Trans Ams and Firebirds have a variety of sheet-metal, plastic, and fiberglass body parts that often need to be restored. This chapter covers the technical aspects of restoring them. Some of these components are unique to the Trans Am and the steps to properly fit them are detailed.
This Tech Tip is From the Full Book, TRANS AM & FIREBIRD RESTORATION: 1970-1/2 – 1981. For a comprehensive guide on this entire subject you can visit this link:
SHARE THIS ARTICLE: Please feel free to share this article on Facebook, in Forums, or with any Clubs you participate in. You can copy and paste this link to share: https://www.pontiacdiy.com/pontiac-trans-am-firebird-restoration-bodywork-guide-doors-spoilers-bumpers-and-wheel-flares-70-81-2/
Over the years, doors often suffer much use and abuse. Like other panels of the body, the doors have been exposed to the elements and often trap moisture. This leads to rust at the bottom of the door skin, which requires cutting out the affected area and grafting in a patch panel.
Cutting and Patching a Door Skin
Step 1: Inspect Door Panel
The sheet metal on this particular Firebird’s door is in very good shape. Therefore, it does not require outer panel replacement. There is, however, evidence of small rust bubbles in the lower rear corners of the outer door panel. Second-generation Firebirds (as well as Camaros) tend to rust in this area and in the forward corners. Be sure to carefully inspect these areas, ascertain the condition, and determine whether or not repair is needed.
Step 2: Strip Lower Corner of Door Panel
Use an orbital sander to evenly strip the paint off the outer door skin. You can use a DA sander with a 6-inch 80-grit sanding disc. It usually takes several minutes to remove the clear coat, paint coats, and primer. Once you sand down to the sheet metal, you see the reason for the bubbling. Someone had used body filler to simply fill in where rust had eaten away, and this does not provide a long-term solution. Filling rust with body filler does not stop rust. It just covers it up. When you see repairs such as this, you need to cut out the improperly filled area and install fresh sheet metal. It’s the only reliable way to maintain body integrity and stop the rust.
Step 3: Cut Outer Door Skin
Use a magnet to see how much sheet metal remains in the affected area. If the area is pitted, it indicates rust beneath the sheet metal. Use a rotary tool with a 3-inch wheel to cut out the body filler and rusted metal. As described earlier, you need to figure out how far the rust extends and then go 1.5 inches beyond it to make sure you have solid metal. Use a Sharpie and masking tape to indicate your cut line.
Step 4: Inspect Sheet Metal
Once you remove the rusted area of the door skin (4 x 8 inches here) you can see where rust has started in the door shell. The rusting metal underneath the door skin must be treated so the door skin does not continue to rust from the inside.
Step 5: Remove Rust and Spray on Neutralizer
Treat the rusted area with a rust neutralizer after cleaning the area and removing the loose particles with a wire brush. Once you have removed the top layer of rust, spray Rust Mort or a similar product on the rusted area inside the door. This product sprays on white and darkens as it sets.
Step 6: Cut New Patch Panel
Use the old metal (top) as a rough guide to cut out the 18-gauge sheet metal patch panel (bottom). If the old sheet metal is left in the door skin, it will rust through in relatively short order.
Step 7: Tack Weld Patch Panel to Door Skin
As with other patch panels, you butt weld it in place. It needs to fit flush with the door and cannot overlap the outer door skin. Make sure the welder is placed on a low-amp setting that’s suitable for welding thin sheet metal. Place the patch panel in the proper position in the opening and use metal shears or tin snips to trim as needed for proper fit. Tack weld the four corners to hold the panel in place. Apply some anti-heat compound to avoid warping the panel from the welding heat.
Step 8: Stitch Weld Patch Panel
Heat management is critical when stitch welding in a patch panel, particularly when the patch panel is small. You need to effectively quench the welds with air once you have welded it in. When laying down the stitch welds, start at the outermost points and work inward. No matter the size of the area it is important to follow these procedures.
Step 9: Grind Stitch Welds
After stitch welding the patch panel, give it 30 minutes to cool. Use an 80-grit wheel to grind the stitch welds flush with the door panel. When using a grinding wheel, be careful not to apply too much heat because you can warp a panel by grinding aggressively.
