sold as a complete assemblyincluding rear rails, crossmembers and rearextension; or sold separately as floor pan skinwith exhaust heat shield only. (Fig.2.48)

Rear Floor Assembly

With the floor pan removed,drill out and replace rear framerail extensions at factoryseams. Use 8mm (5/16 inch)

plug welds to reinstall thereplacement rail extensions.

Railextensions

Fig.2.48 Floor pan skin and rail extensions are serviced


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Rear Floor Panel PartialReplacement


1 Remove all related panels and components,including fuel tank.

2 Visually inspect and restore as much of thedamage as possible.


4 Locate factory seam at front edge ofcrossbar, rearward of seat back. Locate,mark and drill through one layer only, all

factory welds which secure floor to rails.Note the number and location of welds forinstallation of the floor service panel (Fig.2.49).

5 Drill completely through welds that attach

the floorpan to the inner wheelhouse.6 Remove both inner wheelhouse braces.

Identify weld locations and drill throughone layer of metal only.

7 Remove the damaged floor section.

Fig.2.49 Floor pan weld joint on vehicle

Important: On pan only

re-install, wheelhouse

flange must be bent up

on service part to

accommodate welds.

Rear Floor Assembly


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Rear Floor Assembly

Fig.2.50 Reinstall internal floor braces (2 per side)

INSTALL OR CONNECT

1 Prepare mating surfaces with suitableweld-through primer.

2 Drill 8mm (5/16-inch) plug weld holes asnecessary in the locations noted from the

original floor.Notice: In any area damaged beyondrecognition, space plug weld holes every40mm (1-1/2 inches) apart.

Important: Sound deadeners along theinner wheelhouse must be removed priorto welding new panels in place

3 Position the service floor pan, check forproper fit using three-dimensional measuringand plug weld accordingly.

4 Re-install both wheelhouse braces (Fig. 2.50).




7 Apply body sealers and refinish as necessary.Do not combine paint systems. Refer to paintmanufacturers recommendations.



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FLOOR PAN ASSEMBLYThe floor pan assembly comes completeincluding lower rails, crossbar, rear floorextension and various other components.(Fig.2.51)


Notice: One side inner and outer wheelhousesmust be removed when replacing entiresub-assembly.


2 Visually inspect and restore as much of thedamage as possible.


4 Remove 4 inner reinforcements ( 2-dynamicside impact braces-front; 2- floor panbraces-rear) to access spot welds (Fig 2.52).

Notice: If these parts are damaged theymust be ordered separately.

INSTALL OR CONNECT

1 Prepare mating surfaces with suitableweld-through primer.

Notice: In any area damaged beyondrecognition, space plug weld holes every

40mm (1-1/2 inches) apart.2 Drill 8mm (5/16-inch) plug weld holes along

all mating surfaces except where the floormates to each wheelhouse.

3 Position the service floorpan. Check forproper fit using three-dimensionalmeasurements.



5 Apply approved anti-corrosion primer to allbare metal surfaces.

6 Apply body sealers and refinish as necessary.Do not combine paint systems. Refer to paintmanufacturers recommendations.

7 Reinstall all related components.

Fig.2.51 Floor pan assembly

Fig.2.52 Remove all four internal braces to

locate hidden welds

Rear Floor Assembly


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The left and right rear rails are available ascomplete sub-assemblies and can be replaced intheir entirety similar to past model vehicles. Eachconsists of an outer panel, two innerreinforcements and all necessary component

mounting brackets. The outer panel and rearmounting brackets are also available separately.

When replacing a rail in its entirety, the weldflange that mates with the wheelhouse must bebent upwards. The service assembly is suppliedwith this flange in a horizontal position. (Fig.2.53)

Rear Rails

Service assembly with wheelhouse flangebent upwards for installation

Service assembly supplied with horizontalwheelhouse flange

The rear rail can be removed by drilling out allfactory welds at the floor pan. When doing so,the outboard flange at the forward end of the railoverlapping the rocker interior panel must bebent upward. The bottom flange of the crossbar

must be bent downward.Notice: Remove the floor and wheelhousebraces at factory seams to access additionallower rail welds. Reinstall upon completion(see Fig. 2.52).

The rear rail can then be separated from thevehicle.

Fig.2.53 Modify weld flange if ordering and installing entire rear rail only


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The rear end panel is supplied as a completeassembly consisting of three inner reinforce-ments and one outer panel. The rear end panelon the coupe has a single inner reinforcement.Taillight mounting panels, which attach to the

outside corners of the rear end panel assembly,are available separately. Service for all of thesepanels is performed at factory seams (Fig.2.54).




3 Remove sealers, sound deadeners andcorrosion materials as necessary.

4 Locate, mark and drill out all factory welds.Note the number of welds for installation ofthe service assembly.

5 Remove the damaged assembly.

Rear End Panel Assembly

INSTALL OR CONNECT

1 Prepare mating surfaces and check forproper fit o the service assembly.

2 On the service assembly, drill 8mm(5/16-inch) plug weld holes as necessary in

the locations noted from the originalassembly. Apply suitable weld-throughprimer.

3 Position the service assembly, check fit usingbody dimensions and plug weld accordinglywith frequent measurements to ensureproper fit.





7 Reinstall all related panels and components.

Fig.2.54


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Body Dimensions

L:506

W:561

H:810

E

L:

0

W:435

H:133

A

L:2126

W:430

H:360

F

L:2163

W:560

H:834

G

L:2226

W:430

H:371

H

L:2391

W:440

H:400

I

L:2850

W:440

H:400

J

L:2733

W:440

H:364

K

L:2466

W:440

H:375

L

L:2321

W:433

H:369

M

L

:2111

W

:430

H

:369

N

L:1650

W:563

H:400

O

L:292

W:356

H:243

B

L:1215

W:442

H:326

C

L:1250

W:465

H:326

D

CL

ALLDIMENSIONSAREMEASUR

EDFROMAZEROLINE,CENTERLINE,A

NDA

COMMONDATUM.ALLDIMENSIONSARESYMMETRICALUNLESSOTHERWISE

SPECIFIED.


39/40


Body Dimensions

ALL DIMENSIONS ARE MEASURED FROM A ZERO LINE, CENTER LINE, AND A

COMMON DATUM. ALL DIMENSIONS ARE SYMMETRICAL UNLESS OTHERWISE SPECIFIED.

FRONT VIEW

REAR VIEW

W: 517

H: 376

L: 1364

R

W: 374

H: 346

L:3013

V

W: 374

H: 346

L:3013

W

W: 517

H: 376

L: 1364

S

W: 374

H: 346L:3013

T

W: 508

H: 416L:3013

U

W: 517

H: 474L: 1364

Q

W: 508

H: 416L: 1364

P

CL

CL


40/40

1999 Grand Am/AleroUnderbody Dimension Hole Size Chart

Letter Feature Size Usage

A 19mm gage hole

B 20mm cradle attach

C 13mm x 19mm gage slot

D 20mm cradle attach

E 76mm center strut cap

F 15mm rear suspension attach

G 83mm center strut cap

H 15mm rear suspension attach

I 19mm gage hole

J 19mm x 26mm slot

K 19mm x 26mm slot

L 19mm gage holeM 15mm rear suspension attach

N 15mm rear suspension attach

O 19mm gage hole

P 14mm x19mm slot front impact bar

Q 14mm front impact bar

R 14mm x 19mm slot front impact bar

S 14mm front impact bar

T 10mm rear impact bar

U 10mm rear impact bar

V 10mm rear impact bar

W 10mm x 18mm slot rear impact bar

Body Dimensions

alero complete manual

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