If you have ever installed fender welting, then your know how much trouble it can be. If your new to the hobby, this article will guide you through the process of installing fender and body welting. Even if you have been doing this for years, check out some of tricks that may help make the job easier.
First, you might ask your self "What the heck is welting and what is it used for"? The use of seam welting can be found as far back as the turn of the century. Welting was primarily uses in the construction of railroad passenger cars and horse drawn coaches . The use of welting was to provide for a squeak free weather seal between 2 flanged metal surfaces.
Early automotive construction methods utilized welting in their construction to provide squeak free, weather resistant seals between fenders and cowlings. As design methods improved the way sheet metal components were attached to automotive chassis, the need for welting faded.
The advent of new materials such as seam chalk and other products changed the way manufactures built cars and trucks. Some of the first welting used in automotive construction was made of canvas or of a heavy cotton material folded over heavy twine and sewn. The material was then covered in a lacquer based doping material, usually black or brown in color. Because this type of welting was constructed of natural materials, it did not hold up very well over time. Much of the new welting on the market today, is made of vinyl materials and stitched with mono-filament type threads. Another type of welting is made of polyurethane and is extruded in one piece.
The use of these new materials offers the hobbyist a second use for welting, accent. Many manufactures offer custom welting in designer colors that match or accent the vehicles body color. As shown here, this welting in made of polyurethane and tinted Black. It's solid construction makes is a little more difficult to install, but it has a longer life than most other materials on the market today. This photo show's the flanged area where the welting is to be applied.
Originally, the fender would have been attached loosely to the body with enough room to slip the welting in between the fender and body. Slits would have been cut into the material to allow for the fender bolts. The fender is then tightened. The lacquer covering of the original welting was tacky enough to hole the welting in place while the fender was tightened.
Today, if you were to use the same method, you would have problem. The vinyl and polyurethane materials are slick, making them very hard to keep in place during installation. To start our project, we measured and cut a piece of welting. We added about 6" onto our measurement for positioning of the welting later on. With our piece cut to length, we then notched the welting to match our fender radius.This was done by cutting triangle piece from the welting to the bead.
This photo shows the radius notching and the cool tool used to do the job. If for some reason you haven't seen this tool yet, Sears is the place to get one. Once, the notches had been cut, we test fit our work on the fender radius to see if more notching was needed. The spacing used here will work for just about any radius. Straight sections only need trimming at the bolt holes. They can be trimmed out now or after the welting has been attached to the fender. With our piece trimmed and test fit, we moved on.
Shown in this photo are the 3M #90 High Strength Adhesive that we used to attach the welting to the fender and some thinner for clean up. The best type of thinner for this job is a medium temperature lacquer thinner. This allows for clean up of the adhesive, but allows the thinner to evaporate before any damage is done to the finish. Wipe off any excess adhesive fast and don't rub for too long. Quick, wet wipes pickup the adhesive and allows the thinner to fast off quickly. Apply the spray adhesive to both the fender flange and the welting.
Keep a cloth with thinner ready in case you miss. The 3M spray head is adjustable to spray pattern tight enough not to make a mess. Test your spray pattern before you start. This will eliminate surprises. One or two passes is enough for both pieces. Be careful not to pile up the adhesive as you spray. A thin coat is what you are trying to achieve. Allow a 1-2 minutes for the adhesives to tack up and then apply the welting to the fender. Keep the welting bead flush with the top of the fender as you apply the welting. Allow the adhesive to dry for 10 - 20 minutes before attach the fender to the body.
To start our project, we measured and cut a piece of welting. We added about 6" onto our measurement for positioning of the welting later on. With our piece cut to length, we then notched the welting to match our fender radius. This was done by cutting triangle piece from the welting to the bead.
This photo shows the radius notching and the cool tool used to do the job. If for some reason you haven't seen this tool yet, Sears is the place to get one. Once, the notches had been cut, we test fit our work on the fender radius to see if more notching was needed. The spacing used here will work for just about any radius. Straight sections only need trimming at the bolt holes. They can be trimmed out now or after the welting has been attached to the fender.
These 2 photos show the welting applied to the fender. The first is right after the welting was applied. The second photo show the same area after clean up. You really do not want any adhesive on the body side of the welting. This would make positioning of the fender difficult. This photo below, shows the finished results. - CTS