The door glass on the Firebirds uses guides that attach to the door shell at the top under the door panel to guide the glass in the proper position as it rolls up and down. These guides are adjustable to control the glass. They also have pads that wear out, and when they do, the door glass is scratched. The scratches are vertical and limited toward the center of the glass. It is common to see the second-generation Firebird door glass scratched because most people are not aware of these pads until it is too late. The door glass is installed into the top of the window regulator, which moves up and down and folds in a scissor-like fashion.
When assembling the door glass and associated hardware take the opportunity to replace the glass hardware. The plastic rollers tend to seize or partially break off. This is often overlooked and can result in glass operation being compromised.
Step 1: Remove Old Hardware
When replacing the hardware on an original window, you should remove one part at a time and replace it with the same part. It is best just to start at one end and work your way to the other end. There is no real secret in how to change the hardware other than removing it with an open-end wrench. Be careful to not overtighten the fasteners because too much pressure on old glass could shatter it. Use a 7/16-inch wrench to install the new fasteners. If you purchase new glass you do not have to remove the old hardware.
Step 2: Install Window Lift Channel
Once you have all the hardware installed, place the glass lift channel onto the studs to make sure it fits properly.
Step 3: Inspect Window Actuator
The window guides, regulator, and power window motor are shown here the way they should be installed in the door. If you have a manual window the setup is the same; it just does not have the motor. Make sure the regulator teeth are in good shape and that the arms move up and down easily.
Step 4: Install Vertical Guides
The front and rear vertical guides control the up and down motion of the glass. Use a ratchet and socket to install these guides. Two 7/16-inch bolts on top and one 7/16-inch bolt on the bottom hold the glass in place on each side. These bolts should be slightly less than snug once installed so you have some latitude for adjustment.
Step 5: Install Horizontal Guide
The smaller horizontal guide controls the back and forth motion of the glass and two 7/16-inch bolts hold it in place. When these are installed, they should be also left less than snug.
Step 6: Install Lower Track
The short lower track controls tip in and rotation of the glass. Two 7/16-inch bolts hold the lower track in place.
Step 7: Install Window Regulator
The factory riveted the window regulator to the doorframe. Unfortunately, rivets make it difficult to remove and service the regulator. You can replace these rivets with four 7/16-inch nuts and bolts. Three 7/16-inch bolts hold the power window motor to the doorframe.
Step 8: Install Door Glass
Installing the glass requires patience, as it does not simply drop in. You need to remove the glass stop to properly position the glass in the door. Use a socket and ratchet to remove the lower glass stop. One 7/16-inch bolt holds it in the center bottom of the door.
Step 9: Install Door Glass (CONTINUED)
It takes a fair amount of positioning and adjustment to get the glass properly situated with the hardware. First angle the front and rear rollers on the glass. Then, fit the glass into the front and rear vertical guides. It may be necessary to simultaneously tip the glass toward the front and outward to get the front roller in. Repeat for the rear. Once the rollers are in, do not let go of the glass. If you happen to lose grip on the glass, it will fall to the bottom of the door and possibly shatter.
Step 10: Install Window Glass Stops
Once you have lowered the glass into the door, install the lift channel onto the studs and install one 7/16-inch nut in each end to secure the glass to the regulator. It may be necessary to raise and lower the window regulator slightly to gain access to the channel so you can attach it to the glass. Install the guide stops at the top of each vertical guide. A single 7/16-inch bolt attaches these stops to the doorframe. Their function is to prevent the glass from going too far up.
Step 11: Install Door Glass Weatherstrip
While you still have the glass in the lowest position, install the outer door glass weatherstrip, otherwise known as a belt weatherstrip. Five short Phillips-head screws hold the weatherstrip to the door. Be sure to use the correct-length screws for this job. It’s best to stick with the original screws. If you use screws that are too long, they dent the door panel from the inside.
Step 12: Install Door Handle
Slide the latch rod into the outer door handle. Use a wrench or socket and ratchet to secure the two 7/16-inch nuts that hold the latch in place.
Step 13: Install Door Lock
Install the door lock with a spring clip by sliding the clip between the ears on the lock and the door panel. Make sure the lock is properly positioned so that when the key is inserted the teeth are pointed downward.
