Research indicates that people make up their mind in seconds whether they will like your work. In sales, a customer will make this decision in the first 45 seconds, so if the fit and finish is not good as the customer approaches the vehicle, they will not be satisfied. A vehicle is checked at every point of repair to discover and repair a poor fit because fit and finish remains one of the most critical parts of the repair.
Despite its importance, the task of replacing bolted-on parts often is given to the most junior worker in the shop – sometimes without even the simplest guidelines as to what is considered correct for that make and model, because the shop expects the new hire to know. But the many evaluation details take practice and experience. You might notice that as a seasoned worker walks around a vehicle he or she will instinctively look for things such as gaps, positive and negative flushness, and opening and closing effort. This technician will question if the misalignment extends past just the bolted-on parts into a structural area and therefore needs structural alignment, if the fender is hit by the door as it opens, for example, and if the undamaged side is truly undamaged. A telltale sign that a door may have been damaged by a fender hitting it is paint damage on the door's edge. If found, expect that the door may need adjusting along with the new fender. All these items should have been caught and noted in the damage report, but sometimes these details slip by. If you expect a good fit, these details need to be evaluated. For those who have been in the collision repair industry for awhile the thought of checking a service manual for the proper gap may not be what first comes to mind. That's because in the recent past this type of information would not have been in the manual; even today not all gaps will be available, but many manuals do now have them and can be checked easily from your computer, or even from a smart phone.
Removing damaged parts
Even before a part is removed from the vehicle, taking a quick walk around is very helpful. Check the undamaged areas of the vehicle for gap size and uniformity (Figs. 2 & 3), flatness — either negative or positive, and ease of opening on the undamaged parts. These areas should act as a reference for replacement parts. A homemade gap gage can be made by using a paint stick and adding tape to it to match the undamaged side's gap (Fig. 4). Use a flat hand or a credit card to check for positive or negative flushness (Fig 5). The doors and hood, hatch, and other openings should be operated and checked for smoothness or misalignment, all of which should be checked before the old damaged part is removed. If additional damage is noted, a supplement should be prepared.As the old part is disassembled, the fasteners should be bagged and tagged to help with reassembly. Replacements for fasteners that are damaged should be ordered as the vehicle is disassembled, when there is sufficient time to get new ones in before assembly. If any unusual wire routing or attachments are noted, such as how many shims were used, take a quick phone photo (Fig. 6) so you can have it for reference when reassembling. You may be tempted to throw the bolts in your toolbox or workbench, knowing that you will remember how to put a simple replacement part back on. But as time passes, things can get lost or misplaced, and memory fades rapidly — so a tagged bag of parts and a photo will come in handy.
Checking the gaps
During the initial inspection, the vehicle should be checked first for structural damage. Even in minor collisions a vehicle's shape can be misaligned. To visually check this, all the gaps should be checked to determine if they are consistent over the entire vehicle. Gaps generally are from 2 to 8 millimeters, with steel panels having the smallest gaps and plastic and aluminum panels needing more room for terminal expansion. Some shops have the estimator or shop foreman mark the vehicle with "R&R" (Fig. 7) to speed up the entire process.Opening and closing effort
The gaps on all doors, hoods, and deck lids should be even on all sides, and they should open and close with ease. If they bind, it means there may be structural or alignment problems. Doors should smoothly align and close over the striker plate without effort and without needing to be raised to close. On older vehicles, the hinges also should be checked for bushing wear, which is likely not a result of a collision.Flushness
Not all panels are mounted flush. In fact, many manufacturers recommend a slight positive flush mount (0-2 mm) for forward parts such as fenders (Fig 8) to help with wind noise and moisture leaks. As the wind passes over the forward mounted parts, it does not cause a turbulence or noise as it hits the next panel. Also, some fenders must be mounted a bit positive so that as the door opens, it will clear the fender. Often in even minor collisions, as the fender is moved back slightly the now-narrowed gap renders the door inoperable. As the occupant tries to get out and force is applied, the fender incurs more damage.Misalignments
If structural misalignment is suspected, measure the car to determine if corrections are needed before trying to fit the new part. Even with adjustments built into bolted-on parts – such as elongated holes (Fig 9) for forward and aft movement or large square holes (Fig 10) for movement forward and aft as well as inward and out – a structural misalignment, however slight, will make it impossible to align new parts.Types of adjustments vary, such as slotted or elongated holes, large square holes, J clips (Fig 11), shims (Fig 12), and adjustment stops. They are used to fine-tune vehicle alignment as new parts are assembled.
Attaching the new part
Once the vehicle is checked for proper structural alignment and the adjacent panels are checked and protected from damage (Fig 13), the new part can be dry-fitted. This step becomes important if the shop paints the parts off the vehicle then assembles the completed work. Once the part is sent to paint, when it comes back its attachment must be easy and without binding and scraping, so as not to damage the fresh paint.When checking alignment the old attachment marks can help. If the new part is put in place, it is likely that it should be attached where the previous part was placed (Fig 14). When aligning a new part, start the bolts loosely in their holes; then tighten them, starting where the vehicle is stationary, such as at the rocker, where there are now moveable parts. Then move up to the A-pillar, where the door may or may not be aligned correctly. Next, move down to the front and tighten the bolts at the front by the hood.
Note that the bolts are only lightly tightened (except for the rocker bolt) because it may be necessary to loosen them and adjust the gaps and flushness as all the pieces come together. When fitting large parts such as hoods get a fellow technician to help as they are first put in place (Fig 15); you can fine-tune them by yourself later.
With the new panels now in place and the mounting bolts lightly tightened, you can now begin the fine-tuning. Start where the adjacent panels are stationary, moving to where there are a number of movable panels, such as the core support, where fenders, header, and hood all may need to be aligned. By aligning the simplest ones first, it is likely that the more difficult ones will be easier. Check gaps, flushness, and ease of operations. When the alignment is complete, all the bolts should be final tightened.
Though the explanation here is for a fender, all bolted-on parts should be fitted from an area where it is least difficult to align. Stationary parts provide a starting point; progress to areas where multiple movable parts come together. Give special attention to openings such as doors, hood, and deck lid. When fitting an opening, the striker or latch should be removed and the part fitted before the latch is adjusted. That is, the part should be adjusted to the opening, with the latch being adjusted to the fitted part. If the latch is in place as the opening adjustments are attempted, it is much more difficult to complete. Technicians doing it that way have been known to struggle for hours before final adjustments are completed.
Tech tips to remember
1. Verify and inspect new part.
2. Protect adjacent parts.
3. Dry-fit before sending to paint.
4. First fit from stationary adjacent part, then forward and rearward, inward and outward, and finally upward and downward.
5. Use the undamaged side as reference.
6. Use old location marks as references.
7. Remove striker or latches before fitting openings.
8. Use a gauge (paint stick is OK) to check side-to-side gaps.
9. Sight down the gaps for evenness (rockers, hood, etc.).
10. Don't final tighten the fasteners until all adjustments are completed.Controversial techniques
- Using a floor jack to get door-fender gaps. Though unibody vehicles are flexible and may sag when a fender is unbolted, using a floor jack under the fender rocker to flex the upper door fender gap or under the bumper mount to tighten the gap may be a mistake. If a vehicle is resting on its suspension and gaps are not even, there may be structural damage that should be corrected before fitting the fender.
- Jacking the core forward to get proper forward fender adjustment may also be a sign of structural misalignment, and measurement may be necessary.
- n If parts must be forced to obtain alignment, something is wrong. Look for what is causing the difficulty and correct it. If force is used and the vehicle is subjected to normal road vibrations, all of your hard work may be lost.
