Powder coating produces a surface which is very durable and tough. Surfaces which have been powder coated also tend to look good for years. Powder coated surfaces are easily cleaned, making it especially popular for that reason.
However, there is a growing list of indications that powder coating is not the cure-all that it might appear to be.
What I am going to say here is cautionary. I do not yet have enough data that would allow me to say definitively that a person never should use powder coating on his vintage vehicle.
I have watched powder coating become increasingly popular over the years—especially with the vintage vehicle crowd. Chassis, engine tins, rims and seat frames and more. What’s not to like about a coating which protects and which looks so good!
My first indication of a problem came when a company powder coated a friend’s VW engine tins, including the crank and generator pulleys. The coating company failed to mask the shaft orifices, resulting in reduced shaft hole diameters in both pulleys. The coating had to be reamed from orifices so that the pulleys could be installed. This was not an easy task! And, it is difficult to remove the coating without doing some damage to the steel during the process.
Shortly, we noticed that fan belts were being chewed up at a rapid rate. After examination, this deterioration was found to be due to the powder coating in the Vs of both pulleys. Powder coating is not a paint—it often is described as “plastic”. Powder coatings are based on polymer resin systems. Under certain conditions, such as the chafing of the V belt in our illustration, enough friction can result to destroy the belt. In short order, my friend was replacing V belts, having to keep a keen eye to avoid getting caught with a destroyed belt. I rescued him on one occasion when he was caught out on the road at night in his Beetle.
The next time I heard about a powder coating problem was from the owner of a ’67 Beetle. Walter complained of stripped threads in the brake drums. At first he blamed the “cheap” Brazilian brake drums. But, the VW Community has been using Brazilian drums for many, many years without significant problems. Walter’s mechanic even blamed VW rims as being defective, which is unfounded, of course.
Then, it was revealed that Walter had had his rims powder coated.
An Internet search revealed a similar problem with powder-coated steel wheels on a particular model of farm machinery. The report talked about the need for metal-to-metal contact. The torquing of the securing bolts on powder coated surfaces, according to the report, “… is like using a plastic washer under the nut. Plastics creep under load and the nut will loosen”.
Walter and I discussed how he could rectify the problem with his rims. He used a Dremel tool fitted with a grinder to remove the powder coating. This allowed the lug bolt shoulders to torque against raw metal. Later, Walter wrote this: “Since we last spoke I did a more thorough job of removing the powder coating from the bolt holes using a power drill and conical grinder. This was a definite improvement over the Dremel I used first. I then took several trips of 40+ miles, each time following up with a check of the bolts with a torque wrench. So far there has been no loosening of the bolts.”
Not long following Walter’s incident, I received notice from a second person who had a wheel come completely off his 1962 Convertible Beetle. When I asked if the rims had been powder coated, the immediate and emphatic reply was “Yes”. The owner discovered that lug bolts on the other wheels also had loosened. In a follow-up message, the owner revealed that he had removed all wheels and had removed the powder coating where each lug bolt seats.
With these cases under my belt, I decided to interview a powder coating expert. The owner of the company took time to explain the process. He showed me special tape which is used to cover areas where powder coating should not be applied. He also explained that bolt holes, for example, should be plugged so that threads would not be compromised with the coating. He showed me special plugs for the purpose. He indicated that a knowledgeable powder coating company will take necessary precautions to protect areas of concern.
The same day, I spoke with a professional who owns a Volkswagen Formula V fabrication and machine shop. He told me of further concerns about the use of powder coating on vintage vehicles. Since each part which has been coated must pass through an oven during the process, certain parts, such as bearings, bushings, rubber parts, etc., must be removed in order that they not be damaged. Temperatures can reach 400 degreesF and higher, depending upon the application.
This professional told me that VW front axle beams are especially vulnerable to the heating process. He said that the bushings can loosen, resulting in the need to machine special bushings with set screws to hold them in place.
He then told me that should there be a necessary repair to a powder coated chassis, it is very difficult to remove the coating so that welding can be accomplished.
Then, he opened his phone to show me photos of a nice racing vehicle. He told me that the wheels had been powder coated. This, he explained, has resulted in the need for repeated re-torquing of the lug bolts because they loosen constantly.
Many of us are familiar with grounding problems following a repaint. Grounding areas must be cleaned during reassembly so that lights, especially, and other electrical functions will operate properly. Proper grounding can become complicated following the powder coating of a chassis.
There is nothing like painting for preserving vehicles. Paint easily can be removed and reapplied. All types of coatings, other than paint, result in some difficulties. High-end restorations traditionally are done using paint rather than specialty coatings. There are reasons for this, as I have outlined above.
My conclusion is that powder coating should be used with caution, protecting parts where metal-to-metal contact is desirable, protecting threads, and protecting other sensitive parts. Be aware that other difficulties may arise down the road due to such coatings.
Above all—think SAFETY!
Good one, Jay! Lets also keep in mind what Chris Vallone just went through w/ that ’62 vert.