Interior Door Panel Installation
Step 1: Install Water Shield onto Inner Door Shell
Plastic and wax paper water shields are typically available. You can slip either type of water shield over the door handle, in the center. Properly position the water shield and use butyl tape around the entire circumference of the shield. The bottom of the shield sets into a special channel in the lower portion of the door. Make sure the opening around the inner door handle is also sealed with butyl. Restorers often remove the shield and fail to re-install it. That can lead to serious damage because it guides the water to the lower channel and into the door shell, not into the interior.
Step 2: Install Door Panel
The door panel is fairly simple to install. Most of the panel bottom clips in; the top portion hangs over the inner side of the door shell. Make sure the back of the door panel has all of the clips in the back side. Check the side of the door shell to make sure that no clips stayed in the hole when the panel was removed.
Step 3: Install Armrest
Use a No. 3 Phillips screwdriver to install the three Phillips-head screws through the armrest and into the door. Place the armrest against the door panel. Properly align the armrest with the fastener holes. Place the screw on the end of the screwdriver, slide the screw into one of the armrest openings, and tighten the screw.
Step 4: Use Door Panel Removal Tool
This door panel removal tool is used to pop the door panel away from the door shell. It’s important to use this tool so you prevent the door panel from ripping. Slide the tool between the door panel and door shell. The open end of the blade slides over the clip stud. Use the door shell as leverage and push against the door shell. This removes the clip from the retainer opening in the door panel and prevents the door panel backing from getting ripped. Once the back side of the panel is ripped the clip becomes almost impossible to function and hold the door panel in place.
The Endura bumper is made of closed cell foam that was a relatively new product for Pontiac in the late 1960s and it was new to the 1970 Firebird. The Endura front bumper met mandated 5-mph crash standards, but the material and construction of the bumper requires specialized restoration. Pontiac first started using the energy-absorbing material when it fitted the Endura bumper on the 1968 Pontiac GTO. Although the bumper is beautiful, it has serious durability problems. The material has lasted far longer than anyone could have imagined.
The material is subjected to constant expansion and contraction, and deep fissure cracks result. Because the material is constantly in a state of flux, repairs are very difficult to make. I have dealt with these bumpers for 20-plus years, and fortunately the technology to repair the material has changed for the better. Although the repairs last longer, an owner must realize that repaired cracks eventually reappear. When you repair the bumper, you are not changing the original composition of the material. Make sure when you open your hood that you do not lean on the front bumper. It’s fragile and you could damage it.
My opinions and techniques on the repair of these bumpers come from my experience as a restoration shop professional. This repair procedure greatly increases the longevity of the repair and keeps your Firebird looking its best. Over the years, I have developed this repair procedure and it has yielded the best results for my customers. But let me be clear, the repair does not stop the bumper from ever cracking again. When it cracks again depends on which region of the country you live in and how your Firebird is stored and used. As newer materials are developed, the procedures may change.
Bumper Prep and Crack Removal
Step 1: Strip Paint Off Bumper
To repair these bumpers, you must use a DA sander to strip off the paint. The Endura bumper is made of a special material on which you cannot use a chemical stripper because the chemicals are absorbed into the Endura material. If chemicals are used you will never be able to keep the paint on your bumper properly. Use a light-grit sandpaper, such as a 320-grit, to avoid cutting into the bumper material.
Apply light pressure to remove the layers of paint until you reach a gray surface. Hand sand around the grille openings and indentations where the DA sander cannot reach.
Step 3: Inspect Endura Material for Cracks
Once the paint has been removed, you can see the cracks in the material. It is not uncommon to find additional cracks that were covered by the paint. Sometimes the cracks you see in the paint are just the paint separating as the material moves.
Step 4: Remove Cracks in Endura Material
Use a carbide strawberry tip on a drill to gently remove a crack. You need to remove enough material so the carbide bit actually goes below the crack but not too far; you don’t want to remove any more material than absolutely necessary. These cracks travel in any direction so you need to guide the bit along the crack line. Continue grinding along the crack until the crack is no longer visible. In some cases, it may be necessary to go down to the metal substructure, but that is very unusual. To the left, some cracks have been removed. To the right you can see some original cracks. Bear in mind that it takes a fair amount of time to carefully and completely remove all the cracks so be patient. It may take many hours, depending on the starting condition of the bumper.
