Tuesday, 31 July 2007 10:00

Making aftermarket parts work for your project

Written by Rich Evans

If you are repairing an older vehicle or restoring a classic car, it is not always possible to obtain an OEM part or the cost may be prohibitive. This is where aftermarket parts can really help a lot. As you know, OEM parts are those made by the original manufacturer of the parts your vehicle came with. Aftermarket parts include everything outside of that – made by an independent manufacturer who intended the part to work the same way as the original.

The beauty of aftermarket parts is that they are often less expensive than OEM parts. However, the downside is that, although there are plenty of good aftermarket manufacturers with quality products, there are parts out there that are just not up to the quality of the original. So what do you do when you have no choice but to make that aftermarket part work.

This turned out to be the case when installing a set of aftermarket front and rear bumper valences on a ‘53 Chevy pick-up. Immediately upon seeing the parts, it was obvious that they were not going to go straight from the box to paint and then install. In fact, the mounting brackets only had a couple of spot welds that broke immediately during mock-up.

First step

After removing the front and rear bumpers, I mocked up the front and rear valences to show me the fit I had to work with. It also demonstrated the need to reinforce the mounting points of the aftermarket valence. This is done by either TIG or MIG welding the joints of the mounting brackets. Personally, I prefer TIG welding, because there is less grinding involved afterward and it produces a stronger weld.

Next steps

After reinforcing the mounting brackets, I used a one-quarter-inch rod for the rear valence on both the left and right sides. I pre-bent the rods to fit the inside of both sides of the valence. After placing them inside, they were welded in to give the valence a “frenched” look. After finishing with the rear valence, I performed the same operation on the front valence.

Next, I used a long block and lightly sanded the valences to find the high and low spots. Using a hammer and dolly from Martin Hammers, I smoothed everything out. Martin hammers are my tools of choice with their time-tested good balance, and proper weight and clearances to speed and simplify repairs. Martin Hammers are forged from special alloy steel. Handles are of tough second growth hickory and fiberglass shaft with cushion grips. (www.martintoolandforge.com)

After this, I ground off all the primer that came with the parts so that the filler could adhere better to each piece. With these particular valences there was a little step at the bottom of each part, so I used tape to keep the edges of the filler clean and save some work when it came to sanding.

After welding, grinding, and applying the filler, the parts were blocked down with 36 and then 80 grit sandpaper using a long block. Some epoxy primer sealer was sprayed next, followed with some PCL Polyprimer. It’s important not to try and use the epoxy primers as filler, because it is only going to make a mess and ultimately create more problems. So don’t build-up. I used three coats of Polyprimer. Allow 30 minutes to an hour of dry time, depending on the temperature and humidity.

Moving on, the pieces were blocked down with 80 grit and then skim-coated with a black guide coat to determine the high and low spots of the filler. Next, we blocked with 150 grit sand paper and sprayed another quick black guide coat. Finally, all the repaired areas were wet sanded with 400 grit wet sandpaper.

At long last – paint

With the prep work finished, it was time to finally spray some paint on the valences, starting with a reduced down 10% mixture of non-sanding epoxy primer for a sealer – using one part primer, one part catalyst, and 2 parts DT885 reducer. After the sealer dried, I sprayed three coats of base coat and then three coats of clear. With smaller parts, it’s easier to slick out the clear to save a little time and not have to color sand and buff later. But if the parts don’t come out as clean as you like, they can always be color sanded and buffed later.

With the parts dry and looking good, it’s time to install them. Since we had already mocked them up before prep, they slipped right in and there was nothing to do but tighten down the bolts.

In conclusion

Sometimes you don’t have any choice but to use an aftermarket part that might not be up to the required quality, possibly because the OEM parts are either too expensive or unavailable. This is often the case with older vehicles and classic cars. With a little extra effort and prep time, however, they can almost always be made to work. It all depends on the quality desired in repairing your ride.

Rich Evans, owner of Huntington Beach Bodyworks in Southern California, is an award winning painter and fabricator. Currently he is offering workshops at his facility so he can share his special techniques to other industry professionals. Visit www.huntingtonbeachbodyworks.com.