Thanks for this information! No powder coat on my Bug…
Hello, Dave. Thanks for reading the article. We must educate ourselves–then we can make wise choices. Coatings have been especially pertinent to me because for almost 30 years, I was a painting contractor. I encountered many situations over the years and had to make informed decisions before embarking on a particular job. Our vintage vehicles pose some “interesting” coatings situations which require our studied attention. We want our cars to look good, perform well and to withstand the rigors of the road. jay
If you are restoring your Beetle to drive it daily/often, powder coating can be invaluable. As noted, it is important to use a shop that knows what they are doing. Properly done, the finished parts can last a lifetime even used daily. I restored my ’79 vert in ’94. The car has over 260,000 miles and I have never experienced issues like those stated above [wheels, tin, suspension parts, seat frames, top frames etc]. My wife’s ’79 bus, which I restored five years ago has had wheels and engine parts powder coated with no issues, and my ’69, which I’ve owned since 2000, has also had numerous parts powder coated with no issues either. Stepping outside the VW universe you’ll find powder coating in many industrial and commercial cases. One example I’m sure you are familiar with is Harley Davidson. They have been powder coating their frames and many of their parts for decades. If powder coating was a problematic I’m sure it’s uses wouldn’t be as wide spread. The key take away here is using a reputable shop, masking areas you don’t want powder coated, and if threads get accidentally coated, a tap and die set will clean those trouble spots easily.
Good feedback, Jeff.
Hello, Jeffrey…Thank you for your comments. When I wrote the Article, I knew that it would stir discussion.–some favorable and some to the contrary. However, I could not ignore reports of problems.
With the discussion introduced to the VW Community, people can make intelligent, informed choices. And, as I say in my Article–it is a “cautionary article”. There definitely are problems–people just have to make careful choices both in the shops which they use and in how they instruct shops to do the work which they need. jay
The only pieces I have had powder-coated are my fan housing and rear engine tin that I snagged off the internet. Mostly I just needed the shop to bead-blasted them but I opted for black powder coating as well. They came out well and still look very nice despite the inevitable dings, scratches, and other indignities one encounters trying to get the engine back inside. I’ve had no trouble with things coming loose. I think it does depend on the part. Seat frames, engine tin – these seem like worthy, low-risk, candidates for powder coating.
Hi, Stephen–I couldn’t agree with you more. Making informed choices and asking questions when having our vehicles serviced is of utmost importance. I think that a lot of us fail to have a meeting-of-the-minds when having work done to our vintage vehicles. We just sort of “hope” for a good outcome. jay
A healthy conversation here is always welcome. :)
I had no idea there were so many problems with this type of coating…old school paint for me, just like the Germans intended!!
Hello, Todd…I believe that part of the problems with powder coating lie with the lack of communication between shop and customer. However, enough significant issues are surfacing for each of us to seriously consider before just jumping onto the powder coat wagon. One of the issues revolves around what to do if powder coating needs to be removed–for any reason. Powder coating is extremely difficult to remove. Paint, on the other hand, can be removed easily and surfaces can be recoated at will. I talked with a pair of vehicle restoration specialists concerning this factor. Enjoy your ’67 Beetle, Todd! jay
Great article. Thanks Jay. After reading NO power coating on our 67 BUG!
Hello, Frank…it’s good to hear from you! Some of the input about powder coatings took me by surprise. That’s why I wanted to find some answers. As I say in the article, more information needs to
be accumulated in order to give more than a cautionary statement. But I think that we will get some good input here. That’s my desire. Happy Motoring, Frank! jay
Jay I was literally getting quotes to have my rims powder coated this winter. Your article is an awakening! Thank you! Do you have any reservations using a chassis saver like POR15 to paint the rims instead of a powder coat? Assuming of course you use extreme caution not to paint over any metal to metal contact surfaces as your article describes. Thx!
Hello, Gavin…I hope that you and Mary are enjoying the Michigan Summer! Rims can be powder coated but the lug bolt openings should be protected (in my opinion) so that the shoulders of the lugs rest on metal and not on a plastic coating. For me, though, one of the problems which I have with powder coating is its permanence. While that seems to be a plus, if ever there came a time when it needed to be removed, know that powder coating is extremely difficult to remove. Gavin–do some research on POR 15 to see if this is what you need for your rims. Speak to a POR 15 representative to learn its properties and its uses. Maybe you need only to have the rims cleaned and painted. If you do use POR 15, you still will need to paint the rims with the proper top-coating and colors. Maybe the restoration people there at Hagerty will have some good counsel. jay
Folks…I just received (10/18/17) a note from Walter (see above story). Walter reports that since he removed the powder coating from the lug bolt seats, he’s had no further recurrences of loosened lug bolts. In fact, he checks all of the lug bolts in order to verify that they remain properly torqued. Thank you, Walter, for keeping us informed–and safe! jay
Good Article. I was thinking about powder coating my wheels, pan, engine tin, etc on a rare VW I am about to restore. Not so much anymore. I knew about to be careful with the hole sizes and theads but didn’t even consider grounding points or the wheel lugs loosening. Once again, thanks for sharing such good info.
Folks….I just had a conversation with a long-time VW Master Mechanic who also has been helping VW FormulaVee Racing folks. He told me of one of his powder-coating experiences–that the rims can be so slick (from the powder-coating) that when brakes are applied, the tires continue to turn, slipping on the inside bead edge of the rim. I will add more information as it comes to me. jay
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