Step 5: Inspect Crack Removal Area
It is important to look closely at the removal area because some of the cracks are difficult to see. Inspect the bumper surface carefully as you perform the procedure. It may appear that the crack is gone but it is not. If a crack is not fully removed, the repair fails because the crack comes back much sooner. This photo shows the crack still remains and is difficult to see.
Bumper Crack Repair
Step1: Choose Replacement Compound
Once you are fully satisfied that all of the cracks have been eliminated, you can add new material. I use 3M EZ Sand Flexible Parts Repair (PN 05887) for repairing these bumpers. Although other repair products are on the market, this product has proven to be of exceptional quality and the repairs have lasted the longest. When you purchase this kit, it is necessary to purchase the mixing gun with it. The 3M repair kit has two chambers that mix into one when dispensed.
Step 2: Apply Compound
No tools, brushes, or plastic applicators are necessary. You can properly apply the compound to the channels using just your finger (and disposable nitrile or latex gloves). Run your finger over the bead to flatten it. Apply the compound between 60 and 80 degrees F to get the best bonding results.
Step 3: Work Compound into Cracks
Each channel has a thin bead below the surface of the material, and you need to slowly build up channels until they reach the surface of the bumper. When applying compound, let every application thoroughly dry (not tacky) before repeating. It often takes 30 minutes at 70 degrees F. Do not expose the bumper to direct sunlight when performing this procedure because the bumper material absorbs heat and expands, which could potentially ruin the work. Repeat this step exactly the same way until the repair material is slightly higher than the bumper material and is consistent throughout. This step could take days to finish, but it is very important that this step be followed precisely. If you add too much repair material or add it too quickly the material does not dry thoroughly or evenly in the cracks. It dries at a different rate. When it does dry, it could cause the upper repair material to sink and create low spots or new cracks, which undoes all the work.
Step 4: Work Compound into Cracks (CONTINUED)
After all the cracks have been filled and the repair material has dried thoroughly, use a plastic applicator to apply more repair material over the entire bumper. The entire bumper needs to be thoroughly and liberally covered and then allowed to set and dry for 24 hours.
Step 5: Sand Endura Bumper Surface
After the bumper has thoroughly dried, lightly sand the surface by hand or with an orbital sander. It’s a critical stage and you need to be particularly careful because you don’t want to remove too much material or break through to the Endura material itself. Use 220-grit paper and sand the entire exterior to knock down the repair material. You want to create one smooth and even surface that can be repainted.
Step 6: Sand Endura Bumper Surface (CONTINUED)
You have now sanded off the high spots and the bumper should be a light shade of gray. It is time to block and hand sand to make the bumper material smooth. Use 320-grit sandpaper and a Durablock rubber sanding block is helpful because it can flex and forms to the contours of the bumper. Once you have completed sanding the bumper it should be a fairly uniform color of light gray.
Step 7: Apply Guide Coat
Spray a light mist of black paint over the bumper. This is referred to as a guide coat. This is simply a way to check your work for any low spots. Low spots retain the black paint while the rest of the bumper remains light gray.
Step 8: Sand Low Spots
Continue sanding in preparation for final sanding. Use a block with 320-grit sandpaper so that your final sanding verifies the smoothness of the bumper and reveals any low spots by the black remaining behind. If you see low spots, add repair material to the low spots to make the surface smooth (as you did with the fender patch). Repeat the steps as necessary.
Step 9: Apply Epoxy Primer
Once you have determined that the bumper is smooth and no low spots need to be filled in, sand the entire bumper again with 400-grit sandpaper. Do this lightly to smooth the surface so that it feels uniform and soft to the touch as you run your hand over it. Next, apply epoxy primer with a flexible additive to the bumper. The flexible additive needs to be applied so the primer can expand and contract with the bumper and not crack. I have used PPG Universal Flexibilizer (PN DX814) and PPG epoxy primer (PN DP50LF) because they have produced excellent results. The mixing instructions are on the can and are specific to the temperature.
