February 16, 2005

Damaged and broken wheels
by Jim Kerr

I picked up a new set of alloy wheels the other day from a local wheel repair shop. While there, the owner gave me a tour of the facilities and showed me the types of damaged wheels he sees all the time. Some can be repaired - some can be made to look like new, and some must be scrapped. Here are some tips to keep your wheels from becoming scrap and what to do if you do damage them.

It is usually cheaper to replace damaged steel wheels than repair them unless they are rare collector's items. Alloy wheels on the other hand, can cost several hundred dollars each and repairing them is often comparatively economical. The first step in repairing any wheel is assessing the type of damage it has.

Damage to wheels takes many forms. It might be only cosmetic, such as scratches on the outside surface or corrosion around the wheel weights. These wheels may only need the original finish removed, the wheel polished or machined on a lathe and a new finish applied. Many factory wheels have a clear coat paint finish on them and they should be treated with the same care that the paint on the rest of the vehicle receives. Some tire cleaning chemicals can damage the finish so cover the wheels if you spray any cleaner on the tires.

Installing wheel weights when tires are balanced can also damage the finish. The clip on the weight scratches the finish and allows moisture and brake dust to attack the alloy wheel. Many wheel weights are now coated to help prevent damage when they are installed. Stick-on weights can also be used and don't scratch the finish, but the adhesive is difficult to remove after the weights have been in place for long periods.

Many wheels are damaged by impacts. Bounce through that pothole. Cross that rough railway crossing at speed. Slide into a curb on an icy street. Get hit by another vehicle. If the wheel is bent around the hub so it wobbles, it can often be straightened. Wheel repair experts say that the alloy molecules have a memory and will return to their original configuration through the judicious use of hydraulic pressure or a little heat.

Sometimes a wheel breaks in an impact. If the bead flange area is broken, then the wheel can be welded up and re-machined if the broken area is not more than about 4 inches. If the break goes down into the central part of the wheel, then the wheel must be replaced although some shops will fill a hole (such as a bullet hole) if it is not cracked. Spokes and the centre hub will not be repaired if they are broken or cracked and the wheel must be replaced.

Hitting a pothole may bend the wheel. I looked at several current wheels and they are very light and thin. A light wheel provides a better ride but is not as strong. If you hit a big bump, have the wheels inspected for damage. A bent wheel will start to flex as you drive it and a small crack can spread down past the bead into the centre part of the rim. Then the wheel must be replaced.

Damaged lug nut holes can be repaired if the damage is minimal. The wheel's lug nut hole is machined and a thin steel insert is installed into the alloy wheel. Some wheels come with steel inserts even when new. Too much damage and the wheel must be replaced, so keep those lug nuts torqued correctly.

After a wheel is straightened or welded, it is re-machined. Many shops use computer controlled lathes that will take only a minimal cut off the wheel to clean it up. Then it goes to the refinish shop. Some wheels have an unfinished, machine finish. These wheels must be cleaned very often or corrosive brake dust will mar the aluminium alloy. Many wheels are painted. Matching the factory paint finish is sometimes difficult because the wheel manufacturer doesn't release the paint code. They want to sell a new wheel! Most wheel repair shops are able to match the paint fairly closely.

Some wheels have a baked powdercoat finish. It is more durable than paint but if damaged, the wheel must be re-machined to remove the finish and coat it again. Other wheels look like chrome. They are highly polished aluminum, often with a clear coat paint to protect them. Polishing a wheel to a chrome-like finish takes a lot of time, so repairs are more costly.

Repairing wheels isn't for the novice. It takes experience, some brute force, a knowledge of alloy metals, a little art and a lot of patience. Safety is a priority on any wheel repair. Wheel repair specialists can be found in most major cities and they are ready to keep your wheels looking good and running true.

Jim Kerr is a master automotive mechanic and teaches automotive technology. He has been writing automotive articles for fifteen years for newspapers and magazines in Canada and the United States, and is a member of the Automotive Journalist's Association of Canada (AJAC).

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