|April 16, 2001
Alloy Wheel Repair: Scratched, Bent and Maybe Even Cracked Wheels Can Be Saved
A set of large alloy wheels can make a significant difference in a car, with both improved handling and a more sporting appearance. Because of this, enthusiasts have been upgrading their cars to larger wheels for years, while replacing basic steel wheels and hubcaps was a great way to set one's car apart from every other one on the road. More recently, carmakers have begun to embrace consumers' yearnings for things more sporting and have begun to equip such everyday vehicles as family sedans, compact cars and even stationwagons with large-diameter alloy wheels.
While providing the common driver with a much more exciting relationship with their vehicle, the fitment of large alloys to these more utilitarian automotive applications has created a whole new set of problems.
Bent, curbed or damaged wheels are no new occurrence for enthusiasts, though the prevalence of alloys, and larger ones at that, on heavier automobiles has made such problems much more common for the common driver.
Replacement of these damaged wheels, whether by the dealer or through the local performance shop, can be an expensive process. With that in mind, the spotlight begins to fall on the art of alloy wheel repair. Small companies throughout the country advertise their specialty in the repair of wheels. Like any industry, there is a wide range of skill, and it is important to find reputable shops that provide quality workmanship.
One of the better-known wheel repair businesses in the country is Wheel Collision Center (WCC) of Bath, PA. With one of the foremost wheel repair facilities and wheel sourcing networks, a visit to WCC for a look into the practice of wheel repair and specifically their process provided an enlightening view into the pitfalls of large-diameter wheel ownership and how to combat them.
WCC makes use of a their own patented and guaranteed process that claims to return bent, scraped and in some cases, cracked wheels back to their original factory specifications. The process, backed by 2 ½ years of metallurgy testing at Lehigh University's Materials Research department, is a much more affordable one than sourcing new wheels for replacement.
In addition to repairing wheels, WCC offers some other unique services as well. With their own stock of thousands of refinished wheels, in addition to a wide network of sources, WCC can sell or replace wheels and even exchange wheels using their Core Exchange Program.
With the capabilities they have on tap, WCC can also customize a set of wheels to the owner's specification. Polishing, like wheels on the Audi A8, and chroming are two popular options they can offer, in addition to just about any shade or color of painted finish. Repairing rare or out of production wheels that are hard to find and replace is another service offered by WCC.
Over the years, WCC has developed a specific process that all wheels go through while being repaired or refinished in their shop. The meticulousness of this process is representative of their workmanship and helps to exhibit each facet of the repair procedure.
When the wheel is delivered to WCC, either dropped off by the owner, shipped in or picked up within their Southeastern PA and New Jersey pickup area, a work order is generated for each individual wheel detailing the customer's information and any special instructions attributable to the job. Each wheel is assigned its own unique work order number that is engraved on the inside of the rim just below the valve stem so that WCC may track exactly what has been done to the wheel in its history with them. This engraved number also makes it much easier to track one wheel within the thousands of wheels in their inventory and to track it during the repair process.
Once identified, each wheel is washed thoroughly to remove all brake dust that could be hiding additional scratches, gouges or cracks. WCC makes use of a pressure washer system shooting the wheels with an acid-based cleaning compound that is diluted so as not to damage the existing finish.
This is a particularly tricky part of the process because brake dust removal is absolutely essential to determining the level of damage to a wheel, but at the same time wheels that have a polished or anodized finish can become damaged if the wrong washing compound is used. For instance, two-piece wheels with a bright lip that is not chromed is typically an anodized finish. Anodization is performed with a chemical treatment to the lip that prevents it from oxidizing or corroding and it is very hard to see. Were the wrong cleaners or acid used on such a finish, streaking will appear on the wheel surface.
Once thoroughly cleaned, a complete inspection of the wheels is in order. Each wheel is inspected for radial and lateral runout.
Radial runout is up and down, and WCC measures to see just how much the wheel is out of true through the use of a micrometer gauge that measures to a thousandth of an inch. If a wheel has five thousandths of an inch radial runout, this means that you could put a dial indicator on the wheel and then spun the wheel, the distance the wheel traveled up and down while spinning would be five thousandths of an inch.
Lateral runout, on the other hand, is how much the damaged wheel will wobble from side to side. On some of the larger diameter wheels, subjected to a hard pothole hit, the wheel will be bent up and, if hit hard enough, it will bend and twist the spokes. When the plane that would be across the outer lips is no longer parallel to the mounting pad, this is lateral runout.
