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.
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.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.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.
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.