The later 1974 and up Firebirds have urethane bumper covers. The repair procedures use the same repair kits and techniques. The 1970–1973 front bumper is mounted loosely when spraying metallic colors. This keeps the metallic flow consistent on the top and the sides.
The Firebird Formula rear spoiler was standard for some years and optional for other years. The rear spoiler was the only spoiler available for the Formula. The Trans Am rear spoiler was standard equipment and identical to the Formula’s. It’s crucial to follow these installation procedures so water and contaminants are not trapped between the spoiler and trunk lid. If the spoiler is incorrectly installed, the trunk lid and quarter panel can rust.
The rear spoiler is a three-piece fiberglass unit from 1970 through 1978. In 1979 through 1981, the outer ends of the rear spoiler were changed both in shape and in the material used. The later ends are more squared off on the quarter panel sides and the material changed from fiberglass to urethane. The two outer ends attach to the top of the quarter panel on each side while the center spoiler attaches to the trunk lid.
Step 1: Place Caulk Strips Around Stud Holes
This is an important step because the stud holes are larger than the studs. Lay a strip around the opening of the hole just at the edge.
The caulk strips should be about 1/4-inch high and completely surround the spoiler holes.
Step 3: Install Rear Spoiler
Timing is important and you should apply caulk strips to the rear quarter panels as you install each spoiler part. These strips are very sticky and you don’t want them to dry out. In addition, you do not want dirt to stick to the caulk.
Step 4: Align Rear Spoiler
You want all three pieces of the spoiler to align on the same plane. Several methods can be used to attain this alignment. In most cases, these spoilers align fairly closely from the factory but are rarely perfect.
Step 5: Align Rear Spoiler (CONTINUED)
Most of the outer spoiler ends are at different angles when bolted in place. Placing double-sided body-molding tape on the edge props up the spoiler ends and makes the angle change to line up to the trunk-mounted spoiler. It is not visible once installed.
Step 6: Attach Center Spoiler
A combination of bolts and nuts attach the center spoiler to the trunk lid. You can also place double-sided tape at the bottom of the center spoiler to adjust its angle and align it with the end spoilers. Washers can also be used on the ends between the spoiler attaching stud and the trunk lid to raise the end to match the height of the ends. It is important that all these nuts and bolts are tight but not overtightened because that causes the spoiler to distort or crack.
Some replacement wheel flares do not come with the proper attaching points so you must modify the flares to attach them properly. It is important to make sure that excessive body filler from prior bodywork has not compromised the contours of your fenders and quarter panels or that the panel is bent, otherwise proper fitment of the flare is almost impossible. With the exception of gluing the support panels to the flares, these procedures are the same whether original flares or aftermarket flares with the supports already installed. You can use unsupported flares to obtain a better-than-OEM fit.
Wheel flares use a flexible material called welting, which is commonly available through most Pontiac aftermarket suppliers. The welting should be painted the same color as the flare. A light bead of adhesive should be applied prior to flare installation. This welting gives the flare a finished look when installed. To remove the front flare, jack up the front using the subframe rail and place a jackstand under the rail. Then remove the wheel. For best results, turn the wheel inward so you have ample room to work. Remove the screws that are on the edge of the flare just on the wheel opening edge of the fender.
Step 1: Remove Wheelwell Flare
Remove the three bolts on a rectangular sheet-metal panel in the forward part of the wheelhouse to access the lower nut that retains the flare to the fender. Two are at the top of the panel and one is on the bottom just where it curves under. The upper nut for the flare must be accessed from the top side of the engine compartment. There is a gap between the wheelhouse panel and the radiator support for access.
Step 2: Transfer Flare Support
These aftermarket flares do not come with a center support.
The original center support needs to be removed and installed on the replacement flare.
Step 4: Remove Support from Stock Flare
The original support is glued in; remove the support panel by using a putty knife to break the glue spots. You may also have to use a flat-blade screwdriver and a utility knife; apply minimal pressure because you do not want to break the support panel. It may splinter, but that is acceptable.
Step 5: Cut Out Flare Support
If a putty knife or utility knife does not work, you may need to take more drastic measures. Use a Dremel or small electric rotary tool with a small cutoff wheel to loosen the support panel where it is sticking. The assembly glue was not done in a consistent manner so every flare comes apart a bit differently.