Lateral runout is repairable to a certain extent, but this is the hardest type of bend to repair. It also happens to be the most deceptive, because while a wheel may look like it only has minor rim damage, it can actually be fairly significant and not easily seen to the naked eye unless the wheel is spinning. This is especially common on the newer front-wheel-drive cars, where much of the force is cantilevered to the back.
The next point of inspection is for alloy defects such as curb scrapes and cracks. WCC always recommends that the tires be removed because many times the entirety of the damage cannot be seen until the tire has been pulled off.
Cracks are of particular importance, because they are the single most common type of damage that can leave a wheel "beyond repair". When a wheel bends near the base of a spoke, haze marks in the finish can sometimes be seen and are indicative of stress caused to the wheel. If the base of a spoke stresses the alloy, the wheel will either start to crack or be in clear danger of cracking.
Should a crack appear near the base of a spoke, WCC considers the wheel to be irreparable. While the gage of metal around the spoke is thicker and it would be possible to grind out and weld the surface, the proper repair would require cutting out the stressed area, welding the wheel and the finished product would not stand up to WCC's strength criteria.
Another location where cracks may occur that WCC will not repair is near the lug area. This is also irreparable for safety reasons.
The most common place for crack repair is the inner lip of the wheel away from the spokes. If a crack is smaller in size, this type of damage is usually salvageable.
Cracks such as these are particularly common on chrome-plated wheels, where the chroming process tends to render the wheel more brittle than a standard-finish wheel. Sometimes, if a chrome wheel is bent severely, the chrome has to be removed because there can be cracks underneath the chrome as well.
In the case of a cracked chrome wheel, WCC will grind the chrome out and re-weld it, though this is a more difficult process. WCC can also strip the chrome, repair the wheel and then re-chrome the wheel, using an independent California-based chroming shop that has proven to offer the quality levels that they prefer.
Finally, an inspection for finish defects is performed that searches out poor paint finish or additional scuffs and scratches.
Once fully inspected, all information is added to the wheel's work order. With that completed WCC confirms the cost of the work with the customer and also remark on other items that might be involved such as valve stem types, tire mounting and any other details. Once approved, work begins.
If the wheel is in need of refinishing, the wheel is first stripped using acrylic media that is essentially plastic sand. The wheel is placed in a blast cabinet that the media is circulated through, removing the finish without removing metal.
The acrylic medium is superior to the more commonly used steel shot or metal oxide. Though the latter remove the finish more quickly and are cheaper to use, the steel shot and metal oxide also rough up the surface and tear away some of the metal.
The next step in the process is bulk straightening. This step removes the majority of the bending out of the wheel and the bulk of the side-to-side wobble.
After bulk straightening, welding is performed to rebuild the outer lip or repair any scrapes or cracks that may need repair. WCC uses a tig welding process where they match the base alloy with the weld alloy. The weld is then ground and renders the wheel back to its original configuration.
With all welding performed, the wheel is sent off to final truing that brings the wheel back by fixing the minute bends or wobbles. WCC typically returns the wheel to 5 to 10/1000th of an inch, where factory tolerances are typically 15/1,000th of an inch radial runout. For comparison, 25/1000 of an inch roughly what can be detected by the eye.
Once the wheel is repaired and true, it is finally time to refinish, re-machine or re-polish. WCC makes use of a computer colormatching system to match the shades of the factory paint finish. If the color is not on file, the painter can also match by eye if need be. WCC can also deliver a custom finish that is white, anthracite, and colormatched to the car or whatever the owner prescribes, and do so at no extra charge.
WCC backs their wheel finishes with a limited lifetime warranty. They assure that the wheel will be free of material defect. While this warranty does not cover post-repair wheel scraping or damage to the finish due to the use of improper cleaning chemicals, it does cover discoloration, fade or peel for no reason.
If the wheel has a machined finish, it is put on a lathe. WCC has a wide array of patterns for certain wheels that are used once the wheel is finished to add the machined patterns.
Upon completion, each wheel is then subject to a quality check. It is examined for runout and the finish is checked for dirt or dust in the paint, unevenness or orange peel. If everything checks out, the wheel is now ready for tire mounting or delivery.
WCC can also mount tires. This is important because they can mount low profile tires without damaging the wheel. In addition, some wheels are harder to track than others and it is not uncommon for wheel mounting facilities to damage a wheel during tire installation.
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