Step 6: Trim Flare Support Panel
Once the support panel has been removed, trim the splintered edges so you have solid plastic. The support panel has two studs with threads and nuts.
Step 7: Install Flare Support on Fender
Install the support onto the fender using the studs and the two nuts. It is a good idea also to wedge a couple of rubber grommets between the fender and the support panel to give the panel enough height to mate to the flare.
Step 8: Test Fit Flare to Fender
Place the flare against the fender over the support panel to check fitment. (Do not install the welting yet.) Any part of the flare that is preventing it from resting flush against the fender should be hand trimmed. Use 100-grit dry sandpaper to gently sand any edge that extends too far. In most cases, the area of the flare that transitions underneath the fender to the center spoiler needs to be trimmed. You may have to check the fitment several times before achieving a flush fit. Be cautious and proceed slowly as you trim the panel. Remove a little material at a time rather than too much. Sanding off too much material creates a larger gap and requires difficult bodywork to get it back into shape.
Step 9: Install Support Panel
Once the flare fits flush along the leading edge from top to bottom, mate the support panel and flare together.
Step 10: Protect Painted Flare Area
This is a good time to tape the fender where the flare edge will rest. This prevents scratching the paint if the Firebird is already painted.
Step 11: Epoxy Support Panel to Flare
Apply a thick bead of epoxy around the edges of the support panel and place the flare over the support panel.
Step 12: Re-install Fender Flare Screws
Re-install the screws in the wheel opening of the fender edge to hold the flare in place. Tape the flare in place from the bottom and from the fender around to the front. This holds the flare in place so the support bonds together with the flare in the proper position.
Step 13: Allow Panels to Cure
It takes approximately 20 minutes for the epoxy to cure at 70 degrees F. If your room is colder or warmer the curing times vary. Colder temperatures dramatically increase the drying time. It is also important that the parts are at the same temperature as the room where you are working. If you live in a cold climate plan for everything to be in the same room at least 12 hours prior. The same goes for the glue. I do not recommend doing this project when the temperature is below 55 degrees F in your work area. The chemical bond may not last as long. Make sure you read all the cautions about working in a well-ventilated area and skin contact precautions. After about 45 minutes to 1 hour (in a 70-degree room) remove the retaining tape, screws, and attachment nuts, and gently remove the flare.
Step 14: Apply Additional Epoxy to Front Flare
Run additional 3M glue around the outside edge of the support panel where it meets the flare. This fills in areas that may have been missed and gives the flare additional strength. Let dry 30 minutes at 70 degrees F.
Step 15: Apply Additional Epoxy to Rear Flare
Repeat this same procedure for the rear flare. These attachment nuts are accessed through the door opening vent on the lock pillar.
Step 16: Center Spoiler Fitment
The front center spoiler on 1970–1978 Firebirds is also critical for proper fitment of the outer wheel flares. The front center spoiler is really a larger under-bumper filler panel with the spoiler molded in. It rarely fits square and flush with the other parts. Therefore, some adjustment is usually required.
Step 17: Straighten Lower Tie-Bar
You can check front spoiler fitment in a couple of ways. The tabs on the front part of the panel slide into the front lower part of the bumper; the rear portion attaches to the lower tie-bar of the radiator support. Often drivers have hit parking blocks, curbs, or other road obstacles and have damaged the lower part of the radiator support. Straightening the lower tie-bar of the radiator support is not difficult. Usually, a large dead-blow or ball-peen hammer can be used to straighten the tie-bar so the spoiler panel can fit flush.
Step 18: Straighten Lower Tie-Bar (CONTINUED)
Large channel lock pliers can also be used to straighten the edges of the tie-bar so the panel sits flush.
Step 19: Adjust Spoiler Center Section
If the spoiler panel does not fit properly, you can use a heat gun to apply heat to the center section of the panel. Use a jack and blocks to make the panel conform better. Place a jackstand and wood blocks in the center of the spoiler panel. Apply pressure to the area so the panel moves into the correct position. Once the spoiler panel fits correctly, aim the heat gun in the same area as the wood blocks. Be careful to not get too close, as you do not want to overheat the panel. When the panel relaxes a bit, remove the heat gun. Let it cool for 5 to 10 minutes and then slowly remove the wood blocks and jackstand. If the panel is in the correct position, you are done. If not, repeat as needed. Then simply bolt the panel into place. This procedure is not damaging to the panel or the paint if you take your time.
Aligning the fender is important. It is a strong indicator of the quality of the restoration. Attention to detail separates a mediocre restoration from a top-quality restoration. A second-generation F-Body car with accurate and consistent body panel alignment presents well, is satisfying to the owner, and will be well judged in competition.
Many panels depend upon the proper alignment of the fenders. The hood, front bumper, and doors all rely on the fenders being in their proper position. Otherwise, at a minimum, the gaps are not straight and even. Worse case is when the panels interfere with each other and cause damage and impair their function.
Start the alignment process by checking the height of the door top edge compared to the top of the fender closest to the windshield. Add or remove shims as needed to the top cowl panel bolt to raise or lower the fender to meet the door top edge. Snug the bolts as you go.
Every time you make an adjustment, you need to check all other alignment points because the one change you make could possibly affect the other parts of the fender. If the fender needs to come out at the side upper portion to be on the same plane as the door, you may need to shim the fender bolt located in the door opening at the base of the A-pillar.
The wheelhouse provides stability to the fender and affects how the lower portion lines up. Leave the bolts slightly loose. Open the door slowly again to check the clearance to the fender.
Visually check the door-to-fender gap. Stand in front and look for a uniform and consistent line. Once you are satisfied with the rear portion of the fender, it is time to move to the front.
Install the bolts to the upper radiator support and the fender attachment bracket. Tighten the wheelhouse bolts and snug the front upper and lower fender bolts where they attach to the upper and lower tie bars of the radiator support.
Install the hood hinge and hood so that you can check the hood-to-fender gap. Loosen the upper and/or lower front bolts attached to the radiator support to move the fender out as necessary to achieve a consistent gap. If you feel you need to rotate the fender out at the top, you can loosen the top bolts and push it out. The same goes for loosening the lower bolts while the upper bolts stay snug so you can move the line around on the lower portion of the fender.
Aligning a panel can be very time-consuming and frustrating. Depending on your skill and patience (and some luck), you could spend several minutes to many hours getting that gap where you want it. It is not uncommon to have one part where you want the line to be only to find another line moved in the process. Once you finally have the panel where you want it, tighten all the bolts securely.
Step 1: Install Front Fender
Place the fender slightly forward of the wheel and slide it rearward until the rear part is resting on the cowl. Be careful not to hit the windshield or it may crack. If necessary, gently pull out the lower rear portion of the fender to clear the cowl.
Step 2: Install Front Fender (CONTINUED)
Secure the fender with bolts at the corners except where the fender attaches to the upper tie-bar of the radiator support. Only tighten the bolts enough so that the panel can still move slightly with minimal resistance. Place a larger size punch into the top of the radiator support upper tie-bar through the fender attachment hole. This allows the fender to move when aligning it.
Step 3: Check Body Panel Gaps
Inspect the door-to-fender top line as well as the door-to-fender gap. Because this was a fender previously removed from this car it aligns much easier. If you have a used fender, an NOS fender, or a reproduction fender the alignment technique may be more tedious and time consuming to achieve a good fit. The procedures are the same.
Step 4: Check Body Panel Gaps (CONTINUED)
Look down the side of the door and the fender where the two meet. Check how the side of the fender meets up to the door both on the upper and lower curves. Check the middle body contour line. All should be flush and even.
Run your hand over the door-to-fender gap to make sure that the two panels are on the same plane. This verifies what your eyes see.
Carefully open the door to verify that the door clears the fender with enough room to allow for body movement.
At the base of the back of the front fender, move the bottom in or out as needed so the lower portion of the fender and door are on the same plane. You may need to add or remove shims so the curve and clearances are correct. In this particular case I had removed excess filler from the lower portion of the fender and that required additional alignment for proper fit. Remember to check the bodyline to make sure it is not higher or lower than the door line. Snug the bolts once you have the rear portion situated.
Now that the fender is aligned the door to fender gap is consistent.
Written by Melvin Benzaquen and Posted with Permission of CarTechBooks